LCOV - code coverage report
Current view: top level - src/backend/postmaster - autovacuum.c (source / functions) Hit Total Coverage
Test: PostgreSQL 13devel Lines: 756 930 81.3 %
Date: 2019-09-22 08:06:49 Functions: 33 34 97.1 %
Legend: Lines: hit not hit

          Line data    Source code
       1             : /*-------------------------------------------------------------------------
       2             :  *
       3             :  * autovacuum.c
       4             :  *
       5             :  * PostgreSQL Integrated Autovacuum Daemon
       6             :  *
       7             :  * The autovacuum system is structured in two different kinds of processes: the
       8             :  * autovacuum launcher and the autovacuum worker.  The launcher is an
       9             :  * always-running process, started by the postmaster when the autovacuum GUC
      10             :  * parameter is set.  The launcher schedules autovacuum workers to be started
      11             :  * when appropriate.  The workers are the processes which execute the actual
      12             :  * vacuuming; they connect to a database as determined in the launcher, and
      13             :  * once connected they examine the catalogs to select the tables to vacuum.
      14             :  *
      15             :  * The autovacuum launcher cannot start the worker processes by itself,
      16             :  * because doing so would cause robustness issues (namely, failure to shut
      17             :  * them down on exceptional conditions, and also, since the launcher is
      18             :  * connected to shared memory and is thus subject to corruption there, it is
      19             :  * not as robust as the postmaster).  So it leaves that task to the postmaster.
      20             :  *
      21             :  * There is an autovacuum shared memory area, where the launcher stores
      22             :  * information about the database it wants vacuumed.  When it wants a new
      23             :  * worker to start, it sets a flag in shared memory and sends a signal to the
      24             :  * postmaster.  Then postmaster knows nothing more than it must start a worker;
      25             :  * so it forks a new child, which turns into a worker.  This new process
      26             :  * connects to shared memory, and there it can inspect the information that the
      27             :  * launcher has set up.
      28             :  *
      29             :  * If the fork() call fails in the postmaster, it sets a flag in the shared
      30             :  * memory area, and sends a signal to the launcher.  The launcher, upon
      31             :  * noticing the flag, can try starting the worker again by resending the
      32             :  * signal.  Note that the failure can only be transient (fork failure due to
      33             :  * high load, memory pressure, too many processes, etc); more permanent
      34             :  * problems, like failure to connect to a database, are detected later in the
      35             :  * worker and dealt with just by having the worker exit normally.  The launcher
      36             :  * will launch a new worker again later, per schedule.
      37             :  *
      38             :  * When the worker is done vacuuming it sends SIGUSR2 to the launcher.  The
      39             :  * launcher then wakes up and is able to launch another worker, if the schedule
      40             :  * is so tight that a new worker is needed immediately.  At this time the
      41             :  * launcher can also balance the settings for the various remaining workers'
      42             :  * cost-based vacuum delay feature.
      43             :  *
      44             :  * Note that there can be more than one worker in a database concurrently.
      45             :  * They will store the table they are currently vacuuming in shared memory, so
      46             :  * that other workers avoid being blocked waiting for the vacuum lock for that
      47             :  * table.  They will also reload the pgstats data just before vacuuming each
      48             :  * table, to avoid vacuuming a table that was just finished being vacuumed by
      49             :  * another worker and thus is no longer noted in shared memory.  However,
      50             :  * there is a window (caused by pgstat delay) on which a worker may choose a
      51             :  * table that was already vacuumed; this is a bug in the current design.
      52             :  *
      53             :  * Portions Copyright (c) 1996-2019, PostgreSQL Global Development Group
      54             :  * Portions Copyright (c) 1994, Regents of the University of California
      55             :  *
      56             :  *
      57             :  * IDENTIFICATION
      58             :  *    src/backend/postmaster/autovacuum.c
      59             :  *
      60             :  *-------------------------------------------------------------------------
      61             :  */
      62             : #include "postgres.h"
      63             : 
      64             : #include <signal.h>
      65             : #include <sys/time.h>
      66             : #include <unistd.h>
      67             : 
      68             : #include "access/heapam.h"
      69             : #include "access/htup_details.h"
      70             : #include "access/multixact.h"
      71             : #include "access/reloptions.h"
      72             : #include "access/tableam.h"
      73             : #include "access/transam.h"
      74             : #include "access/xact.h"
      75             : #include "catalog/dependency.h"
      76             : #include "catalog/namespace.h"
      77             : #include "catalog/pg_database.h"
      78             : #include "commands/dbcommands.h"
      79             : #include "commands/vacuum.h"
      80             : #include "lib/ilist.h"
      81             : #include "libpq/pqsignal.h"
      82             : #include "miscadmin.h"
      83             : #include "nodes/makefuncs.h"
      84             : #include "pgstat.h"
      85             : #include "postmaster/autovacuum.h"
      86             : #include "postmaster/fork_process.h"
      87             : #include "postmaster/postmaster.h"
      88             : #include "storage/bufmgr.h"
      89             : #include "storage/ipc.h"
      90             : #include "storage/latch.h"
      91             : #include "storage/lmgr.h"
      92             : #include "storage/pmsignal.h"
      93             : #include "storage/proc.h"
      94             : #include "storage/procsignal.h"
      95             : #include "storage/sinvaladt.h"
      96             : #include "storage/smgr.h"
      97             : #include "tcop/tcopprot.h"
      98             : #include "utils/fmgroids.h"
      99             : #include "utils/fmgrprotos.h"
     100             : #include "utils/lsyscache.h"
     101             : #include "utils/memutils.h"
     102             : #include "utils/ps_status.h"
     103             : #include "utils/rel.h"
     104             : #include "utils/snapmgr.h"
     105             : #include "utils/syscache.h"
     106             : #include "utils/timeout.h"
     107             : #include "utils/timestamp.h"
     108             : 
     109             : 
     110             : /*
     111             :  * GUC parameters
     112             :  */
     113             : bool        autovacuum_start_daemon = false;
     114             : int         autovacuum_max_workers;
     115             : int         autovacuum_work_mem = -1;
     116             : int         autovacuum_naptime;
     117             : int         autovacuum_vac_thresh;
     118             : double      autovacuum_vac_scale;
     119             : int         autovacuum_anl_thresh;
     120             : double      autovacuum_anl_scale;
     121             : int         autovacuum_freeze_max_age;
     122             : int         autovacuum_multixact_freeze_max_age;
     123             : 
     124             : double      autovacuum_vac_cost_delay;
     125             : int         autovacuum_vac_cost_limit;
     126             : 
     127             : int         Log_autovacuum_min_duration = -1;
     128             : 
     129             : /* how long to keep pgstat data in the launcher, in milliseconds */
     130             : #define STATS_READ_DELAY 1000
     131             : 
     132             : /* the minimum allowed time between two awakenings of the launcher */
     133             : #define MIN_AUTOVAC_SLEEPTIME 100.0 /* milliseconds */
     134             : #define MAX_AUTOVAC_SLEEPTIME 300   /* seconds */
     135             : 
     136             : /* Flags to tell if we are in an autovacuum process */
     137             : static bool am_autovacuum_launcher = false;
     138             : static bool am_autovacuum_worker = false;
     139             : 
     140             : /* Flags set by signal handlers */
     141             : static volatile sig_atomic_t got_SIGHUP = false;
     142             : static volatile sig_atomic_t got_SIGUSR2 = false;
     143             : static volatile sig_atomic_t got_SIGTERM = false;
     144             : 
     145             : /* Comparison points for determining whether freeze_max_age is exceeded */
     146             : static TransactionId recentXid;
     147             : static MultiXactId recentMulti;
     148             : 
     149             : /* Default freeze ages to use for autovacuum (varies by database) */
     150             : static int  default_freeze_min_age;
     151             : static int  default_freeze_table_age;
     152             : static int  default_multixact_freeze_min_age;
     153             : static int  default_multixact_freeze_table_age;
     154             : 
     155             : /* Memory context for long-lived data */
     156             : static MemoryContext AutovacMemCxt;
     157             : 
     158             : /* struct to keep track of databases in launcher */
     159             : typedef struct avl_dbase
     160             : {
     161             :     Oid         adl_datid;      /* hash key -- must be first */
     162             :     TimestampTz adl_next_worker;
     163             :     int         adl_score;
     164             :     dlist_node  adl_node;
     165             : } avl_dbase;
     166             : 
     167             : /* struct to keep track of databases in worker */
     168             : typedef struct avw_dbase
     169             : {
     170             :     Oid         adw_datid;
     171             :     char       *adw_name;
     172             :     TransactionId adw_frozenxid;
     173             :     MultiXactId adw_minmulti;
     174             :     PgStat_StatDBEntry *adw_entry;
     175             : } avw_dbase;
     176             : 
     177             : /* struct to keep track of tables to vacuum and/or analyze, in 1st pass */
     178             : typedef struct av_relation
     179             : {
     180             :     Oid         ar_toastrelid;  /* hash key - must be first */
     181             :     Oid         ar_relid;
     182             :     bool        ar_hasrelopts;
     183             :     AutoVacOpts ar_reloptions;  /* copy of AutoVacOpts from the main table's
     184             :                                  * reloptions, or NULL if none */
     185             : } av_relation;
     186             : 
     187             : /* struct to keep track of tables to vacuum and/or analyze, after rechecking */
     188             : typedef struct autovac_table
     189             : {
     190             :     Oid         at_relid;
     191             :     VacuumParams at_params;
     192             :     double      at_vacuum_cost_delay;
     193             :     int         at_vacuum_cost_limit;
     194             :     bool        at_dobalance;
     195             :     bool        at_sharedrel;
     196             :     char       *at_relname;
     197             :     char       *at_nspname;
     198             :     char       *at_datname;
     199             : } autovac_table;
     200             : 
     201             : /*-------------
     202             :  * This struct holds information about a single worker's whereabouts.  We keep
     203             :  * an array of these in shared memory, sized according to
     204             :  * autovacuum_max_workers.
     205             :  *
     206             :  * wi_links     entry into free list or running list
     207             :  * wi_dboid     OID of the database this worker is supposed to work on
     208             :  * wi_tableoid  OID of the table currently being vacuumed, if any
     209             :  * wi_sharedrel flag indicating whether table is marked relisshared
     210             :  * wi_proc      pointer to PGPROC of the running worker, NULL if not started
     211             :  * wi_launchtime Time at which this worker was launched
     212             :  * wi_cost_*    Vacuum cost-based delay parameters current in this worker
     213             :  *
     214             :  * All fields are protected by AutovacuumLock, except for wi_tableoid and
     215             :  * wi_sharedrel which are protected by AutovacuumScheduleLock (note these
     216             :  * two fields are read-only for everyone except that worker itself).
     217             :  *-------------
     218             :  */
     219             : typedef struct WorkerInfoData
     220             : {
     221             :     dlist_node  wi_links;
     222             :     Oid         wi_dboid;
     223             :     Oid         wi_tableoid;
     224             :     PGPROC     *wi_proc;
     225             :     TimestampTz wi_launchtime;
     226             :     bool        wi_dobalance;
     227             :     bool        wi_sharedrel;
     228             :     double      wi_cost_delay;
     229             :     int         wi_cost_limit;
     230             :     int         wi_cost_limit_base;
     231             : } WorkerInfoData;
     232             : 
     233             : typedef struct WorkerInfoData *WorkerInfo;
     234             : 
     235             : /*
     236             :  * Possible signals received by the launcher from remote processes.  These are
     237             :  * stored atomically in shared memory so that other processes can set them
     238             :  * without locking.
     239             :  */
     240             : typedef enum
     241             : {
     242             :     AutoVacForkFailed,          /* failed trying to start a worker */
     243             :     AutoVacRebalance,           /* rebalance the cost limits */
     244             :     AutoVacNumSignals           /* must be last */
     245             : }           AutoVacuumSignal;
     246             : 
     247             : /*
     248             :  * Autovacuum workitem array, stored in AutoVacuumShmem->av_workItems.  This
     249             :  * list is mostly protected by AutovacuumLock, except that if an item is
     250             :  * marked 'active' other processes must not modify the work-identifying
     251             :  * members.
     252             :  */
     253             : typedef struct AutoVacuumWorkItem
     254             : {
     255             :     AutoVacuumWorkItemType avw_type;
     256             :     bool        avw_used;       /* below data is valid */
     257             :     bool        avw_active;     /* being processed */
     258             :     Oid         avw_database;
     259             :     Oid         avw_relation;
     260             :     BlockNumber avw_blockNumber;
     261             : } AutoVacuumWorkItem;
     262             : 
     263             : #define NUM_WORKITEMS   256
     264             : 
     265             : /*-------------
     266             :  * The main autovacuum shmem struct.  On shared memory we store this main
     267             :  * struct and the array of WorkerInfo structs.  This struct keeps:
     268             :  *
     269             :  * av_signal        set by other processes to indicate various conditions
     270             :  * av_launcherpid   the PID of the autovacuum launcher
     271             :  * av_freeWorkers   the WorkerInfo freelist
     272             :  * av_runningWorkers the WorkerInfo non-free queue
     273             :  * av_startingWorker pointer to WorkerInfo currently being started (cleared by
     274             :  *                  the worker itself as soon as it's up and running)
     275             :  * av_workItems     work item array
     276             :  *
     277             :  * This struct is protected by AutovacuumLock, except for av_signal and parts
     278             :  * of the worker list (see above).
     279             :  *-------------
     280             :  */
     281             : typedef struct
     282             : {
     283             :     sig_atomic_t av_signal[AutoVacNumSignals];
     284             :     pid_t       av_launcherpid;
     285             :     dlist_head  av_freeWorkers;
     286             :     dlist_head  av_runningWorkers;
     287             :     WorkerInfo  av_startingWorker;
     288             :     AutoVacuumWorkItem av_workItems[NUM_WORKITEMS];
     289             : } AutoVacuumShmemStruct;
     290             : 
     291             : static AutoVacuumShmemStruct *AutoVacuumShmem;
     292             : 
     293             : /*
     294             :  * the database list (of avl_dbase elements) in the launcher, and the context
     295             :  * that contains it
     296             :  */
     297             : static dlist_head DatabaseList = DLIST_STATIC_INIT(DatabaseList);
     298             : static MemoryContext DatabaseListCxt = NULL;
     299             : 
     300             : /* Pointer to my own WorkerInfo, valid on each worker */
     301             : static WorkerInfo MyWorkerInfo = NULL;
     302             : 
     303             : /* PID of launcher, valid only in worker while shutting down */
     304             : int         AutovacuumLauncherPid = 0;
     305             : 
     306             : #ifdef EXEC_BACKEND
     307             : static pid_t avlauncher_forkexec(void);
     308             : static pid_t avworker_forkexec(void);
     309             : #endif
     310             : NON_EXEC_STATIC void AutoVacWorkerMain(int argc, char *argv[]) pg_attribute_noreturn();
     311             : NON_EXEC_STATIC void AutoVacLauncherMain(int argc, char *argv[]) pg_attribute_noreturn();
     312             : 
     313             : static Oid  do_start_worker(void);
     314             : static void launcher_determine_sleep(bool canlaunch, bool recursing,
     315             :                                      struct timeval *nap);
     316             : static void launch_worker(TimestampTz now);
     317             : static List *get_database_list(void);
     318             : static void rebuild_database_list(Oid newdb);
     319             : static int  db_comparator(const void *a, const void *b);
     320             : static void autovac_balance_cost(void);
     321             : 
     322             : static void do_autovacuum(void);
     323             : static void FreeWorkerInfo(int code, Datum arg);
     324             : 
     325             : static autovac_table *table_recheck_autovac(Oid relid, HTAB *table_toast_map,
     326             :                                             TupleDesc pg_class_desc,
     327             :                                             int effective_multixact_freeze_max_age);
     328             : static void relation_needs_vacanalyze(Oid relid, AutoVacOpts *relopts,
     329             :                                       Form_pg_class classForm,
     330             :                                       PgStat_StatTabEntry *tabentry,
     331             :                                       int effective_multixact_freeze_max_age,
     332             :                                       bool *dovacuum, bool *doanalyze, bool *wraparound);
     333             : 
     334             : static void autovacuum_do_vac_analyze(autovac_table *tab,
     335             :                                       BufferAccessStrategy bstrategy);
     336             : static AutoVacOpts *extract_autovac_opts(HeapTuple tup,
     337             :                                          TupleDesc pg_class_desc);
     338             : static PgStat_StatTabEntry *get_pgstat_tabentry_relid(Oid relid, bool isshared,
     339             :                                                       PgStat_StatDBEntry *shared,
     340             :                                                       PgStat_StatDBEntry *dbentry);
     341             : static void perform_work_item(AutoVacuumWorkItem *workitem);
     342             : static void autovac_report_activity(autovac_table *tab);
     343             : static void autovac_report_workitem(AutoVacuumWorkItem *workitem,
     344             :                                     const char *nspname, const char *relname);
     345             : static void av_sighup_handler(SIGNAL_ARGS);
     346             : static void avl_sigusr2_handler(SIGNAL_ARGS);
     347             : static void avl_sigterm_handler(SIGNAL_ARGS);
     348             : static void autovac_refresh_stats(void);
     349             : 
     350             : 
     351             : 
     352             : /********************************************************************
     353             :  *                    AUTOVACUUM LAUNCHER CODE
     354             :  ********************************************************************/
     355             : 
     356             : #ifdef EXEC_BACKEND
     357             : /*
     358             :  * forkexec routine for the autovacuum launcher process.
     359             :  *
     360             :  * Format up the arglist, then fork and exec.
     361             :  */
     362             : static pid_t
     363             : avlauncher_forkexec(void)
     364             : {
     365             :     char       *av[10];
     366             :     int         ac = 0;
     367             : 
     368             :     av[ac++] = "postgres";
     369             :     av[ac++] = "--forkavlauncher";
     370             :     av[ac++] = NULL;            /* filled in by postmaster_forkexec */
     371             :     av[ac] = NULL;
     372             : 
     373             :     Assert(ac < lengthof(av));
     374             : 
     375             :     return postmaster_forkexec(ac, av);
     376             : }
     377             : 
     378             : /*
     379             :  * We need this set from the outside, before InitProcess is called
     380             :  */
     381             : void
     382             : AutovacuumLauncherIAm(void)
     383             : {
     384             :     am_autovacuum_launcher = true;
     385             : }
     386             : #endif
     387             : 
     388             : /*
     389             :  * Main entry point for autovacuum launcher process, to be called from the
     390             :  * postmaster.
     391             :  */
     392             : int
     393         480 : StartAutoVacLauncher(void)
     394             : {
     395             :     pid_t       AutoVacPID;
     396             : 
     397             : #ifdef EXEC_BACKEND
     398             :     switch ((AutoVacPID = avlauncher_forkexec()))
     399             : #else
     400         480 :     switch ((AutoVacPID = fork_process()))
     401             : #endif
     402             :     {
     403             :         case -1:
     404           0 :             ereport(LOG,
     405             :                     (errmsg("could not fork autovacuum launcher process: %m")));
     406           0 :             return 0;
     407             : 
     408             : #ifndef EXEC_BACKEND
     409             :         case 0:
     410             :             /* in postmaster child ... */
     411         346 :             InitPostmasterChild();
     412             : 
     413             :             /* Close the postmaster's sockets */
     414         346 :             ClosePostmasterPorts(false);
     415             : 
     416         346 :             AutoVacLauncherMain(0, NULL);
     417             :             break;
     418             : #endif
     419             :         default:
     420         480 :             return (int) AutoVacPID;
     421             :     }
     422             : 
     423             :     /* shouldn't get here */
     424             :     return 0;
     425             : }
     426             : 
     427             : /*
     428             :  * Main loop for the autovacuum launcher process.
     429             :  */
     430             : NON_EXEC_STATIC void
     431         346 : AutoVacLauncherMain(int argc, char *argv[])
     432             : {
     433             :     sigjmp_buf  local_sigjmp_buf;
     434             : 
     435         346 :     am_autovacuum_launcher = true;
     436             : 
     437             :     /* Identify myself via ps */
     438         346 :     init_ps_display(pgstat_get_backend_desc(B_AUTOVAC_LAUNCHER), "", "", "");
     439             : 
     440         346 :     ereport(DEBUG1,
     441             :             (errmsg("autovacuum launcher started")));
     442             : 
     443         346 :     if (PostAuthDelay)
     444           0 :         pg_usleep(PostAuthDelay * 1000000L);
     445             : 
     446         346 :     SetProcessingMode(InitProcessing);
     447             : 
     448             :     /*
     449             :      * Set up signal handlers.  We operate on databases much like a regular
     450             :      * backend, so we use the same signal handling.  See equivalent code in
     451             :      * tcop/postgres.c.
     452             :      */
     453         346 :     pqsignal(SIGHUP, av_sighup_handler);
     454         346 :     pqsignal(SIGINT, StatementCancelHandler);
     455         346 :     pqsignal(SIGTERM, avl_sigterm_handler);
     456             : 
     457         346 :     pqsignal(SIGQUIT, quickdie);
     458         346 :     InitializeTimeouts();       /* establishes SIGALRM handler */
     459             : 
     460         346 :     pqsignal(SIGPIPE, SIG_IGN);
     461         346 :     pqsignal(SIGUSR1, procsignal_sigusr1_handler);
     462         346 :     pqsignal(SIGUSR2, avl_sigusr2_handler);
     463         346 :     pqsignal(SIGFPE, FloatExceptionHandler);
     464         346 :     pqsignal(SIGCHLD, SIG_DFL);
     465             : 
     466             :     /* Early initialization */
     467         346 :     BaseInit();
     468             : 
     469             :     /*
     470             :      * Create a per-backend PGPROC struct in shared memory, except in the
     471             :      * EXEC_BACKEND case where this was done in SubPostmasterMain. We must do
     472             :      * this before we can use LWLocks (and in the EXEC_BACKEND case we already
     473             :      * had to do some stuff with LWLocks).
     474             :      */
     475             : #ifndef EXEC_BACKEND
     476         346 :     InitProcess();
     477             : #endif
     478             : 
     479         346 :     InitPostgres(NULL, InvalidOid, NULL, InvalidOid, NULL, false);
     480             : 
     481         346 :     SetProcessingMode(NormalProcessing);
     482             : 
     483             :     /*
     484             :      * Create a memory context that we will do all our work in.  We do this so
     485             :      * that we can reset the context during error recovery and thereby avoid
     486             :      * possible memory leaks.
     487             :      */
     488         346 :     AutovacMemCxt = AllocSetContextCreate(TopMemoryContext,
     489             :                                           "Autovacuum Launcher",
     490             :                                           ALLOCSET_DEFAULT_SIZES);
     491         346 :     MemoryContextSwitchTo(AutovacMemCxt);
     492             : 
     493             :     /*
     494             :      * If an exception is encountered, processing resumes here.
     495             :      *
     496             :      * This code is a stripped down version of PostgresMain error recovery.
     497             :      */
     498         346 :     if (sigsetjmp(local_sigjmp_buf, 1) != 0)
     499             :     {
     500             :         /* since not using PG_TRY, must reset error stack by hand */
     501           0 :         error_context_stack = NULL;
     502             : 
     503             :         /* Prevents interrupts while cleaning up */
     504           0 :         HOLD_INTERRUPTS();
     505             : 
     506             :         /* Forget any pending QueryCancel or timeout request */
     507           0 :         disable_all_timeouts(false);
     508           0 :         QueryCancelPending = false; /* second to avoid race condition */
     509             : 
     510             :         /* Report the error to the server log */
     511           0 :         EmitErrorReport();
     512             : 
     513             :         /* Abort the current transaction in order to recover */
     514           0 :         AbortCurrentTransaction();
     515             : 
     516             :         /*
     517             :          * Release any other resources, for the case where we were not in a
     518             :          * transaction.
     519             :          */
     520           0 :         LWLockReleaseAll();
     521           0 :         pgstat_report_wait_end();
     522           0 :         AbortBufferIO();
     523           0 :         UnlockBuffers();
     524             :         /* this is probably dead code, but let's be safe: */
     525           0 :         if (AuxProcessResourceOwner)
     526           0 :             ReleaseAuxProcessResources(false);
     527           0 :         AtEOXact_Buffers(false);
     528           0 :         AtEOXact_SMgr();
     529           0 :         AtEOXact_Files(false);
     530           0 :         AtEOXact_HashTables(false);
     531             : 
     532             :         /*
     533             :          * Now return to normal top-level context and clear ErrorContext for
     534             :          * next time.
     535             :          */
     536           0 :         MemoryContextSwitchTo(AutovacMemCxt);
     537           0 :         FlushErrorState();
     538             : 
     539             :         /* Flush any leaked data in the top-level context */
     540           0 :         MemoryContextResetAndDeleteChildren(AutovacMemCxt);
     541             : 
     542             :         /* don't leave dangling pointers to freed memory */
     543           0 :         DatabaseListCxt = NULL;
     544           0 :         dlist_init(&DatabaseList);
     545             : 
     546             :         /*
     547             :          * Make sure pgstat also considers our stat data as gone.  Note: we
     548             :          * mustn't use autovac_refresh_stats here.
     549             :          */
     550           0 :         pgstat_clear_snapshot();
     551             : 
     552             :         /* Now we can allow interrupts again */
     553           0 :         RESUME_INTERRUPTS();
     554             : 
     555             :         /* if in shutdown mode, no need for anything further; just go away */
     556           0 :         if (got_SIGTERM)
     557           0 :             goto shutdown;
     558             : 
     559             :         /*
     560             :          * Sleep at least 1 second after any error.  We don't want to be
     561             :          * filling the error logs as fast as we can.
     562             :          */
     563           0 :         pg_usleep(1000000L);
     564             :     }
     565             : 
     566             :     /* We can now handle ereport(ERROR) */
     567         346 :     PG_exception_stack = &local_sigjmp_buf;
     568             : 
     569             :     /* must unblock signals before calling rebuild_database_list */
     570         346 :     PG_SETMASK(&UnBlockSig);
     571             : 
     572             :     /*
     573             :      * Set always-secure search path.  Launcher doesn't connect to a database,
     574             :      * so this has no effect.
     575             :      */
     576         346 :     SetConfigOption("search_path", "", PGC_SUSET, PGC_S_OVERRIDE);
     577             : 
     578             :     /*
     579             :      * Force zero_damaged_pages OFF in the autovac process, even if it is set
     580             :      * in postgresql.conf.  We don't really want such a dangerous option being
     581             :      * applied non-interactively.
     582             :      */
     583         346 :     SetConfigOption("zero_damaged_pages", "false", PGC_SUSET, PGC_S_OVERRIDE);
     584             : 
     585             :     /*
     586             :      * Force settable timeouts off to avoid letting these settings prevent
     587             :      * regular maintenance from being executed.
     588             :      */
     589         346 :     SetConfigOption("statement_timeout", "0", PGC_SUSET, PGC_S_OVERRIDE);
     590         346 :     SetConfigOption("lock_timeout", "0", PGC_SUSET, PGC_S_OVERRIDE);
     591         346 :     SetConfigOption("idle_in_transaction_session_timeout", "0",
     592             :                     PGC_SUSET, PGC_S_OVERRIDE);
     593             : 
     594             :     /*
     595             :      * Force default_transaction_isolation to READ COMMITTED.  We don't want
     596             :      * to pay the overhead of serializable mode, nor add any risk of causing
     597             :      * deadlocks or delaying other transactions.
     598             :      */
     599         346 :     SetConfigOption("default_transaction_isolation", "read committed",
     600             :                     PGC_SUSET, PGC_S_OVERRIDE);
     601             : 
     602             :     /*
     603             :      * In emergency mode, just start a worker (unless shutdown was requested)
     604             :      * and go away.
     605             :      */
     606         346 :     if (!AutoVacuumingActive())
     607             :     {
     608           0 :         if (!got_SIGTERM)
     609           0 :             do_start_worker();
     610           0 :         proc_exit(0);           /* done */
     611             :     }
     612             : 
     613         346 :     AutoVacuumShmem->av_launcherpid = MyProcPid;
     614             : 
     615             :     /*
     616             :      * Create the initial database list.  The invariant we want this list to
     617             :      * keep is that it's ordered by decreasing next_time.  As soon as an entry
     618             :      * is updated to a higher time, it will be moved to the front (which is
     619             :      * correct because the only operation is to add autovacuum_naptime to the
     620             :      * entry, and time always increases).
     621             :      */
     622         346 :     rebuild_database_list(InvalidOid);
     623             : 
     624             :     /* loop until shutdown request */
     625        2352 :     while (!got_SIGTERM)
     626             :     {
     627             :         struct timeval nap;
     628        2004 :         TimestampTz current_time = 0;
     629             :         bool        can_launch;
     630             : 
     631             :         /*
     632             :          * This loop is a bit different from the normal use of WaitLatch,
     633             :          * because we'd like to sleep before the first launch of a child
     634             :          * process.  So it's WaitLatch, then ResetLatch, then check for
     635             :          * wakening conditions.
     636             :          */
     637             : 
     638        4008 :         launcher_determine_sleep(!dlist_is_empty(&AutoVacuumShmem->av_freeWorkers),
     639        2004 :                                  false, &nap);
     640             : 
     641             :         /*
     642             :          * Wait until naptime expires or we get some type of signal (all the
     643             :          * signal handlers will wake us by calling SetLatch).
     644             :          */
     645        2004 :         (void) WaitLatch(MyLatch,
     646             :                          WL_LATCH_SET | WL_TIMEOUT | WL_EXIT_ON_PM_DEATH,
     647        2004 :                          (nap.tv_sec * 1000L) + (nap.tv_usec / 1000L),
     648             :                          WAIT_EVENT_AUTOVACUUM_MAIN);
     649             : 
     650        1998 :         ResetLatch(MyLatch);
     651             : 
     652             :         /* Process sinval catchup interrupts that happened while sleeping */
     653        1998 :         ProcessCatchupInterrupt();
     654             : 
     655             :         /* the normal shutdown case */
     656        1998 :         if (got_SIGTERM)
     657         676 :             break;
     658             : 
     659        1660 :         if (got_SIGHUP)
     660             :         {
     661           8 :             got_SIGHUP = false;
     662           8 :             ProcessConfigFile(PGC_SIGHUP);
     663             : 
     664             :             /* shutdown requested in config file? */
     665           8 :             if (!AutoVacuumingActive())
     666           0 :                 break;
     667             : 
     668             :             /* rebalance in case the default cost parameters changed */
     669           8 :             LWLockAcquire(AutovacuumLock, LW_EXCLUSIVE);
     670           8 :             autovac_balance_cost();
     671           8 :             LWLockRelease(AutovacuumLock);
     672             : 
     673             :             /* rebuild the list in case the naptime changed */
     674           8 :             rebuild_database_list(InvalidOid);
     675             :         }
     676             : 
     677             :         /*
     678             :          * a worker finished, or postmaster signalled failure to start a
     679             :          * worker
     680             :          */
     681        1660 :         if (got_SIGUSR2)
     682             :         {
     683         104 :             got_SIGUSR2 = false;
     684             : 
     685             :             /* rebalance cost limits, if needed */
     686         104 :             if (AutoVacuumShmem->av_signal[AutoVacRebalance])
     687             :             {
     688          52 :                 LWLockAcquire(AutovacuumLock, LW_EXCLUSIVE);
     689          52 :                 AutoVacuumShmem->av_signal[AutoVacRebalance] = false;
     690          52 :                 autovac_balance_cost();
     691          52 :                 LWLockRelease(AutovacuumLock);
     692             :             }
     693             : 
     694         104 :             if (AutoVacuumShmem->av_signal[AutoVacForkFailed])
     695             :             {
     696             :                 /*
     697             :                  * If the postmaster failed to start a new worker, we sleep
     698             :                  * for a little while and resend the signal.  The new worker's
     699             :                  * state is still in memory, so this is sufficient.  After
     700             :                  * that, we restart the main loop.
     701             :                  *
     702             :                  * XXX should we put a limit to the number of times we retry?
     703             :                  * I don't think it makes much sense, because a future start
     704             :                  * of a worker will continue to fail in the same way.
     705             :                  */
     706           0 :                 AutoVacuumShmem->av_signal[AutoVacForkFailed] = false;
     707           0 :                 pg_usleep(1000000L);    /* 1s */
     708           0 :                 SendPostmasterSignal(PMSIGNAL_START_AUTOVAC_WORKER);
     709          10 :                 continue;
     710             :             }
     711             :         }
     712             : 
     713             :         /*
     714             :          * There are some conditions that we need to check before trying to
     715             :          * start a worker.  First, we need to make sure that there is a worker
     716             :          * slot available.  Second, we need to make sure that no other worker
     717             :          * failed while starting up.
     718             :          */
     719             : 
     720        1660 :         current_time = GetCurrentTimestamp();
     721        1660 :         LWLockAcquire(AutovacuumLock, LW_SHARED);
     722             : 
     723        1660 :         can_launch = !dlist_is_empty(&AutoVacuumShmem->av_freeWorkers);
     724             : 
     725        1660 :         if (AutoVacuumShmem->av_startingWorker != NULL)
     726             :         {
     727             :             int         waittime;
     728          10 :             WorkerInfo  worker = AutoVacuumShmem->av_startingWorker;
     729             : 
     730             :             /*
     731             :              * We can't launch another worker when another one is still
     732             :              * starting up (or failed while doing so), so just sleep for a bit
     733             :              * more; that worker will wake us up again as soon as it's ready.
     734             :              * We will only wait autovacuum_naptime seconds (up to a maximum
     735             :              * of 60 seconds) for this to happen however.  Note that failure
     736             :              * to connect to a particular database is not a problem here,
     737             :              * because the worker removes itself from the startingWorker
     738             :              * pointer before trying to connect.  Problems detected by the
     739             :              * postmaster (like fork() failure) are also reported and handled
     740             :              * differently.  The only problems that may cause this code to
     741             :              * fire are errors in the earlier sections of AutoVacWorkerMain,
     742             :              * before the worker removes the WorkerInfo from the
     743             :              * startingWorker pointer.
     744             :              */
     745          10 :             waittime = Min(autovacuum_naptime, 60) * 1000;
     746          10 :             if (TimestampDifferenceExceeds(worker->wi_launchtime, current_time,
     747             :                                            waittime))
     748             :             {
     749           0 :                 LWLockRelease(AutovacuumLock);
     750           0 :                 LWLockAcquire(AutovacuumLock, LW_EXCLUSIVE);
     751             : 
     752             :                 /*
     753             :                  * No other process can put a worker in starting mode, so if
     754             :                  * startingWorker is still INVALID after exchanging our lock,
     755             :                  * we assume it's the same one we saw above (so we don't
     756             :                  * recheck the launch time).
     757             :                  */
     758           0 :                 if (AutoVacuumShmem->av_startingWorker != NULL)
     759             :                 {
     760           0 :                     worker = AutoVacuumShmem->av_startingWorker;
     761           0 :                     worker->wi_dboid = InvalidOid;
     762           0 :                     worker->wi_tableoid = InvalidOid;
     763           0 :                     worker->wi_sharedrel = false;
     764           0 :                     worker->wi_proc = NULL;
     765           0 :                     worker->wi_launchtime = 0;
     766           0 :                     dlist_push_head(&AutoVacuumShmem->av_freeWorkers,
     767             :                                     &worker->wi_links);
     768           0 :                     AutoVacuumShmem->av_startingWorker = NULL;
     769           0 :                     elog(WARNING, "worker took too long to start; canceled");
     770             :                 }
     771             :             }
     772             :             else
     773          10 :                 can_launch = false;
     774             :         }
     775        1660 :         LWLockRelease(AutovacuumLock);  /* either shared or exclusive */
     776             : 
     777             :         /* if we can't do anything, just go back to sleep */
     778        1660 :         if (!can_launch)
     779          10 :             continue;
     780             : 
     781             :         /* We're OK to start a new worker */
     782             : 
     783        1650 :         if (dlist_is_empty(&DatabaseList))
     784             :         {
     785             :             /*
     786             :              * Special case when the list is empty: start a worker right away.
     787             :              * This covers the initial case, when no database is in pgstats
     788             :              * (thus the list is empty).  Note that the constraints in
     789             :              * launcher_determine_sleep keep us from starting workers too
     790             :              * quickly (at most once every autovacuum_naptime when the list is
     791             :              * empty).
     792             :              */
     793         296 :             launch_worker(current_time);
     794             :         }
     795             :         else
     796             :         {
     797             :             /*
     798             :              * because rebuild_database_list constructs a list with most
     799             :              * distant adl_next_worker first, we obtain our database from the
     800             :              * tail of the list.
     801             :              */
     802             :             avl_dbase  *avdb;
     803             : 
     804        1354 :             avdb = dlist_tail_element(avl_dbase, adl_node, &DatabaseList);
     805             : 
     806             :             /*
     807             :              * launch a worker if next_worker is right now or it is in the
     808             :              * past
     809             :              */
     810        1354 :             if (TimestampDifferenceExceeds(avdb->adl_next_worker,
     811             :                                            current_time, 0))
     812          22 :                 launch_worker(current_time);
     813             :         }
     814             :     }
     815             : 
     816             :     /* Normal exit from the autovac launcher is here */
     817             : shutdown:
     818         340 :     ereport(DEBUG1,
     819             :             (errmsg("autovacuum launcher shutting down")));
     820         340 :     AutoVacuumShmem->av_launcherpid = 0;
     821             : 
     822         340 :     proc_exit(0);               /* done */
     823             : }
     824             : 
     825             : /*
     826             :  * Determine the time to sleep, based on the database list.
     827             :  *
     828             :  * The "canlaunch" parameter indicates whether we can start a worker right now,
     829             :  * for example due to the workers being all busy.  If this is false, we will
     830             :  * cause a long sleep, which will be interrupted when a worker exits.
     831             :  */
     832             : static void
     833        2004 : launcher_determine_sleep(bool canlaunch, bool recursing, struct timeval *nap)
     834             : {
     835             :     /*
     836             :      * We sleep until the next scheduled vacuum.  We trust that when the
     837             :      * database list was built, care was taken so that no entries have times
     838             :      * in the past; if the first entry has too close a next_worker value, or a
     839             :      * time in the past, we will sleep a small nominal time.
     840             :      */
     841        2004 :     if (!canlaunch)
     842             :     {
     843           0 :         nap->tv_sec = autovacuum_naptime;
     844           0 :         nap->tv_usec = 0;
     845             :     }
     846        2004 :     else if (!dlist_is_empty(&DatabaseList))
     847             :     {
     848        1478 :         TimestampTz current_time = GetCurrentTimestamp();
     849             :         TimestampTz next_wakeup;
     850             :         avl_dbase  *avdb;
     851             :         long        secs;
     852             :         int         usecs;
     853             : 
     854        1478 :         avdb = dlist_tail_element(avl_dbase, adl_node, &DatabaseList);
     855             : 
     856        1478 :         next_wakeup = avdb->adl_next_worker;
     857        1478 :         TimestampDifference(current_time, next_wakeup, &secs, &usecs);
     858             : 
     859        1478 :         nap->tv_sec = secs;
     860        1478 :         nap->tv_usec = usecs;
     861             :     }
     862             :     else
     863             :     {
     864             :         /* list is empty, sleep for whole autovacuum_naptime seconds  */
     865         526 :         nap->tv_sec = autovacuum_naptime;
     866         526 :         nap->tv_usec = 0;
     867             :     }
     868             : 
     869             :     /*
     870             :      * If the result is exactly zero, it means a database had an entry with
     871             :      * time in the past.  Rebuild the list so that the databases are evenly
     872             :      * distributed again, and recalculate the time to sleep.  This can happen
     873             :      * if there are more tables needing vacuum than workers, and they all take
     874             :      * longer to vacuum than autovacuum_naptime.
     875             :      *
     876             :      * We only recurse once.  rebuild_database_list should always return times
     877             :      * in the future, but it seems best not to trust too much on that.
     878             :      */
     879        2004 :     if (nap->tv_sec == 0 && nap->tv_usec == 0 && !recursing)
     880             :     {
     881           0 :         rebuild_database_list(InvalidOid);
     882           0 :         launcher_determine_sleep(canlaunch, true, nap);
     883           0 :         return;
     884             :     }
     885             : 
     886             :     /* The smallest time we'll allow the launcher to sleep. */
     887        2004 :     if (nap->tv_sec <= 0 && nap->tv_usec <= MIN_AUTOVAC_SLEEPTIME * 1000)
     888             :     {
     889           0 :         nap->tv_sec = 0;
     890           0 :         nap->tv_usec = MIN_AUTOVAC_SLEEPTIME * 1000;
     891             :     }
     892             : 
     893             :     /*
     894             :      * If the sleep time is too large, clamp it to an arbitrary maximum (plus
     895             :      * any fractional seconds, for simplicity).  This avoids an essentially
     896             :      * infinite sleep in strange cases like the system clock going backwards a
     897             :      * few years.
     898             :      */
     899        2004 :     if (nap->tv_sec > MAX_AUTOVAC_SLEEPTIME)
     900           0 :         nap->tv_sec = MAX_AUTOVAC_SLEEPTIME;
     901             : }
     902             : 
     903             : /*
     904             :  * Build an updated DatabaseList.  It must only contain databases that appear
     905             :  * in pgstats, and must be sorted by next_worker from highest to lowest,
     906             :  * distributed regularly across the next autovacuum_naptime interval.
     907             :  *
     908             :  * Receives the Oid of the database that made this list be generated (we call
     909             :  * this the "new" database, because when the database was already present on
     910             :  * the list, we expect that this function is not called at all).  The
     911             :  * preexisting list, if any, will be used to preserve the order of the
     912             :  * databases in the autovacuum_naptime period.  The new database is put at the
     913             :  * end of the interval.  The actual values are not saved, which should not be
     914             :  * much of a problem.
     915             :  */
     916             : static void
     917         388 : rebuild_database_list(Oid newdb)
     918             : {
     919             :     List       *dblist;
     920             :     ListCell   *cell;
     921             :     MemoryContext newcxt;
     922             :     MemoryContext oldcxt;
     923             :     MemoryContext tmpcxt;
     924             :     HASHCTL     hctl;
     925             :     int         score;
     926             :     int         nelems;
     927             :     HTAB       *dbhash;
     928             :     dlist_iter  iter;
     929             : 
     930             :     /* use fresh stats */
     931         388 :     autovac_refresh_stats();
     932             : 
     933         388 :     newcxt = AllocSetContextCreate(AutovacMemCxt,
     934             :                                    "AV dblist",
     935             :                                    ALLOCSET_DEFAULT_SIZES);
     936         388 :     tmpcxt = AllocSetContextCreate(newcxt,
     937             :                                    "tmp AV dblist",
     938             :                                    ALLOCSET_DEFAULT_SIZES);
     939         388 :     oldcxt = MemoryContextSwitchTo(tmpcxt);
     940             : 
     941             :     /*
     942             :      * Implementing this is not as simple as it sounds, because we need to put
     943             :      * the new database at the end of the list; next the databases that were
     944             :      * already on the list, and finally (at the tail of the list) all the
     945             :      * other databases that are not on the existing list.
     946             :      *
     947             :      * To do this, we build an empty hash table of scored databases.  We will
     948             :      * start with the lowest score (zero) for the new database, then
     949             :      * increasing scores for the databases in the existing list, in order, and
     950             :      * lastly increasing scores for all databases gotten via
     951             :      * get_database_list() that are not already on the hash.
     952             :      *
     953             :      * Then we will put all the hash elements into an array, sort the array by
     954             :      * score, and finally put the array elements into the new doubly linked
     955             :      * list.
     956             :      */
     957         388 :     hctl.keysize = sizeof(Oid);
     958         388 :     hctl.entrysize = sizeof(avl_dbase);
     959         388 :     hctl.hcxt = tmpcxt;
     960         388 :     dbhash = hash_create("db hash", 20, &hctl,    /* magic number here FIXME */
     961             :                          HASH_ELEM | HASH_BLOBS | HASH_CONTEXT);
     962             : 
     963             :     /* start by inserting the new database */
     964         388 :     score = 0;
     965         388 :     if (OidIsValid(newdb))
     966             :     {
     967             :         avl_dbase  *db;
     968             :         PgStat_StatDBEntry *entry;
     969             : 
     970             :         /* only consider this database if it has a pgstat entry */
     971          34 :         entry = pgstat_fetch_stat_dbentry(newdb);
     972          34 :         if (entry != NULL)
     973             :         {
     974             :             /* we assume it isn't found because the hash was just created */
     975          34 :             db = hash_search(dbhash, &newdb, HASH_ENTER, NULL);
     976             : 
     977             :             /* hash_search already filled in the key */
     978          34 :             db->adl_score = score++;
     979             :             /* next_worker is filled in later */
     980             :         }
     981             :     }
     982             : 
     983             :     /* Now insert the databases from the existing list */
     984         392 :     dlist_foreach(iter, &DatabaseList)
     985             :     {
     986           4 :         avl_dbase  *avdb = dlist_container(avl_dbase, adl_node, iter.cur);
     987             :         avl_dbase  *db;
     988             :         bool        found;
     989             :         PgStat_StatDBEntry *entry;
     990             : 
     991             :         /*
     992             :          * skip databases with no stat entries -- in particular, this gets rid
     993             :          * of dropped databases
     994             :          */
     995           4 :         entry = pgstat_fetch_stat_dbentry(avdb->adl_datid);
     996           4 :         if (entry == NULL)
     997           0 :             continue;
     998             : 
     999           4 :         db = hash_search(dbhash, &(avdb->adl_datid), HASH_ENTER, &found);
    1000             : 
    1001           4 :         if (!found)
    1002             :         {
    1003             :             /* hash_search already filled in the key */
    1004           4 :             db->adl_score = score++;
    1005             :             /* next_worker is filled in later */
    1006             :         }
    1007             :     }
    1008             : 
    1009             :     /* finally, insert all qualifying databases not previously inserted */
    1010         388 :     dblist = get_database_list();
    1011        1666 :     foreach(cell, dblist)
    1012             :     {
    1013        1278 :         avw_dbase  *avdb = lfirst(cell);
    1014             :         avl_dbase  *db;
    1015             :         bool        found;
    1016             :         PgStat_StatDBEntry *entry;
    1017             : 
    1018             :         /* only consider databases with a pgstat entry */
    1019        1278 :         entry = pgstat_fetch_stat_dbentry(avdb->adw_datid);
    1020        1278 :         if (entry == NULL)
    1021        1094 :             continue;
    1022             : 
    1023         184 :         db = hash_search(dbhash, &(avdb->adw_datid), HASH_ENTER, &found);
    1024             :         /* only update the score if the database was not already on the hash */
    1025         184 :         if (!found)
    1026             :         {
    1027             :             /* hash_search already filled in the key */
    1028         146 :             db->adl_score = score++;
    1029             :             /* next_worker is filled in later */
    1030             :         }
    1031             :     }
    1032         388 :     nelems = score;
    1033             : 
    1034             :     /* from here on, the allocated memory belongs to the new list */
    1035         388 :     MemoryContextSwitchTo(newcxt);
    1036         388 :     dlist_init(&DatabaseList);
    1037             : 
    1038         388 :     if (nelems > 0)
    1039             :     {
    1040             :         TimestampTz current_time;
    1041             :         int         millis_increment;
    1042             :         avl_dbase  *dbary;
    1043             :         avl_dbase  *db;
    1044             :         HASH_SEQ_STATUS seq;
    1045             :         int         i;
    1046             : 
    1047             :         /* put all the hash elements into an array */
    1048         124 :         dbary = palloc(nelems * sizeof(avl_dbase));
    1049             : 
    1050         124 :         i = 0;
    1051         124 :         hash_seq_init(&seq, dbhash);
    1052         432 :         while ((db = hash_seq_search(&seq)) != NULL)
    1053         184 :             memcpy(&(dbary[i++]), db, sizeof(avl_dbase));
    1054             : 
    1055             :         /* sort the array */
    1056         124 :         qsort(dbary, nelems, sizeof(avl_dbase), db_comparator);
    1057             : 
    1058             :         /*
    1059             :          * Determine the time interval between databases in the schedule. If
    1060             :          * we see that the configured naptime would take us to sleep times
    1061             :          * lower than our min sleep time (which launcher_determine_sleep is
    1062             :          * coded not to allow), silently use a larger naptime (but don't touch
    1063             :          * the GUC variable).
    1064             :          */
    1065         124 :         millis_increment = 1000.0 * autovacuum_naptime / nelems;
    1066         124 :         if (millis_increment <= MIN_AUTOVAC_SLEEPTIME)
    1067           0 :             millis_increment = MIN_AUTOVAC_SLEEPTIME * 1.1;
    1068             : 
    1069         124 :         current_time = GetCurrentTimestamp();
    1070             : 
    1071             :         /*
    1072             :          * move the elements from the array into the dlist, setting the
    1073             :          * next_worker while walking the array
    1074             :          */
    1075         308 :         for (i = 0; i < nelems; i++)
    1076             :         {
    1077         184 :             avl_dbase  *db = &(dbary[i]);
    1078             : 
    1079         184 :             current_time = TimestampTzPlusMilliseconds(current_time,
    1080             :                                                        millis_increment);
    1081         184 :             db->adl_next_worker = current_time;
    1082             : 
    1083             :             /* later elements should go closer to the head of the list */
    1084         184 :             dlist_push_head(&DatabaseList, &db->adl_node);
    1085             :         }
    1086             :     }
    1087             : 
    1088             :     /* all done, clean up memory */
    1089         388 :     if (DatabaseListCxt != NULL)
    1090          42 :         MemoryContextDelete(DatabaseListCxt);
    1091         388 :     MemoryContextDelete(tmpcxt);
    1092         388 :     DatabaseListCxt = newcxt;
    1093         388 :     MemoryContextSwitchTo(oldcxt);
    1094         388 : }
    1095             : 
    1096             : /* qsort comparator for avl_dbase, using adl_score */
    1097             : static int
    1098          96 : db_comparator(const void *a, const void *b)
    1099             : {
    1100          96 :     if (((const avl_dbase *) a)->adl_score == ((const avl_dbase *) b)->adl_score)
    1101           0 :         return 0;
    1102             :     else
    1103          96 :         return (((const avl_dbase *) a)->adl_score < ((const avl_dbase *) b)->adl_score) ? 1 : -1;
    1104             : }
    1105             : 
    1106             : /*
    1107             :  * do_start_worker
    1108             :  *
    1109             :  * Bare-bones procedure for starting an autovacuum worker from the launcher.
    1110             :  * It determines what database to work on, sets up shared memory stuff and
    1111             :  * signals postmaster to start the worker.  It fails gracefully if invoked when
    1112             :  * autovacuum_workers are already active.
    1113             :  *
    1114             :  * Return value is the OID of the database that the worker is going to process,
    1115             :  * or InvalidOid if no worker was actually started.
    1116             :  */
    1117             : static Oid
    1118         318 : do_start_worker(void)
    1119             : {
    1120             :     List       *dblist;
    1121             :     ListCell   *cell;
    1122             :     TransactionId xidForceLimit;
    1123             :     MultiXactId multiForceLimit;
    1124             :     bool        for_xid_wrap;
    1125             :     bool        for_multi_wrap;
    1126             :     avw_dbase  *avdb;
    1127             :     TimestampTz current_time;
    1128         318 :     bool        skipit = false;
    1129         318 :     Oid         retval = InvalidOid;
    1130             :     MemoryContext tmpcxt,
    1131             :                 oldcxt;
    1132             : 
    1133             :     /* return quickly when there are no free workers */
    1134         318 :     LWLockAcquire(AutovacuumLock, LW_SHARED);
    1135         318 :     if (dlist_is_empty(&AutoVacuumShmem->av_freeWorkers))
    1136             :     {
    1137           0 :         LWLockRelease(AutovacuumLock);
    1138           0 :         return InvalidOid;
    1139             :     }
    1140         318 :     LWLockRelease(AutovacuumLock);
    1141             : 
    1142             :     /*
    1143             :      * Create and switch to a temporary context to avoid leaking the memory
    1144             :      * allocated for the database list.
    1145             :      */
    1146         318 :     tmpcxt = AllocSetContextCreate(CurrentMemoryContext,
    1147             :                                    "Start worker tmp cxt",
    1148             :                                    ALLOCSET_DEFAULT_SIZES);
    1149         318 :     oldcxt = MemoryContextSwitchTo(tmpcxt);
    1150             : 
    1151             :     /* use fresh stats */
    1152         318 :     autovac_refresh_stats();
    1153             : 
    1154             :     /* Get a list of databases */
    1155         318 :     dblist = get_database_list();
    1156             : 
    1157             :     /*
    1158             :      * Determine the oldest datfrozenxid/relfrozenxid that we will allow to
    1159             :      * pass without forcing a vacuum.  (This limit can be tightened for
    1160             :      * particular tables, but not loosened.)
    1161             :      */
    1162         318 :     recentXid = ReadNewTransactionId();
    1163         318 :     xidForceLimit = recentXid - autovacuum_freeze_max_age;
    1164             :     /* ensure it's a "normal" XID, else TransactionIdPrecedes misbehaves */
    1165             :     /* this can cause the limit to go backwards by 3, but that's OK */
    1166         318 :     if (xidForceLimit < FirstNormalTransactionId)
    1167           0 :         xidForceLimit -= FirstNormalTransactionId;
    1168             : 
    1169             :     /* Also determine the oldest datminmxid we will consider. */
    1170         318 :     recentMulti = ReadNextMultiXactId();
    1171         318 :     multiForceLimit = recentMulti - MultiXactMemberFreezeThreshold();
    1172         318 :     if (multiForceLimit < FirstMultiXactId)
    1173           0 :         multiForceLimit -= FirstMultiXactId;
    1174             : 
    1175             :     /*
    1176             :      * Choose a database to connect to.  We pick the database that was least
    1177             :      * recently auto-vacuumed, or one that needs vacuuming to prevent Xid
    1178             :      * wraparound-related data loss.  If any db at risk of Xid wraparound is
    1179             :      * found, we pick the one with oldest datfrozenxid, independently of
    1180             :      * autovacuum times; similarly we pick the one with the oldest datminmxid
    1181             :      * if any is in MultiXactId wraparound.  Note that those in Xid wraparound
    1182             :      * danger are given more priority than those in multi wraparound danger.
    1183             :      *
    1184             :      * Note that a database with no stats entry is not considered, except for
    1185             :      * Xid wraparound purposes.  The theory is that if no one has ever
    1186             :      * connected to it since the stats were last initialized, it doesn't need
    1187             :      * vacuuming.
    1188             :      *
    1189             :      * XXX This could be improved if we had more info about whether it needs
    1190             :      * vacuuming before connecting to it.  Perhaps look through the pgstats
    1191             :      * data for the database's tables?  One idea is to keep track of the
    1192             :      * number of new and dead tuples per database in pgstats.  However it
    1193             :      * isn't clear how to construct a metric that measures that and not cause
    1194             :      * starvation for less busy databases.
    1195             :      */
    1196         318 :     avdb = NULL;
    1197         318 :     for_xid_wrap = false;
    1198         318 :     for_multi_wrap = false;
    1199         318 :     current_time = GetCurrentTimestamp();
    1200        1360 :     foreach(cell, dblist)
    1201             :     {
    1202        1042 :         avw_dbase  *tmp = lfirst(cell);
    1203             :         dlist_iter  iter;
    1204             : 
    1205             :         /* Check to see if this one is at risk of wraparound */
    1206        1042 :         if (TransactionIdPrecedes(tmp->adw_frozenxid, xidForceLimit))
    1207             :         {
    1208           0 :             if (avdb == NULL ||
    1209           0 :                 TransactionIdPrecedes(tmp->adw_frozenxid,
    1210             :                                       avdb->adw_frozenxid))
    1211           0 :                 avdb = tmp;
    1212           0 :             for_xid_wrap = true;
    1213         954 :             continue;
    1214             :         }
    1215        1042 :         else if (for_xid_wrap)
    1216           0 :             continue;           /* ignore not-at-risk DBs */
    1217        1042 :         else if (MultiXactIdPrecedes(tmp->adw_minmulti, multiForceLimit))
    1218             :         {
    1219           0 :             if (avdb == NULL ||
    1220           0 :                 MultiXactIdPrecedes(tmp->adw_minmulti, avdb->adw_minmulti))
    1221           0 :                 avdb = tmp;
    1222           0 :             for_multi_wrap = true;
    1223           0 :             continue;
    1224             :         }
    1225        1042 :         else if (for_multi_wrap)
    1226           0 :             continue;           /* ignore not-at-risk DBs */
    1227             : 
    1228             :         /* Find pgstat entry if any */
    1229        1042 :         tmp->adw_entry = pgstat_fetch_stat_dbentry(tmp->adw_datid);
    1230             : 
    1231             :         /*
    1232             :          * Skip a database with no pgstat entry; it means it hasn't seen any
    1233             :          * activity.
    1234             :          */
    1235        1042 :         if (!tmp->adw_entry)
    1236         922 :             continue;
    1237             : 
    1238             :         /*
    1239             :          * Also, skip a database that appears on the database list as having
    1240             :          * been processed recently (less than autovacuum_naptime seconds ago).
    1241             :          * We do this so that we don't select a database which we just
    1242             :          * selected, but that pgstat hasn't gotten around to updating the last
    1243             :          * autovacuum time yet.
    1244             :          */
    1245         120 :         skipit = false;
    1246             : 
    1247         186 :         dlist_reverse_foreach(iter, &DatabaseList)
    1248             :         {
    1249         120 :             avl_dbase  *dbp = dlist_container(avl_dbase, adl_node, iter.cur);
    1250             : 
    1251         120 :             if (dbp->adl_datid == tmp->adw_datid)
    1252             :             {
    1253             :                 /*
    1254             :                  * Skip this database if its next_worker value falls between
    1255             :                  * the current time and the current time plus naptime.
    1256             :                  */
    1257          54 :                 if (!TimestampDifferenceExceeds(dbp->adl_next_worker,
    1258          32 :                                                 current_time, 0) &&
    1259          32 :                     !TimestampDifferenceExceeds(current_time,
    1260             :                                                 dbp->adl_next_worker,
    1261             :                                                 autovacuum_naptime * 1000))
    1262          32 :                     skipit = true;
    1263             : 
    1264          54 :                 break;
    1265             :             }
    1266             :         }
    1267         120 :         if (skipit)
    1268          32 :             continue;
    1269             : 
    1270             :         /*
    1271             :          * Remember the db with oldest autovac time.  (If we are here, both
    1272             :          * tmp->entry and db->entry must be non-null.)
    1273             :          */
    1274         122 :         if (avdb == NULL ||
    1275          34 :             tmp->adw_entry->last_autovac_time < avdb->adw_entry->last_autovac_time)
    1276          54 :             avdb = tmp;
    1277             :     }
    1278             : 
    1279             :     /* Found a database -- process it */
    1280         318 :     if (avdb != NULL)
    1281             :     {
    1282             :         WorkerInfo  worker;
    1283             :         dlist_node *wptr;
    1284             : 
    1285          54 :         LWLockAcquire(AutovacuumLock, LW_EXCLUSIVE);
    1286             : 
    1287             :         /*
    1288             :          * Get a worker entry from the freelist.  We checked above, so there
    1289             :          * really should be a free slot.
    1290             :          */
    1291          54 :         wptr = dlist_pop_head_node(&AutoVacuumShmem->av_freeWorkers);
    1292             : 
    1293          54 :         worker = dlist_container(WorkerInfoData, wi_links, wptr);
    1294          54 :         worker->wi_dboid = avdb->adw_datid;
    1295          54 :         worker->wi_proc = NULL;
    1296          54 :         worker->wi_launchtime = GetCurrentTimestamp();
    1297             : 
    1298          54 :         AutoVacuumShmem->av_startingWorker = worker;
    1299             : 
    1300          54 :         LWLockRelease(AutovacuumLock);
    1301             : 
    1302          54 :         SendPostmasterSignal(PMSIGNAL_START_AUTOVAC_WORKER);
    1303             : 
    1304          54 :         retval = avdb->adw_datid;
    1305             :     }
    1306         264 :     else if (skipit)
    1307             :     {
    1308             :         /*
    1309             :          * If we skipped all databases on the list, rebuild it, because it
    1310             :          * probably contains a dropped database.
    1311             :          */
    1312           0 :         rebuild_database_list(InvalidOid);
    1313             :     }
    1314             : 
    1315         318 :     MemoryContextSwitchTo(oldcxt);
    1316         318 :     MemoryContextDelete(tmpcxt);
    1317             : 
    1318         318 :     return retval;
    1319             : }
    1320             : 
    1321             : /*
    1322             :  * launch_worker
    1323             :  *
    1324             :  * Wrapper for starting a worker from the launcher.  Besides actually starting
    1325             :  * it, update the database list to reflect the next time that another one will
    1326             :  * need to be started on the selected database.  The actual database choice is
    1327             :  * left to do_start_worker.
    1328             :  *
    1329             :  * This routine is also expected to insert an entry into the database list if
    1330             :  * the selected database was previously absent from the list.
    1331             :  */
    1332             : static void
    1333         318 : launch_worker(TimestampTz now)
    1334             : {
    1335             :     Oid         dbid;
    1336             :     dlist_iter  iter;
    1337             : 
    1338         318 :     dbid = do_start_worker();
    1339         318 :     if (OidIsValid(dbid))
    1340             :     {
    1341          54 :         bool        found = false;
    1342             : 
    1343             :         /*
    1344             :          * Walk the database list and update the corresponding entry.  If the
    1345             :          * database is not on the list, we'll recreate the list.
    1346             :          */
    1347          88 :         dlist_foreach(iter, &DatabaseList)
    1348             :         {
    1349          54 :             avl_dbase  *avdb = dlist_container(avl_dbase, adl_node, iter.cur);
    1350             : 
    1351          54 :             if (avdb->adl_datid == dbid)
    1352             :             {
    1353          20 :                 found = true;
    1354             : 
    1355             :                 /*
    1356             :                  * add autovacuum_naptime seconds to the current time, and use
    1357             :                  * that as the new "next_worker" field for this database.
    1358             :                  */
    1359          20 :                 avdb->adl_next_worker =
    1360          20 :                     TimestampTzPlusMilliseconds(now, autovacuum_naptime * 1000);
    1361             : 
    1362          20 :                 dlist_move_head(&DatabaseList, iter.cur);
    1363          20 :                 break;
    1364             :             }
    1365             :         }
    1366             : 
    1367             :         /*
    1368             :          * If the database was not present in the database list, we rebuild
    1369             :          * the list.  It's possible that the database does not get into the
    1370             :          * list anyway, for example if it's a database that doesn't have a
    1371             :          * pgstat entry, but this is not a problem because we don't want to
    1372             :          * schedule workers regularly into those in any case.
    1373             :          */
    1374          54 :         if (!found)
    1375          34 :             rebuild_database_list(dbid);
    1376             :     }
    1377         318 : }
    1378             : 
    1379             : /*
    1380             :  * Called from postmaster to signal a failure to fork a process to become
    1381             :  * worker.  The postmaster should kill(SIGUSR2) the launcher shortly
    1382             :  * after calling this function.
    1383             :  */
    1384             : void
    1385           0 : AutoVacWorkerFailed(void)
    1386             : {
    1387           0 :     AutoVacuumShmem->av_signal[AutoVacForkFailed] = true;
    1388           0 : }
    1389             : 
    1390             : /* SIGHUP: set flag to re-read config file at next convenient time */
    1391             : static void
    1392           8 : av_sighup_handler(SIGNAL_ARGS)
    1393             : {
    1394           8 :     int         save_errno = errno;
    1395             : 
    1396           8 :     got_SIGHUP = true;
    1397           8 :     SetLatch(MyLatch);
    1398             : 
    1399           8 :     errno = save_errno;
    1400           8 : }
    1401             : 
    1402             : /* SIGUSR2: a worker is up and running, or just finished, or failed to fork */
    1403             : static void
    1404         104 : avl_sigusr2_handler(SIGNAL_ARGS)
    1405             : {
    1406         104 :     int         save_errno = errno;
    1407             : 
    1408         104 :     got_SIGUSR2 = true;
    1409         104 :     SetLatch(MyLatch);
    1410             : 
    1411         104 :     errno = save_errno;
    1412         104 : }
    1413             : 
    1414             : /* SIGTERM: time to die */
    1415             : static void
    1416         348 : avl_sigterm_handler(SIGNAL_ARGS)
    1417             : {
    1418         348 :     int         save_errno = errno;
    1419             : 
    1420         348 :     got_SIGTERM = true;
    1421         348 :     SetLatch(MyLatch);
    1422             : 
    1423         348 :     errno = save_errno;
    1424         348 : }
    1425             : 
    1426             : 
    1427             : /********************************************************************
    1428             :  *                    AUTOVACUUM WORKER CODE
    1429             :  ********************************************************************/
    1430             : 
    1431             : #ifdef EXEC_BACKEND
    1432             : /*
    1433             :  * forkexec routines for the autovacuum worker.
    1434             :  *
    1435             :  * Format up the arglist, then fork and exec.
    1436             :  */
    1437             : static pid_t
    1438             : avworker_forkexec(void)
    1439             : {
    1440             :     char       *av[10];
    1441             :     int         ac = 0;
    1442             : 
    1443             :     av[ac++] = "postgres";
    1444             :     av[ac++] = "--forkavworker";
    1445             :     av[ac++] = NULL;            /* filled in by postmaster_forkexec */
    1446             :     av[ac] = NULL;
    1447             : 
    1448             :     Assert(ac < lengthof(av));
    1449             : 
    1450             :     return postmaster_forkexec(ac, av);
    1451             : }
    1452             : 
    1453             : /*
    1454             :  * We need this set from the outside, before InitProcess is called
    1455             :  */
    1456             : void
    1457             : AutovacuumWorkerIAm(void)
    1458             : {
    1459             :     am_autovacuum_worker = true;
    1460             : }
    1461             : #endif
    1462             : 
    1463             : /*
    1464             :  * Main entry point for autovacuum worker process.
    1465             :  *
    1466             :  * This code is heavily based on pgarch.c, q.v.
    1467             :  */
    1468             : int
    1469          62 : StartAutoVacWorker(void)
    1470             : {
    1471             :     pid_t       worker_pid;
    1472             : 
    1473             : #ifdef EXEC_BACKEND
    1474             :     switch ((worker_pid = avworker_forkexec()))
    1475             : #else
    1476          62 :     switch ((worker_pid = fork_process()))
    1477             : #endif
    1478             :     {
    1479             :         case -1:
    1480           0 :             ereport(LOG,
    1481             :                     (errmsg("could not fork autovacuum worker process: %m")));
    1482           0 :             return 0;
    1483             : 
    1484             : #ifndef EXEC_BACKEND
    1485             :         case 0:
    1486             :             /* in postmaster child ... */
    1487          60 :             InitPostmasterChild();
    1488             : 
    1489             :             /* Close the postmaster's sockets */
    1490          60 :             ClosePostmasterPorts(false);
    1491             : 
    1492          60 :             AutoVacWorkerMain(0, NULL);
    1493             :             break;
    1494             : #endif
    1495             :         default:
    1496          62 :             return (int) worker_pid;
    1497             :     }
    1498             : 
    1499             :     /* shouldn't get here */
    1500             :     return 0;
    1501             : }
    1502             : 
    1503             : /*
    1504             :  * AutoVacWorkerMain
    1505             :  */
    1506             : NON_EXEC_STATIC void
    1507          60 : AutoVacWorkerMain(int argc, char *argv[])
    1508             : {
    1509             :     sigjmp_buf  local_sigjmp_buf;
    1510             :     Oid         dbid;
    1511             : 
    1512          60 :     am_autovacuum_worker = true;
    1513             : 
    1514             :     /* Identify myself via ps */
    1515          60 :     init_ps_display(pgstat_get_backend_desc(B_AUTOVAC_WORKER), "", "", "");
    1516             : 
    1517          60 :     SetProcessingMode(InitProcessing);
    1518             : 
    1519             :     /*
    1520             :      * Set up signal handlers.  We operate on databases much like a regular
    1521             :      * backend, so we use the same signal handling.  See equivalent code in
    1522             :      * tcop/postgres.c.
    1523             :      */
    1524          60 :     pqsignal(SIGHUP, av_sighup_handler);
    1525             : 
    1526             :     /*
    1527             :      * SIGINT is used to signal canceling the current table's vacuum; SIGTERM
    1528             :      * means abort and exit cleanly, and SIGQUIT means abandon ship.
    1529             :      */
    1530          60 :     pqsignal(SIGINT, StatementCancelHandler);
    1531          60 :     pqsignal(SIGTERM, die);
    1532          60 :     pqsignal(SIGQUIT, quickdie);
    1533          60 :     InitializeTimeouts();       /* establishes SIGALRM handler */
    1534             : 
    1535          60 :     pqsignal(SIGPIPE, SIG_IGN);
    1536          60 :     pqsignal(SIGUSR1, procsignal_sigusr1_handler);
    1537          60 :     pqsignal(SIGUSR2, SIG_IGN);
    1538          60 :     pqsignal(SIGFPE, FloatExceptionHandler);
    1539          60 :     pqsignal(SIGCHLD, SIG_DFL);
    1540             : 
    1541             :     /* Early initialization */
    1542          60 :     BaseInit();
    1543             : 
    1544             :     /*
    1545             :      * Create a per-backend PGPROC struct in shared memory, except in the
    1546             :      * EXEC_BACKEND case where this was done in SubPostmasterMain. We must do
    1547             :      * this before we can use LWLocks (and in the EXEC_BACKEND case we already
    1548             :      * had to do some stuff with LWLocks).
    1549             :      */
    1550             : #ifndef EXEC_BACKEND
    1551          60 :     InitProcess();
    1552             : #endif
    1553             : 
    1554             :     /*
    1555             :      * If an exception is encountered, processing resumes here.
    1556             :      *
    1557             :      * See notes in postgres.c about the design of this coding.
    1558             :      */
    1559          60 :     if (sigsetjmp(local_sigjmp_buf, 1) != 0)
    1560             :     {
    1561             :         /* Prevents interrupts while cleaning up */
    1562           0 :         HOLD_INTERRUPTS();
    1563             : 
    1564             :         /* Report the error to the server log */
    1565           0 :         EmitErrorReport();
    1566             : 
    1567             :         /*
    1568             :          * We can now go away.  Note that because we called InitProcess, a
    1569             :          * callback was registered to do ProcKill, which will clean up
    1570             :          * necessary state.
    1571             :          */
    1572           0 :         proc_exit(0);
    1573             :     }
    1574             : 
    1575             :     /* We can now handle ereport(ERROR) */
    1576          60 :     PG_exception_stack = &local_sigjmp_buf;
    1577             : 
    1578          60 :     PG_SETMASK(&UnBlockSig);
    1579             : 
    1580             :     /*
    1581             :      * Set always-secure search path, so malicious users can't redirect user
    1582             :      * code (e.g. pg_index.indexprs).  (That code runs in a
    1583             :      * SECURITY_RESTRICTED_OPERATION sandbox, so malicious users could not
    1584             :      * take control of the entire autovacuum worker in any case.)
    1585             :      */
    1586          60 :     SetConfigOption("search_path", "", PGC_SUSET, PGC_S_OVERRIDE);
    1587             : 
    1588             :     /*
    1589             :      * Force zero_damaged_pages OFF in the autovac process, even if it is set
    1590             :      * in postgresql.conf.  We don't really want such a dangerous option being
    1591             :      * applied non-interactively.
    1592             :      */
    1593          60 :     SetConfigOption("zero_damaged_pages", "false", PGC_SUSET, PGC_S_OVERRIDE);
    1594             : 
    1595             :     /*
    1596             :      * Force settable timeouts off to avoid letting these settings prevent
    1597             :      * regular maintenance from being executed.
    1598             :      */
    1599          60 :     SetConfigOption("statement_timeout", "0", PGC_SUSET, PGC_S_OVERRIDE);
    1600          60 :     SetConfigOption("lock_timeout", "0", PGC_SUSET, PGC_S_OVERRIDE);
    1601          60 :     SetConfigOption("idle_in_transaction_session_timeout", "0",
    1602             :                     PGC_SUSET, PGC_S_OVERRIDE);
    1603             : 
    1604             :     /*
    1605             :      * Force default_transaction_isolation to READ COMMITTED.  We don't want
    1606             :      * to pay the overhead of serializable mode, nor add any risk of causing
    1607             :      * deadlocks or delaying other transactions.
    1608             :      */
    1609          60 :     SetConfigOption("default_transaction_isolation", "read committed",
    1610             :                     PGC_SUSET, PGC_S_OVERRIDE);
    1611             : 
    1612             :     /*
    1613             :      * Force synchronous replication off to allow regular maintenance even if
    1614             :      * we are waiting for standbys to connect. This is important to ensure we
    1615             :      * aren't blocked from performing anti-wraparound tasks.
    1616             :      */
    1617          60 :     if (synchronous_commit > SYNCHRONOUS_COMMIT_LOCAL_FLUSH)
    1618          60 :         SetConfigOption("synchronous_commit", "local",
    1619             :                         PGC_SUSET, PGC_S_OVERRIDE);
    1620             : 
    1621             :     /*
    1622             :      * Get the info about the database we're going to work on.
    1623             :      */
    1624          60 :     LWLockAcquire(AutovacuumLock, LW_EXCLUSIVE);
    1625             : 
    1626             :     /*
    1627             :      * beware of startingWorker being INVALID; this should normally not
    1628             :      * happen, but if a worker fails after forking and before this, the
    1629             :      * launcher might have decided to remove it from the queue and start
    1630             :      * again.
    1631             :      */
    1632          60 :     if (AutoVacuumShmem->av_startingWorker != NULL)
    1633             :     {
    1634          60 :         MyWorkerInfo = AutoVacuumShmem->av_startingWorker;
    1635          60 :         dbid = MyWorkerInfo->wi_dboid;
    1636          60 :         MyWorkerInfo->wi_proc = MyProc;
    1637             : 
    1638             :         /* insert into the running list */
    1639          60 :         dlist_push_head(&AutoVacuumShmem->av_runningWorkers,
    1640          60 :                         &MyWorkerInfo->wi_links);
    1641             : 
    1642             :         /*
    1643             :          * remove from the "starting" pointer, so that the launcher can start
    1644             :          * a new worker if required
    1645             :          */
    1646          60 :         AutoVacuumShmem->av_startingWorker = NULL;
    1647          60 :         LWLockRelease(AutovacuumLock);
    1648             : 
    1649          60 :         on_shmem_exit(FreeWorkerInfo, 0);
    1650             : 
    1651             :         /* wake up the launcher */
    1652          60 :         if (AutoVacuumShmem->av_launcherpid != 0)
    1653          60 :             kill(AutoVacuumShmem->av_launcherpid, SIGUSR2);
    1654             :     }
    1655             :     else
    1656             :     {
    1657             :         /* no worker entry for me, go away */
    1658           0 :         elog(WARNING, "autovacuum worker started without a worker entry");
    1659           0 :         dbid = InvalidOid;
    1660           0 :         LWLockRelease(AutovacuumLock);
    1661             :     }
    1662             : 
    1663          60 :     if (OidIsValid(dbid))
    1664             :     {
    1665             :         char        dbname[NAMEDATALEN];
    1666             : 
    1667             :         /*
    1668             :          * Report autovac startup to the stats collector.  We deliberately do
    1669             :          * this before InitPostgres, so that the last_autovac_time will get
    1670             :          * updated even if the connection attempt fails.  This is to prevent
    1671             :          * autovac from getting "stuck" repeatedly selecting an unopenable
    1672             :          * database, rather than making any progress on stuff it can connect
    1673             :          * to.
    1674             :          */
    1675          60 :         pgstat_report_autovac(dbid);
    1676             : 
    1677             :         /*
    1678             :          * Connect to the selected database
    1679             :          *
    1680             :          * Note: if we have selected a just-deleted database (due to using
    1681             :          * stale stats info), we'll fail and exit here.
    1682             :          */
    1683          60 :         InitPostgres(NULL, dbid, NULL, InvalidOid, dbname, false);
    1684          60 :         SetProcessingMode(NormalProcessing);
    1685          60 :         set_ps_display(dbname, false);
    1686          60 :         ereport(DEBUG1,
    1687             :                 (errmsg("autovacuum: processing database \"%s\"", dbname)));
    1688             : 
    1689          60 :         if (PostAuthDelay)
    1690           0 :             pg_usleep(PostAuthDelay * 1000000L);
    1691             : 
    1692             :         /* And do an appropriate amount of work */
    1693          60 :         recentXid = ReadNewTransactionId();
    1694          60 :         recentMulti = ReadNextMultiXactId();
    1695          60 :         do_autovacuum();
    1696             :     }
    1697             : 
    1698             :     /*
    1699             :      * The launcher will be notified of my death in ProcKill, *if* we managed
    1700             :      * to get a worker slot at all
    1701             :      */
    1702             : 
    1703             :     /* All done, go away */
    1704          60 :     proc_exit(0);
    1705             : }
    1706             : 
    1707             : /*
    1708             :  * Return a WorkerInfo to the free list
    1709             :  */
    1710             : static void
    1711          60 : FreeWorkerInfo(int code, Datum arg)
    1712             : {
    1713          60 :     if (MyWorkerInfo != NULL)
    1714             :     {
    1715          60 :         LWLockAcquire(AutovacuumLock, LW_EXCLUSIVE);
    1716             : 
    1717             :         /*
    1718             :          * Wake the launcher up so that he can launch a new worker immediately
    1719             :          * if required.  We only save the launcher's PID in local memory here;
    1720             :          * the actual signal will be sent when the PGPROC is recycled.  Note
    1721             :          * that we always do this, so that the launcher can rebalance the cost
    1722             :          * limit setting of the remaining workers.
    1723             :          *
    1724             :          * We somewhat ignore the risk that the launcher changes its PID
    1725             :          * between us reading it and the actual kill; we expect ProcKill to be
    1726             :          * called shortly after us, and we assume that PIDs are not reused too
    1727             :          * quickly after a process exits.
    1728             :          */
    1729          60 :         AutovacuumLauncherPid = AutoVacuumShmem->av_launcherpid;
    1730             : 
    1731          60 :         dlist_delete(&MyWorkerInfo->wi_links);
    1732          60 :         MyWorkerInfo->wi_dboid = InvalidOid;
    1733          60 :         MyWorkerInfo->wi_tableoid = InvalidOid;
    1734          60 :         MyWorkerInfo->wi_sharedrel = false;
    1735          60 :         MyWorkerInfo->wi_proc = NULL;
    1736          60 :         MyWorkerInfo->wi_launchtime = 0;
    1737          60 :         MyWorkerInfo->wi_dobalance = false;
    1738          60 :         MyWorkerInfo->wi_cost_delay = 0;
    1739          60 :         MyWorkerInfo->wi_cost_limit = 0;
    1740          60 :         MyWorkerInfo->wi_cost_limit_base = 0;
    1741          60 :         dlist_push_head(&AutoVacuumShmem->av_freeWorkers,
    1742          60 :                         &MyWorkerInfo->wi_links);
    1743             :         /* not mine anymore */
    1744          60 :         MyWorkerInfo = NULL;
    1745             : 
    1746             :         /*
    1747             :          * now that we're inactive, cause a rebalancing of the surviving
    1748             :          * workers
    1749             :          */
    1750          60 :         AutoVacuumShmem->av_signal[AutoVacRebalance] = true;
    1751          60 :         LWLockRelease(AutovacuumLock);
    1752             :     }
    1753          60 : }
    1754             : 
    1755             : /*
    1756             :  * Update the cost-based delay parameters, so that multiple workers consume
    1757             :  * each a fraction of the total available I/O.
    1758             :  */
    1759             : void
    1760        1372 : AutoVacuumUpdateDelay(void)
    1761             : {
    1762        1372 :     if (MyWorkerInfo)
    1763             :     {
    1764        1372 :         VacuumCostDelay = MyWorkerInfo->wi_cost_delay;
    1765        1372 :         VacuumCostLimit = MyWorkerInfo->wi_cost_limit;
    1766             :     }
    1767        1372 : }
    1768             : 
    1769             : /*
    1770             :  * autovac_balance_cost
    1771             :  *      Recalculate the cost limit setting for each active worker.
    1772             :  *
    1773             :  * Caller must hold the AutovacuumLock in exclusive mode.
    1774             :  */
    1775             : static void
    1776         492 : autovac_balance_cost(void)
    1777             : {
    1778             :     /*
    1779             :      * The idea here is that we ration out I/O equally.  The amount of I/O
    1780             :      * that a worker can consume is determined by cost_limit/cost_delay, so we
    1781             :      * try to equalize those ratios rather than the raw limit settings.
    1782             :      *
    1783             :      * note: in cost_limit, zero also means use value from elsewhere, because
    1784             :      * zero is not a valid value.
    1785             :      */
    1786         984 :     int         vac_cost_limit = (autovacuum_vac_cost_limit > 0 ?
    1787         492 :                                   autovacuum_vac_cost_limit : VacuumCostLimit);
    1788         984 :     double      vac_cost_delay = (autovacuum_vac_cost_delay >= 0 ?
    1789         492 :                                   autovacuum_vac_cost_delay : VacuumCostDelay);
    1790             :     double      cost_total;
    1791             :     double      cost_avail;
    1792             :     dlist_iter  iter;
    1793             : 
    1794             :     /* not set? nothing to do */
    1795         492 :     if (vac_cost_limit <= 0 || vac_cost_delay <= 0)
    1796          60 :         return;
    1797             : 
    1798             :     /* calculate the total base cost limit of participating active workers */
    1799         492 :     cost_total = 0.0;
    1800         924 :     dlist_foreach(iter, &AutoVacuumShmem->av_runningWorkers)
    1801             :     {
    1802         432 :         WorkerInfo  worker = dlist_container(WorkerInfoData, wi_links, iter.cur);
    1803             : 
    1804         864 :         if (worker->wi_proc != NULL &&
    1805         864 :             worker->wi_dobalance &&
    1806         864 :             worker->wi_cost_limit_base > 0 && worker->wi_cost_delay > 0)
    1807         432 :             cost_total +=
    1808         432 :                 (double) worker->wi_cost_limit_base / worker->wi_cost_delay;
    1809             :     }
    1810             : 
    1811             :     /* there are no cost limits -- nothing to do */
    1812         492 :     if (cost_total <= 0)
    1813          60 :         return;
    1814             : 
    1815             :     /*
    1816             :      * Adjust cost limit of each active worker to balance the total of cost
    1817             :      * limit to autovacuum_vacuum_cost_limit.
    1818             :      */
    1819         432 :     cost_avail = (double) vac_cost_limit / vac_cost_delay;
    1820         864 :     dlist_foreach(iter, &AutoVacuumShmem->av_runningWorkers)
    1821             :     {
    1822         432 :         WorkerInfo  worker = dlist_container(WorkerInfoData, wi_links, iter.cur);
    1823             : 
    1824         864 :         if (worker->wi_proc != NULL &&
    1825         864 :             worker->wi_dobalance &&
    1826         864 :             worker->wi_cost_limit_base > 0 && worker->wi_cost_delay > 0)
    1827             :         {
    1828         432 :             int         limit = (int)
    1829         432 :             (cost_avail * worker->wi_cost_limit_base / cost_total);
    1830             : 
    1831             :             /*
    1832             :              * We put a lower bound of 1 on the cost_limit, to avoid division-
    1833             :              * by-zero in the vacuum code.  Also, in case of roundoff trouble
    1834             :              * in these calculations, let's be sure we don't ever set
    1835             :              * cost_limit to more than the base value.
    1836             :              */
    1837         432 :             worker->wi_cost_limit = Max(Min(limit,
    1838             :                                             worker->wi_cost_limit_base),
    1839             :                                         1);
    1840             :         }
    1841             : 
    1842         432 :         if (worker->wi_proc != NULL)
    1843         432 :             elog(DEBUG2, "autovac_balance_cost(pid=%u db=%u, rel=%u, dobalance=%s cost_limit=%d, cost_limit_base=%d, cost_delay=%g)",
    1844             :                  worker->wi_proc->pid, worker->wi_dboid, worker->wi_tableoid,
    1845             :                  worker->wi_dobalance ? "yes" : "no",
    1846             :                  worker->wi_cost_limit, worker->wi_cost_limit_base,
    1847             :                  worker->wi_cost_delay);
    1848             :     }
    1849             : }
    1850             : 
    1851             : /*
    1852             :  * get_database_list
    1853             :  *      Return a list of all databases found in pg_database.
    1854             :  *
    1855             :  * The list and associated data is allocated in the caller's memory context,
    1856             :  * which is in charge of ensuring that it's properly cleaned up afterwards.
    1857             :  *
    1858             :  * Note: this is the only function in which the autovacuum launcher uses a
    1859             :  * transaction.  Although we aren't attached to any particular database and
    1860             :  * therefore can't access most catalogs, we do have enough infrastructure
    1861             :  * to do a seqscan on pg_database.
    1862             :  */
    1863             : static List *
    1864         706 : get_database_list(void)
    1865             : {
    1866         706 :     List       *dblist = NIL;
    1867             :     Relation    rel;
    1868             :     TableScanDesc scan;
    1869             :     HeapTuple   tup;
    1870             :     MemoryContext resultcxt;
    1871             : 
    1872             :     /* This is the context that we will allocate our output data in */
    1873         706 :     resultcxt = CurrentMemoryContext;
    1874             : 
    1875             :     /*
    1876             :      * Start a transaction so we can access pg_database, and get a snapshot.
    1877             :      * We don't have a use for the snapshot itself, but we're interested in
    1878             :      * the secondary effect that it sets RecentGlobalXmin.  (This is critical
    1879             :      * for anything that reads heap pages, because HOT may decide to prune
    1880             :      * them even if the process doesn't attempt to modify any tuples.)
    1881             :      */
    1882         706 :     StartTransactionCommand();
    1883         706 :     (void) GetTransactionSnapshot();
    1884             : 
    1885         706 :     rel = table_open(DatabaseRelationId, AccessShareLock);
    1886         706 :     scan = table_beginscan_catalog(rel, 0, NULL);
    1887             : 
    1888        3732 :     while (HeapTupleIsValid(tup = heap_getnext(scan, ForwardScanDirection)))
    1889             :     {
    1890        2320 :         Form_pg_database pgdatabase = (Form_pg_database) GETSTRUCT(tup);
    1891             :         avw_dbase  *avdb;
    1892             :         MemoryContext oldcxt;
    1893             : 
    1894             :         /*
    1895             :          * Allocate our results in the caller's context, not the
    1896             :          * transaction's. We do this inside the loop, and restore the original
    1897             :          * context at the end, so that leaky things like heap_getnext() are
    1898             :          * not called in a potentially long-lived context.
    1899             :          */
    1900        2320 :         oldcxt = MemoryContextSwitchTo(resultcxt);
    1901             : 
    1902        2320 :         avdb = (avw_dbase *) palloc(sizeof(avw_dbase));
    1903             : 
    1904        2320 :         avdb->adw_datid = pgdatabase->oid;
    1905        2320 :         avdb->adw_name = pstrdup(NameStr(pgdatabase->datname));
    1906        2320 :         avdb->adw_frozenxid = pgdatabase->datfrozenxid;
    1907        2320 :         avdb->adw_minmulti = pgdatabase->datminmxid;
    1908             :         /* this gets set later: */
    1909        2320 :         avdb->adw_entry = NULL;
    1910             : 
    1911        2320 :         dblist = lappend(dblist, avdb);
    1912        2320 :         MemoryContextSwitchTo(oldcxt);
    1913             :     }
    1914             : 
    1915         706 :     table_endscan(scan);
    1916         706 :     table_close(rel, AccessShareLock);
    1917             : 
    1918         706 :     CommitTransactionCommand();
    1919             : 
    1920         706 :     return dblist;
    1921             : }
    1922             : 
    1923             : /*
    1924             :  * Process a database table-by-table
    1925             :  *
    1926             :  * Note that CHECK_FOR_INTERRUPTS is supposed to be used in certain spots in
    1927             :  * order not to ignore shutdown commands for too long.
    1928             :  */
    1929             : static void
    1930          60 : do_autovacuum(void)
    1931             : {
    1932             :     Relation    classRel;
    1933             :     HeapTuple   tuple;
    1934             :     TableScanDesc relScan;
    1935             :     Form_pg_database dbForm;
    1936          60 :     List       *table_oids = NIL;
    1937          60 :     List       *orphan_oids = NIL;
    1938             :     HASHCTL     ctl;
    1939             :     HTAB       *table_toast_map;
    1940             :     ListCell   *volatile cell;
    1941             :     PgStat_StatDBEntry *shared;
    1942             :     PgStat_StatDBEntry *dbentry;
    1943             :     BufferAccessStrategy bstrategy;
    1944             :     ScanKeyData key;
    1945             :     TupleDesc   pg_class_desc;
    1946             :     int         effective_multixact_freeze_max_age;
    1947          60 :     bool        did_vacuum = false;
    1948          60 :     bool        found_concurrent_worker = false;
    1949             :     int         i;
    1950             : 
    1951             :     /*
    1952             :      * StartTransactionCommand and CommitTransactionCommand will automatically
    1953             :      * switch to other contexts.  We need this one to keep the list of
    1954             :      * relations to vacuum/analyze across transactions.
    1955             :      */
    1956          60 :     AutovacMemCxt = AllocSetContextCreate(TopMemoryContext,
    1957             :                                           "AV worker",
    1958             :                                           ALLOCSET_DEFAULT_SIZES);
    1959          60 :     MemoryContextSwitchTo(AutovacMemCxt);
    1960             : 
    1961             :     /*
    1962             :      * may be NULL if we couldn't find an entry (only happens if we are
    1963             :      * forcing a vacuum for anti-wrap purposes).
    1964             :      */
    1965          60 :     dbentry = pgstat_fetch_stat_dbentry(MyDatabaseId);
    1966             : 
    1967             :     /* Start a transaction so our commands have one to play into. */
    1968          60 :     StartTransactionCommand();
    1969             : 
    1970             :     /*
    1971             :      * Clean up any dead statistics collector entries for this DB. We always
    1972             :      * want to do this exactly once per DB-processing cycle, even if we find
    1973             :      * nothing worth vacuuming in the database.
    1974             :      */
    1975          60 :     pgstat_vacuum_stat();
    1976             : 
    1977             :     /*
    1978             :      * Compute the multixact age for which freezing is urgent.  This is
    1979             :      * normally autovacuum_multixact_freeze_max_age, but may be less if we are
    1980             :      * short of multixact member space.
    1981             :      */
    1982          60 :     effective_multixact_freeze_max_age = MultiXactMemberFreezeThreshold();
    1983             : 
    1984             :     /*
    1985             :      * Find the pg_database entry and select the default freeze ages. We use
    1986             :      * zero in template and nonconnectable databases, else the system-wide
    1987             :      * default.
    1988             :      */
    1989          60 :     tuple = SearchSysCache1(DATABASEOID, ObjectIdGetDatum(MyDatabaseId));
    1990          60 :     if (!HeapTupleIsValid(tuple))
    1991           0 :         elog(ERROR, "cache lookup failed for database %u", MyDatabaseId);
    1992          60 :     dbForm = (Form_pg_database) GETSTRUCT(tuple);
    1993             : 
    1994          60 :     if (dbForm->datistemplate || !dbForm->datallowconn)
    1995             :     {
    1996           2 :         default_freeze_min_age = 0;
    1997           2 :         default_freeze_table_age = 0;
    1998           2 :         default_multixact_freeze_min_age = 0;
    1999           2 :         default_multixact_freeze_table_age = 0;
    2000             :     }
    2001             :     else
    2002             :     {
    2003          58 :         default_freeze_min_age = vacuum_freeze_min_age;
    2004          58 :         default_freeze_table_age = vacuum_freeze_table_age;
    2005          58 :         default_multixact_freeze_min_age = vacuum_multixact_freeze_min_age;
    2006          58 :         default_multixact_freeze_table_age = vacuum_multixact_freeze_table_age;
    2007             :     }
    2008             : 
    2009          60 :     ReleaseSysCache(tuple);
    2010             : 
    2011             :     /* StartTransactionCommand changed elsewhere */
    2012          60 :     MemoryContextSwitchTo(AutovacMemCxt);
    2013             : 
    2014             :     /* The database hash where pgstat keeps shared relations */
    2015          60 :     shared = pgstat_fetch_stat_dbentry(InvalidOid);
    2016             : 
    2017          60 :     classRel = table_open(RelationRelationId, AccessShareLock);
    2018             : 
    2019             :     /* create a copy so we can use it after closing pg_class */
    2020          60 :     pg_class_desc = CreateTupleDescCopy(RelationGetDescr(classRel));
    2021             : 
    2022             :     /* create hash table for toast <-> main relid mapping */
    2023          60 :     MemSet(&ctl, 0, sizeof(ctl));
    2024          60 :     ctl.keysize = sizeof(Oid);
    2025          60 :     ctl.entrysize = sizeof(av_relation);
    2026             : 
    2027          60 :     table_toast_map = hash_create("TOAST to main relid map",
    2028             :                                   100,
    2029             :                                   &ctl,
    2030             :                                   HASH_ELEM | HASH_BLOBS);
    2031             : 
    2032             :     /*
    2033             :      * Scan pg_class to determine which tables to vacuum.
    2034             :      *
    2035             :      * We do this in two passes: on the first one we collect the list of plain
    2036             :      * relations and materialized views, and on the second one we collect
    2037             :      * TOAST tables. The reason for doing the second pass is that during it we
    2038             :      * want to use the main relation's pg_class.reloptions entry if the TOAST
    2039             :      * table does not have any, and we cannot obtain it unless we know
    2040             :      * beforehand what's the main table OID.
    2041             :      *
    2042             :      * We need to check TOAST tables separately because in cases with short,
    2043             :      * wide tables there might be proportionally much more activity in the
    2044             :      * TOAST table than in its parent.
    2045             :      */
    2046          60 :     relScan = table_beginscan_catalog(classRel, 0, NULL);
    2047             : 
    2048             :     /*
    2049             :      * On the first pass, we collect main tables to vacuum, and also the main
    2050             :      * table relid to TOAST relid mapping.
    2051             :      */
    2052       28328 :     while ((tuple = heap_getnext(relScan, ForwardScanDirection)) != NULL)
    2053             :     {
    2054       28208 :         Form_pg_class classForm = (Form_pg_class) GETSTRUCT(tuple);
    2055             :         PgStat_StatTabEntry *tabentry;
    2056             :         AutoVacOpts *relopts;
    2057             :         Oid         relid;
    2058             :         bool        dovacuum;
    2059             :         bool        doanalyze;
    2060             :         bool        wraparound;
    2061             : 
    2062       50520 :         if (classForm->relkind != RELKIND_RELATION &&
    2063       22312 :             classForm->relkind != RELKIND_MATVIEW)
    2064       44540 :             continue;
    2065             : 
    2066        5938 :         relid = classForm->oid;
    2067             : 
    2068             :         /*
    2069             :          * Check if it is a temp table (presumably, of some other backend's).
    2070             :          * We cannot safely process other backends' temp tables.
    2071             :          */
    2072        5938 :         if (classForm->relpersistence == RELPERSISTENCE_TEMP)
    2073             :         {
    2074             :             /*
    2075             :              * We just ignore it if the owning backend is still active and
    2076             :              * using the temporary schema.
    2077             :              */
    2078           0 :             if (!isTempNamespaceInUse(classForm->relnamespace))
    2079             :             {
    2080             :                 /*
    2081             :                  * The table seems to be orphaned -- although it might be that
    2082             :                  * the owning backend has already deleted it and exited; our
    2083             :                  * pg_class scan snapshot is not necessarily up-to-date
    2084             :                  * anymore, so we could be looking at a committed-dead entry.
    2085             :                  * Remember it so we can try to delete it later.
    2086             :                  */
    2087           0 :                 orphan_oids = lappend_oid(orphan_oids, relid);
    2088             :             }
    2089           0 :             continue;
    2090             :         }
    2091             : 
    2092             :         /* Fetch reloptions and the pgstat entry for this table */
    2093        5938 :         relopts = extract_autovac_opts(tuple, pg_class_desc);
    2094        5938 :         tabentry = get_pgstat_tabentry_relid(relid, classForm->relisshared,
    2095             :                                              shared, dbentry);
    2096             : 
    2097             :         /* Check if it needs vacuum or analyze */
    2098        5938 :         relation_needs_vacanalyze(relid, relopts, classForm, tabentry,
    2099             :                                   effective_multixact_freeze_max_age,
    2100             :                                   &dovacuum, &doanalyze, &wraparound);
    2101             : 
    2102             :         /* Relations that need work are added to table_oids */
    2103        5938 :         if (dovacuum || doanalyze)
    2104         432 :             table_oids = lappend_oid(table_oids, relid);
    2105             : 
    2106             :         /*
    2107             :          * Remember TOAST associations for the second pass.  Note: we must do
    2108             :          * this whether or not the table is going to be vacuumed, because we
    2109             :          * don't automatically vacuum toast tables along the parent table.
    2110             :          */
    2111        5938 :         if (OidIsValid(classForm->reltoastrelid))
    2112             :         {
    2113             :             av_relation *hentry;
    2114             :             bool        found;
    2115             : 
    2116        3260 :             hentry = hash_search(table_toast_map,
    2117        3260 :                                  &classForm->reltoastrelid,
    2118             :                                  HASH_ENTER, &found);
    2119             : 
    2120        3260 :             if (!found)
    2121             :             {
    2122             :                 /* hash_search already filled in the key */
    2123        3260 :                 hentry->ar_relid = relid;
    2124        3260 :                 hentry->ar_hasrelopts = false;
    2125        3260 :                 if (relopts != NULL)
    2126             :                 {
    2127          20 :                     hentry->ar_hasrelopts = true;
    2128          20 :                     memcpy(&hentry->ar_reloptions, relopts,
    2129             :                            sizeof(AutoVacOpts));
    2130             :                 }
    2131             :             }
    2132             :         }
    2133             :     }
    2134             : 
    2135          60 :     table_endscan(relScan);
    2136             : 
    2137             :     /* second pass: check TOAST tables */
    2138          60 :     ScanKeyInit(&key,
    2139             :                 Anum_pg_class_relkind,
    2140             :                 BTEqualStrategyNumber, F_CHAREQ,
    2141             :                 CharGetDatum(RELKIND_TOASTVALUE));
    2142             : 
    2143          60 :     relScan = table_beginscan_catalog(classRel, 1, &key);
    2144        3380 :     while ((tuple = heap_getnext(relScan, ForwardScanDirection)) != NULL)
    2145             :     {
    2146        3260 :         Form_pg_class classForm = (Form_pg_class) GETSTRUCT(tuple);
    2147             :         PgStat_StatTabEntry *tabentry;
    2148             :         Oid         relid;
    2149        3260 :         AutoVacOpts *relopts = NULL;
    2150             :         bool        dovacuum;
    2151             :         bool        doanalyze;
    2152             :         bool        wraparound;
    2153             : 
    2154             :         /*
    2155             :          * We cannot safely process other backends' temp tables, so skip 'em.
    2156             :          */
    2157        3260 :         if (classForm->relpersistence == RELPERSISTENCE_TEMP)
    2158           0 :             continue;
    2159             : 
    2160        3260 :         relid = classForm->oid;
    2161             : 
    2162             :         /*
    2163             :          * fetch reloptions -- if this toast table does not have them, try the
    2164             :          * main rel
    2165             :          */
    2166        3260 :         relopts = extract_autovac_opts(tuple, pg_class_desc);
    2167        3260 :         if (relopts == NULL)
    2168             :         {
    2169             :             av_relation *hentry;
    2170             :             bool        found;
    2171             : 
    2172        3258 :             hentry = hash_search(table_toast_map, &relid, HASH_FIND, &found);
    2173        3258 :             if (found && hentry->ar_hasrelopts)
    2174          18 :                 relopts = &hentry->ar_reloptions;
    2175             :         }
    2176             : 
    2177             :         /* Fetch the pgstat entry for this table */
    2178        3260 :         tabentry = get_pgstat_tabentry_relid(relid, classForm->relisshared,
    2179             :                                              shared, dbentry);
    2180             : 
    2181        3260 :         relation_needs_vacanalyze(relid, relopts, classForm, tabentry,
    2182             :                                   effective_multixact_freeze_max_age,
    2183             :                                   &dovacuum, &doanalyze, &wraparound);
    2184             : 
    2185             :         /* ignore analyze for toast tables */
    2186        3260 :         if (dovacuum)
    2187           0 :             table_oids = lappend_oid(table_oids, relid);
    2188             :     }
    2189             : 
    2190          60 :     table_endscan(relScan);
    2191          60 :     table_close(classRel, AccessShareLock);
    2192             : 
    2193             :     /*
    2194             :      * Recheck orphan temporary tables, and if they still seem orphaned, drop
    2195             :      * them.  We'll eat a transaction per dropped table, which might seem
    2196             :      * excessive, but we should only need to do anything as a result of a
    2197             :      * previous backend crash, so this should not happen often enough to
    2198             :      * justify "optimizing".  Using separate transactions ensures that we
    2199             :      * don't bloat the lock table if there are many temp tables to be dropped,
    2200             :      * and it ensures that we don't lose work if a deletion attempt fails.
    2201             :      */
    2202          60 :     foreach(cell, orphan_oids)
    2203             :     {
    2204           0 :         Oid         relid = lfirst_oid(cell);
    2205             :         Form_pg_class classForm;
    2206             :         ObjectAddress object;
    2207             : 
    2208             :         /*
    2209             :          * Check for user-requested abort.
    2210             :          */
    2211           0 :         CHECK_FOR_INTERRUPTS();
    2212             : 
    2213             :         /*
    2214             :          * Try to lock the table.  If we can't get the lock immediately,
    2215             :          * somebody else is using (or dropping) the table, so it's not our
    2216             :          * concern anymore.  Having the lock prevents race conditions below.
    2217             :          */
    2218           0 :         if (!ConditionalLockRelationOid(relid, AccessExclusiveLock))
    2219           0 :             continue;
    2220             : 
    2221             :         /*
    2222             :          * Re-fetch the pg_class tuple and re-check whether it still seems to
    2223             :          * be an orphaned temp table.  If it's not there or no longer the same
    2224             :          * relation, ignore it.
    2225             :          */
    2226           0 :         tuple = SearchSysCacheCopy1(RELOID, ObjectIdGetDatum(relid));
    2227           0 :         if (!HeapTupleIsValid(tuple))
    2228             :         {
    2229             :             /* be sure to drop useless lock so we don't bloat lock table */
    2230           0 :             UnlockRelationOid(relid, AccessExclusiveLock);
    2231           0 :             continue;
    2232             :         }
    2233           0 :         classForm = (Form_pg_class) GETSTRUCT(tuple);
    2234             : 
    2235             :         /*
    2236             :          * Make all the same tests made in the loop above.  In event of OID
    2237             :          * counter wraparound, the pg_class entry we have now might be
    2238             :          * completely unrelated to the one we saw before.
    2239             :          */
    2240           0 :         if (!((classForm->relkind == RELKIND_RELATION ||
    2241           0 :                classForm->relkind == RELKIND_MATVIEW) &&
    2242           0 :               classForm->relpersistence == RELPERSISTENCE_TEMP))
    2243             :         {
    2244           0 :             UnlockRelationOid(relid, AccessExclusiveLock);
    2245           0 :             continue;
    2246             :         }
    2247             : 
    2248           0 :         if (isTempNamespaceInUse(classForm->relnamespace))
    2249             :         {
    2250           0 :             UnlockRelationOid(relid, AccessExclusiveLock);
    2251           0 :             continue;
    2252             :         }
    2253             : 
    2254             :         /* OK, let's delete it */
    2255           0 :         ereport(LOG,
    2256             :                 (errmsg("autovacuum: dropping orphan temp table \"%s.%s.%s\"",
    2257             :                         get_database_name(MyDatabaseId),
    2258             :                         get_namespace_name(classForm->relnamespace),
    2259             :                         NameStr(classForm->relname))));
    2260             : 
    2261           0 :         object.classId = RelationRelationId;
    2262           0 :         object.objectId = relid;
    2263           0 :         object.objectSubId = 0;
    2264           0 :         performDeletion(&object, DROP_CASCADE,
    2265             :                         PERFORM_DELETION_INTERNAL |
    2266             :                         PERFORM_DELETION_QUIETLY |
    2267             :                         PERFORM_DELETION_SKIP_EXTENSIONS);
    2268             : 
    2269             :         /*
    2270             :          * To commit the deletion, end current transaction and start a new
    2271             :          * one.  Note this also releases the lock we took.
    2272             :          */
    2273           0 :         CommitTransactionCommand();
    2274           0 :         StartTransactionCommand();
    2275             : 
    2276             :         /* StartTransactionCommand changed current memory context */
    2277           0 :         MemoryContextSwitchTo(AutovacMemCxt);
    2278             :     }
    2279             : 
    2280             :     /*
    2281             :      * Create a buffer access strategy object for VACUUM to use.  We want to
    2282             :      * use the same one across all the vacuum operations we perform, since the
    2283             :      * point is for VACUUM not to blow out the shared cache.
    2284             :      */
    2285          60 :     bstrategy = GetAccessStrategy(BAS_VACUUM);
    2286             : 
    2287             :     /*
    2288             :      * create a memory context to act as fake PortalContext, so that the
    2289             :      * contexts created in the vacuum code are cleaned up for each table.
    2290             :      */
    2291          60 :     PortalContext = AllocSetContextCreate(AutovacMemCxt,
    2292             :                                           "Autovacuum Portal",
    2293             :                                           ALLOCSET_DEFAULT_SIZES);
    2294             : 
    2295             :     /*
    2296             :      * Perform operations on collected tables.
    2297             :      */
    2298         492 :     foreach(cell, table_oids)
    2299             :     {
    2300         432 :         Oid         relid = lfirst_oid(cell);
    2301             :         HeapTuple   classTup;
    2302             :         autovac_table *tab;
    2303             :         bool        isshared;
    2304             :         bool        skipit;
    2305             :         double      stdVacuumCostDelay;
    2306             :         int         stdVacuumCostLimit;
    2307             :         dlist_iter  iter;
    2308             : 
    2309         432 :         CHECK_FOR_INTERRUPTS();
    2310             : 
    2311             :         /*
    2312             :          * Check for config changes before processing each collected table.
    2313             :          */
    2314         432 :         if (got_SIGHUP)
    2315             :         {
    2316           0 :             got_SIGHUP = false;
    2317           0 :             ProcessConfigFile(PGC_SIGHUP);
    2318             : 
    2319             :             /*
    2320             :              * You might be tempted to bail out if we see autovacuum is now
    2321             :              * disabled.  Must resist that temptation -- this might be a
    2322             :              * for-wraparound emergency worker, in which case that would be
    2323             :              * entirely inappropriate.
    2324             :              */
    2325             :         }
    2326             : 
    2327             :         /*
    2328             :          * Find out whether the table is shared or not.  (It's slightly
    2329             :          * annoying to fetch the syscache entry just for this, but in typical
    2330             :          * cases it adds little cost because table_recheck_autovac would
    2331             :          * refetch the entry anyway.  We could buy that back by copying the
    2332             :          * tuple here and passing it to table_recheck_autovac, but that
    2333             :          * increases the odds of that function working with stale data.)
    2334             :          */
    2335         432 :         classTup = SearchSysCache1(RELOID, ObjectIdGetDatum(relid));
    2336         432 :         if (!HeapTupleIsValid(classTup))
    2337           0 :             continue;           /* somebody deleted the rel, forget it */
    2338         432 :         isshared = ((Form_pg_class) GETSTRUCT(classTup))->relisshared;
    2339         432 :         ReleaseSysCache(classTup);
    2340             : 
    2341             :         /*
    2342             :          * Hold schedule lock from here until we've claimed the table.  We
    2343             :          * also need the AutovacuumLock to walk the worker array, but that one
    2344             :          * can just be a shared lock.
    2345             :          */
    2346         432 :         LWLockAcquire(AutovacuumScheduleLock, LW_EXCLUSIVE);
    2347         432 :         LWLockAcquire(AutovacuumLock, LW_SHARED);
    2348             : 
    2349             :         /*
    2350             :          * Check whether the table is being vacuumed concurrently by another
    2351             :          * worker.
    2352             :          */
    2353         432 :         skipit = false;
    2354         864 :         dlist_foreach(iter, &AutoVacuumShmem->av_runningWorkers)
    2355             :         {
    2356         432 :             WorkerInfo  worker = dlist_container(WorkerInfoData, wi_links, iter.cur);
    2357             : 
    2358             :             /* ignore myself */
    2359         432 :             if (worker == MyWorkerInfo)
    2360         432 :                 continue;
    2361             : 
    2362             :             /* ignore workers in other databases (unless table is shared) */
    2363           0 :             if (!worker->wi_sharedrel && worker->wi_dboid != MyDatabaseId)
    2364           0 :                 continue;
    2365             : 
    2366           0 :             if (worker->wi_tableoid == relid)
    2367             :             {
    2368           0 :                 skipit = true;
    2369           0 :                 found_concurrent_worker = true;
    2370           0 :                 break;
    2371             :             }
    2372             :         }
    2373         432 :         LWLockRelease(AutovacuumLock);
    2374         432 :         if (skipit)
    2375             :         {
    2376           0 :             LWLockRelease(AutovacuumScheduleLock);
    2377           0 :             continue;
    2378             :         }
    2379             : 
    2380             :         /*
    2381             :          * Store the table's OID in shared memory before releasing the
    2382             :          * schedule lock, so that other workers don't try to vacuum it
    2383             :          * concurrently.  (We claim it here so as not to hold
    2384             :          * AutovacuumScheduleLock while rechecking the stats.)
    2385             :          */
    2386         432 :         MyWorkerInfo->wi_tableoid = relid;
    2387         432 :         MyWorkerInfo->wi_sharedrel = isshared;
    2388         432 :         LWLockRelease(AutovacuumScheduleLock);
    2389             : 
    2390             :         /*
    2391             :          * Check whether pgstat data still says we need to vacuum this table.
    2392             :          * It could have changed if something else processed the table while
    2393             :          * we weren't looking.
    2394             :          *
    2395             :          * Note: we have a special case in pgstat code to ensure that the
    2396             :          * stats we read are as up-to-date as possible, to avoid the problem
    2397             :          * that somebody just finished vacuuming this table.  The window to
    2398             :          * the race condition is not closed but it is very small.
    2399             :          */
    2400         432 :         MemoryContextSwitchTo(AutovacMemCxt);
    2401         432 :         tab = table_recheck_autovac(relid, table_toast_map, pg_class_desc,
    2402             :                                     effective_multixact_freeze_max_age);
    2403         432 :         if (tab == NULL)
    2404             :         {
    2405             :             /* someone else vacuumed the table, or it went away */
    2406           0 :             LWLockAcquire(AutovacuumScheduleLock, LW_EXCLUSIVE);
    2407           0 :             MyWorkerInfo->wi_tableoid = InvalidOid;
    2408           0 :             MyWorkerInfo->wi_sharedrel = false;
    2409           0 :             LWLockRelease(AutovacuumScheduleLock);
    2410           0 :             continue;
    2411             :         }
    2412             : 
    2413             :         /*
    2414             :          * Remember the prevailing values of the vacuum cost GUCs.  We have to
    2415             :          * restore these at the bottom of the loop, else we'll compute wrong
    2416             :          * values in the next iteration of autovac_balance_cost().
    2417             :          */
    2418         432 :         stdVacuumCostDelay = VacuumCostDelay;
    2419         432 :         stdVacuumCostLimit = VacuumCostLimit;
    2420             : 
    2421             :         /* Must hold AutovacuumLock while mucking with cost balance info */
    2422         432 :         LWLockAcquire(AutovacuumLock, LW_EXCLUSIVE);
    2423             : 
    2424             :         /* advertise my cost delay parameters for the balancing algorithm */
    2425         432 :         MyWorkerInfo->wi_dobalance = tab->at_dobalance;
    2426         432 :         MyWorkerInfo->wi_cost_delay = tab->at_vacuum_cost_delay;
    2427         432 :         MyWorkerInfo->wi_cost_limit = tab->at_vacuum_cost_limit;
    2428         432 :         MyWorkerInfo->wi_cost_limit_base = tab->at_vacuum_cost_limit;
    2429             : 
    2430             :         /* do a balance */
    2431         432 :         autovac_balance_cost();
    2432             : 
    2433             :         /* set the active cost parameters from the result of that */
    2434         432 :         AutoVacuumUpdateDelay();
    2435             : 
    2436             :         /* done */
    2437         432 :         LWLockRelease(AutovacuumLock);
    2438             : 
    2439             :         /* clean up memory before each iteration */
    2440         432 :         MemoryContextResetAndDeleteChildren(PortalContext);
    2441             : 
    2442             :         /*
    2443             :          * Save the relation name for a possible error message, to avoid a
    2444             :          * catalog lookup in case of an error.  If any of these return NULL,
    2445             :          * then the relation has been dropped since last we checked; skip it.
    2446             :          * Note: they must live in a long-lived memory context because we call
    2447             :          * vacuum and analyze in different transactions.
    2448             :          */
    2449             : 
    2450         432 :         tab->at_relname = get_rel_name(tab->at_relid);
    2451         432 :         tab->at_nspname = get_namespace_name(get_rel_namespace(tab->at_relid));
    2452         432 :         tab->at_datname = get_database_name(MyDatabaseId);
    2453         432 :         if (!tab->at_relname || !tab->at_nspname || !tab->at_datname)
    2454             :             goto deleted;
    2455             : 
    2456             :         /*
    2457             :          * We will abort vacuuming the current table if something errors out,
    2458             :          * and continue with the next one in schedule; in particular, this
    2459             :          * happens if we are interrupted with SIGINT.
    2460             :          */
    2461         432 :         PG_TRY();
    2462             :         {
    2463             :             /* Use PortalContext for any per-table allocations */
    2464         432 :             MemoryContextSwitchTo(PortalContext);
    2465             : 
    2466             :             /* have at it */
    2467         432 :             autovacuum_do_vac_analyze(tab, bstrategy);
    2468             : 
    2469             :             /*
    2470             :              * Clear a possible query-cancel signal, to avoid a late reaction
    2471             :              * to an automatically-sent signal because of vacuuming the
    2472             :              * current table (we're done with it, so it would make no sense to
    2473             :              * cancel at this point.)
    2474             :              */
    2475         432 :             QueryCancelPending = false;
    2476             :         }
    2477           0 :         PG_CATCH();
    2478             :         {
    2479             :             /*
    2480             :              * Abort the transaction, start a new one, and proceed with the
    2481             :              * next table in our list.
    2482             :              */
    2483           0 :             HOLD_INTERRUPTS();
    2484           0 :             if (tab->at_params.options & VACOPT_VACUUM)
    2485           0 :                 errcontext("automatic vacuum of table \"%s.%s.%s\"",
    2486             :                            tab->at_datname, tab->at_nspname, tab->at_relname);
    2487             :             else
    2488           0 :                 errcontext("automatic analyze of table \"%s.%s.%s\"",
    2489             :                            tab->at_datname, tab->at_nspname, tab->at_relname);
    2490           0 :             EmitErrorReport();
    2491             : 
    2492             :             /* this resets the PGXACT flags too */
    2493           0 :             AbortOutOfAnyTransaction();
    2494           0 :             FlushErrorState();
    2495           0 :             MemoryContextResetAndDeleteChildren(PortalContext);
    2496             : 
    2497             :             /* restart our transaction for the following operations */
    2498           0 :             StartTransactionCommand();
    2499           0 :             RESUME_INTERRUPTS();
    2500             :         }
    2501         432 :         PG_END_TRY();
    2502             : 
    2503             :         /* Make sure we're back in AutovacMemCxt */
    2504         432 :         MemoryContextSwitchTo(AutovacMemCxt);
    2505             : 
    2506         432 :         did_vacuum = true;
    2507             : 
    2508             :         /* the PGXACT flags are reset at the next end of transaction */
    2509             : 
    2510             :         /* be tidy */
    2511             : deleted:
    2512         432 :         if (tab->at_datname != NULL)
    2513         432 :             pfree(tab->at_datname);
    2514         432 :         if (tab->at_nspname != NULL)
    2515         432 :             pfree(tab->at_nspname);
    2516         432 :         if (tab->at_relname != NULL)
    2517         432 :             pfree(tab->at_relname);
    2518         432 :         pfree(tab);
    2519             : 
    2520             :         /*
    2521             :          * Remove my info from shared memory.  We could, but intentionally
    2522             :          * don't, clear wi_cost_limit and friends --- this is on the
    2523             :          * assumption that we probably have more to do with similar cost
    2524             :          * settings, so we don't want to give up our share of I/O for a very
    2525             :          * short interval and thereby thrash the global balance.
    2526             :          */
    2527         432 :         LWLockAcquire(AutovacuumScheduleLock, LW_EXCLUSIVE);
    2528         432 :         MyWorkerInfo->wi_tableoid = InvalidOid;
    2529         432 :         MyWorkerInfo->wi_sharedrel = false;
    2530         432 :         LWLockRelease(AutovacuumScheduleLock);
    2531             : 
    2532             :         /* restore vacuum cost GUCs for the next iteration */
    2533         432 :         VacuumCostDelay = stdVacuumCostDelay;
    2534         432 :         VacuumCostLimit = stdVacuumCostLimit;
    2535             :     }
    2536             : 
    2537             :     /*
    2538             :      * Perform additional work items, as requested by backends.
    2539             :      */
    2540          60 :     LWLockAcquire(AutovacuumLock, LW_EXCLUSIVE);
    2541       15420 :     for (i = 0; i < NUM_WORKITEMS; i++)
    2542             :     {
    2543       15360 :         AutoVacuumWorkItem *workitem = &AutoVacuumShmem->av_workItems[i];
    2544             : 
    2545       15360 :         if (!workitem->avw_used)
    2546       15354 :             continue;
    2547           6 :         if (workitem->avw_active)
    2548           0 :             continue;
    2549           6 :         if (workitem->avw_database != MyDatabaseId)
    2550           0 :             continue;
    2551             : 
    2552             :         /* claim this one, and release lock while performing it */
    2553           6 :         workitem->avw_active = true;
    2554           6 :         LWLockRelease(AutovacuumLock);
    2555             : 
    2556           6 :         perform_work_item(workitem);
    2557             : 
    2558             :         /*
    2559             :          * Check for config changes before acquiring lock for further jobs.
    2560             :          */
    2561           6 :         CHECK_FOR_INTERRUPTS();
    2562           6 :         if (got_SIGHUP)
    2563             :         {
    2564           0 :             got_SIGHUP = false;
    2565           0 :             ProcessConfigFile(PGC_SIGHUP);
    2566             :         }
    2567             : 
    2568           6 :         LWLockAcquire(AutovacuumLock, LW_EXCLUSIVE);
    2569             : 
    2570             :         /* and mark it done */
    2571           6 :         workitem->avw_active = false;
    2572           6 :         workitem->avw_used = false;
    2573             :     }
    2574          60 :     LWLockRelease(AutovacuumLock);
    2575             : 
    2576             :     /*
    2577             :      * We leak table_toast_map here (among other things), but since we're
    2578             :      * going away soon, it's not a problem.
    2579             :      */
    2580             : 
    2581             :     /*
    2582             :      * Update pg_database.datfrozenxid, and truncate pg_xact if possible. We
    2583             :      * only need to do this once, not after each table.
    2584             :      *
    2585             :      * Even if we didn't vacuum anything, it may still be important to do
    2586             :      * this, because one indirect effect of vac_update_datfrozenxid() is to
    2587             :      * update ShmemVariableCache->xidVacLimit.  That might need to be done
    2588             :      * even if we haven't vacuumed anything, because relations with older
    2589             :      * relfrozenxid values or other databases with older datfrozenxid values
    2590             :      * might have been dropped, allowing xidVacLimit to advance.
    2591             :      *
    2592             :      * However, it's also important not to do this blindly in all cases,
    2593             :      * because when autovacuum=off this will restart the autovacuum launcher.
    2594             :      * If we're not careful, an infinite loop can result, where workers find
    2595             :      * no work to do and restart the launcher, which starts another worker in
    2596             :      * the same database that finds no work to do.  To prevent that, we skip
    2597             :      * this if (1) we found no work to do and (2) we skipped at least one
    2598             :      * table due to concurrent autovacuum activity.  In that case, the other
    2599             :      * worker has already done it, or will do so when it finishes.
    2600             :      */
    2601          60 :     if (did_vacuum || !found_concurrent_worker)
    2602          60 :         vac_update_datfrozenxid();
    2603             : 
    2604             :     /* Finally close out the last transaction. */
    2605          60 :     CommitTransactionCommand();
    2606          60 : }
    2607             : 
    2608             : /*
    2609             :  * Execute a previously registered work item.
    2610             :  */
    2611             : static void
    2612           6 : perform_work_item(AutoVacuumWorkItem *workitem)
    2613             : {
    2614           6 :     char       *cur_datname = NULL;
    2615           6 :     char       *cur_nspname = NULL;
    2616           6 :     char       *cur_relname = NULL;
    2617             : 
    2618             :     /*
    2619             :      * Note we do not store table info in MyWorkerInfo, since this is not
    2620             :      * vacuuming proper.
    2621             :      */
    2622             : 
    2623             :     /*
    2624             :      * Save the relation name for a possible error message, to avoid a catalog
    2625             :      * lookup in case of an error.  If any of these return NULL, then the
    2626             :      * relation has been dropped since last we checked; skip it.
    2627             :      */
    2628             :     Assert(CurrentMemoryContext == AutovacMemCxt);
    2629             : 
    2630           6 :     cur_relname = get_rel_name(workitem->avw_relation);
    2631           6 :     cur_nspname = get_namespace_name(get_rel_namespace(workitem->avw_relation));
    2632           6 :     cur_datname = get_database_name(MyDatabaseId);
    2633           6 :     if (!cur_relname || !cur_nspname || !cur_datname)
    2634             :         goto deleted2;
    2635             : 
    2636           6 :     autovac_report_workitem(workitem, cur_nspname, cur_relname);
    2637             : 
    2638             :     /* clean up memory before each work item */
    2639           6 :     MemoryContextResetAndDeleteChildren(PortalContext);
    2640             : 
    2641             :     /*
    2642             :      * We will abort the current work item if something errors out, and
    2643             :      * continue with the next one; in particular, this happens if we are
    2644             :      * interrupted with SIGINT.  Note that this means that the work item list
    2645             :      * can be lossy.
    2646             :      */
    2647           6 :     PG_TRY();
    2648             :     {
    2649             :         /* Use PortalContext for any per-work-item allocations */
    2650           6 :         MemoryContextSwitchTo(PortalContext);
    2651             : 
    2652             :         /* have at it */
    2653           6 :         switch (workitem->avw_type)
    2654             :         {
    2655             :             case AVW_BRINSummarizeRange:
    2656           6 :                 DirectFunctionCall2(brin_summarize_range,
    2657             :                                     ObjectIdGetDatum(workitem->avw_relation),
    2658             :                                     Int64GetDatum((int64) workitem->avw_blockNumber));
    2659           6 :                 break;
    2660             :             default:
    2661           0 :                 elog(WARNING, "unrecognized work item found: type %d",
    2662             :                      workitem->avw_type);
    2663           0 :                 break;
    2664             :         }
    2665             : 
    2666             :         /*
    2667             :          * Clear a possible query-cancel signal, to avoid a late reaction to
    2668             :          * an automatically-sent signal because of vacuuming the current table
    2669             :          * (we're done with it, so it would make no sense to cancel at this
    2670             :          * point.)
    2671             :          */
    2672           6 :         QueryCancelPending = false;
    2673             :     }
    2674           0 :     PG_CATCH();
    2675             :     {
    2676             :         /*
    2677             :          * Abort the transaction, start a new one, and proceed with the next
    2678             :          * table in our list.
    2679             :          */
    2680           0 :         HOLD_INTERRUPTS();
    2681           0 :         errcontext("processing work entry for relation \"%s.%s.%s\"",
    2682             :                    cur_datname, cur_nspname, cur_relname);
    2683           0 :         EmitErrorReport();
    2684             : 
    2685             :         /* this resets the PGXACT flags too */
    2686           0 :         AbortOutOfAnyTransaction();
    2687           0 :         FlushErrorState();
    2688           0 :         MemoryContextResetAndDeleteChildren(PortalContext);
    2689             : 
    2690             :         /* restart our transaction for the following operations */
    2691           0 :         StartTransactionCommand();
    2692           0 :         RESUME_INTERRUPTS();
    2693             :     }
    2694           6 :     PG_END_TRY();
    2695             : 
    2696             :     /* Make sure we're back in AutovacMemCxt */
    2697           6 :     MemoryContextSwitchTo(AutovacMemCxt);
    2698             : 
    2699             :     /* We intentionally do not set did_vacuum here */
    2700             : 
    2701             :     /* be tidy */
    2702             : deleted2:
    2703           6 :     if (cur_datname)
    2704           6 :         pfree(cur_datname);
    2705           6 :     if (cur_nspname)
    2706           6 :         pfree(cur_nspname);
    2707           6 :     if (cur_relname)
    2708           6 :         pfree(cur_relname);
    2709           6 : }
    2710             : 
    2711             : /*
    2712             :  * extract_autovac_opts
    2713             :  *
    2714             :  * Given a relation's pg_class tuple, return the AutoVacOpts portion of
    2715             :  * reloptions, if set; otherwise, return NULL.
    2716             :  */
    2717             : static AutoVacOpts *
    2718        9630 : extract_autovac_opts(HeapTuple tup, TupleDesc pg_class_desc)
    2719             : {
    2720             :     bytea      *relopts;
    2721             :     AutoVacOpts *av;
    2722             : 
    2723             :     Assert(((Form_pg_class) GETSTRUCT(tup))->relkind == RELKIND_RELATION ||
    2724             :            ((Form_pg_class) GETSTRUCT(tup))->relkind == RELKIND_MATVIEW ||
    2725             :            ((Form_pg_class) GETSTRUCT(tup))->relkind == RELKIND_TOASTVALUE);
    2726             : 
    2727        9630 :     relopts = extractRelOptions(tup, pg_class_desc, NULL);
    2728        9630 :     if (relopts == NULL)
    2729        9592 :         return NULL;
    2730             : 
    2731          38 :     av = palloc(sizeof(AutoVacOpts));
    2732          38 :     memcpy(av, &(((StdRdOptions *) relopts)->autovacuum), sizeof(AutoVacOpts));
    2733          38 :     pfree(relopts);
    2734             : 
    2735          38 :     return av;
    2736             : }
    2737             : 
    2738             : /*
    2739             :  * get_pgstat_tabentry_relid
    2740             :  *
    2741             :  * Fetch the pgstat entry of a table, either local to a database or shared.
    2742             :  */
    2743             : static PgStat_StatTabEntry *
    2744        9630 : get_pgstat_tabentry_relid(Oid relid, bool isshared, PgStat_StatDBEntry *shared,
    2745             :                           PgStat_StatDBEntry *dbentry)
    2746             : {
    2747        9630 :     PgStat_StatTabEntry *tabentry = NULL;
    2748             : 
    2749        9630 :     if (isshared)
    2750             :     {
    2751        1224 :         if (PointerIsValid(shared))
    2752        1224 :             tabentry = hash_search(shared->tables, &relid,
    2753             :                                    HASH_FIND, NULL);
    2754             :     }
    2755        8406 :     else if (PointerIsValid(dbentry))
    2756        8406 :         tabentry = hash_search(dbentry->tables, &relid,
    2757             :                                HASH_FIND, NULL);
    2758             : 
    2759        9630 :     return tabentry;
    2760             : }
    2761             : 
    2762             : /*
    2763             :  * table_recheck_autovac
    2764             :  *
    2765             :  * Recheck whether a table still needs vacuum or analyze.  Return value is a
    2766             :  * valid autovac_table pointer if it does, NULL otherwise.
    2767             :  *
    2768             :  * Note that the returned autovac_table does not have the name fields set.
    2769             :  */
    2770             : static autovac_table *
    2771         432 : table_recheck_autovac(Oid relid, HTAB *table_toast_map,
    2772             :                       TupleDesc pg_class_desc,
    2773             :                       int effective_multixact_freeze_max_age)
    2774             : {
    2775             :     Form_pg_class classForm;
    2776             :     HeapTuple   classTup;
    2777             :     bool        dovacuum;
    2778             :     bool        doanalyze;
    2779         432 :     autovac_table *tab = NULL;
    2780             :     PgStat_StatTabEntry *tabentry;
    2781             :     PgStat_StatDBEntry *shared;
    2782             :     PgStat_StatDBEntry *dbentry;
    2783             :     bool        wraparound;
    2784             :     AutoVacOpts *avopts;
    2785             : 
    2786             :     /* use fresh stats */
    2787         432 :     autovac_refresh_stats();
    2788             : 
    2789         432 :     shared = pgstat_fetch_stat_dbentry(InvalidOid);
    2790         432 :     dbentry = pgstat_fetch_stat_dbentry(MyDatabaseId);
    2791             : 
    2792             :     /* fetch the relation's relcache entry */
    2793         432 :     classTup = SearchSysCacheCopy1(RELOID, ObjectIdGetDatum(relid));
    2794         432 :     if (!HeapTupleIsValid(classTup))
    2795           0 :         return NULL;
    2796         432 :     classForm = (Form_pg_class) GETSTRUCT(classTup);
    2797             : 
    2798             :     /*
    2799             :      * Get the applicable reloptions.  If it is a TOAST table, try to get the
    2800             :      * main table reloptions if the toast table itself doesn't have.
    2801             :      */
    2802         432 :     avopts = extract_autovac_opts(classTup, pg_class_desc);
    2803         432 :     if (classForm->relkind == RELKIND_TOASTVALUE &&
    2804           0 :         avopts == NULL && table_toast_map != NULL)
    2805             :     {
    2806             :         av_relation *hentry;
    2807             :         bool        found;
    2808             : 
    2809           0 :         hentry = hash_search(table_toast_map, &relid, HASH_FIND, &found);
    2810           0 :         if (found && hentry->ar_hasrelopts)
    2811           0 :             avopts = &hentry->ar_reloptions;
    2812             :     }
    2813             : 
    2814             :     /* fetch the pgstat table entry */
    2815         432 :     tabentry = get_pgstat_tabentry_relid(relid, classForm->relisshared,
    2816             :                                          shared, dbentry);
    2817             : 
    2818         432 :     relation_needs_vacanalyze(relid, avopts, classForm, tabentry,
    2819             :                               effective_multixact_freeze_max_age,
    2820             :                               &dovacuum, &doanalyze, &wraparound);
    2821             : 
    2822             :     /* ignore ANALYZE for toast tables */
    2823         432 :     if (classForm->relkind == RELKIND_TOASTVALUE)
    2824           0 :         doanalyze = false;
    2825             : 
    2826             :     /* OK, it needs something done */
    2827         432 :     if (doanalyze || dovacuum)
    2828             :     {
    2829             :         int         freeze_min_age;
    2830             :         int         freeze_table_age;
    2831             :         int         multixact_freeze_min_age;
    2832             :         int         multixact_freeze_table_age;
    2833             :         int         vac_cost_limit;
    2834             :         double      vac_cost_delay;
    2835             :         int         log_min_duration;
    2836             : 
    2837             :         /*
    2838             :          * Calculate the vacuum cost parameters and the freeze ages.  If there
    2839             :          * are options set in pg_class.reloptions, use them; in the case of a
    2840             :          * toast table, try the main table too.  Otherwise use the GUC
    2841             :          * defaults, autovacuum's own first and plain vacuum second.
    2842             :          */
    2843             : 
    2844             :         /* -1 in autovac setting means use plain vacuum_cost_delay */
    2845         440 :         vac_cost_delay = (avopts && avopts->vacuum_cost_delay >= 0)
    2846             :             ? avopts->vacuum_cost_delay
    2847         864 :             : (autovacuum_vac_cost_delay >= 0)
    2848             :             ? autovacuum_vac_cost_delay
    2849         432 :             : VacuumCostDelay;
    2850             : 
    2851             :         /* 0 or -1 in autovac setting means use plain vacuum_cost_limit */
    2852         440 :         vac_cost_limit = (avopts && avopts->vacuum_cost_limit > 0)
    2853             :             ? avopts->vacuum_cost_limit
    2854         864 :             : (autovacuum_vac_cost_limit > 0)
    2855             :             ? autovacuum_vac_cost_limit
    2856         432 :             : VacuumCostLimit;
    2857             : 
    2858             :         /* -1 in autovac setting means use log_autovacuum_min_duration */
    2859         440 :         log_min_duration = (avopts && avopts->log_min_duration >= 0)
    2860             :             ? avopts->log_min_duration
    2861         432 :             : Log_autovacuum_min_duration;
    2862             : 
    2863             :         /* these do not have autovacuum-specific settings */
    2864         440 :         freeze_min_age = (avopts && avopts->freeze_min_age >= 0)
    2865             :             ? avopts->freeze_min_age
    2866         432 :             : default_freeze_min_age;
    2867             : 
    2868         440 :         freeze_table_age = (avopts && avopts->freeze_table_age >= 0)
    2869             :             ? avopts->freeze_table_age
    2870         432 :             : default_freeze_table_age;
    2871             : 
    2872         440 :         multixact_freeze_min_age = (avopts &&
    2873           8 :                                     avopts->multixact_freeze_min_age >= 0)
    2874             :             ? avopts->multixact_freeze_min_age
    2875         432 :             : default_multixact_freeze_min_age;
    2876             : 
    2877         440 :         multixact_freeze_table_age = (avopts &&
    2878           8 :                                       avopts->multixact_freeze_table_age >= 0)
    2879             :             ? avopts->multixact_freeze_table_age
    2880         432 :             : default_multixact_freeze_table_age;
    2881             : 
    2882         432 :         tab = palloc(sizeof(autovac_table));
    2883         432 :         tab->at_relid = relid;
    2884         432 :         tab->at_sharedrel = classForm->relisshared;
    2885         864 :         tab->at_params.options = VACOPT_SKIPTOAST |
    2886         864 :             (dovacuum ? VACOPT_VACUUM : 0) |
    2887         864 :             (doanalyze ? VACOPT_ANALYZE : 0) |
    2888         432 :             (!wraparound ? VACOPT_SKIP_LOCKED : 0);
    2889         432 :         tab->at_params.index_cleanup = VACOPT_TERNARY_DEFAULT;
    2890         432 :         tab->at_params.truncate = VACOPT_TERNARY_DEFAULT;
    2891         432 :         tab->at_params.freeze_min_age = freeze_min_age;
    2892         432 :         tab->at_params.freeze_table_age = freeze_table_age;
    2893         432 :         tab->at_params.multixact_freeze_min_age = multixact_freeze_min_age;
    2894         432 :         tab->at_params.multixact_freeze_table_age = multixact_freeze_table_age;
    2895         432 :         tab->at_params.is_wraparound = wraparound;
    2896         432 :         tab->at_params.log_min_duration = log_min_duration;
    2897         432 :         tab->at_vacuum_cost_limit = vac_cost_limit;
    2898         432 :         tab->at_vacuum_cost_delay = vac_cost_delay;
    2899         432 :         tab->at_relname = NULL;
    2900         432 :         tab->at_nspname = NULL;
    2901         432 :         tab->at_datname = NULL;
    2902             : 
    2903             :         /*
    2904             :          * If any of the cost delay parameters has been set individually for
    2905             :          * this table, disable the balancing algorithm.
    2906             :          */
    2907         432 :         tab->at_dobalance =
    2908         440 :             !(avopts && (avopts->vacuum_cost_limit > 0 ||
    2909           8 :                          avopts->vacuum_cost_delay > 0));
    2910             :     }
    2911             : 
    2912         432 :     heap_freetuple(classTup);
    2913             : 
    2914         432 :     return tab;
    2915             : }
    2916             : 
    2917             : /*
    2918             :  * relation_needs_vacanalyze
    2919             :  *
    2920             :  * Check whether a relation needs to be vacuumed or analyzed; return each into
    2921             :  * "dovacuum" and "doanalyze", respectively.  Also return whether the vacuum is
    2922             :  * being forced because of Xid or multixact wraparound.
    2923             :  *
    2924             :  * relopts is a pointer to the AutoVacOpts options (either for itself in the
    2925             :  * case of a plain table, or for either itself or its parent table in the case
    2926             :  * of a TOAST table), NULL if none; tabentry is the pgstats entry, which can be
    2927             :  * NULL.
    2928             :  *
    2929             :  * A table needs to be vacuumed if the number of dead tuples exceeds a
    2930             :  * threshold.  This threshold is calculated as
    2931             :  *
    2932             :  * threshold = vac_base_thresh + vac_scale_factor * reltuples
    2933             :  *
    2934             :  * For analyze, the analysis done is that the number of tuples inserted,
    2935             :  * deleted and updated since the last analyze exceeds a threshold calculated
    2936             :  * in the same fashion as above.  Note that the collector actually stores
    2937             :  * the number of tuples (both live and dead) that there were as of the last
    2938             :  * analyze.  This is asymmetric to the VACUUM case.
    2939             :  *
    2940             :  * We also force vacuum if the table's relfrozenxid is more than freeze_max_age
    2941             :  * transactions back, and if its relminmxid is more than
    2942             :  * multixact_freeze_max_age multixacts back.
    2943             :  *
    2944             :  * A table whose autovacuum_enabled option is false is
    2945             :  * automatically skipped (unless we have to vacuum it due to freeze_max_age).
    2946             :  * Thus autovacuum can be disabled for specific tables. Also, when the stats
    2947             :  * collector does not have data about a table, it will be skipped.
    2948             :  *
    2949             :  * A table whose vac_base_thresh value is < 0 takes the base value from the
    2950             :  * autovacuum_vacuum_threshold GUC variable.  Similarly, a vac_scale_factor
    2951             :  * value < 0 is substituted with the value of
    2952             :  * autovacuum_vacuum_scale_factor GUC variable.  Ditto for analyze.
    2953             :  */
    2954             : static void
    2955        9630 : relation_needs_vacanalyze(Oid relid,
    2956             :                           AutoVacOpts *relopts,
    2957             :                           Form_pg_class classForm,
    2958             :                           PgStat_StatTabEntry *tabentry,
    2959             :                           int effective_multixact_freeze_max_age,
    2960             :  /* output params below */
    2961             :                           bool *dovacuum,
    2962             :                           bool *doanalyze,
    2963             :                           bool *wraparound)
    2964             : {
    2965             :     bool        force_vacuum;
    2966             :     bool        av_enabled;
    2967             :     float4      reltuples;      /* pg_class.reltuples */
    2968             : 
    2969             :     /* constants from reloptions or GUC variables */
    2970             :     int         vac_base_thresh,
    2971             :                 anl_base_thresh;
    2972             :     float4      vac_scale_factor,
    2973             :                 anl_scale_factor;
    2974             : 
    2975             :     /* thresholds calculated from above constants */
    2976             :     float4      vacthresh,
    2977             :                 anlthresh;
    2978             : 
    2979             :     /* number of vacuum (resp. analyze) tuples at this time */
    2980             :     float4      vactuples,
    2981             :                 anltuples;
    2982             : 
    2983             :     /* freeze parameters */
    2984             :     int         freeze_max_age;
    2985             :     int         multixact_freeze_max_age;
    2986             :     TransactionId xidForceLimit;
    2987             :     MultiXactId multiForceLimit;
    2988             : 
    2989             :     AssertArg(classForm != NULL);
    2990             :     AssertArg(OidIsValid(relid));
    2991             : 
    2992             :     /*
    2993             :      * Determine vacuum/analyze equation parameters.  We have two possible
    2994             :      * sources: the passed reloptions (which could be a main table or a toast
    2995             :      * table), or the autovacuum GUC variables.
    2996             :      */
    2997             : 
    2998             :     /* -1 in autovac setting means use plain vacuum_scale_factor */
    2999        9686 :     vac_scale_factor = (relopts && relopts->vacuum_scale_factor >= 0)
    3000           0 :         ? relopts->vacuum_scale_factor
    3001        9630 :         : autovacuum_vac_scale;
    3002             : 
    3003        9686 :     vac_base_thresh = (relopts && relopts->vacuum_threshold >= 0)
    3004             :         ? relopts->vacuum_threshold
    3005        9630 :         : autovacuum_vac_thresh;
    3006             : 
    3007        9686 :     anl_scale_factor = (relopts && relopts->analyze_scale_factor >= 0)
    3008           0 :         ? relopts->analyze_scale_factor
    3009        9630 :         : autovacuum_anl_scale;
    3010             : 
    3011        9686 :     anl_base_thresh = (relopts && relopts->analyze_threshold >= 0)
    3012             :         ? relopts->analyze_threshold
    3013        9630 :         : autovacuum_anl_thresh;
    3014             : 
    3015        9686 :     freeze_max_age = (relopts && relopts->freeze_max_age >= 0)
    3016           0 :         ? Min(relopts->freeze_max_age, autovacuum_freeze_max_age)
    3017        9630 :         : autovacuum_freeze_max_age;
    3018             : 
    3019        9686 :     multixact_freeze_max_age = (relopts && relopts->multixact_freeze_max_age >= 0)
    3020           0 :         ? Min(relopts->multixact_freeze_max_age, effective_multixact_freeze_max_age)
    3021        9630 :         : effective_multixact_freeze_max_age;
    3022             : 
    3023        9630 :     av_enabled = (relopts ? relopts->enabled : true);
    3024             : 
    3025             :     /* Force vacuum if table is at risk of wraparound */
    3026        9630 :     xidForceLimit = recentXid - freeze_max_age;
    3027        9630 :     if (xidForceLimit < FirstNormalTransactionId)
    3028           0 :         xidForceLimit -= FirstNormalTransactionId;
    3029       19260 :     force_vacuum = (TransactionIdIsNormal(classForm->relfrozenxid) &&
    3030        9630 :                     TransactionIdPrecedes(classForm->relfrozenxid,
    3031             :                                           xidForceLimit));
    3032        9630 :     if (!force_vacuum)
    3033             :     {
    3034        9630 :         multiForceLimit = recentMulti - multixact_freeze_max_age;
    3035        9630 :         if (multiForceLimit < FirstMultiXactId)
    3036           0 :             multiForceLimit -= FirstMultiXactId;
    3037       19260 :         force_vacuum = MultiXactIdIsValid(classForm->relminmxid) &&
    3038        9630 :             MultiXactIdPrecedes(classForm->relminmxid, multiForceLimit);
    3039             :     }
    3040        9630 :     *wraparound = force_vacuum;
    3041             : 
    3042             :     /* User disabled it in pg_class.reloptions?  (But ignore if at risk) */
    3043        9630 :     if (!av_enabled && !force_vacuum)
    3044             :     {
    3045          18 :         *doanalyze = false;
    3046          18 :         *dovacuum = false;
    3047          18 :         return;
    3048             :     }
    3049             : 
    3050             :     /*
    3051             :      * If we found the table in the stats hash, and autovacuum is currently
    3052             :      * enabled, make a threshold-based decision whether to vacuum and/or
    3053             :      * analyze.  If autovacuum is currently disabled, we must be here for
    3054             :      * anti-wraparound vacuuming only, so don't vacuum (or analyze) anything
    3055             :      * that's not being forced.
    3056             :      */
    3057        9612 :     if (PointerIsValid(tabentry) && AutoVacuumingActive())
    3058             :     {
    3059        5042 :         reltuples = classForm->reltuples;
    3060        5042 :         vactuples = tabentry->n_dead_tuples;
    3061        5042 :         anltuples = tabentry->changes_since_analyze;
    3062             : 
    3063        5042 :         vacthresh = (float4) vac_base_thresh + vac_scale_factor * reltuples;
    3064        5042 :         anlthresh = (float4) anl_base_thresh + anl_scale_factor * reltuples;
    3065             : 
    3066             :         /*
    3067             :          * Note that we don't need to take special consideration for stat
    3068             :          * reset, because if that happens, the last vacuum and analyze counts
    3069             :          * will be reset too.
    3070             :          */
    3071        5042 :         elog(DEBUG3, "%s: vac: %.0f (threshold %.0f), anl: %.0f (threshold %.0f)",
    3072             :              NameStr(classForm->relname),
    3073             :              vactuples, vacthresh, anltuples, anlthresh);
    3074             : 
    3075             :         /* Determine if this table needs vacuum or analyze. */
    3076        5042 :         *dovacuum = force_vacuum || (vactuples > vacthresh);
    3077        5042 :         *doanalyze = (anltuples > anlthresh);
    3078             :     }
    3079             :     else
    3080             :     {
    3081             :         /*
    3082             :          * Skip a table not found in stat hash, unless we have to force vacuum
    3083             :          * for anti-wrap purposes.  If it's not acted upon, there's no need to
    3084             :          * vacuum it.
    3085             :          */
    3086        4570 :         *dovacuum = force_vacuum;
    3087        4570 :         *doanalyze = false;
    3088             :     }
    3089             : 
    3090             :     /* ANALYZE refuses to work with pg_statistic */
    3091        9612 :     if (relid == StatisticRelationId)
    3092          70 :         *doanalyze = false;
    3093             : }
    3094             : 
    3095             : /*
    3096             :  * autovacuum_do_vac_analyze
    3097             :  *      Vacuum and/or analyze the specified table
    3098             :  */
    3099             : static void
    3100         432 : autovacuum_do_vac_analyze(autovac_table *tab, BufferAccessStrategy bstrategy)
    3101             : {
    3102             :     RangeVar   *rangevar;
    3103             :     VacuumRelation *rel;
    3104             :     List       *rel_list;
    3105             : 
    3106             :     /* Let pgstat know what we're doing */
    3107         432 :     autovac_report_activity(tab);
    3108             : 
    3109             :     /* Set up one VacuumRelation target, identified by OID, for vacuum() */
    3110         432 :     rangevar = makeRangeVar(tab->at_nspname, tab->at_relname, -1);
    3111         432 :     rel = makeVacuumRelation(rangevar, tab->at_relid, NIL);
    3112         432 :     rel_list = list_make1(rel);
    3113             : 
    3114         432 :     vacuum(rel_list, &tab->at_params, bstrategy, true);
    3115         432 : }
    3116             : 
    3117             : /*
    3118             :  * autovac_report_activity
    3119             :  *      Report to pgstat what autovacuum is doing
    3120             :  *
    3121             :  * We send a SQL string corresponding to what the user would see if the
    3122             :  * equivalent command was to be issued manually.
    3123             :  *
    3124             :  * Note we assume that we are going to report the next command as soon as we're
    3125             :  * done with the current one, and exit right after the last one, so we don't
    3126             :  * bother to report "<IDLE>" or some such.
    3127             :  */
    3128             : static void
    3129         432 : autovac_report_activity(autovac_table *tab)
    3130             : {
    3131             : #define MAX_AUTOVAC_ACTIV_LEN (NAMEDATALEN * 2 + 56)
    3132             :     char        activity[MAX_AUTOVAC_ACTIV_LEN];
    3133             :     int         len;
    3134             : 
    3135             :     /* Report the command and possible options */
    3136         432 :     if (tab->at_params.options & VACOPT_VACUUM)
    3137         154 :         snprintf(activity, MAX_AUTOVAC_ACTIV_LEN,
    3138             :                  "autovacuum: VACUUM%s",
    3139         154 :                  tab->at_params.options & VACOPT_ANALYZE ? " ANALYZE" : "");
    3140             :     else
    3141         278 :         snprintf(activity, MAX_AUTOVAC_ACTIV_LEN,
    3142             :                  "autovacuum: ANALYZE");
    3143             : 
    3144             :     /*
    3145             :      * Report the qualified name of the relation.
    3146             :      */
    3147         432 :     len = strlen(activity);
    3148             : 
    3149         432 :     snprintf(activity + len, MAX_AUTOVAC_ACTIV_LEN - len,
    3150             :              " %s.%s%s", tab->at_nspname, tab->at_relname,
    3151         432 :              tab->at_params.is_wraparound ? " (to prevent wraparound)" : "");
    3152             : 
    3153             :     /* Set statement_timestamp() to current time for pg_stat_activity */
    3154         432 :     SetCurrentStatementStartTimestamp();
    3155             : 
    3156         432 :     pgstat_report_activity(STATE_RUNNING, activity);
    3157         432 : }
    3158             : 
    3159             : /*
    3160             :  * autovac_report_workitem
    3161             :  *      Report to pgstat that autovacuum is processing a work item
    3162             :  */
    3163             : static void
    3164           6 : autovac_report_workitem(AutoVacuumWorkItem *workitem,
    3165             :                         const char *nspname, const char *relname)
    3166             : {
    3167             :     char        activity[MAX_AUTOVAC_ACTIV_LEN + 12 + 2];
    3168             :     char        blk[12 + 2];
    3169             :     int         len;
    3170             : 
    3171           6 :     switch (workitem->avw_type)
    3172             :     {
    3173             :         case AVW_BRINSummarizeRange:
    3174           6 :             snprintf(activity, MAX_AUTOVAC_ACTIV_LEN,
    3175             :                      "autovacuum: BRIN summarize");
    3176           6 :             break;
    3177             :     }
    3178             : 
    3179             :     /*
    3180             :      * Report the qualified name of the relation, and the block number if any
    3181             :      */
    3182           6 :     len = strlen(activity);
    3183             : 
    3184           6 :     if (BlockNumberIsValid(workitem->avw_blockNumber))
    3185           6 :         snprintf(blk, sizeof(blk), " %u", workitem->avw_blockNumber);
    3186             :     else
    3187           0 :         blk[0] = '\0';
    3188             : 
    3189           6 :     snprintf(activity + len, MAX_AUTOVAC_ACTIV_LEN - len,
    3190             :              " %s.%s%s", nspname, relname, blk);
    3191             : 
    3192             :     /* Set statement_timestamp() to current time for pg_stat_activity */
    3193           6 :     SetCurrentStatementStartTimestamp();
    3194             : 
    3195           6 :     pgstat_report_activity(STATE_RUNNING, activity);
    3196           6 : }
    3197             : 
    3198             : /*
    3199             :  * AutoVacuumingActive
    3200             :  *      Check GUC vars and report whether the autovacuum process should be
    3201             :  *      running.
    3202             :  */
    3203             : bool
    3204        8692 : AutoVacuumingActive(void)
    3205             : {
    3206        8692 :     if (!autovacuum_start_daemon || !pgstat_track_counts)
    3207         226 :         return false;
    3208        8466 :     return true;
    3209             : }
    3210             : 
    3211             : /*
    3212             :  * Request one work item to the next autovacuum run processing our database.
    3213             :  * Return false if the request can't be recorded.
    3214             :  */
    3215             : bool
    3216           6 : AutoVacuumRequestWork(AutoVacuumWorkItemType type, Oid relationId,
    3217             :                       BlockNumber blkno)
    3218             : {
    3219             :     int         i;
    3220           6 :     bool        result = false;
    3221             : 
    3222           6 :     LWLockAcquire(AutovacuumLock, LW_EXCLUSIVE);
    3223             : 
    3224             :     /*
    3225             :      * Locate an unused work item and fill it with the given data.
    3226             :      */
    3227          24 :     for (i = 0; i < NUM_WORKITEMS; i++)
    3228             :     {
    3229          12 :         AutoVacuumWorkItem *workitem = &AutoVacuumShmem->av_workItems[i];
    3230             : 
    3231          12 :         if (workitem->avw_used)
    3232           6 :             continue;
    3233             : 
    3234           6 :         workitem->avw_used = true;
    3235           6 :         workitem->avw_active = false;
    3236           6 :         workitem->avw_type = type;
    3237           6 :         workitem->avw_database = MyDatabaseId;
    3238           6 :         workitem->avw_relation = relationId;
    3239           6 :         workitem->avw_blockNumber = blkno;
    3240           6 :         result = true;
    3241             : 
    3242             :         /* done */
    3243           6 :         break;
    3244             :     }
    3245             : 
    3246           6 :     LWLockRelease(AutovacuumLock);
    3247             : 
    3248           6 :     return result;
    3249             : }
    3250             : 
    3251             : /*
    3252             :  * autovac_init
    3253             :  *      This is called at postmaster initialization.
    3254             :  *
    3255             :  * All we do here is annoy the user if he got it wrong.
    3256             :  */
    3257             : void
    3258         572 : autovac_init(void)
    3259             : {
    3260         572 :     if (autovacuum_start_daemon && !pgstat_track_counts)
    3261           0 :         ereport(WARNING,
    3262             :                 (errmsg("autovacuum not started because of misconfiguration"),
    3263             :                  errhint("Enable the \"track_counts\" option.")));
    3264         572 : }
    3265             : 
    3266             : /*
    3267             :  * IsAutoVacuum functions
    3268             :  *      Return whether this is either a launcher autovacuum process or a worker
    3269             :  *      process.
    3270             :  */
    3271             : bool
    3272       56140 : IsAutoVacuumLauncherProcess(void)
    3273             : {
    3274       56140 :     return am_autovacuum_launcher;
    3275             : }
    3276             : 
    3277             : bool
    3278      270352 : IsAutoVacuumWorkerProcess(void)
    3279             : {
    3280      270352 :     return am_autovacuum_worker;
    3281             : }
    3282             : 
    3283             : 
    3284             : /*
    3285             :  * AutoVacuumShmemSize
    3286             :  *      Compute space needed for autovacuum-related shared memory
    3287             :  */
    3288             : Size
    3289        3716 : AutoVacuumShmemSize(void)
    3290             : {
    3291             :     Size        size;
    3292             : 
    3293             :     /*
    3294             :      * Need the fixed struct and the array of WorkerInfoData.
    3295             :      */
    3296        3716 :     size = sizeof(AutoVacuumShmemStruct);
    3297        3716 :     size = MAXALIGN(size);
    3298        3716 :     size = add_size(size, mul_size(autovacuum_max_workers,
    3299             :                                    sizeof(WorkerInfoData)));
    3300        3716 :     return size;
    3301             : }
    3302             : 
    3303             : /*
    3304             :  * AutoVacuumShmemInit
    3305             :  *      Allocate and initialize autovacuum-related shared memory
    3306             :  */
    3307             : void
    3308        1856 : AutoVacuumShmemInit(void)
    3309             : {
    3310             :     bool        found;
    3311             : 
    3312        1856 :     AutoVacuumShmem = (AutoVacuumShmemStruct *)
    3313        1856 :         ShmemInitStruct("AutoVacuum Data",
    3314             :                         AutoVacuumShmemSize(),
    3315             :                         &found);
    3316             : 
    3317        1856 :     if (!IsUnderPostmaster)
    3318             :     {
    3319             :         WorkerInfo  worker;
    3320             :         int         i;
    3321             : 
    3322             :         Assert(!found);
    3323             : 
    3324        1856 :         AutoVacuumShmem->av_launcherpid = 0;
    3325        1856 :         dlist_init(&AutoVacuumShmem->av_freeWorkers);
    3326        1856 :         dlist_init(&AutoVacuumShmem->av_runningWorkers);
    3327        1856 :         AutoVacuumShmem->av_startingWorker = NULL;
    3328        1856 :         memset(AutoVacuumShmem->av_workItems, 0,
    3329             :                sizeof(AutoVacuumWorkItem) * NUM_WORKITEMS);
    3330             : 
    3331        1856 :         worker = (WorkerInfo) ((char *) AutoVacuumShmem +
    3332             :                                MAXALIGN(sizeof(AutoVacuumShmemStruct)));
    3333             : 
    3334             :         /* initialize the WorkerInfo free list */
    3335        7424 :         for (i = 0; i < autovacuum_max_workers; i++)
    3336        5568 :             dlist_push_head(&AutoVacuumShmem->av_freeWorkers,
    3337        5568 :                             &worker[i].wi_links);
    3338             :     }
    3339             :     else
    3340             :         Assert(found);
    3341        1856 : }
    3342             : 
    3343             : /*
    3344             :  * autovac_refresh_stats
    3345             :  *      Refresh pgstats data for an autovacuum process
    3346             :  *
    3347             :  * Cause the next pgstats read operation to obtain fresh data, but throttle
    3348             :  * such refreshing in the autovacuum launcher.  This is mostly to avoid
    3349             :  * rereading the pgstats files too many times in quick succession when there
    3350             :  * are many databases.
    3351             :  *
    3352             :  * Note: we avoid throttling in the autovac worker, as it would be
    3353             :  * counterproductive in the recheck logic.
    3354             :  */
    3355             : static void
    3356        1138 : autovac_refresh_stats(void)
    3357             : {
    3358        1138 :     if (IsAutoVacuumLauncherProcess())
    3359             :     {
    3360             :         static TimestampTz last_read = 0;
    3361             :         TimestampTz current_time;
    3362             : 
    3363         706 :         current_time = GetCurrentTimestamp();
    3364             : 
    3365         706 :         if (!TimestampDifferenceExceeds(last_read, current_time,
    3366             :                                         STATS_READ_DELAY))
    3367         304 :             return;
    3368             : 
    3369         402 :         last_read = current_time;
    3370             :     }
    3371             : 
    3372         834 :     pgstat_clear_snapshot();
    3373             : }

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