Branch data Line data Source code
1 : : /*-------------------------------------------------------------------------
2 : : *
3 : : * walsender.c
4 : : *
5 : : * The WAL sender process (walsender) is new as of Postgres 9.0. It takes
6 : : * care of sending XLOG from the primary server to a single recipient.
7 : : * (Note that there can be more than one walsender process concurrently.)
8 : : * It is started by the postmaster when the walreceiver of a standby server
9 : : * connects to the primary server and requests XLOG streaming replication.
10 : : *
11 : : * A walsender is similar to a regular backend, ie. there is a one-to-one
12 : : * relationship between a connection and a walsender process, but instead
13 : : * of processing SQL queries, it understands a small set of special
14 : : * replication-mode commands. The START_REPLICATION command begins streaming
15 : : * WAL to the client. While streaming, the walsender keeps reading XLOG
16 : : * records from the disk and sends them to the standby server over the
17 : : * COPY protocol, until either side ends the replication by exiting COPY
18 : : * mode (or until the connection is closed).
19 : : *
20 : : * Normal termination is by SIGTERM, which instructs the walsender to
21 : : * close the connection and exit(0) at the next convenient moment. Emergency
22 : : * termination is by SIGQUIT; like any backend, the walsender will simply
23 : : * abort and exit on SIGQUIT. A close of the connection and a FATAL error
24 : : * are treated as not a crash but approximately normal termination;
25 : : * the walsender will exit quickly without sending any more XLOG records.
26 : : *
27 : : * If the server is shut down, checkpointer sends us
28 : : * PROCSIG_WALSND_INIT_STOPPING after all regular backends have exited. If
29 : : * the backend is idle or runs an SQL query this causes the backend to
30 : : * shutdown, if logical replication is in progress all existing WAL records
31 : : * are processed followed by a shutdown. Otherwise this causes the walsender
32 : : * to switch to the "stopping" state. In this state, the walsender will reject
33 : : * any further replication commands. The checkpointer begins the shutdown
34 : : * checkpoint once all walsenders are confirmed as stopping. When the shutdown
35 : : * checkpoint finishes, the postmaster sends us SIGUSR2. This instructs
36 : : * walsender to send any outstanding WAL, including the shutdown checkpoint
37 : : * record, wait for it to be replicated to the standby, and then exit.
38 : : * This waiting time can be limited by the wal_sender_shutdown_timeout
39 : : * parameter.
40 : : *
41 : : *
42 : : * Portions Copyright (c) 2010-2026, PostgreSQL Global Development Group
43 : : *
44 : : * IDENTIFICATION
45 : : * src/backend/replication/walsender.c
46 : : *
47 : : *-------------------------------------------------------------------------
48 : : */
49 : : #include "postgres.h"
50 : :
51 : : #include <signal.h>
52 : : #include <unistd.h>
53 : :
54 : : #include "access/timeline.h"
55 : : #include "access/transam.h"
56 : : #include "access/twophase.h"
57 : : #include "access/xact.h"
58 : : #include "access/xlog_internal.h"
59 : : #include "access/xlogreader.h"
60 : : #include "access/xlogrecovery.h"
61 : : #include "access/xlogutils.h"
62 : : #include "backup/basebackup.h"
63 : : #include "backup/basebackup_incremental.h"
64 : : #include "catalog/pg_authid.h"
65 : : #include "catalog/pg_type.h"
66 : : #include "commands/defrem.h"
67 : : #include "funcapi.h"
68 : : #include "libpq/libpq.h"
69 : : #include "libpq/pqformat.h"
70 : : #include "libpq/protocol.h"
71 : : #include "miscadmin.h"
72 : : #include "nodes/replnodes.h"
73 : : #include "pgstat.h"
74 : : #include "postmaster/interrupt.h"
75 : : #include "replication/decode.h"
76 : : #include "replication/logical.h"
77 : : #include "replication/slotsync.h"
78 : : #include "replication/slot.h"
79 : : #include "replication/snapbuild.h"
80 : : #include "replication/syncrep.h"
81 : : #include "replication/walreceiver.h"
82 : : #include "replication/walsender.h"
83 : : #include "replication/walsender_private.h"
84 : : #include "storage/condition_variable.h"
85 : : #include "storage/aio_subsys.h"
86 : : #include "storage/fd.h"
87 : : #include "storage/ipc.h"
88 : : #include "storage/pmsignal.h"
89 : : #include "storage/proc.h"
90 : : #include "storage/procarray.h"
91 : : #include "storage/subsystems.h"
92 : : #include "tcop/dest.h"
93 : : #include "tcop/tcopprot.h"
94 : : #include "utils/acl.h"
95 : : #include "utils/builtins.h"
96 : : #include "utils/guc.h"
97 : : #include "utils/lsyscache.h"
98 : : #include "utils/memutils.h"
99 : : #include "utils/pg_lsn.h"
100 : : #include "utils/pgstat_internal.h"
101 : : #include "utils/ps_status.h"
102 : : #include "utils/timeout.h"
103 : : #include "utils/timestamp.h"
104 : : #include "utils/wait_event.h"
105 : :
106 : : /* Minimum interval used by walsender for stats flushes, in ms */
107 : : #define WALSENDER_STATS_FLUSH_INTERVAL 1000
108 : :
109 : : /*
110 : : * Maximum data payload in a WAL data message. Must be >= XLOG_BLCKSZ.
111 : : *
112 : : * We don't have a good idea of what a good value would be; there's some
113 : : * overhead per message in both walsender and walreceiver, but on the other
114 : : * hand sending large batches makes walsender less responsive to signals
115 : : * because signals are checked only between messages. 128kB (with
116 : : * default 8k blocks) seems like a reasonable guess for now.
117 : : */
118 : : #define MAX_SEND_SIZE (XLOG_BLCKSZ * 16)
119 : :
120 : : /* Array of WalSnds in shared memory */
121 : : WalSndCtlData *WalSndCtl = NULL;
122 : :
123 : : static void WalSndShmemRequest(void *arg);
124 : : static void WalSndShmemInit(void *arg);
125 : :
126 : : const ShmemCallbacks WalSndShmemCallbacks = {
127 : : .request_fn = WalSndShmemRequest,
128 : : .init_fn = WalSndShmemInit,
129 : : };
130 : :
131 : : /* My slot in the shared memory array */
132 : : WalSnd *MyWalSnd = NULL;
133 : :
134 : : /* Global state */
135 : : bool am_walsender = false; /* Am I a walsender process? */
136 : : bool am_cascading_walsender = false; /* Am I cascading WAL to another
137 : : * standby? */
138 : : bool am_db_walsender = false; /* Connected to a database? */
139 : :
140 : : /* GUC variables */
141 : : int max_wal_senders = 10; /* the maximum number of concurrent
142 : : * walsenders */
143 : : int wal_sender_timeout = 60 * 1000; /* maximum time to send one WAL
144 : : * data message */
145 : :
146 : : int wal_sender_shutdown_timeout = -1; /* maximum time to wait during
147 : : * shutdown for WAL
148 : : * replication */
149 : :
150 : : bool log_replication_commands = false;
151 : :
152 : : /*
153 : : * State for WalSndWakeupRequest
154 : : */
155 : : bool wake_wal_senders = false;
156 : :
157 : : /*
158 : : * xlogreader used for replication. Note that a WAL sender doing physical
159 : : * replication does not need xlogreader to read WAL, but it needs one to
160 : : * keep a state of its work.
161 : : */
162 : : static XLogReaderState *xlogreader = NULL;
163 : :
164 : : /*
165 : : * If the UPLOAD_MANIFEST command is used to provide a backup manifest in
166 : : * preparation for an incremental backup, uploaded_manifest will be point
167 : : * to an object containing information about its contexts, and
168 : : * uploaded_manifest_mcxt will point to the memory context that contains
169 : : * that object and all of its subordinate data. Otherwise, both values will
170 : : * be NULL.
171 : : */
172 : : static IncrementalBackupInfo *uploaded_manifest = NULL;
173 : : static MemoryContext uploaded_manifest_mcxt = NULL;
174 : :
175 : : /*
176 : : * These variables keep track of the state of the timeline we're currently
177 : : * sending. sendTimeLine identifies the timeline. If sendTimeLineIsHistoric,
178 : : * the timeline is not the latest timeline on this server, and the server's
179 : : * history forked off from that timeline at sendTimeLineValidUpto.
180 : : */
181 : : static TimeLineID sendTimeLine = 0;
182 : : static TimeLineID sendTimeLineNextTLI = 0;
183 : : static bool sendTimeLineIsHistoric = false;
184 : : static XLogRecPtr sendTimeLineValidUpto = InvalidXLogRecPtr;
185 : :
186 : : /*
187 : : * How far have we sent WAL already? This is also advertised in
188 : : * MyWalSnd->sentPtr. (Actually, this is the next WAL location to send.)
189 : : */
190 : : static XLogRecPtr sentPtr = InvalidXLogRecPtr;
191 : :
192 : : /* Buffers for constructing outgoing messages and processing reply messages. */
193 : : static StringInfoData output_message;
194 : : static StringInfoData reply_message;
195 : : static StringInfoData tmpbuf;
196 : :
197 : : /* Timestamp of last ProcessRepliesIfAny(). */
198 : : static TimestampTz last_processing = 0;
199 : :
200 : : /*
201 : : * Timestamp of last ProcessRepliesIfAny() that saw a reply from the
202 : : * standby. Set to 0 if wal_sender_timeout doesn't need to be active.
203 : : */
204 : : static TimestampTz last_reply_timestamp = 0;
205 : :
206 : : /* Have we sent a heartbeat message asking for reply, since last reply? */
207 : : static bool waiting_for_ping_response = false;
208 : :
209 : : /* Timestamp when walsender received the shutdown request */
210 : : static TimestampTz shutdown_request_timestamp = 0;
211 : :
212 : : /*
213 : : * Set after queueing the CommandComplete message that ends WAL streaming
214 : : * during shutdown. This prevents WalSndDone() and WalSndDoneImmediate()
215 : : * from queueing the same message twice.
216 : : */
217 : : static bool shutdown_stream_done_queued = false;
218 : :
219 : : /*
220 : : * While streaming WAL in Copy mode, streamingDoneSending is set to true
221 : : * after we have sent CopyDone. We should not send any more CopyData messages
222 : : * after that. streamingDoneReceiving is set to true when we receive CopyDone
223 : : * from the other end. When both become true, it's time to exit Copy mode.
224 : : */
225 : : static bool streamingDoneSending;
226 : : static bool streamingDoneReceiving;
227 : :
228 : : /* Are we there yet? */
229 : : static bool WalSndCaughtUp = false;
230 : :
231 : : /* Flags set by signal handlers for later service in main loop */
232 : : static volatile sig_atomic_t got_SIGUSR2 = false;
233 : : static volatile sig_atomic_t got_STOPPING = false;
234 : :
235 : : /*
236 : : * This is set while we are streaming. When not set
237 : : * PROCSIG_WALSND_INIT_STOPPING signal will be handled like SIGTERM. When set,
238 : : * the main loop is responsible for checking got_STOPPING and terminating when
239 : : * it's set (after streaming any remaining WAL).
240 : : */
241 : : static volatile sig_atomic_t replication_active = false;
242 : :
243 : : static LogicalDecodingContext *logical_decoding_ctx = NULL;
244 : :
245 : : /* A sample associating a WAL location with the time it was written. */
246 : : typedef struct
247 : : {
248 : : XLogRecPtr lsn;
249 : : TimestampTz time;
250 : : } WalTimeSample;
251 : :
252 : : /* The size of our buffer of time samples. */
253 : : #define LAG_TRACKER_BUFFER_SIZE 8192
254 : :
255 : : /* A mechanism for tracking replication lag. */
256 : : typedef struct
257 : : {
258 : : XLogRecPtr last_lsn;
259 : : WalTimeSample buffer[LAG_TRACKER_BUFFER_SIZE];
260 : : int write_head;
261 : : int read_heads[NUM_SYNC_REP_WAIT_MODE];
262 : : WalTimeSample last_read[NUM_SYNC_REP_WAIT_MODE];
263 : :
264 : : /*
265 : : * Overflow entries for read heads that collide with the write head.
266 : : *
267 : : * When the cyclic buffer fills (write head is about to collide with a
268 : : * read head), we save that read head's current sample here and mark it as
269 : : * using overflow (read_heads[i] = -1). This allows the write head to
270 : : * continue advancing while the overflowed mode continues lag computation
271 : : * using the saved sample.
272 : : *
273 : : * Once the standby's reported LSN advances past the overflow entry's LSN,
274 : : * we transition back to normal buffer-based tracking.
275 : : */
276 : : WalTimeSample overflowed[NUM_SYNC_REP_WAIT_MODE];
277 : : } LagTracker;
278 : :
279 : : static LagTracker *lag_tracker;
280 : :
281 : : /* Signal handlers */
282 : : static void WalSndLastCycleHandler(SIGNAL_ARGS);
283 : :
284 : : /* Prototypes for private functions */
285 : : typedef void (*WalSndSendDataCallback) (void);
286 : : static void WalSndLoop(WalSndSendDataCallback send_data);
287 : : static void InitWalSenderSlot(void);
288 : : static void WalSndKill(int code, Datum arg);
289 : : pg_noreturn static void WalSndShutdown(void);
290 : : static void XLogSendPhysical(void);
291 : : static void XLogSendLogical(void);
292 : : pg_noreturn static void WalSndDoneImmediate(void);
293 : : static void WalSndDone(WalSndSendDataCallback send_data);
294 : : static void IdentifySystem(void);
295 : : static void UploadManifest(void);
296 : : static bool HandleUploadManifestPacket(StringInfo buf, off_t *offset,
297 : : IncrementalBackupInfo *ib);
298 : : static void ReadReplicationSlot(ReadReplicationSlotCmd *cmd);
299 : : static void CreateReplicationSlot(CreateReplicationSlotCmd *cmd);
300 : : static void DropReplicationSlot(DropReplicationSlotCmd *cmd);
301 : : static void StartReplication(StartReplicationCmd *cmd);
302 : : static void StartLogicalReplication(StartReplicationCmd *cmd);
303 : : static void ProcessStandbyMessage(void);
304 : : static void ProcessStandbyReplyMessage(void);
305 : : static void ProcessStandbyHSFeedbackMessage(void);
306 : : static void ProcessStandbyPSRequestMessage(void);
307 : : static void ProcessRepliesIfAny(void);
308 : : static void ProcessPendingWrites(void);
309 : : static void WalSndKeepalive(bool requestReply, XLogRecPtr writePtr);
310 : : static void WalSndKeepaliveIfNecessary(void);
311 : : static void WalSndCheckTimeOut(void);
312 : : static void WalSndCheckShutdownTimeout(void);
313 : : static long WalSndComputeSleeptime(TimestampTz now);
314 : : static void WalSndWait(uint32 socket_events, long timeout, uint32 wait_event);
315 : : static void WalSndPrepareWrite(LogicalDecodingContext *ctx, XLogRecPtr lsn, TransactionId xid, bool last_write);
316 : : static void WalSndWriteData(LogicalDecodingContext *ctx, XLogRecPtr lsn, TransactionId xid, bool last_write);
317 : : static void WalSndUpdateProgress(LogicalDecodingContext *ctx, XLogRecPtr lsn, TransactionId xid,
318 : : bool skipped_xact);
319 : : static XLogRecPtr WalSndWaitForWal(XLogRecPtr loc);
320 : : static void LagTrackerWrite(XLogRecPtr lsn, TimestampTz local_flush_time);
321 : : static TimeOffset LagTrackerRead(int head, XLogRecPtr lsn, TimestampTz now);
322 : : static bool TransactionIdInRecentPast(TransactionId xid, uint32 epoch);
323 : :
324 : : static void WalSndSegmentOpen(XLogReaderState *state, XLogSegNo nextSegNo,
325 : : TimeLineID *tli_p);
326 : :
327 : :
328 : : /* Initialize walsender process before entering the main command loop */
329 : : void
330 : 1327 : InitWalSender(void)
331 : : {
332 : 1327 : am_cascading_walsender = RecoveryInProgress();
333 : :
334 : : /* Create a per-walsender data structure in shared memory */
335 : 1327 : InitWalSenderSlot();
336 : :
337 : : /* need resource owner for e.g. basebackups */
338 : 1327 : CreateAuxProcessResourceOwner();
339 : :
340 : : /*
341 : : * Let postmaster know that we're a WAL sender. Once we've declared us as
342 : : * a WAL sender process, postmaster will let us outlive the bgwriter and
343 : : * kill us last in the shutdown sequence, so we get a chance to stream all
344 : : * remaining WAL at shutdown, including the shutdown checkpoint. Note that
345 : : * there's no going back, and we mustn't write any WAL records after this.
346 : : */
347 : 1327 : MarkPostmasterChildWalSender();
348 : 1327 : SendPostmasterSignal(PMSIGNAL_ADVANCE_STATE_MACHINE);
349 : :
350 : : /*
351 : : * If the client didn't specify a database to connect to, show in PGPROC
352 : : * that our advertised xmin should affect vacuum horizons in all
353 : : * databases. This allows physical replication clients to send hot
354 : : * standby feedback that will delay vacuum cleanup in all databases.
355 : : */
356 [ + + ]: 1327 : if (MyDatabaseId == InvalidOid)
357 : : {
358 : : Assert(MyProc->xmin == InvalidTransactionId);
359 : 516 : LWLockAcquire(ProcArrayLock, LW_EXCLUSIVE);
360 : 516 : MyProc->statusFlags |= PROC_AFFECTS_ALL_HORIZONS;
361 : 516 : ProcGlobal->statusFlags[MyProc->pgxactoff] = MyProc->statusFlags;
362 : 516 : LWLockRelease(ProcArrayLock);
363 : : }
364 : :
365 : : /* Initialize empty timestamp buffer for lag tracking. */
366 : 1327 : lag_tracker = MemoryContextAllocZero(TopMemoryContext, sizeof(LagTracker));
367 : 1327 : }
368 : :
369 : : /*
370 : : * Clean up after an error.
371 : : *
372 : : * WAL sender processes don't use transactions like regular backends do.
373 : : * This function does any cleanup required after an error in a WAL sender
374 : : * process, similar to what transaction abort does in a regular backend.
375 : : */
376 : : void
377 : 51 : WalSndErrorCleanup(void)
378 : : {
379 : 51 : LWLockReleaseAll();
380 : 51 : ConditionVariableCancelSleep();
381 : 51 : pgstat_report_wait_end();
382 : 51 : pgaio_error_cleanup();
383 : :
384 [ + + + + ]: 51 : if (xlogreader != NULL && xlogreader->seg.ws_file >= 0)
385 : 7 : wal_segment_close(xlogreader);
386 : :
387 [ + + ]: 51 : if (MyReplicationSlot != NULL)
388 : 17 : ReplicationSlotRelease();
389 : :
390 : 51 : ReplicationSlotCleanup(false);
391 : :
392 : 51 : replication_active = false;
393 : :
394 : : /*
395 : : * If there is a transaction in progress, it will clean up our
396 : : * ResourceOwner, but if a replication command set up a resource owner
397 : : * without a transaction, we've got to clean that up now.
398 : : */
399 [ + + ]: 51 : if (!IsTransactionOrTransactionBlock())
400 : 49 : ReleaseAuxProcessResources(false);
401 : :
402 [ + + - + ]: 51 : if (got_STOPPING || got_SIGUSR2)
403 : 1 : proc_exit(0);
404 : :
405 : : /* Revert back to startup state */
406 : 50 : WalSndSetState(WALSNDSTATE_STARTUP);
407 : 50 : }
408 : :
409 : : /*
410 : : * Handle a client's connection abort in an orderly manner.
411 : : */
412 : : static void
413 : 5 : WalSndShutdown(void)
414 : : {
415 : : /*
416 : : * Reset whereToSendOutput to prevent ereport from attempting to send any
417 : : * more messages to the standby.
418 : : */
419 [ + - ]: 5 : if (whereToSendOutput == DestRemote)
420 : 5 : whereToSendOutput = DestNone;
421 : :
422 : 5 : proc_exit(0);
423 : : }
424 : :
425 : : /*
426 : : * Handle the IDENTIFY_SYSTEM command.
427 : : */
428 : : static void
429 : 841 : IdentifySystem(void)
430 : : {
431 : : char sysid[32];
432 : : char xloc[MAXFNAMELEN];
433 : : XLogRecPtr logptr;
434 : 841 : char *dbname = NULL;
435 : : DestReceiver *dest;
436 : : TupOutputState *tstate;
437 : : TupleDesc tupdesc;
438 : : Datum values[4];
439 : 841 : bool nulls[4] = {0};
440 : : TimeLineID currTLI;
441 : :
442 : : /*
443 : : * Reply with a result set with one row, four columns. First col is system
444 : : * ID, second is timeline ID, third is current xlog location and the
445 : : * fourth contains the database name if we are connected to one.
446 : : */
447 : :
448 : 841 : snprintf(sysid, sizeof(sysid), UINT64_FORMAT,
449 : : GetSystemIdentifier());
450 : :
451 : 841 : am_cascading_walsender = RecoveryInProgress();
452 [ + + ]: 841 : if (am_cascading_walsender)
453 : 69 : logptr = GetStandbyFlushRecPtr(&currTLI);
454 : : else
455 : 772 : logptr = GetFlushRecPtr(&currTLI);
456 : :
457 : 841 : snprintf(xloc, sizeof(xloc), "%X/%08X", LSN_FORMAT_ARGS(logptr));
458 : :
459 [ + + ]: 841 : if (MyDatabaseId != InvalidOid)
460 : : {
461 : 312 : MemoryContext cur = CurrentMemoryContext;
462 : :
463 : : /* syscache access needs a transaction env. */
464 : 312 : StartTransactionCommand();
465 : 312 : dbname = get_database_name(MyDatabaseId);
466 : : /* copy dbname out of TX context */
467 : 312 : dbname = MemoryContextStrdup(cur, dbname);
468 : 312 : CommitTransactionCommand();
469 : : }
470 : :
471 : 841 : dest = CreateDestReceiver(DestRemoteSimple);
472 : :
473 : : /* need a tuple descriptor representing four columns */
474 : 841 : tupdesc = CreateTemplateTupleDesc(4);
475 : 841 : TupleDescInitBuiltinEntry(tupdesc, (AttrNumber) 1, "systemid",
476 : : TEXTOID, -1, 0);
477 : 841 : TupleDescInitBuiltinEntry(tupdesc, (AttrNumber) 2, "timeline",
478 : : INT8OID, -1, 0);
479 : 841 : TupleDescInitBuiltinEntry(tupdesc, (AttrNumber) 3, "xlogpos",
480 : : TEXTOID, -1, 0);
481 : 841 : TupleDescInitBuiltinEntry(tupdesc, (AttrNumber) 4, "dbname",
482 : : TEXTOID, -1, 0);
483 : 841 : TupleDescFinalize(tupdesc);
484 : :
485 : : /* prepare for projection of tuples */
486 : 841 : tstate = begin_tup_output_tupdesc(dest, tupdesc, &TTSOpsVirtual);
487 : :
488 : : /* column 1: system identifier */
489 : 841 : values[0] = CStringGetTextDatum(sysid);
490 : :
491 : : /* column 2: timeline */
492 : 841 : values[1] = Int64GetDatum(currTLI);
493 : :
494 : : /* column 3: wal location */
495 : 841 : values[2] = CStringGetTextDatum(xloc);
496 : :
497 : : /* column 4: database name, or NULL if none */
498 [ + + ]: 841 : if (dbname)
499 : 312 : values[3] = CStringGetTextDatum(dbname);
500 : : else
501 : 529 : nulls[3] = true;
502 : :
503 : : /* send it to dest */
504 : 841 : do_tup_output(tstate, values, nulls);
505 : :
506 : 841 : end_tup_output(tstate);
507 : 841 : }
508 : :
509 : : /* Handle READ_REPLICATION_SLOT command */
510 : : static void
511 : 6 : ReadReplicationSlot(ReadReplicationSlotCmd *cmd)
512 : : {
513 : : #define READ_REPLICATION_SLOT_COLS 3
514 : : ReplicationSlot *slot;
515 : : DestReceiver *dest;
516 : : TupOutputState *tstate;
517 : : TupleDesc tupdesc;
518 : 6 : Datum values[READ_REPLICATION_SLOT_COLS] = {0};
519 : : bool nulls[READ_REPLICATION_SLOT_COLS];
520 : :
521 : 6 : tupdesc = CreateTemplateTupleDesc(READ_REPLICATION_SLOT_COLS);
522 : 6 : TupleDescInitBuiltinEntry(tupdesc, (AttrNumber) 1, "slot_type",
523 : : TEXTOID, -1, 0);
524 : 6 : TupleDescInitBuiltinEntry(tupdesc, (AttrNumber) 2, "restart_lsn",
525 : : TEXTOID, -1, 0);
526 : : /* TimeLineID is unsigned, so int4 is not wide enough. */
527 : 6 : TupleDescInitBuiltinEntry(tupdesc, (AttrNumber) 3, "restart_tli",
528 : : INT8OID, -1, 0);
529 : 6 : TupleDescFinalize(tupdesc);
530 : :
531 : 6 : memset(nulls, true, READ_REPLICATION_SLOT_COLS * sizeof(bool));
532 : :
533 : 6 : LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
534 : 6 : slot = SearchNamedReplicationSlot(cmd->slotname, false);
535 [ + + - + ]: 6 : if (slot == NULL || !slot->in_use)
536 : : {
537 : 2 : LWLockRelease(ReplicationSlotControlLock);
538 : : }
539 : : else
540 : : {
541 : : ReplicationSlot slot_contents;
542 : 4 : int i = 0;
543 : :
544 : : /* Copy slot contents while holding spinlock */
545 : 4 : SpinLockAcquire(&slot->mutex);
546 : 4 : slot_contents = *slot;
547 : 4 : SpinLockRelease(&slot->mutex);
548 : 4 : LWLockRelease(ReplicationSlotControlLock);
549 : :
550 [ + + ]: 4 : if (OidIsValid(slot_contents.data.database))
551 [ + - ]: 1 : ereport(ERROR,
552 : : errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
553 : : errmsg("cannot use %s with a logical replication slot",
554 : : "READ_REPLICATION_SLOT"));
555 : :
556 : : /* slot type */
557 : 3 : values[i] = CStringGetTextDatum("physical");
558 : 3 : nulls[i] = false;
559 : 3 : i++;
560 : :
561 : : /* start LSN */
562 [ + - ]: 3 : if (XLogRecPtrIsValid(slot_contents.data.restart_lsn))
563 : : {
564 : : char xloc[64];
565 : :
566 : 3 : snprintf(xloc, sizeof(xloc), "%X/%08X",
567 : 3 : LSN_FORMAT_ARGS(slot_contents.data.restart_lsn));
568 : 3 : values[i] = CStringGetTextDatum(xloc);
569 : 3 : nulls[i] = false;
570 : : }
571 : 3 : i++;
572 : :
573 : : /* timeline this WAL was produced on */
574 [ + - ]: 3 : if (XLogRecPtrIsValid(slot_contents.data.restart_lsn))
575 : : {
576 : : TimeLineID slots_position_timeline;
577 : : TimeLineID current_timeline;
578 : 3 : List *timeline_history = NIL;
579 : :
580 : : /*
581 : : * While in recovery, use as timeline the currently-replaying one
582 : : * to get the LSN position's history.
583 : : */
584 [ - + ]: 3 : if (RecoveryInProgress())
585 : 0 : (void) GetXLogReplayRecPtr(¤t_timeline);
586 : : else
587 : 3 : current_timeline = GetWALInsertionTimeLine();
588 : :
589 : 3 : timeline_history = readTimeLineHistory(current_timeline);
590 : 3 : slots_position_timeline = tliOfPointInHistory(slot_contents.data.restart_lsn,
591 : : timeline_history);
592 : 3 : values[i] = Int64GetDatum((int64) slots_position_timeline);
593 : 3 : nulls[i] = false;
594 : : }
595 : 3 : i++;
596 : :
597 : : Assert(i == READ_REPLICATION_SLOT_COLS);
598 : : }
599 : :
600 : 5 : dest = CreateDestReceiver(DestRemoteSimple);
601 : 5 : tstate = begin_tup_output_tupdesc(dest, tupdesc, &TTSOpsVirtual);
602 : 5 : do_tup_output(tstate, values, nulls);
603 : 5 : end_tup_output(tstate);
604 : 5 : }
605 : :
606 : :
607 : : /*
608 : : * Handle TIMELINE_HISTORY command.
609 : : */
610 : : static void
611 : 16 : SendTimeLineHistory(TimeLineHistoryCmd *cmd)
612 : : {
613 : : DestReceiver *dest;
614 : : TupleDesc tupdesc;
615 : : StringInfoData buf;
616 : : char histfname[MAXFNAMELEN];
617 : : char path[MAXPGPATH];
618 : : int fd;
619 : : off_t histfilelen;
620 : : size_t bytesleft;
621 : : Size len;
622 : :
623 : 16 : dest = CreateDestReceiver(DestRemoteSimple);
624 : :
625 : : /*
626 : : * Reply with a result set with one row, and two columns. The first col is
627 : : * the name of the history file, 2nd is the contents.
628 : : */
629 : 16 : tupdesc = CreateTemplateTupleDesc(2);
630 : 16 : TupleDescInitBuiltinEntry(tupdesc, (AttrNumber) 1, "filename", TEXTOID, -1, 0);
631 : 16 : TupleDescInitBuiltinEntry(tupdesc, (AttrNumber) 2, "content", TEXTOID, -1, 0);
632 : 16 : TupleDescFinalize(tupdesc);
633 : :
634 : 16 : TLHistoryFileName(histfname, cmd->timeline);
635 : 16 : TLHistoryFilePath(path, cmd->timeline);
636 : :
637 : : /* Send a RowDescription message */
638 : 16 : dest->rStartup(dest, CMD_SELECT, tupdesc);
639 : :
640 : : /* Send a DataRow message */
641 : 16 : pq_beginmessage(&buf, PqMsg_DataRow);
642 : 16 : pq_sendint16(&buf, 2); /* # of columns */
643 : 16 : len = strlen(histfname);
644 : 16 : pq_sendint32(&buf, len); /* col1 len */
645 : 16 : pq_sendbytes(&buf, histfname, len);
646 : :
647 : 16 : fd = OpenTransientFile(path, O_RDONLY | PG_BINARY);
648 [ - + ]: 16 : if (fd < 0)
649 [ # # ]: 0 : ereport(ERROR,
650 : : (errcode_for_file_access(),
651 : : errmsg("could not open file \"%s\": %m", path)));
652 : :
653 : : /* Determine file length and send it to client */
654 : 16 : histfilelen = lseek(fd, 0, SEEK_END);
655 [ - + ]: 16 : if (histfilelen < 0)
656 [ # # ]: 0 : ereport(ERROR,
657 : : (errcode_for_file_access(),
658 : : errmsg("could not seek to end of file \"%s\": %m", path)));
659 [ - + ]: 16 : if (lseek(fd, 0, SEEK_SET) != 0)
660 [ # # ]: 0 : ereport(ERROR,
661 : : (errcode_for_file_access(),
662 : : errmsg("could not seek to beginning of file \"%s\": %m", path)));
663 : :
664 : : /*
665 : : * unlikely in practice, but to document the implicit integer conversion
666 : : */
667 [ - + ]: 16 : if (histfilelen > UINT32_MAX)
668 [ # # ]: 0 : elog(ERROR, "timeline history file is too large");
669 : :
670 : 16 : pq_sendint32(&buf, histfilelen); /* col2 len */
671 : :
672 : 16 : bytesleft = histfilelen;
673 [ + + ]: 32 : while (bytesleft > 0)
674 : : {
675 : : PGAlignedBlock rbuf;
676 : : ssize_t nread;
677 : :
678 : 16 : pgstat_report_wait_start(WAIT_EVENT_WALSENDER_TIMELINE_HISTORY_READ);
679 : 16 : nread = read(fd, rbuf.data, sizeof(rbuf));
680 : 16 : pgstat_report_wait_end();
681 [ - + ]: 16 : if (nread < 0)
682 [ # # ]: 0 : ereport(ERROR,
683 : : (errcode_for_file_access(),
684 : : errmsg("could not read file \"%s\": %m",
685 : : path)));
686 [ - + ]: 16 : else if (nread == 0)
687 [ # # ]: 0 : ereport(ERROR,
688 : : (errcode(ERRCODE_DATA_CORRUPTED),
689 : : errmsg("could not read file \"%s\": read %zd of %zu",
690 : : path, nread, bytesleft)));
691 : :
692 : : /*
693 : : * We could have read more than expected if the file changed
694 : : * concurrently. In that case, only send as much as we expected and
695 : : * make sure the loop aborts properly (no wrap of bytesleft). (This
696 : : * isn't possible in practice, because the files are updated by atomic
697 : : * renames, but it's a safer programming practice.)
698 : : */
699 : 16 : nread = Min(nread, bytesleft);
700 : :
701 : 16 : pq_sendbytes(&buf, rbuf.data, nread);
702 : :
703 : 16 : bytesleft -= nread;
704 : : }
705 : :
706 [ - + ]: 16 : if (CloseTransientFile(fd) != 0)
707 [ # # ]: 0 : ereport(ERROR,
708 : : (errcode_for_file_access(),
709 : : errmsg("could not close file \"%s\": %m", path)));
710 : :
711 : 16 : pq_endmessage(&buf);
712 : 16 : }
713 : :
714 : : /*
715 : : * Handle UPLOAD_MANIFEST command.
716 : : */
717 : : static void
718 : 14 : UploadManifest(void)
719 : : {
720 : : MemoryContext mcxt;
721 : : IncrementalBackupInfo *ib;
722 : 14 : off_t offset = 0;
723 : : StringInfoData buf;
724 : :
725 : : /*
726 : : * parsing the manifest will use the cryptohash stuff, which requires a
727 : : * resource owner
728 : : */
729 : : Assert(AuxProcessResourceOwner != NULL);
730 : : Assert(CurrentResourceOwner == AuxProcessResourceOwner ||
731 : : CurrentResourceOwner == NULL);
732 : 14 : CurrentResourceOwner = AuxProcessResourceOwner;
733 : :
734 : : /* Prepare to read manifest data into a temporary context. */
735 : 14 : mcxt = AllocSetContextCreate(CurrentMemoryContext,
736 : : "incremental backup information",
737 : : ALLOCSET_DEFAULT_SIZES);
738 : 14 : ib = CreateIncrementalBackupInfo(mcxt);
739 : :
740 : : /* Send a CopyInResponse message */
741 : 14 : pq_beginmessage(&buf, PqMsg_CopyInResponse);
742 : 14 : pq_sendbyte(&buf, 0);
743 : 14 : pq_sendint16(&buf, 0);
744 : 14 : pq_endmessage_reuse(&buf);
745 : 14 : pq_flush();
746 : :
747 : : /* Receive packets from client until done. */
748 [ + + ]: 56 : while (HandleUploadManifestPacket(&buf, &offset, ib))
749 : : ;
750 : :
751 : : /* Finish up manifest processing. */
752 : 13 : FinalizeIncrementalManifest(ib);
753 : :
754 : : /*
755 : : * Discard any old manifest information and arrange to preserve the new
756 : : * information we just got.
757 : : *
758 : : * We assume that MemoryContextDelete and MemoryContextSetParent won't
759 : : * fail, and thus we shouldn't end up bailing out of here in such a way as
760 : : * to leave dangling pointers.
761 : : */
762 [ - + ]: 13 : if (uploaded_manifest_mcxt != NULL)
763 : 0 : MemoryContextDelete(uploaded_manifest_mcxt);
764 : 13 : MemoryContextSetParent(mcxt, CacheMemoryContext);
765 : 13 : uploaded_manifest = ib;
766 : 13 : uploaded_manifest_mcxt = mcxt;
767 : :
768 : : /* clean up the resource owner we created */
769 : 13 : ReleaseAuxProcessResources(true);
770 : 13 : }
771 : :
772 : : /*
773 : : * Process one packet received during the handling of an UPLOAD_MANIFEST
774 : : * operation.
775 : : *
776 : : * 'buf' is scratch space. This function expects it to be initialized, doesn't
777 : : * care what the current contents are, and may override them with completely
778 : : * new contents.
779 : : *
780 : : * The return value is true if the caller should continue processing
781 : : * additional packets and false if the UPLOAD_MANIFEST operation is complete.
782 : : */
783 : : static bool
784 : 56 : HandleUploadManifestPacket(StringInfo buf, off_t *offset,
785 : : IncrementalBackupInfo *ib)
786 : : {
787 : : int mtype;
788 : : int maxmsglen;
789 : :
790 : 56 : HOLD_CANCEL_INTERRUPTS();
791 : :
792 : 56 : pq_startmsgread();
793 : 56 : mtype = pq_getbyte();
794 [ - + ]: 56 : if (mtype == EOF)
795 [ # # ]: 0 : ereport(ERROR,
796 : : (errcode(ERRCODE_CONNECTION_FAILURE),
797 : : errmsg("unexpected EOF on client connection with an open transaction")));
798 : :
799 [ + + - ]: 56 : switch (mtype)
800 : : {
801 : 43 : case PqMsg_CopyData:
802 : 43 : maxmsglen = PQ_LARGE_MESSAGE_LIMIT;
803 : 43 : break;
804 : 13 : case PqMsg_CopyDone:
805 : : case PqMsg_CopyFail:
806 : : case PqMsg_Flush:
807 : : case PqMsg_Sync:
808 : 13 : maxmsglen = PQ_SMALL_MESSAGE_LIMIT;
809 : 13 : break;
810 : 0 : default:
811 [ # # ]: 0 : ereport(ERROR,
812 : : (errcode(ERRCODE_PROTOCOL_VIOLATION),
813 : : errmsg("unexpected message type 0x%02X during COPY from stdin",
814 : : mtype)));
815 : : maxmsglen = 0; /* keep compiler quiet */
816 : : break;
817 : : }
818 : :
819 : : /* Now collect the message body */
820 [ - + ]: 56 : if (pq_getmessage(buf, maxmsglen))
821 [ # # ]: 0 : ereport(ERROR,
822 : : (errcode(ERRCODE_CONNECTION_FAILURE),
823 : : errmsg("unexpected EOF on client connection with an open transaction")));
824 : 56 : RESUME_CANCEL_INTERRUPTS();
825 : :
826 : : /* Process the message */
827 [ + + - - : 56 : switch (mtype)
- ]
828 : : {
829 : 43 : case PqMsg_CopyData:
830 : 43 : AppendIncrementalManifestData(ib, buf->data, buf->len);
831 : 42 : return true;
832 : :
833 : 13 : case PqMsg_CopyDone:
834 : 13 : return false;
835 : :
836 : 0 : case PqMsg_Sync:
837 : : case PqMsg_Flush:
838 : : /* Ignore these while in CopyOut mode as we do elsewhere. */
839 : 0 : return true;
840 : :
841 : 0 : case PqMsg_CopyFail:
842 [ # # ]: 0 : ereport(ERROR,
843 : : (errcode(ERRCODE_QUERY_CANCELED),
844 : : errmsg("COPY from stdin failed: %s",
845 : : pq_getmsgstring(buf))));
846 : : }
847 : :
848 : : /* Not reached. */
849 : : Assert(false);
850 : 0 : return false;
851 : : }
852 : :
853 : : /*
854 : : * Handle START_REPLICATION command.
855 : : *
856 : : * At the moment, this never returns, but an ereport(ERROR) will take us back
857 : : * to the main loop.
858 : : */
859 : : static void
860 : 313 : StartReplication(StartReplicationCmd *cmd)
861 : : {
862 : : StringInfoData buf;
863 : : XLogRecPtr FlushPtr;
864 : : TimeLineID FlushTLI;
865 : :
866 : : /* create xlogreader for physical replication */
867 : 313 : xlogreader =
868 : 313 : XLogReaderAllocate(wal_segment_size, NULL,
869 : 313 : XL_ROUTINE(.segment_open = WalSndSegmentOpen,
870 : : .segment_close = wal_segment_close),
871 : : NULL);
872 : :
873 [ - + ]: 313 : if (!xlogreader)
874 [ # # ]: 0 : ereport(ERROR,
875 : : (errcode(ERRCODE_OUT_OF_MEMORY),
876 : : errmsg("out of memory"),
877 : : errdetail("Failed while allocating a WAL reading processor.")));
878 : :
879 : : /*
880 : : * We assume here that we're logging enough information in the WAL for
881 : : * log-shipping, since this is checked in PostmasterMain().
882 : : *
883 : : * NOTE: wal_level can only change at shutdown, so in most cases it is
884 : : * difficult for there to be WAL data that we can still see that was
885 : : * written at wal_level='minimal'.
886 : : */
887 : :
888 [ + + ]: 313 : if (cmd->slotname)
889 : : {
890 : 208 : ReplicationSlotAcquire(cmd->slotname, true, true);
891 [ - + ]: 205 : if (SlotIsLogical(MyReplicationSlot))
892 [ # # ]: 0 : ereport(ERROR,
893 : : (errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
894 : : errmsg("cannot use a logical replication slot for physical replication")));
895 : :
896 : : /*
897 : : * We don't need to verify the slot's restart_lsn here; instead we
898 : : * rely on the caller requesting the starting point to use. If the
899 : : * WAL segment doesn't exist, we'll fail later.
900 : : */
901 : : }
902 : :
903 : : /*
904 : : * Select the timeline. If it was given explicitly by the client, use
905 : : * that. Otherwise use the timeline of the last replayed record.
906 : : */
907 : 310 : am_cascading_walsender = RecoveryInProgress();
908 [ + + ]: 310 : if (am_cascading_walsender)
909 : 17 : FlushPtr = GetStandbyFlushRecPtr(&FlushTLI);
910 : : else
911 : 293 : FlushPtr = GetFlushRecPtr(&FlushTLI);
912 : :
913 [ + + ]: 310 : if (cmd->timeline != 0)
914 : : {
915 : : XLogRecPtr switchpoint;
916 : :
917 : 309 : sendTimeLine = cmd->timeline;
918 [ + + ]: 309 : if (sendTimeLine == FlushTLI)
919 : : {
920 : 300 : sendTimeLineIsHistoric = false;
921 : 300 : sendTimeLineValidUpto = InvalidXLogRecPtr;
922 : : }
923 : : else
924 : : {
925 : : List *timeLineHistory;
926 : :
927 : 9 : sendTimeLineIsHistoric = true;
928 : :
929 : : /*
930 : : * Check that the timeline the client requested exists, and the
931 : : * requested start location is on that timeline.
932 : : */
933 : 9 : timeLineHistory = readTimeLineHistory(FlushTLI);
934 : 9 : switchpoint = tliSwitchPoint(cmd->timeline, timeLineHistory,
935 : : &sendTimeLineNextTLI);
936 : 9 : list_free_deep(timeLineHistory);
937 : :
938 : : /*
939 : : * Found the requested timeline in the history. Check that
940 : : * requested startpoint is on that timeline in our history.
941 : : *
942 : : * This is quite loose on purpose. We only check that we didn't
943 : : * fork off the requested timeline before the switchpoint. We
944 : : * don't check that we switched *to* it before the requested
945 : : * starting point. This is because the client can legitimately
946 : : * request to start replication from the beginning of the WAL
947 : : * segment that contains switchpoint, but on the new timeline, so
948 : : * that it doesn't end up with a partial segment. If you ask for
949 : : * too old a starting point, you'll get an error later when we
950 : : * fail to find the requested WAL segment in pg_wal.
951 : : *
952 : : * XXX: we could be more strict here and only allow a startpoint
953 : : * that's older than the switchpoint, if it's still in the same
954 : : * WAL segment.
955 : : */
956 [ + - ]: 9 : if (XLogRecPtrIsValid(switchpoint) &&
957 [ - + ]: 9 : switchpoint < cmd->startpoint)
958 : : {
959 [ # # ]: 0 : ereport(ERROR,
960 : : errmsg("requested starting point %X/%08X on timeline %u is not in this server's history",
961 : : LSN_FORMAT_ARGS(cmd->startpoint),
962 : : cmd->timeline),
963 : : errdetail("This server's history forked from timeline %u at %X/%08X.",
964 : : cmd->timeline,
965 : : LSN_FORMAT_ARGS(switchpoint)));
966 : : }
967 : 9 : sendTimeLineValidUpto = switchpoint;
968 : : }
969 : : }
970 : : else
971 : : {
972 : 1 : sendTimeLine = FlushTLI;
973 : 1 : sendTimeLineValidUpto = InvalidXLogRecPtr;
974 : 1 : sendTimeLineIsHistoric = false;
975 : : }
976 : :
977 : 310 : streamingDoneSending = streamingDoneReceiving = false;
978 : :
979 : : /* If there is nothing to stream, don't even enter COPY mode */
980 [ + + + - ]: 310 : if (!sendTimeLineIsHistoric || cmd->startpoint < sendTimeLineValidUpto)
981 : : {
982 : : /*
983 : : * When we first start replication the standby will be behind the
984 : : * primary. For some applications, for example synchronous
985 : : * replication, it is important to have a clear state for this initial
986 : : * catchup mode, so we can trigger actions when we change streaming
987 : : * state later. We may stay in this state for a long time, which is
988 : : * exactly why we want to be able to monitor whether or not we are
989 : : * still here.
990 : : */
991 : 310 : WalSndSetState(WALSNDSTATE_CATCHUP);
992 : :
993 : : /* Send a CopyBothResponse message, and start streaming */
994 : 310 : pq_beginmessage(&buf, PqMsg_CopyBothResponse);
995 : 310 : pq_sendbyte(&buf, 0);
996 : 310 : pq_sendint16(&buf, 0);
997 : 310 : pq_endmessage(&buf);
998 : 310 : pq_flush();
999 : :
1000 : : /*
1001 : : * Don't allow a request to stream from a future point in WAL that
1002 : : * hasn't been flushed to disk in this server yet.
1003 : : */
1004 [ - + ]: 310 : if (FlushPtr < cmd->startpoint)
1005 : : {
1006 [ # # ]: 0 : ereport(ERROR,
1007 : : errmsg("requested starting point %X/%08X is ahead of the WAL flush position of this server %X/%08X",
1008 : : LSN_FORMAT_ARGS(cmd->startpoint),
1009 : : LSN_FORMAT_ARGS(FlushPtr)));
1010 : : }
1011 : :
1012 : : /* Start streaming from the requested point */
1013 : 310 : sentPtr = cmd->startpoint;
1014 : :
1015 : : /* Initialize shared memory status, too */
1016 : 310 : SpinLockAcquire(&MyWalSnd->mutex);
1017 : 310 : MyWalSnd->sentPtr = sentPtr;
1018 : 310 : SpinLockRelease(&MyWalSnd->mutex);
1019 : :
1020 : 310 : SyncRepInitConfig();
1021 : :
1022 : : /* Main loop of walsender */
1023 : 310 : replication_active = true;
1024 : :
1025 : 310 : WalSndLoop(XLogSendPhysical);
1026 : :
1027 : 169 : replication_active = false;
1028 [ - + ]: 169 : if (got_STOPPING)
1029 : 0 : proc_exit(0);
1030 : 169 : WalSndSetState(WALSNDSTATE_STARTUP);
1031 : :
1032 : : Assert(streamingDoneSending && streamingDoneReceiving);
1033 : : }
1034 : :
1035 [ + + ]: 169 : if (cmd->slotname)
1036 : 154 : ReplicationSlotRelease();
1037 : :
1038 : : /*
1039 : : * Copy is finished now. Send a single-row result set indicating the next
1040 : : * timeline.
1041 : : */
1042 [ + + ]: 169 : if (sendTimeLineIsHistoric)
1043 : : {
1044 : : char startpos_str[8 + 1 + 8 + 1];
1045 : : DestReceiver *dest;
1046 : : TupOutputState *tstate;
1047 : : TupleDesc tupdesc;
1048 : : Datum values[2];
1049 : 12 : bool nulls[2] = {0};
1050 : :
1051 : 12 : snprintf(startpos_str, sizeof(startpos_str), "%X/%08X",
1052 : 12 : LSN_FORMAT_ARGS(sendTimeLineValidUpto));
1053 : :
1054 : 12 : dest = CreateDestReceiver(DestRemoteSimple);
1055 : :
1056 : : /*
1057 : : * Need a tuple descriptor representing two columns. int8 may seem
1058 : : * like a surprising data type for this, but in theory int4 would not
1059 : : * be wide enough for this, as TimeLineID is unsigned.
1060 : : */
1061 : 12 : tupdesc = CreateTemplateTupleDesc(2);
1062 : 12 : TupleDescInitBuiltinEntry(tupdesc, (AttrNumber) 1, "next_tli",
1063 : : INT8OID, -1, 0);
1064 : 12 : TupleDescInitBuiltinEntry(tupdesc, (AttrNumber) 2, "next_tli_startpos",
1065 : : TEXTOID, -1, 0);
1066 : 12 : TupleDescFinalize(tupdesc);
1067 : :
1068 : : /* prepare for projection of tuple */
1069 : 12 : tstate = begin_tup_output_tupdesc(dest, tupdesc, &TTSOpsVirtual);
1070 : :
1071 : 12 : values[0] = Int64GetDatum((int64) sendTimeLineNextTLI);
1072 : 12 : values[1] = CStringGetTextDatum(startpos_str);
1073 : :
1074 : : /* send it to dest */
1075 : 12 : do_tup_output(tstate, values, nulls);
1076 : :
1077 : 12 : end_tup_output(tstate);
1078 : : }
1079 : :
1080 : : /* Send CommandComplete message */
1081 : 169 : EndReplicationCommand("START_STREAMING");
1082 : 169 : }
1083 : :
1084 : : /*
1085 : : * XLogReaderRoutine->page_read callback for logical decoding contexts, as a
1086 : : * walsender process.
1087 : : *
1088 : : * Inside the walsender we can do better than read_local_xlog_page,
1089 : : * which has to do a plain sleep/busy loop, because the walsender's latch gets
1090 : : * set every time WAL is flushed.
1091 : : */
1092 : : static int
1093 : 23804 : logical_read_xlog_page(XLogReaderState *state, XLogRecPtr targetPagePtr, int reqLen,
1094 : : XLogRecPtr targetRecPtr, char *cur_page)
1095 : : {
1096 : : XLogRecPtr flushptr;
1097 : : int count;
1098 : : WALReadError errinfo;
1099 : : XLogSegNo segno;
1100 : : TimeLineID currTLI;
1101 : :
1102 : : /*
1103 : : * Make sure we have enough WAL available before retrieving the current
1104 : : * timeline.
1105 : : */
1106 : 23804 : flushptr = WalSndWaitForWal(targetPagePtr + reqLen);
1107 : :
1108 : : /* Fail if not enough (implies we are going to shut down) */
1109 [ + + ]: 23569 : if (flushptr < targetPagePtr + reqLen)
1110 : 4856 : return -1;
1111 : :
1112 : : /*
1113 : : * Since logical decoding is also permitted on a standby server, we need
1114 : : * to check if the server is in recovery to decide how to get the current
1115 : : * timeline ID (so that it also covers the promotion or timeline change
1116 : : * cases). We must determine am_cascading_walsender after waiting for the
1117 : : * required WAL so that it is correct when the walsender wakes up after a
1118 : : * promotion.
1119 : : */
1120 : 18713 : am_cascading_walsender = RecoveryInProgress();
1121 : :
1122 [ + + ]: 18713 : if (am_cascading_walsender)
1123 : : {
1124 : : TimeLineID insertTLI;
1125 : :
1126 : : /*
1127 : : * If the insertion timeline has already been set, use it.
1128 : : * InsertTimeLineID is set before the WAL segments of the old timeline
1129 : : * are removed, before SharedRecoveryState switches to
1130 : : * RECOVERY_STATE_DONE.
1131 : : *
1132 : : * There is a window where RecoveryInProgress() still returns true but
1133 : : * the old timeline's WAL segments have already been removed or
1134 : : * recycled. Using the WAL insertion timeline avoids attempting to
1135 : : * read from those removed segments, improving availability, and is a
1136 : : * safe thing to do as promotion copies the contents in the last
1137 : : * segment of the old timeline to the first segment of the new
1138 : : * timeline, up to the switchpoint.
1139 : : */
1140 : 1637 : insertTLI = GetWALInsertionTimeLineIfSet();
1141 [ - + ]: 1637 : if (insertTLI != 0)
1142 : 0 : currTLI = insertTLI;
1143 : : else
1144 : 1637 : GetXLogReplayRecPtr(&currTLI);
1145 : : }
1146 : : else
1147 : 17076 : currTLI = GetWALInsertionTimeLine();
1148 : :
1149 : 18713 : XLogReadDetermineTimeline(state, targetPagePtr, reqLen, currTLI);
1150 : 18713 : sendTimeLineIsHistoric = (state->currTLI != currTLI);
1151 : 18713 : sendTimeLine = state->currTLI;
1152 : 18713 : sendTimeLineValidUpto = state->currTLIValidUntil;
1153 : 18713 : sendTimeLineNextTLI = state->nextTLI;
1154 : :
1155 [ + + ]: 18713 : if (targetPagePtr + XLOG_BLCKSZ <= flushptr)
1156 : 16610 : count = XLOG_BLCKSZ; /* more than one block available */
1157 : : else
1158 : 2103 : count = flushptr - targetPagePtr; /* part of the page available */
1159 : :
1160 : : /* now actually read the data, we know it's there */
1161 [ - + ]: 18713 : if (!WALRead(state,
1162 : : cur_page,
1163 : : targetPagePtr,
1164 : : count,
1165 : : currTLI, /* Pass the current TLI because only
1166 : : * WalSndSegmentOpen controls whether new TLI
1167 : : * is needed. */
1168 : : &errinfo))
1169 : 0 : WALReadRaiseError(&errinfo);
1170 : :
1171 : : /*
1172 : : * After reading into the buffer, check that what we read was valid. We do
1173 : : * this after reading, because even though the segment was present when we
1174 : : * opened it, it might get recycled or removed while we read it. The
1175 : : * read() succeeds in that case, but the data we tried to read might
1176 : : * already have been overwritten with new WAL records.
1177 : : */
1178 : 18713 : XLByteToSeg(targetPagePtr, segno, state->segcxt.ws_segsize);
1179 : 18713 : CheckXLogRemoved(segno, state->seg.ws_tli);
1180 : :
1181 : 18713 : return count;
1182 : : }
1183 : :
1184 : : /*
1185 : : * Process extra options given to CREATE_REPLICATION_SLOT.
1186 : : */
1187 : : static void
1188 : 524 : parseCreateReplSlotOptions(CreateReplicationSlotCmd *cmd,
1189 : : bool *reserve_wal,
1190 : : CRSSnapshotAction *snapshot_action,
1191 : : bool *two_phase, bool *failover)
1192 : : {
1193 : : ListCell *lc;
1194 : 524 : bool snapshot_action_given = false;
1195 : 524 : bool reserve_wal_given = false;
1196 : 524 : bool two_phase_given = false;
1197 : 524 : bool failover_given = false;
1198 : :
1199 : : /* Parse options */
1200 [ + + + + : 1061 : foreach(lc, cmd->options)
+ + ]
1201 : : {
1202 : 537 : DefElem *defel = (DefElem *) lfirst(lc);
1203 : :
1204 [ + + ]: 537 : if (strcmp(defel->defname, "snapshot") == 0)
1205 : : {
1206 : : char *action;
1207 : :
1208 [ + - - + ]: 367 : if (snapshot_action_given || cmd->kind != REPLICATION_KIND_LOGICAL)
1209 [ # # ]: 0 : ereport(ERROR,
1210 : : (errcode(ERRCODE_SYNTAX_ERROR),
1211 : : errmsg("conflicting or redundant options")));
1212 : :
1213 : 367 : action = defGetString(defel);
1214 : 367 : snapshot_action_given = true;
1215 : :
1216 [ + + ]: 367 : if (strcmp(action, "export") == 0)
1217 : 1 : *snapshot_action = CRS_EXPORT_SNAPSHOT;
1218 [ + + ]: 366 : else if (strcmp(action, "nothing") == 0)
1219 : 152 : *snapshot_action = CRS_NOEXPORT_SNAPSHOT;
1220 [ + - ]: 214 : else if (strcmp(action, "use") == 0)
1221 : 214 : *snapshot_action = CRS_USE_SNAPSHOT;
1222 : : else
1223 [ # # ]: 0 : ereport(ERROR,
1224 : : (errcode(ERRCODE_INVALID_PARAMETER_VALUE),
1225 : : errmsg("unrecognized value for %s option \"%s\": \"%s\"",
1226 : : "CREATE_REPLICATION_SLOT", defel->defname, action)));
1227 : : }
1228 [ + + ]: 170 : else if (strcmp(defel->defname, "reserve_wal") == 0)
1229 : : {
1230 [ + - - + ]: 156 : if (reserve_wal_given || cmd->kind != REPLICATION_KIND_PHYSICAL)
1231 [ # # ]: 0 : ereport(ERROR,
1232 : : (errcode(ERRCODE_SYNTAX_ERROR),
1233 : : errmsg("conflicting or redundant options")));
1234 : :
1235 : 156 : reserve_wal_given = true;
1236 : 156 : *reserve_wal = defGetBoolean(defel);
1237 : : }
1238 [ + + ]: 14 : else if (strcmp(defel->defname, "two_phase") == 0)
1239 : : {
1240 [ + - - + ]: 2 : if (two_phase_given || cmd->kind != REPLICATION_KIND_LOGICAL)
1241 [ # # ]: 0 : ereport(ERROR,
1242 : : (errcode(ERRCODE_SYNTAX_ERROR),
1243 : : errmsg("conflicting or redundant options")));
1244 : 2 : two_phase_given = true;
1245 : 2 : *two_phase = defGetBoolean(defel);
1246 : : }
1247 [ + - ]: 12 : else if (strcmp(defel->defname, "failover") == 0)
1248 : : {
1249 [ + - - + ]: 12 : if (failover_given || cmd->kind != REPLICATION_KIND_LOGICAL)
1250 [ # # ]: 0 : ereport(ERROR,
1251 : : (errcode(ERRCODE_SYNTAX_ERROR),
1252 : : errmsg("conflicting or redundant options")));
1253 : 12 : failover_given = true;
1254 : 12 : *failover = defGetBoolean(defel);
1255 : : }
1256 : : else
1257 [ # # ]: 0 : elog(ERROR, "unrecognized option: %s", defel->defname);
1258 : : }
1259 : 524 : }
1260 : :
1261 : : /*
1262 : : * Create a new replication slot.
1263 : : */
1264 : : static void
1265 : 524 : CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
1266 : : {
1267 : 524 : const char *snapshot_name = NULL;
1268 : : char xloc[MAXFNAMELEN];
1269 : : char *slot_name;
1270 : 524 : bool reserve_wal = false;
1271 : 524 : bool two_phase = false;
1272 : 524 : bool failover = false;
1273 : 524 : CRSSnapshotAction snapshot_action = CRS_EXPORT_SNAPSHOT;
1274 : : DestReceiver *dest;
1275 : : TupOutputState *tstate;
1276 : : TupleDesc tupdesc;
1277 : : Datum values[4];
1278 : 524 : bool nulls[4] = {0};
1279 : :
1280 : : Assert(!MyReplicationSlot);
1281 : :
1282 : 524 : parseCreateReplSlotOptions(cmd, &reserve_wal, &snapshot_action, &two_phase,
1283 : : &failover);
1284 : :
1285 [ + + ]: 524 : if (cmd->kind == REPLICATION_KIND_PHYSICAL)
1286 : : {
1287 : 157 : ReplicationSlotCreate(cmd->slotname, false,
1288 [ + + ]: 157 : cmd->temporary ? RS_TEMPORARY : RS_PERSISTENT,
1289 : : false, false, false, false);
1290 : :
1291 [ + + ]: 156 : if (reserve_wal)
1292 : : {
1293 : 155 : ReplicationSlotReserveWal();
1294 : :
1295 : 155 : ReplicationSlotMarkDirty();
1296 : :
1297 : : /* Write this slot to disk if it's a permanent one. */
1298 [ + + ]: 155 : if (!cmd->temporary)
1299 : 4 : ReplicationSlotSave();
1300 : : }
1301 : : }
1302 : : else
1303 : : {
1304 : : LogicalDecodingContext *ctx;
1305 : 367 : bool need_full_snapshot = false;
1306 : :
1307 : : Assert(cmd->kind == REPLICATION_KIND_LOGICAL);
1308 : :
1309 : 367 : CheckLogicalDecodingRequirements(false);
1310 : :
1311 : : /*
1312 : : * Initially create persistent slot as ephemeral - that allows us to
1313 : : * nicely handle errors during initialization because it'll get
1314 : : * dropped if this transaction fails. We'll make it persistent at the
1315 : : * end. Temporary slots can be created as temporary from beginning as
1316 : : * they get dropped on error as well.
1317 : : */
1318 : 367 : ReplicationSlotCreate(cmd->slotname, true,
1319 [ - + ]: 367 : cmd->temporary ? RS_TEMPORARY : RS_EPHEMERAL,
1320 : : two_phase, false, failover, false);
1321 : :
1322 : : /*
1323 : : * Do options check early so that we can bail before calling the
1324 : : * DecodingContextFindStartpoint which can take long time.
1325 : : */
1326 [ + + ]: 367 : if (snapshot_action == CRS_EXPORT_SNAPSHOT)
1327 : : {
1328 [ - + ]: 1 : if (IsTransactionBlock())
1329 [ # # ]: 0 : ereport(ERROR,
1330 : : /*- translator: %s is a CREATE_REPLICATION_SLOT statement */
1331 : : (errmsg("%s must not be called inside a transaction",
1332 : : "CREATE_REPLICATION_SLOT ... (SNAPSHOT 'export')")));
1333 : :
1334 : 1 : need_full_snapshot = true;
1335 : : }
1336 [ + + ]: 366 : else if (snapshot_action == CRS_USE_SNAPSHOT)
1337 : : {
1338 [ - + ]: 214 : if (!IsTransactionBlock())
1339 [ # # ]: 0 : ereport(ERROR,
1340 : : /*- translator: %s is a CREATE_REPLICATION_SLOT statement */
1341 : : (errmsg("%s must be called inside a transaction",
1342 : : "CREATE_REPLICATION_SLOT ... (SNAPSHOT 'use')")));
1343 : :
1344 [ - + ]: 214 : if (XactIsoLevel != XACT_REPEATABLE_READ)
1345 [ # # ]: 0 : ereport(ERROR,
1346 : : /*- translator: %s is a CREATE_REPLICATION_SLOT statement */
1347 : : (errmsg("%s must be called in REPEATABLE READ isolation mode transaction",
1348 : : "CREATE_REPLICATION_SLOT ... (SNAPSHOT 'use')")));
1349 [ - + ]: 214 : if (!XactReadOnly)
1350 [ # # ]: 0 : ereport(ERROR,
1351 : : /*- translator: %s is a CREATE_REPLICATION_SLOT statement */
1352 : : (errmsg("%s must be called in a read-only transaction",
1353 : : "CREATE_REPLICATION_SLOT ... (SNAPSHOT 'use')")));
1354 : :
1355 [ - + ]: 214 : if (FirstSnapshotSet)
1356 [ # # ]: 0 : ereport(ERROR,
1357 : : /*- translator: %s is a CREATE_REPLICATION_SLOT statement */
1358 : : (errmsg("%s must be called before any query",
1359 : : "CREATE_REPLICATION_SLOT ... (SNAPSHOT 'use')")));
1360 : :
1361 [ - + ]: 214 : if (IsSubTransaction())
1362 [ # # ]: 0 : ereport(ERROR,
1363 : : /*- translator: %s is a CREATE_REPLICATION_SLOT statement */
1364 : : (errmsg("%s must not be called in a subtransaction",
1365 : : "CREATE_REPLICATION_SLOT ... (SNAPSHOT 'use')")));
1366 : :
1367 : 214 : need_full_snapshot = true;
1368 : : }
1369 : :
1370 : : /*
1371 : : * Ensure the logical decoding is enabled before initializing the
1372 : : * logical decoding context.
1373 : : */
1374 : 367 : EnsureLogicalDecodingEnabled();
1375 : : Assert(IsLogicalDecodingEnabled());
1376 : :
1377 : 367 : ctx = CreateInitDecodingContext(cmd->plugin, NIL, need_full_snapshot,
1378 : : false,
1379 : : InvalidXLogRecPtr,
1380 : 367 : XL_ROUTINE(.page_read = logical_read_xlog_page,
1381 : : .segment_open = WalSndSegmentOpen,
1382 : : .segment_close = wal_segment_close),
1383 : : WalSndPrepareWrite, WalSndWriteData,
1384 : : WalSndUpdateProgress);
1385 : :
1386 : : /*
1387 : : * Signal that we don't need the timeout mechanism. We're just
1388 : : * creating the replication slot and don't yet accept feedback
1389 : : * messages or send keepalives. As we possibly need to wait for
1390 : : * further WAL the walsender would otherwise possibly be killed too
1391 : : * soon.
1392 : : */
1393 : 367 : last_reply_timestamp = 0;
1394 : :
1395 : : /* build initial snapshot, might take a while */
1396 : 367 : DecodingContextFindStartpoint(ctx);
1397 : :
1398 : : /*
1399 : : * Export or use the snapshot if we've been asked to do so.
1400 : : *
1401 : : * NB. We will convert the snapbuild.c kind of snapshot to normal
1402 : : * snapshot when doing this.
1403 : : */
1404 [ + + ]: 367 : if (snapshot_action == CRS_EXPORT_SNAPSHOT)
1405 : : {
1406 : 1 : snapshot_name = SnapBuildExportSnapshot(ctx->snapshot_builder);
1407 : : }
1408 [ + + ]: 366 : else if (snapshot_action == CRS_USE_SNAPSHOT)
1409 : : {
1410 : : Snapshot snap;
1411 : :
1412 : 214 : snap = SnapBuildInitialSnapshot(ctx->snapshot_builder);
1413 : 214 : RestoreTransactionSnapshot(snap, MyProc);
1414 : : }
1415 : :
1416 : : /* don't need the decoding context anymore */
1417 : 367 : FreeDecodingContext(ctx);
1418 : :
1419 [ + - ]: 367 : if (!cmd->temporary)
1420 : 367 : ReplicationSlotPersist();
1421 : : }
1422 : :
1423 : 523 : snprintf(xloc, sizeof(xloc), "%X/%08X",
1424 : 523 : LSN_FORMAT_ARGS(MyReplicationSlot->data.confirmed_flush));
1425 : :
1426 : 523 : dest = CreateDestReceiver(DestRemoteSimple);
1427 : :
1428 : : /*----------
1429 : : * Need a tuple descriptor representing four columns:
1430 : : * - first field: the slot name
1431 : : * - second field: LSN at which we became consistent
1432 : : * - third field: exported snapshot's name
1433 : : * - fourth field: output plugin
1434 : : */
1435 : 523 : tupdesc = CreateTemplateTupleDesc(4);
1436 : 523 : TupleDescInitBuiltinEntry(tupdesc, (AttrNumber) 1, "slot_name",
1437 : : TEXTOID, -1, 0);
1438 : 523 : TupleDescInitBuiltinEntry(tupdesc, (AttrNumber) 2, "consistent_point",
1439 : : TEXTOID, -1, 0);
1440 : 523 : TupleDescInitBuiltinEntry(tupdesc, (AttrNumber) 3, "snapshot_name",
1441 : : TEXTOID, -1, 0);
1442 : 523 : TupleDescInitBuiltinEntry(tupdesc, (AttrNumber) 4, "output_plugin",
1443 : : TEXTOID, -1, 0);
1444 : 523 : TupleDescFinalize(tupdesc);
1445 : :
1446 : : /* prepare for projection of tuples */
1447 : 523 : tstate = begin_tup_output_tupdesc(dest, tupdesc, &TTSOpsVirtual);
1448 : :
1449 : : /* slot_name */
1450 : 523 : slot_name = NameStr(MyReplicationSlot->data.name);
1451 : 523 : values[0] = CStringGetTextDatum(slot_name);
1452 : :
1453 : : /* consistent wal location */
1454 : 523 : values[1] = CStringGetTextDatum(xloc);
1455 : :
1456 : : /* snapshot name, or NULL if none */
1457 [ + + ]: 523 : if (snapshot_name != NULL)
1458 : 1 : values[2] = CStringGetTextDatum(snapshot_name);
1459 : : else
1460 : 522 : nulls[2] = true;
1461 : :
1462 : : /* plugin, or NULL if none */
1463 [ + + ]: 523 : if (cmd->plugin != NULL)
1464 : 367 : values[3] = CStringGetTextDatum(cmd->plugin);
1465 : : else
1466 : 156 : nulls[3] = true;
1467 : :
1468 : : /* send it to dest */
1469 : 523 : do_tup_output(tstate, values, nulls);
1470 : 523 : end_tup_output(tstate);
1471 : :
1472 : 523 : ReplicationSlotRelease();
1473 : 523 : }
1474 : :
1475 : : /*
1476 : : * Get rid of a replication slot that is no longer wanted.
1477 : : */
1478 : : static void
1479 : 297 : DropReplicationSlot(DropReplicationSlotCmd *cmd)
1480 : : {
1481 : 297 : ReplicationSlotDrop(cmd->slotname, !cmd->wait);
1482 : 296 : }
1483 : :
1484 : : /*
1485 : : * Change the definition of a replication slot.
1486 : : */
1487 : : static void
1488 : 7 : AlterReplicationSlot(AlterReplicationSlotCmd *cmd)
1489 : : {
1490 : 7 : bool failover_given = false;
1491 : 7 : bool two_phase_given = false;
1492 : : bool failover;
1493 : : bool two_phase;
1494 : :
1495 : : /* Parse options */
1496 [ + - + + : 21 : foreach_ptr(DefElem, defel, cmd->options)
+ + ]
1497 : : {
1498 [ + + ]: 7 : if (strcmp(defel->defname, "failover") == 0)
1499 : : {
1500 [ - + ]: 6 : if (failover_given)
1501 [ # # ]: 0 : ereport(ERROR,
1502 : : (errcode(ERRCODE_SYNTAX_ERROR),
1503 : : errmsg("conflicting or redundant options")));
1504 : 6 : failover_given = true;
1505 : 6 : failover = defGetBoolean(defel);
1506 : : }
1507 [ + - ]: 1 : else if (strcmp(defel->defname, "two_phase") == 0)
1508 : : {
1509 [ - + ]: 1 : if (two_phase_given)
1510 [ # # ]: 0 : ereport(ERROR,
1511 : : (errcode(ERRCODE_SYNTAX_ERROR),
1512 : : errmsg("conflicting or redundant options")));
1513 : 1 : two_phase_given = true;
1514 : 1 : two_phase = defGetBoolean(defel);
1515 : : }
1516 : : else
1517 [ # # ]: 0 : elog(ERROR, "unrecognized option: %s", defel->defname);
1518 : : }
1519 : :
1520 [ + + + + ]: 7 : ReplicationSlotAlter(cmd->slotname,
1521 : : failover_given ? &failover : NULL,
1522 : : two_phase_given ? &two_phase : NULL);
1523 : 5 : }
1524 : :
1525 : : /*
1526 : : * Load previously initiated logical slot and prepare for sending data (via
1527 : : * WalSndLoop).
1528 : : */
1529 : : static void
1530 : 479 : StartLogicalReplication(StartReplicationCmd *cmd)
1531 : : {
1532 : : StringInfoData buf;
1533 : : QueryCompletion qc;
1534 : :
1535 : : /* make sure that our requirements are still fulfilled */
1536 : 479 : CheckLogicalDecodingRequirements(false);
1537 : :
1538 : : Assert(!MyReplicationSlot);
1539 : :
1540 : 477 : ReplicationSlotAcquire(cmd->slotname, true, true);
1541 : :
1542 : : /*
1543 : : * Force a disconnect, so that the decoding code doesn't need to care
1544 : : * about an eventual switch from running in recovery, to running in a
1545 : : * normal environment. Client code is expected to handle reconnects.
1546 : : */
1547 [ + + - + ]: 472 : if (am_cascading_walsender && !RecoveryInProgress())
1548 : : {
1549 [ # # ]: 0 : ereport(LOG,
1550 : : (errmsg("terminating walsender process after promotion")));
1551 : 0 : got_STOPPING = true;
1552 : : }
1553 : :
1554 : : /*
1555 : : * Create our decoding context, making it start at the previously ack'ed
1556 : : * position.
1557 : : *
1558 : : * Do this before sending a CopyBothResponse message, so that any errors
1559 : : * are reported early.
1560 : : */
1561 : 471 : logical_decoding_ctx =
1562 : 472 : CreateDecodingContext(cmd->startpoint, cmd->options, false,
1563 : 472 : XL_ROUTINE(.page_read = logical_read_xlog_page,
1564 : : .segment_open = WalSndSegmentOpen,
1565 : : .segment_close = wal_segment_close),
1566 : : WalSndPrepareWrite, WalSndWriteData,
1567 : : WalSndUpdateProgress);
1568 : 471 : xlogreader = logical_decoding_ctx->reader;
1569 : :
1570 : 471 : WalSndSetState(WALSNDSTATE_CATCHUP);
1571 : :
1572 : : /* Send a CopyBothResponse message, and start streaming */
1573 : 471 : pq_beginmessage(&buf, PqMsg_CopyBothResponse);
1574 : 471 : pq_sendbyte(&buf, 0);
1575 : 471 : pq_sendint16(&buf, 0);
1576 : 471 : pq_endmessage(&buf);
1577 : 471 : pq_flush();
1578 : :
1579 : : /* Start reading WAL from the oldest required WAL. */
1580 : 471 : XLogBeginRead(logical_decoding_ctx->reader,
1581 : 471 : MyReplicationSlot->data.restart_lsn);
1582 : :
1583 : : /*
1584 : : * Report the location after which we'll send out further commits as the
1585 : : * current sentPtr.
1586 : : */
1587 : 471 : sentPtr = MyReplicationSlot->data.confirmed_flush;
1588 : :
1589 : : /* Also update the sent position status in shared memory */
1590 : 471 : SpinLockAcquire(&MyWalSnd->mutex);
1591 : 471 : MyWalSnd->sentPtr = MyReplicationSlot->data.restart_lsn;
1592 : 471 : SpinLockRelease(&MyWalSnd->mutex);
1593 : :
1594 : 471 : replication_active = true;
1595 : :
1596 : 471 : SyncRepInitConfig();
1597 : :
1598 : : /* Main loop of walsender */
1599 : 471 : WalSndLoop(XLogSendLogical);
1600 : :
1601 : 211 : FreeDecodingContext(logical_decoding_ctx);
1602 : 211 : ReplicationSlotRelease();
1603 : :
1604 : 211 : replication_active = false;
1605 [ - + ]: 211 : if (got_STOPPING)
1606 : 0 : proc_exit(0);
1607 : 211 : WalSndSetState(WALSNDSTATE_STARTUP);
1608 : :
1609 : : /* Get out of COPY mode (CommandComplete). */
1610 : 211 : SetQueryCompletion(&qc, CMDTAG_COPY, 0);
1611 : 211 : EndCommand(&qc, DestRemote, false);
1612 : 211 : }
1613 : :
1614 : : /*
1615 : : * LogicalDecodingContext 'prepare_write' callback.
1616 : : *
1617 : : * Prepare a write into a StringInfo.
1618 : : *
1619 : : * Don't do anything lasting in here, it's quite possible that nothing will be done
1620 : : * with the data.
1621 : : */
1622 : : static void
1623 : 206196 : WalSndPrepareWrite(LogicalDecodingContext *ctx, XLogRecPtr lsn, TransactionId xid, bool last_write)
1624 : : {
1625 : : /* can't have sync rep confused by sending the same LSN several times */
1626 [ + + ]: 206196 : if (!last_write)
1627 : 500 : lsn = InvalidXLogRecPtr;
1628 : :
1629 : 206196 : resetStringInfo(ctx->out);
1630 : :
1631 : 206196 : pq_sendbyte(ctx->out, PqReplMsg_WALData);
1632 : 206196 : pq_sendint64(ctx->out, lsn); /* dataStart */
1633 : 206196 : pq_sendint64(ctx->out, lsn); /* walEnd */
1634 : :
1635 : : /*
1636 : : * Fill out the sendtime later, just as it's done in XLogSendPhysical, but
1637 : : * reserve space here.
1638 : : */
1639 : 206196 : pq_sendint64(ctx->out, 0); /* sendtime */
1640 : 206196 : }
1641 : :
1642 : : /*
1643 : : * LogicalDecodingContext 'write' callback.
1644 : : *
1645 : : * Actually write out data previously prepared by WalSndPrepareWrite out to
1646 : : * the network. Take as long as needed, but process replies from the other
1647 : : * side and check timeouts during that.
1648 : : */
1649 : : static void
1650 : 206196 : WalSndWriteData(LogicalDecodingContext *ctx, XLogRecPtr lsn, TransactionId xid,
1651 : : bool last_write)
1652 : : {
1653 : : TimestampTz now;
1654 : :
1655 : : /*
1656 : : * Fill the send timestamp last, so that it is taken as late as possible.
1657 : : * This is somewhat ugly, but the protocol is set as it's already used for
1658 : : * several releases by streaming physical replication.
1659 : : */
1660 : 206196 : resetStringInfo(&tmpbuf);
1661 : 206196 : now = GetCurrentTimestamp();
1662 : 206196 : pq_sendint64(&tmpbuf, now);
1663 : 206196 : memcpy(&ctx->out->data[1 + sizeof(int64) + sizeof(int64)],
1664 : 206196 : tmpbuf.data, sizeof(int64));
1665 : :
1666 : : /* output previously gathered data in a CopyData packet */
1667 : 206196 : pq_putmessage_noblock(PqMsg_CopyData, ctx->out->data, ctx->out->len);
1668 : :
1669 [ - + ]: 206196 : CHECK_FOR_INTERRUPTS();
1670 : :
1671 : : /* Try to flush pending output to the client */
1672 [ + + ]: 206196 : if (pq_flush_if_writable() != 0)
1673 : 5 : WalSndShutdown();
1674 : :
1675 : : /* Try taking fast path unless we get too close to walsender timeout. */
1676 [ + - ]: 206191 : if (now < TimestampTzPlusMilliseconds(last_reply_timestamp,
1677 : 206191 : wal_sender_timeout / 2) &&
1678 [ + + ]: 206191 : !pq_is_send_pending())
1679 : : {
1680 : 205657 : return;
1681 : : }
1682 : :
1683 : : /* If we have pending write here, go to slow path */
1684 : 534 : ProcessPendingWrites();
1685 : : }
1686 : :
1687 : : /*
1688 : : * Handle configuration reload.
1689 : : *
1690 : : * Process the pending configuration file reload and reinitializes synchronous
1691 : : * replication settings. Also releases any waiters that may now be satisfied due
1692 : : * to changes in synchronous replication requirements.
1693 : : */
1694 : : static void
1695 : 1175195 : WalSndHandleConfigReload(void)
1696 : : {
1697 [ + + ]: 1175195 : if (!ConfigReloadPending)
1698 : 1175158 : return;
1699 : :
1700 : 37 : ConfigReloadPending = false;
1701 : 37 : ProcessConfigFile(PGC_SIGHUP);
1702 : 37 : SyncRepInitConfig();
1703 : :
1704 : : /*
1705 : : * Recheck and release any now-satisfied waiters after config reload
1706 : : * changes synchronous replication requirements (e.g., reducing the number
1707 : : * of sync standbys or changing the standby names).
1708 : : */
1709 [ + + ]: 37 : if (!am_cascading_walsender)
1710 : 34 : SyncRepReleaseWaiters();
1711 : : }
1712 : :
1713 : : /*
1714 : : * Wait until there is no pending write. Also process replies from the other
1715 : : * side and check timeouts during that.
1716 : : */
1717 : : static void
1718 : 534 : ProcessPendingWrites(void)
1719 : : {
1720 : : for (;;)
1721 : 748 : {
1722 : : long sleeptime;
1723 : :
1724 : : /* Check for input from the client */
1725 : 1282 : ProcessRepliesIfAny();
1726 : :
1727 : : /* die if timeout was reached */
1728 : 1282 : WalSndCheckTimeOut();
1729 : :
1730 : : /*
1731 : : * During shutdown, die if the shutdown timeout expires. Call this
1732 : : * before WalSndComputeSleeptime() so the timeout is considered when
1733 : : * computing sleep time.
1734 : : */
1735 : 1282 : WalSndCheckShutdownTimeout();
1736 : :
1737 : : /* Send keepalive if the time has come */
1738 : 1281 : WalSndKeepaliveIfNecessary();
1739 : :
1740 [ + + ]: 1281 : if (!pq_is_send_pending())
1741 : 533 : break;
1742 : :
1743 : 748 : sleeptime = WalSndComputeSleeptime(GetCurrentTimestamp());
1744 : :
1745 : : /* Sleep until something happens or we time out */
1746 : 748 : WalSndWait(WL_SOCKET_WRITEABLE | WL_SOCKET_READABLE, sleeptime,
1747 : : WAIT_EVENT_WAL_SENDER_WRITE_DATA);
1748 : :
1749 : : /* Clear any already-pending wakeups */
1750 : 748 : ResetLatch(MyLatch);
1751 : :
1752 [ - + ]: 748 : CHECK_FOR_INTERRUPTS();
1753 : :
1754 : : /* Process any requests or signals received recently */
1755 : 748 : WalSndHandleConfigReload();
1756 : :
1757 : : /* Try to flush pending output to the client */
1758 [ - + ]: 748 : if (pq_flush_if_writable() != 0)
1759 : 0 : WalSndShutdown();
1760 : : }
1761 : :
1762 : : /* reactivate latch so WalSndLoop knows to continue */
1763 : 533 : SetLatch(MyLatch);
1764 : 533 : }
1765 : :
1766 : : /*
1767 : : * LogicalDecodingContext 'update_progress' callback.
1768 : : *
1769 : : * Write the current position to the lag tracker (see XLogSendPhysical).
1770 : : *
1771 : : * When skipping empty transactions, send a keepalive message if necessary.
1772 : : */
1773 : : static void
1774 : 3209 : WalSndUpdateProgress(LogicalDecodingContext *ctx, XLogRecPtr lsn, TransactionId xid,
1775 : : bool skipped_xact)
1776 : : {
1777 : : static TimestampTz sendTime = 0;
1778 : 3209 : TimestampTz now = GetCurrentTimestamp();
1779 : 3209 : bool pending_writes = false;
1780 : 3209 : bool end_xact = ctx->end_xact;
1781 : :
1782 : : /*
1783 : : * Track lag no more than once per WALSND_LOGICAL_LAG_TRACK_INTERVAL_MS to
1784 : : * avoid flooding the lag tracker when we commit frequently.
1785 : : *
1786 : : * We don't have a mechanism to get the ack for any LSN other than end
1787 : : * xact LSN from the downstream. So, we track lag only for end of
1788 : : * transaction LSN.
1789 : : */
1790 : : #define WALSND_LOGICAL_LAG_TRACK_INTERVAL_MS 1000
1791 [ + + + + ]: 3209 : if (end_xact && TimestampDifferenceExceeds(sendTime, now,
1792 : : WALSND_LOGICAL_LAG_TRACK_INTERVAL_MS))
1793 : : {
1794 : 351 : LagTrackerWrite(lsn, now);
1795 : 351 : sendTime = now;
1796 : : }
1797 : :
1798 : : /*
1799 : : * When skipping empty transactions in synchronous replication, we send a
1800 : : * keepalive message to avoid delaying such transactions.
1801 : : *
1802 : : * It is okay to check sync_standbys_status without lock here as in the
1803 : : * worst case we will just send an extra keepalive message when it is
1804 : : * really not required.
1805 : : */
1806 [ + + ]: 3209 : if (skipped_xact &&
1807 [ + - + - ]: 821 : SyncRepRequested() &&
1808 [ - + ]: 821 : (((volatile WalSndCtlData *) WalSndCtl)->sync_standbys_status & SYNC_STANDBY_DEFINED))
1809 : : {
1810 : 0 : WalSndKeepalive(false, lsn);
1811 : :
1812 : : /* Try to flush pending output to the client */
1813 [ # # ]: 0 : if (pq_flush_if_writable() != 0)
1814 : 0 : WalSndShutdown();
1815 : :
1816 : : /* If we have pending write here, make sure it's actually flushed */
1817 [ # # ]: 0 : if (pq_is_send_pending())
1818 : 0 : pending_writes = true;
1819 : : }
1820 : :
1821 : : /*
1822 : : * Process pending writes if any or try to send a keepalive if required.
1823 : : * We don't need to try sending keep alive messages at the transaction end
1824 : : * as that will be done at a later point in time. This is required only
1825 : : * for large transactions where we don't send any changes to the
1826 : : * downstream and the receiver can timeout due to that.
1827 : : */
1828 [ + - + + ]: 3209 : if (pending_writes || (!end_xact &&
1829 [ - + ]: 1748 : now >= TimestampTzPlusMilliseconds(last_reply_timestamp,
1830 : : wal_sender_timeout / 2)))
1831 : 0 : ProcessPendingWrites();
1832 : 3209 : }
1833 : :
1834 : : /*
1835 : : * Wake up the logical walsender processes with logical failover slots if the
1836 : : * currently acquired physical slot is specified in synchronized_standby_slots GUC.
1837 : : */
1838 : : void
1839 : 41630 : PhysicalWakeupLogicalWalSnd(void)
1840 : : {
1841 : : Assert(MyReplicationSlot && SlotIsPhysical(MyReplicationSlot));
1842 : :
1843 : : /*
1844 : : * If we are running in a standby, there is no need to wake up walsenders.
1845 : : * This is because we do not support syncing slots to cascading standbys,
1846 : : * so, there are no walsenders waiting for standbys to catch up.
1847 : : */
1848 [ + + ]: 41630 : if (RecoveryInProgress())
1849 : 55 : return;
1850 : :
1851 [ + + ]: 41575 : if (SlotExistsInSyncStandbySlots(NameStr(MyReplicationSlot->data.name)))
1852 : 8 : ConditionVariableBroadcast(&WalSndCtl->wal_confirm_rcv_cv);
1853 : : }
1854 : :
1855 : : /*
1856 : : * Returns true if not all standbys have caught up to the flushed position
1857 : : * (flushed_lsn) when the current acquired slot is a logical failover
1858 : : * slot and we are streaming; otherwise, returns false.
1859 : : *
1860 : : * If returning true, the function sets the appropriate wait event in
1861 : : * wait_event; otherwise, wait_event is set to 0.
1862 : : */
1863 : : static bool
1864 : 23408 : NeedToWaitForStandbys(XLogRecPtr flushed_lsn, uint32 *wait_event)
1865 : : {
1866 [ + + ]: 23408 : int elevel = got_STOPPING ? ERROR : WARNING;
1867 : : bool failover_slot;
1868 : :
1869 [ + + + + ]: 23408 : failover_slot = (replication_active && MyReplicationSlot->data.failover);
1870 : :
1871 : : /*
1872 : : * Note that after receiving the shutdown signal, an ERROR is reported if
1873 : : * any slots are dropped, invalidated, or inactive. This measure is taken
1874 : : * to prevent the walsender from waiting indefinitely.
1875 : : */
1876 [ + + + + ]: 23408 : if (failover_slot && !StandbySlotsHaveCaughtup(flushed_lsn, elevel))
1877 : : {
1878 : 11 : *wait_event = WAIT_EVENT_WAIT_FOR_STANDBY_CONFIRMATION;
1879 : 11 : return true;
1880 : : }
1881 : :
1882 : 23396 : *wait_event = 0;
1883 : 23396 : return false;
1884 : : }
1885 : :
1886 : : /*
1887 : : * Returns true if we need to wait for WALs to be flushed to disk, or if not
1888 : : * all standbys have caught up to the flushed position (flushed_lsn) when the
1889 : : * current acquired slot is a logical failover slot and we are
1890 : : * streaming; otherwise, returns false.
1891 : : *
1892 : : * If returning true, the function sets the appropriate wait event in
1893 : : * wait_event; otherwise, wait_event is set to 0.
1894 : : */
1895 : : static bool
1896 : 38757 : NeedToWaitForWal(XLogRecPtr target_lsn, XLogRecPtr flushed_lsn,
1897 : : uint32 *wait_event)
1898 : : {
1899 : : /* Check if we need to wait for WALs to be flushed to disk */
1900 [ + + ]: 38757 : if (target_lsn > flushed_lsn)
1901 : : {
1902 : 20035 : *wait_event = WAIT_EVENT_WAL_SENDER_WAIT_FOR_WAL;
1903 : 20035 : return true;
1904 : : }
1905 : :
1906 : : /* Check if the standby slots have caught up to the flushed position */
1907 : 18722 : return NeedToWaitForStandbys(flushed_lsn, wait_event);
1908 : : }
1909 : :
1910 : : /*
1911 : : * Wait till WAL < loc is flushed to disk so it can be safely sent to client.
1912 : : *
1913 : : * If the walsender holds a logical failover slot, we also wait for all the
1914 : : * specified streaming replication standby servers to confirm receipt of WAL
1915 : : * up to RecentFlushPtr. It is beneficial to wait here for the confirmation
1916 : : * up to RecentFlushPtr rather than waiting before transmitting each change
1917 : : * to logical subscribers, which is already covered by RecentFlushPtr.
1918 : : *
1919 : : * Returns end LSN of flushed WAL. Normally this will be >= loc, but if we
1920 : : * detect a shutdown request (either from postmaster or client) we will return
1921 : : * early, so caller must always check.
1922 : : */
1923 : : static XLogRecPtr
1924 : 23804 : WalSndWaitForWal(XLogRecPtr loc)
1925 : : {
1926 : : int wakeEvents;
1927 : 23804 : uint32 wait_event = 0;
1928 : : static XLogRecPtr RecentFlushPtr = InvalidXLogRecPtr;
1929 : 23804 : TimestampTz last_flush = 0;
1930 : :
1931 : : /*
1932 : : * Fast path to avoid acquiring the spinlock in case we already know we
1933 : : * have enough WAL available and all the standby servers have confirmed
1934 : : * receipt of WAL up to RecentFlushPtr. This is particularly interesting
1935 : : * if we're far behind.
1936 : : */
1937 [ + + ]: 23804 : if (XLogRecPtrIsValid(RecentFlushPtr) &&
1938 [ + + ]: 23165 : !NeedToWaitForWal(loc, RecentFlushPtr, &wait_event))
1939 : 16711 : return RecentFlushPtr;
1940 : :
1941 : : /*
1942 : : * Within the loop, we wait for the necessary WALs to be flushed to disk
1943 : : * first, followed by waiting for standbys to catch up if there are enough
1944 : : * WALs (see NeedToWaitForWal()) or upon receiving the shutdown signal.
1945 : : */
1946 : : for (;;)
1947 : 13419 : {
1948 : 20512 : bool wait_for_standby_at_stop = false;
1949 : : long sleeptime;
1950 : : TimestampTz now;
1951 : :
1952 : : /* Clear any already-pending wakeups */
1953 : 20512 : ResetLatch(MyLatch);
1954 : :
1955 [ + + ]: 20512 : CHECK_FOR_INTERRUPTS();
1956 : :
1957 : : /* Process any requests or signals received recently */
1958 : 20505 : WalSndHandleConfigReload();
1959 : :
1960 : : /* Check for input from the client */
1961 : 20505 : ProcessRepliesIfAny();
1962 : :
1963 : : /*
1964 : : * If we're shutting down, trigger pending WAL to be written out,
1965 : : * otherwise we'd possibly end up waiting for WAL that never gets
1966 : : * written, because walwriter has shut down already.
1967 : : *
1968 : : * Note that GetXLogInsertEndRecPtr() is used to obtain the WAL flush
1969 : : * request location instead of GetXLogInsertRecPtr(). Because if the
1970 : : * last WAL record ends at a page boundary, GetXLogInsertRecPtr() can
1971 : : * return an LSN pointing past the page header, which may cause
1972 : : * XLogFlush() to report an error.
1973 : : */
1974 [ + + + + ]: 20278 : if (got_STOPPING && !RecoveryInProgress())
1975 : 3258 : XLogFlush(GetXLogInsertEndRecPtr());
1976 : :
1977 : : /*
1978 : : * To avoid the scenario where standbys need to catch up to a newer
1979 : : * WAL location in each iteration, we update our idea of the currently
1980 : : * flushed position only if we are not waiting for standbys to catch
1981 : : * up.
1982 : : */
1983 [ + + ]: 20278 : if (wait_event != WAIT_EVENT_WAIT_FOR_STANDBY_CONFIRMATION)
1984 : : {
1985 [ + + ]: 20267 : if (!RecoveryInProgress())
1986 : 18557 : RecentFlushPtr = GetFlushRecPtr(NULL);
1987 : : else
1988 : 1710 : RecentFlushPtr = GetXLogReplayRecPtr(NULL);
1989 : : }
1990 : :
1991 : : /*
1992 : : * If postmaster asked us to stop and the standby slots have caught up
1993 : : * to the flushed position, don't wait anymore.
1994 : : *
1995 : : * It's important to do this check after the recomputation of
1996 : : * RecentFlushPtr, so we can send all remaining data before shutting
1997 : : * down.
1998 : : */
1999 [ + + ]: 20278 : if (got_STOPPING)
2000 : : {
2001 [ + + ]: 4686 : if (NeedToWaitForStandbys(RecentFlushPtr, &wait_event))
2002 : 1 : wait_for_standby_at_stop = true;
2003 : : else
2004 : 4684 : break;
2005 : : }
2006 : :
2007 : : /*
2008 : : * We only send regular messages to the client for full decoded
2009 : : * transactions, but a synchronous replication and walsender shutdown
2010 : : * possibly are waiting for a later location. So, before sleeping, we
2011 : : * send a ping containing the flush location. If the receiver is
2012 : : * otherwise idle, this keepalive will trigger a reply. Processing the
2013 : : * reply will update these MyWalSnd locations.
2014 : : */
2015 [ + + ]: 15593 : if (MyWalSnd->flush < sentPtr &&
2016 [ + + ]: 2652 : MyWalSnd->write < sentPtr &&
2017 [ + - ]: 2050 : !waiting_for_ping_response)
2018 : 2050 : WalSndKeepalive(false, InvalidXLogRecPtr);
2019 : :
2020 : : /*
2021 : : * Exit the loop if already caught up and doesn't need to wait for
2022 : : * standby slots.
2023 : : */
2024 [ + + ]: 15593 : if (!wait_for_standby_at_stop &&
2025 [ + + ]: 15592 : !NeedToWaitForWal(loc, RecentFlushPtr, &wait_event))
2026 : 2001 : break;
2027 : :
2028 : : /*
2029 : : * Waiting for new WAL or waiting for standbys to catch up. Since we
2030 : : * need to wait, we're now caught up.
2031 : : */
2032 : 13592 : WalSndCaughtUp = true;
2033 : :
2034 : : /*
2035 : : * Try to flush any pending output to the client.
2036 : : */
2037 [ - + ]: 13592 : if (pq_flush_if_writable() != 0)
2038 : 0 : WalSndShutdown();
2039 : :
2040 : : /*
2041 : : * If we have received CopyDone from the client, sent CopyDone
2042 : : * ourselves, and the output buffer is empty, it's time to exit
2043 : : * streaming, so fail the current WAL fetch request.
2044 : : */
2045 [ + + + - ]: 13592 : if (streamingDoneReceiving && streamingDoneSending &&
2046 [ + - ]: 173 : !pq_is_send_pending())
2047 : 173 : break;
2048 : :
2049 : : /* die if timeout was reached */
2050 : 13419 : WalSndCheckTimeOut();
2051 : :
2052 : : /*
2053 : : * During shutdown, die if the shutdown timeout expires. Call this
2054 : : * before WalSndComputeSleeptime() so the timeout is considered when
2055 : : * computing sleep time.
2056 : : */
2057 : 13419 : WalSndCheckShutdownTimeout();
2058 : :
2059 : : /* Send keepalive if the time has come */
2060 : 13419 : WalSndKeepaliveIfNecessary();
2061 : :
2062 : : /*
2063 : : * Sleep until something happens or we time out. Also wait for the
2064 : : * socket becoming writable, if there's still pending output.
2065 : : * Otherwise we might sit on sendable output data while waiting for
2066 : : * new WAL to be generated. (But if we have nothing to send, we don't
2067 : : * want to wake on socket-writable.)
2068 : : */
2069 : 13419 : now = GetCurrentTimestamp();
2070 : 13419 : sleeptime = WalSndComputeSleeptime(now);
2071 : :
2072 : 13419 : wakeEvents = WL_SOCKET_READABLE;
2073 : :
2074 [ - + ]: 13419 : if (pq_is_send_pending())
2075 : 0 : wakeEvents |= WL_SOCKET_WRITEABLE;
2076 : :
2077 : : Assert(wait_event != 0);
2078 : :
2079 : : /* Report IO statistics, if needed */
2080 [ + + ]: 13419 : if (TimestampDifferenceExceeds(last_flush, now,
2081 : : WALSENDER_STATS_FLUSH_INTERVAL))
2082 : : {
2083 : 1707 : pgstat_flush_io(false);
2084 : 1707 : (void) pgstat_flush_backend(false, PGSTAT_BACKEND_FLUSH_IO);
2085 : 1707 : last_flush = now;
2086 : : }
2087 : :
2088 : 13419 : WalSndWait(wakeEvents, sleeptime, wait_event);
2089 : : }
2090 : :
2091 : : /* reactivate latch so WalSndLoop knows to continue */
2092 : 6858 : SetLatch(MyLatch);
2093 : 6858 : return RecentFlushPtr;
2094 : : }
2095 : :
2096 : : /*
2097 : : * Execute an incoming replication command.
2098 : : *
2099 : : * Returns true if the cmd_string was recognized as WalSender command, false
2100 : : * if not.
2101 : : */
2102 : : bool
2103 : 5968 : exec_replication_command(const char *cmd_string)
2104 : : {
2105 : : yyscan_t scanner;
2106 : : int parse_rc;
2107 : : Node *cmd_node;
2108 : : const char *cmdtag;
2109 : 5968 : MemoryContext old_context = CurrentMemoryContext;
2110 : :
2111 : : /* We save and re-use the cmd_context across calls */
2112 : : static MemoryContext cmd_context = NULL;
2113 : :
2114 : : /*
2115 : : * If WAL sender has been told that shutdown is getting close, switch its
2116 : : * status accordingly to handle the next replication commands correctly.
2117 : : */
2118 [ - + ]: 5968 : if (got_STOPPING)
2119 : 0 : WalSndSetState(WALSNDSTATE_STOPPING);
2120 : :
2121 : : /*
2122 : : * Throw error if in stopping mode. We need prevent commands that could
2123 : : * generate WAL while the shutdown checkpoint is being written. To be
2124 : : * safe, we just prohibit all new commands.
2125 : : */
2126 [ - + ]: 5968 : if (MyWalSnd->state == WALSNDSTATE_STOPPING)
2127 [ # # ]: 0 : ereport(ERROR,
2128 : : (errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
2129 : : errmsg("cannot execute new commands while WAL sender is in stopping mode")));
2130 : :
2131 : : /*
2132 : : * CREATE_REPLICATION_SLOT ... LOGICAL exports a snapshot until the next
2133 : : * command arrives. Clean up the old stuff if there's anything.
2134 : : */
2135 : 5968 : SnapBuildClearExportedSnapshot();
2136 : :
2137 [ - + ]: 5968 : CHECK_FOR_INTERRUPTS();
2138 : :
2139 : : /*
2140 : : * Prepare to parse and execute the command.
2141 : : *
2142 : : * Because replication command execution can involve beginning or ending
2143 : : * transactions, we need a working context that will survive that, so we
2144 : : * make it a child of TopMemoryContext. That in turn creates a hazard of
2145 : : * long-lived memory leaks if we lose track of the working context. We
2146 : : * deal with that by creating it only once per walsender, and resetting it
2147 : : * for each new command. (Normally this reset is a no-op, but if the
2148 : : * prior exec_replication_command call failed with an error, it won't be.)
2149 : : *
2150 : : * This is subtler than it looks. The transactions we manage can extend
2151 : : * across replication commands, indeed SnapBuildClearExportedSnapshot
2152 : : * might have just ended one. Because transaction exit will revert to the
2153 : : * memory context that was current at transaction start, we need to be
2154 : : * sure that that context is still valid. That motivates re-using the
2155 : : * same cmd_context rather than making a new one each time.
2156 : : */
2157 [ + + ]: 5968 : if (cmd_context == NULL)
2158 : 1327 : cmd_context = AllocSetContextCreate(TopMemoryContext,
2159 : : "Replication command context",
2160 : : ALLOCSET_DEFAULT_SIZES);
2161 : : else
2162 : 4641 : MemoryContextReset(cmd_context);
2163 : :
2164 : 5968 : MemoryContextSwitchTo(cmd_context);
2165 : :
2166 : 5968 : replication_scanner_init(cmd_string, &scanner);
2167 : :
2168 : : /*
2169 : : * Is it a WalSender command?
2170 : : */
2171 [ + + ]: 5968 : if (!replication_scanner_is_replication_command(scanner))
2172 : : {
2173 : : /* Nope; clean up and get out. */
2174 : 2626 : replication_scanner_finish(scanner);
2175 : :
2176 : 2626 : MemoryContextSwitchTo(old_context);
2177 : 2626 : MemoryContextReset(cmd_context);
2178 : :
2179 : : /* XXX this is a pretty random place to make this check */
2180 [ - + ]: 2626 : if (MyDatabaseId == InvalidOid)
2181 [ # # ]: 0 : ereport(ERROR,
2182 : : (errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
2183 : : errmsg("cannot execute SQL commands in WAL sender for physical replication")));
2184 : :
2185 : : /* Tell the caller that this wasn't a WalSender command. */
2186 : 2626 : return false;
2187 : : }
2188 : :
2189 : : /*
2190 : : * Looks like a WalSender command, so parse it.
2191 : : */
2192 : 3342 : parse_rc = replication_yyparse(&cmd_node, scanner);
2193 [ - + ]: 3342 : if (parse_rc != 0)
2194 [ # # ]: 0 : ereport(ERROR,
2195 : : (errcode(ERRCODE_SYNTAX_ERROR),
2196 : : errmsg_internal("replication command parser returned %d",
2197 : : parse_rc)));
2198 : 3342 : replication_scanner_finish(scanner);
2199 : :
2200 : : /*
2201 : : * Report query to various monitoring facilities. For this purpose, we
2202 : : * report replication commands just like SQL commands.
2203 : : */
2204 : 3342 : debug_query_string = cmd_string;
2205 : :
2206 : 3342 : pgstat_report_activity(STATE_RUNNING, cmd_string);
2207 : :
2208 : : /*
2209 : : * Log replication command if log_replication_commands is enabled. Even
2210 : : * when it's disabled, log the command with DEBUG1 level for backward
2211 : : * compatibility.
2212 : : */
2213 [ + - + - ]: 3342 : ereport(log_replication_commands ? LOG : DEBUG1,
2214 : : (errmsg("received replication command: %s", cmd_string)));
2215 : :
2216 : : /*
2217 : : * Disallow replication commands in aborted transaction blocks.
2218 : : */
2219 [ - + ]: 3342 : if (IsAbortedTransactionBlockState())
2220 [ # # ]: 0 : ereport(ERROR,
2221 : : (errcode(ERRCODE_IN_FAILED_SQL_TRANSACTION),
2222 : : errmsg("current transaction is aborted, "
2223 : : "commands ignored until end of transaction block")));
2224 : :
2225 [ - + ]: 3342 : CHECK_FOR_INTERRUPTS();
2226 : :
2227 : : /*
2228 : : * Allocate buffers that will be used for each outgoing and incoming
2229 : : * message. We do this just once per command to reduce palloc overhead.
2230 : : */
2231 : 3342 : initStringInfo(&output_message);
2232 : 3342 : initStringInfo(&reply_message);
2233 : 3342 : initStringInfo(&tmpbuf);
2234 : :
2235 [ + + + + : 3342 : switch (cmd_node->type)
+ + + + +
+ - ]
2236 : : {
2237 : 841 : case T_IdentifySystemCmd:
2238 : 841 : cmdtag = "IDENTIFY_SYSTEM";
2239 : 841 : set_ps_display(cmdtag);
2240 : 841 : IdentifySystem();
2241 : 841 : EndReplicationCommand(cmdtag);
2242 : 841 : break;
2243 : :
2244 : 6 : case T_ReadReplicationSlotCmd:
2245 : 6 : cmdtag = "READ_REPLICATION_SLOT";
2246 : 6 : set_ps_display(cmdtag);
2247 : 6 : ReadReplicationSlot((ReadReplicationSlotCmd *) cmd_node);
2248 : 5 : EndReplicationCommand(cmdtag);
2249 : 5 : break;
2250 : :
2251 : 201 : case T_BaseBackupCmd:
2252 : 201 : cmdtag = "BASE_BACKUP";
2253 : 201 : set_ps_display(cmdtag);
2254 : 201 : PreventInTransactionBlock(true, cmdtag);
2255 : 201 : SendBaseBackup((BaseBackupCmd *) cmd_node, uploaded_manifest);
2256 : 174 : EndReplicationCommand(cmdtag);
2257 : 174 : break;
2258 : :
2259 : 524 : case T_CreateReplicationSlotCmd:
2260 : 524 : cmdtag = "CREATE_REPLICATION_SLOT";
2261 : 524 : set_ps_display(cmdtag);
2262 : 524 : CreateReplicationSlot((CreateReplicationSlotCmd *) cmd_node);
2263 : 523 : EndReplicationCommand(cmdtag);
2264 : 523 : break;
2265 : :
2266 : 297 : case T_DropReplicationSlotCmd:
2267 : 297 : cmdtag = "DROP_REPLICATION_SLOT";
2268 : 297 : set_ps_display(cmdtag);
2269 : 297 : DropReplicationSlot((DropReplicationSlotCmd *) cmd_node);
2270 : 296 : EndReplicationCommand(cmdtag);
2271 : 296 : break;
2272 : :
2273 : 7 : case T_AlterReplicationSlotCmd:
2274 : 7 : cmdtag = "ALTER_REPLICATION_SLOT";
2275 : 7 : set_ps_display(cmdtag);
2276 : 7 : AlterReplicationSlot((AlterReplicationSlotCmd *) cmd_node);
2277 : 5 : EndReplicationCommand(cmdtag);
2278 : 5 : break;
2279 : :
2280 : 792 : case T_StartReplicationCmd:
2281 : : {
2282 : 792 : StartReplicationCmd *cmd = (StartReplicationCmd *) cmd_node;
2283 : :
2284 : 792 : cmdtag = "START_REPLICATION";
2285 : 792 : set_ps_display(cmdtag);
2286 : 792 : PreventInTransactionBlock(true, cmdtag);
2287 : :
2288 [ + + ]: 792 : if (cmd->kind == REPLICATION_KIND_PHYSICAL)
2289 : 313 : StartReplication(cmd);
2290 : : else
2291 : 479 : StartLogicalReplication(cmd);
2292 : :
2293 : : /* dupe, but necessary per libpqrcv_endstreaming */
2294 : 380 : EndReplicationCommand(cmdtag);
2295 : :
2296 : : Assert(xlogreader != NULL);
2297 : 380 : break;
2298 : : }
2299 : :
2300 : 16 : case T_TimeLineHistoryCmd:
2301 : 16 : cmdtag = "TIMELINE_HISTORY";
2302 : 16 : set_ps_display(cmdtag);
2303 : 16 : PreventInTransactionBlock(true, cmdtag);
2304 : 16 : SendTimeLineHistory((TimeLineHistoryCmd *) cmd_node);
2305 : 16 : EndReplicationCommand(cmdtag);
2306 : 16 : break;
2307 : :
2308 : 644 : case T_VariableShowStmt:
2309 : : {
2310 : 644 : DestReceiver *dest = CreateDestReceiver(DestRemoteSimple);
2311 : 644 : VariableShowStmt *n = (VariableShowStmt *) cmd_node;
2312 : :
2313 : 644 : cmdtag = "SHOW";
2314 : 644 : set_ps_display(cmdtag);
2315 : :
2316 : : /* syscache access needs a transaction environment */
2317 : 644 : StartTransactionCommand();
2318 : 644 : GetPGVariable(n->name, dest);
2319 : 644 : CommitTransactionCommand();
2320 : 644 : EndReplicationCommand(cmdtag);
2321 : : }
2322 : 644 : break;
2323 : :
2324 : 14 : case T_UploadManifestCmd:
2325 : 14 : cmdtag = "UPLOAD_MANIFEST";
2326 : 14 : set_ps_display(cmdtag);
2327 : 14 : PreventInTransactionBlock(true, cmdtag);
2328 : 14 : UploadManifest();
2329 : 13 : EndReplicationCommand(cmdtag);
2330 : 13 : break;
2331 : :
2332 : 0 : default:
2333 [ # # ]: 0 : elog(ERROR, "unrecognized replication command node tag: %u",
2334 : : cmd_node->type);
2335 : : }
2336 : :
2337 : : /*
2338 : : * Done. Revert to caller's memory context, and clean out the cmd_context
2339 : : * to recover memory right away.
2340 : : */
2341 : 2897 : MemoryContextSwitchTo(old_context);
2342 : 2897 : MemoryContextReset(cmd_context);
2343 : :
2344 : : /*
2345 : : * We need not update ps display or pg_stat_activity, because PostgresMain
2346 : : * will reset those to "idle". But we must reset debug_query_string to
2347 : : * ensure it doesn't become a dangling pointer.
2348 : : */
2349 : 2897 : debug_query_string = NULL;
2350 : :
2351 : 2897 : return true;
2352 : : }
2353 : :
2354 : : /*
2355 : : * Process any incoming messages while streaming. Also checks if the remote
2356 : : * end has closed the connection.
2357 : : */
2358 : : static void
2359 : 1175729 : ProcessRepliesIfAny(void)
2360 : : {
2361 : : unsigned char firstchar;
2362 : : int maxmsglen;
2363 : : int r;
2364 : 1175729 : bool received = false;
2365 : :
2366 : 1175729 : last_processing = GetCurrentTimestamp();
2367 : :
2368 : : /*
2369 : : * If we already received a CopyDone from the frontend, any subsequent
2370 : : * message is the beginning of a new command, and should be processed in
2371 : : * the main processing loop.
2372 : : */
2373 [ + + ]: 2475794 : while (!streamingDoneReceiving)
2374 : : {
2375 : 1299296 : pq_startmsgread();
2376 : 1299296 : r = pq_getbyte_if_available(&firstchar);
2377 [ + + ]: 1299296 : if (r < 0)
2378 : : {
2379 : : /* unexpected error or EOF */
2380 [ + - ]: 17 : ereport(COMMERROR,
2381 : : (errcode(ERRCODE_PROTOCOL_VIOLATION),
2382 : : errmsg("unexpected EOF on standby connection")));
2383 : 17 : proc_exit(0);
2384 : : }
2385 [ + + ]: 1299279 : if (r == 0)
2386 : : {
2387 : : /* no data available without blocking */
2388 : 1174624 : pq_endmsgread();
2389 : 1174624 : break;
2390 : : }
2391 : :
2392 : : /* Validate message type and set packet size limit */
2393 [ + + - ]: 124655 : switch (firstchar)
2394 : : {
2395 : 123956 : case PqMsg_CopyData:
2396 : 123956 : maxmsglen = PQ_LARGE_MESSAGE_LIMIT;
2397 : 123956 : break;
2398 : 699 : case PqMsg_CopyDone:
2399 : : case PqMsg_Terminate:
2400 : 699 : maxmsglen = PQ_SMALL_MESSAGE_LIMIT;
2401 : 699 : break;
2402 : 0 : default:
2403 [ # # ]: 0 : ereport(FATAL,
2404 : : (errcode(ERRCODE_PROTOCOL_VIOLATION),
2405 : : errmsg("invalid standby message type \"%c\"",
2406 : : firstchar)));
2407 : : maxmsglen = 0; /* keep compiler quiet */
2408 : : break;
2409 : : }
2410 : :
2411 : : /* Read the message contents */
2412 : 124655 : resetStringInfo(&reply_message);
2413 [ - + ]: 124655 : if (pq_getmessage(&reply_message, maxmsglen))
2414 : : {
2415 [ # # ]: 0 : ereport(COMMERROR,
2416 : : (errcode(ERRCODE_PROTOCOL_VIOLATION),
2417 : : errmsg("unexpected EOF on standby connection")));
2418 : 0 : proc_exit(0);
2419 : : }
2420 : :
2421 : : /* ... and process it */
2422 [ + + + - ]: 124655 : switch (firstchar)
2423 : : {
2424 : : /*
2425 : : * PqMsg_CopyData means a standby reply wrapped in a CopyData
2426 : : * packet.
2427 : : */
2428 : 123956 : case PqMsg_CopyData:
2429 : 123956 : ProcessStandbyMessage();
2430 : 123956 : received = true;
2431 : 123956 : break;
2432 : :
2433 : : /*
2434 : : * PqMsg_CopyDone means the standby requested to finish
2435 : : * streaming. Reply with CopyDone, if we had not sent that
2436 : : * already.
2437 : : */
2438 : 380 : case PqMsg_CopyDone:
2439 [ + + ]: 380 : if (!streamingDoneSending)
2440 : : {
2441 : 368 : pq_putmessage_noblock(PqMsg_CopyDone, NULL, 0);
2442 : 368 : streamingDoneSending = true;
2443 : : }
2444 : :
2445 : 380 : streamingDoneReceiving = true;
2446 : 380 : received = true;
2447 : 380 : break;
2448 : :
2449 : : /*
2450 : : * PqMsg_Terminate means that the standby is closing down the
2451 : : * socket.
2452 : : */
2453 : 319 : case PqMsg_Terminate:
2454 : 319 : proc_exit(0);
2455 : :
2456 : 124336 : default:
2457 : : Assert(false); /* NOT REACHED */
2458 : : }
2459 : : }
2460 : :
2461 : : /*
2462 : : * Save the last reply timestamp if we've received at least one reply.
2463 : : */
2464 [ + + ]: 1175393 : if (received)
2465 : : {
2466 : 69262 : last_reply_timestamp = last_processing;
2467 : 69262 : waiting_for_ping_response = false;
2468 : : }
2469 : 1175393 : }
2470 : :
2471 : : /*
2472 : : * Process a status update message received from standby.
2473 : : */
2474 : : static void
2475 : 123956 : ProcessStandbyMessage(void)
2476 : : {
2477 : : char msgtype;
2478 : :
2479 : : /*
2480 : : * Check message type from the first byte.
2481 : : */
2482 : 123956 : msgtype = pq_getmsgbyte(&reply_message);
2483 : :
2484 [ + + + - ]: 123956 : switch (msgtype)
2485 : : {
2486 : 113577 : case PqReplMsg_StandbyStatusUpdate:
2487 : 113577 : ProcessStandbyReplyMessage();
2488 : 113577 : break;
2489 : :
2490 : 159 : case PqReplMsg_HotStandbyFeedback:
2491 : 159 : ProcessStandbyHSFeedbackMessage();
2492 : 159 : break;
2493 : :
2494 : 10220 : case PqReplMsg_PrimaryStatusRequest:
2495 : 10220 : ProcessStandbyPSRequestMessage();
2496 : 10220 : break;
2497 : :
2498 : 0 : default:
2499 [ # # ]: 0 : ereport(COMMERROR,
2500 : : (errcode(ERRCODE_PROTOCOL_VIOLATION),
2501 : : errmsg("unexpected message type \"%c\"", msgtype)));
2502 : 0 : proc_exit(0);
2503 : : }
2504 : 123956 : }
2505 : :
2506 : : /*
2507 : : * Remember that a walreceiver just confirmed receipt of lsn `lsn`.
2508 : : */
2509 : : static void
2510 : 92456 : PhysicalConfirmReceivedLocation(XLogRecPtr lsn)
2511 : : {
2512 : 92456 : bool changed = false;
2513 : 92456 : ReplicationSlot *slot = MyReplicationSlot;
2514 : :
2515 : : Assert(XLogRecPtrIsValid(lsn));
2516 : 92456 : SpinLockAcquire(&slot->mutex);
2517 [ + + ]: 92456 : if (slot->data.restart_lsn != lsn)
2518 : : {
2519 : 41623 : changed = true;
2520 : 41623 : slot->data.restart_lsn = lsn;
2521 : : }
2522 : 92456 : SpinLockRelease(&slot->mutex);
2523 : :
2524 [ + + ]: 92456 : if (changed)
2525 : : {
2526 : 41623 : ReplicationSlotMarkDirty();
2527 : 41623 : ReplicationSlotsComputeRequiredLSN();
2528 : 41623 : PhysicalWakeupLogicalWalSnd();
2529 : : }
2530 : :
2531 : : /*
2532 : : * One could argue that the slot should be saved to disk now, but that'd
2533 : : * be energy wasted - the worst thing lost information could cause here is
2534 : : * to give wrong information in a statistics view - we'll just potentially
2535 : : * be more conservative in removing files.
2536 : : */
2537 : 92456 : }
2538 : :
2539 : : /*
2540 : : * Regular reply from standby advising of WAL locations on standby server.
2541 : : */
2542 : : static void
2543 : 113577 : ProcessStandbyReplyMessage(void)
2544 : : {
2545 : : XLogRecPtr writePtr,
2546 : : flushPtr,
2547 : : applyPtr;
2548 : : bool replyRequested;
2549 : : TimeOffset writeLag,
2550 : : flushLag,
2551 : : applyLag;
2552 : : bool clearLagTimes;
2553 : : TimestampTz now;
2554 : : TimestampTz replyTime;
2555 : :
2556 : : static XLogRecPtr prevWritePtr = InvalidXLogRecPtr;
2557 : : static XLogRecPtr prevFlushPtr = InvalidXLogRecPtr;
2558 : : static XLogRecPtr prevApplyPtr = InvalidXLogRecPtr;
2559 : :
2560 : : /* the caller already consumed the msgtype byte */
2561 : 113577 : writePtr = pq_getmsgint64(&reply_message);
2562 : 113577 : flushPtr = pq_getmsgint64(&reply_message);
2563 : 113577 : applyPtr = pq_getmsgint64(&reply_message);
2564 : 113577 : replyTime = pq_getmsgint64(&reply_message);
2565 : 113577 : replyRequested = pq_getmsgbyte(&reply_message);
2566 : :
2567 [ + + ]: 113577 : if (message_level_is_interesting(DEBUG2))
2568 : : {
2569 : : char *replyTimeStr;
2570 : :
2571 : : /* Copy because timestamptz_to_str returns a static buffer */
2572 : 630 : replyTimeStr = pstrdup(timestamptz_to_str(replyTime));
2573 : :
2574 [ + - - + ]: 630 : elog(DEBUG2, "write %X/%08X flush %X/%08X apply %X/%08X%s reply_time %s",
2575 : : LSN_FORMAT_ARGS(writePtr),
2576 : : LSN_FORMAT_ARGS(flushPtr),
2577 : : LSN_FORMAT_ARGS(applyPtr),
2578 : : replyRequested ? " (reply requested)" : "",
2579 : : replyTimeStr);
2580 : :
2581 : 630 : pfree(replyTimeStr);
2582 : : }
2583 : :
2584 : : /* See if we can compute the round-trip lag for these positions. */
2585 : 113577 : now = GetCurrentTimestamp();
2586 : 113577 : writeLag = LagTrackerRead(SYNC_REP_WAIT_WRITE, writePtr, now);
2587 : 113577 : flushLag = LagTrackerRead(SYNC_REP_WAIT_FLUSH, flushPtr, now);
2588 : 113577 : applyLag = LagTrackerRead(SYNC_REP_WAIT_APPLY, applyPtr, now);
2589 : :
2590 : : /*
2591 : : * If the standby reports that it has fully replayed the WAL, and the
2592 : : * write/flush/apply positions remain unchanged across two consecutive
2593 : : * reply messages, forget the lag times measured when it last
2594 : : * wrote/flushed/applied a WAL record.
2595 : : *
2596 : : * The second message with unchanged positions typically results from
2597 : : * wal_receiver_status_interval expiring on the standby, so lag values are
2598 : : * usually cleared after that interval when there is no activity. This
2599 : : * avoids displaying stale lag data until more WAL traffic arrives.
2600 : : */
2601 [ + + ]: 10783 : clearLagTimes = (applyPtr == sentPtr && flushPtr == sentPtr &&
2602 [ + + + + : 132465 : writePtr == prevWritePtr && flushPtr == prevFlushPtr &&
+ + ]
2603 [ + + ]: 8105 : applyPtr == prevApplyPtr);
2604 : :
2605 : 113577 : prevWritePtr = writePtr;
2606 : 113577 : prevFlushPtr = flushPtr;
2607 : 113577 : prevApplyPtr = applyPtr;
2608 : :
2609 : : /* Send a reply if the standby requested one. */
2610 [ - + ]: 113577 : if (replyRequested)
2611 : 0 : WalSndKeepalive(false, InvalidXLogRecPtr);
2612 : :
2613 : : /*
2614 : : * Update shared state for this WalSender process based on reply data from
2615 : : * standby.
2616 : : */
2617 : : {
2618 : 113577 : WalSnd *walsnd = MyWalSnd;
2619 : :
2620 : 113577 : SpinLockAcquire(&walsnd->mutex);
2621 : 113577 : walsnd->write = writePtr;
2622 : 113577 : walsnd->flush = flushPtr;
2623 : 113577 : walsnd->apply = applyPtr;
2624 [ + + + + ]: 113577 : if (writeLag != -1 || clearLagTimes)
2625 : 68601 : walsnd->writeLag = writeLag;
2626 [ + + + + ]: 113577 : if (flushLag != -1 || clearLagTimes)
2627 : 87607 : walsnd->flushLag = flushLag;
2628 [ + + + + ]: 113577 : if (applyLag != -1 || clearLagTimes)
2629 : 95560 : walsnd->applyLag = applyLag;
2630 : 113577 : walsnd->replyTime = replyTime;
2631 : 113577 : SpinLockRelease(&walsnd->mutex);
2632 : : }
2633 : :
2634 [ + + ]: 113577 : if (!am_cascading_walsender)
2635 : 113275 : SyncRepReleaseWaiters();
2636 : :
2637 : : /*
2638 : : * Advance our local xmin horizon when the client confirmed a flush.
2639 : : */
2640 [ + + + + ]: 113577 : if (MyReplicationSlot && XLogRecPtrIsValid(flushPtr))
2641 : : {
2642 [ + + ]: 110382 : if (SlotIsLogical(MyReplicationSlot))
2643 : 17926 : LogicalConfirmReceivedLocation(flushPtr);
2644 : : else
2645 : 92456 : PhysicalConfirmReceivedLocation(flushPtr);
2646 : : }
2647 : 113577 : }
2648 : :
2649 : : /* compute new replication slot xmin horizon if needed */
2650 : : static void
2651 : 69 : PhysicalReplicationSlotNewXmin(TransactionId feedbackXmin, TransactionId feedbackCatalogXmin)
2652 : : {
2653 : 69 : bool changed = false;
2654 : 69 : ReplicationSlot *slot = MyReplicationSlot;
2655 : :
2656 : 69 : SpinLockAcquire(&slot->mutex);
2657 : 69 : MyProc->xmin = InvalidTransactionId;
2658 : :
2659 : : /*
2660 : : * For physical replication we don't need the interlock provided by xmin
2661 : : * and effective_xmin since the consequences of a missed increase are
2662 : : * limited to query cancellations, so set both at once.
2663 : : */
2664 [ + + + + ]: 69 : if (!TransactionIdIsNormal(slot->data.xmin) ||
2665 [ + + ]: 31 : !TransactionIdIsNormal(feedbackXmin) ||
2666 : 31 : TransactionIdPrecedes(slot->data.xmin, feedbackXmin))
2667 : : {
2668 : 49 : changed = true;
2669 : 49 : slot->data.xmin = feedbackXmin;
2670 : 49 : slot->effective_xmin = feedbackXmin;
2671 : : }
2672 [ + + + + ]: 69 : if (!TransactionIdIsNormal(slot->data.catalog_xmin) ||
2673 [ + + ]: 15 : !TransactionIdIsNormal(feedbackCatalogXmin) ||
2674 : 15 : TransactionIdPrecedes(slot->data.catalog_xmin, feedbackCatalogXmin))
2675 : : {
2676 : 55 : changed = true;
2677 : 55 : slot->data.catalog_xmin = feedbackCatalogXmin;
2678 : 55 : slot->effective_catalog_xmin = feedbackCatalogXmin;
2679 : : }
2680 : 69 : SpinLockRelease(&slot->mutex);
2681 : :
2682 [ + + ]: 69 : if (changed)
2683 : : {
2684 : 59 : ReplicationSlotMarkDirty();
2685 : 59 : ReplicationSlotsComputeRequiredXmin(false);
2686 : : }
2687 : 69 : }
2688 : :
2689 : : /*
2690 : : * Check that the provided xmin/epoch are sane, that is, not in the future
2691 : : * and not so far back as to be already wrapped around.
2692 : : *
2693 : : * Epoch of nextXid should be same as standby, or if the counter has
2694 : : * wrapped, then one greater than standby.
2695 : : *
2696 : : * This check doesn't care about whether clog exists for these xids
2697 : : * at all.
2698 : : */
2699 : : static bool
2700 : 70 : TransactionIdInRecentPast(TransactionId xid, uint32 epoch)
2701 : : {
2702 : : FullTransactionId nextFullXid;
2703 : : TransactionId nextXid;
2704 : : uint32 nextEpoch;
2705 : :
2706 : 70 : nextFullXid = ReadNextFullTransactionId();
2707 : 70 : nextXid = XidFromFullTransactionId(nextFullXid);
2708 : 70 : nextEpoch = EpochFromFullTransactionId(nextFullXid);
2709 : :
2710 [ + - ]: 70 : if (xid <= nextXid)
2711 : : {
2712 [ - + ]: 70 : if (epoch != nextEpoch)
2713 : 0 : return false;
2714 : : }
2715 : : else
2716 : : {
2717 [ # # ]: 0 : if (epoch + 1 != nextEpoch)
2718 : 0 : return false;
2719 : : }
2720 : :
2721 [ - + ]: 70 : if (!TransactionIdPrecedesOrEquals(xid, nextXid))
2722 : 0 : return false; /* epoch OK, but it's wrapped around */
2723 : :
2724 : 70 : return true;
2725 : : }
2726 : :
2727 : : /*
2728 : : * Hot Standby feedback
2729 : : */
2730 : : static void
2731 : 159 : ProcessStandbyHSFeedbackMessage(void)
2732 : : {
2733 : : TransactionId feedbackXmin;
2734 : : uint32 feedbackEpoch;
2735 : : TransactionId feedbackCatalogXmin;
2736 : : uint32 feedbackCatalogEpoch;
2737 : : TimestampTz replyTime;
2738 : :
2739 : : /*
2740 : : * Decipher the reply message. The caller already consumed the msgtype
2741 : : * byte. See XLogWalRcvSendHSFeedback() in walreceiver.c for the creation
2742 : : * of this message.
2743 : : */
2744 : 159 : replyTime = pq_getmsgint64(&reply_message);
2745 : 159 : feedbackXmin = pq_getmsgint(&reply_message, 4);
2746 : 159 : feedbackEpoch = pq_getmsgint(&reply_message, 4);
2747 : 159 : feedbackCatalogXmin = pq_getmsgint(&reply_message, 4);
2748 : 159 : feedbackCatalogEpoch = pq_getmsgint(&reply_message, 4);
2749 : :
2750 [ + + ]: 159 : if (message_level_is_interesting(DEBUG2))
2751 : : {
2752 : : char *replyTimeStr;
2753 : :
2754 : : /* Copy because timestamptz_to_str returns a static buffer */
2755 : 4 : replyTimeStr = pstrdup(timestamptz_to_str(replyTime));
2756 : :
2757 [ + - ]: 4 : elog(DEBUG2, "hot standby feedback xmin %u epoch %u, catalog_xmin %u epoch %u reply_time %s",
2758 : : feedbackXmin,
2759 : : feedbackEpoch,
2760 : : feedbackCatalogXmin,
2761 : : feedbackCatalogEpoch,
2762 : : replyTimeStr);
2763 : :
2764 : 4 : pfree(replyTimeStr);
2765 : : }
2766 : :
2767 : : /*
2768 : : * Update shared state for this WalSender process based on reply data from
2769 : : * standby.
2770 : : */
2771 : : {
2772 : 159 : WalSnd *walsnd = MyWalSnd;
2773 : :
2774 : 159 : SpinLockAcquire(&walsnd->mutex);
2775 : 159 : walsnd->replyTime = replyTime;
2776 : 159 : SpinLockRelease(&walsnd->mutex);
2777 : : }
2778 : :
2779 : : /*
2780 : : * Unset WalSender's xmins if the feedback message values are invalid.
2781 : : * This happens when the downstream turned hot_standby_feedback off.
2782 : : */
2783 [ + + ]: 159 : if (!TransactionIdIsNormal(feedbackXmin)
2784 [ + - ]: 111 : && !TransactionIdIsNormal(feedbackCatalogXmin))
2785 : : {
2786 : 111 : MyProc->xmin = InvalidTransactionId;
2787 [ + + ]: 111 : if (MyReplicationSlot != NULL)
2788 : 25 : PhysicalReplicationSlotNewXmin(feedbackXmin, feedbackCatalogXmin);
2789 : 111 : return;
2790 : : }
2791 : :
2792 : : /*
2793 : : * Check that the provided xmin/epoch are sane, that is, not in the future
2794 : : * and not so far back as to be already wrapped around. Ignore if not.
2795 : : */
2796 [ + - ]: 48 : if (TransactionIdIsNormal(feedbackXmin) &&
2797 [ - + ]: 48 : !TransactionIdInRecentPast(feedbackXmin, feedbackEpoch))
2798 : 0 : return;
2799 : :
2800 [ + + ]: 48 : if (TransactionIdIsNormal(feedbackCatalogXmin) &&
2801 [ - + ]: 22 : !TransactionIdInRecentPast(feedbackCatalogXmin, feedbackCatalogEpoch))
2802 : 0 : return;
2803 : :
2804 : : /*
2805 : : * Set the WalSender's xmin equal to the standby's requested xmin, so that
2806 : : * the xmin will be taken into account by GetSnapshotData() /
2807 : : * ComputeXidHorizons(). This will hold back the removal of dead rows and
2808 : : * thereby prevent the generation of cleanup conflicts on the standby
2809 : : * server.
2810 : : *
2811 : : * There is a small window for a race condition here: although we just
2812 : : * checked that feedbackXmin precedes nextXid, the nextXid could have
2813 : : * gotten advanced between our fetching it and applying the xmin below,
2814 : : * perhaps far enough to make feedbackXmin wrap around. In that case the
2815 : : * xmin we set here would be "in the future" and have no effect. No point
2816 : : * in worrying about this since it's too late to save the desired data
2817 : : * anyway. Assuming that the standby sends us an increasing sequence of
2818 : : * xmins, this could only happen during the first reply cycle, else our
2819 : : * own xmin would prevent nextXid from advancing so far.
2820 : : *
2821 : : * We don't bother taking the ProcArrayLock here. Setting the xmin field
2822 : : * is assumed atomic, and there's no real need to prevent concurrent
2823 : : * horizon determinations. (If we're moving our xmin forward, this is
2824 : : * obviously safe, and if we're moving it backwards, well, the data is at
2825 : : * risk already since a VACUUM could already have determined the horizon.)
2826 : : *
2827 : : * If we're using a replication slot we reserve the xmin via that,
2828 : : * otherwise via the walsender's PGPROC entry. We can only track the
2829 : : * catalog xmin separately when using a slot, so we store the least of the
2830 : : * two provided when not using a slot.
2831 : : *
2832 : : * XXX: It might make sense to generalize the ephemeral slot concept and
2833 : : * always use the slot mechanism to handle the feedback xmin.
2834 : : */
2835 [ + + ]: 48 : if (MyReplicationSlot != NULL) /* XXX: persistency configurable? */
2836 : 44 : PhysicalReplicationSlotNewXmin(feedbackXmin, feedbackCatalogXmin);
2837 : : else
2838 : : {
2839 [ - + ]: 4 : if (TransactionIdIsNormal(feedbackCatalogXmin)
2840 [ # # ]: 0 : && TransactionIdPrecedes(feedbackCatalogXmin, feedbackXmin))
2841 : 0 : MyProc->xmin = feedbackCatalogXmin;
2842 : : else
2843 : 4 : MyProc->xmin = feedbackXmin;
2844 : : }
2845 : : }
2846 : :
2847 : : /*
2848 : : * Process the request for a primary status update message.
2849 : : */
2850 : : static void
2851 : 10220 : ProcessStandbyPSRequestMessage(void)
2852 : : {
2853 : 10220 : XLogRecPtr lsn = InvalidXLogRecPtr;
2854 : : TransactionId oldestXidInCommit;
2855 : : TransactionId oldestGXidInCommit;
2856 : : FullTransactionId nextFullXid;
2857 : : FullTransactionId fullOldestXidInCommit;
2858 : 10220 : WalSnd *walsnd = MyWalSnd;
2859 : : TimestampTz replyTime;
2860 : :
2861 : : /*
2862 : : * This shouldn't happen because we don't support getting primary status
2863 : : * message from standby.
2864 : : */
2865 [ - + ]: 10220 : if (RecoveryInProgress())
2866 [ # # ]: 0 : elog(ERROR, "the primary status is unavailable during recovery");
2867 : :
2868 : 10220 : replyTime = pq_getmsgint64(&reply_message);
2869 : :
2870 : : /*
2871 : : * Update shared state for this WalSender process based on reply data from
2872 : : * standby.
2873 : : */
2874 : 10220 : SpinLockAcquire(&walsnd->mutex);
2875 : 10220 : walsnd->replyTime = replyTime;
2876 : 10220 : SpinLockRelease(&walsnd->mutex);
2877 : :
2878 : : /*
2879 : : * Consider transactions in the current database, as only these are the
2880 : : * ones replicated.
2881 : : */
2882 : 10220 : oldestXidInCommit = GetOldestActiveTransactionId(true, false);
2883 : 10220 : oldestGXidInCommit = TwoPhaseGetOldestXidInCommit();
2884 : :
2885 : : /*
2886 : : * Update the oldest xid for standby transmission if an older prepared
2887 : : * transaction exists and is currently in commit phase.
2888 : : */
2889 [ + + + - ]: 20392 : if (TransactionIdIsValid(oldestGXidInCommit) &&
2890 : 10172 : TransactionIdPrecedes(oldestGXidInCommit, oldestXidInCommit))
2891 : 10172 : oldestXidInCommit = oldestGXidInCommit;
2892 : :
2893 : 10220 : nextFullXid = ReadNextFullTransactionId();
2894 : 10220 : fullOldestXidInCommit = FullTransactionIdFromAllowableAt(nextFullXid,
2895 : : oldestXidInCommit);
2896 : 10220 : lsn = GetXLogWriteRecPtr();
2897 : :
2898 [ + + ]: 10220 : elog(DEBUG2, "sending primary status");
2899 : :
2900 : : /* construct the message... */
2901 : 10220 : resetStringInfo(&output_message);
2902 : 10220 : pq_sendbyte(&output_message, PqReplMsg_PrimaryStatusUpdate);
2903 : 10220 : pq_sendint64(&output_message, lsn);
2904 : 10220 : pq_sendint64(&output_message, (int64) U64FromFullTransactionId(fullOldestXidInCommit));
2905 : 10220 : pq_sendint64(&output_message, (int64) U64FromFullTransactionId(nextFullXid));
2906 : 10220 : pq_sendint64(&output_message, GetCurrentTimestamp());
2907 : :
2908 : : /* ... and send it wrapped in CopyData */
2909 : 10220 : pq_putmessage_noblock(PqMsg_CopyData, output_message.data, output_message.len);
2910 : 10220 : }
2911 : :
2912 : : /*
2913 : : * Compute how long send/receive loops should sleep.
2914 : : *
2915 : : * If wal_sender_timeout is enabled we want to wake up in time to send
2916 : : * keepalives and to abort the connection if wal_sender_timeout has been
2917 : : * reached.
2918 : : *
2919 : : * If wal_sender_shutdown_timeout is enabled, during shutdown, we want to
2920 : : * wake up in time to exit when it expires.
2921 : : */
2922 : : static long
2923 : 106511 : WalSndComputeSleeptime(TimestampTz now)
2924 : : {
2925 : : TimestampTz wakeup_time;
2926 : 106511 : long sleeptime = 10000; /* 10 s */
2927 : :
2928 [ + - + + ]: 106511 : if (wal_sender_timeout > 0 && last_reply_timestamp > 0)
2929 : : {
2930 : : /*
2931 : : * At the latest stop sleeping once wal_sender_timeout has been
2932 : : * reached.
2933 : : */
2934 : 106438 : wakeup_time = TimestampTzPlusMilliseconds(last_reply_timestamp,
2935 : : wal_sender_timeout);
2936 : :
2937 : : /*
2938 : : * If no ping has been sent yet, wakeup when it's time to do so.
2939 : : * WalSndKeepaliveIfNecessary() wants to send a keepalive once half of
2940 : : * the timeout passed without a response.
2941 : : */
2942 [ + + ]: 106438 : if (!waiting_for_ping_response)
2943 : 104441 : wakeup_time = TimestampTzPlusMilliseconds(last_reply_timestamp,
2944 : : wal_sender_timeout / 2);
2945 : :
2946 : : /* Compute relative time until wakeup. */
2947 : 106438 : sleeptime = TimestampDifferenceMilliseconds(now, wakeup_time);
2948 : : }
2949 : :
2950 [ + + + + ]: 106511 : if (shutdown_request_timestamp != 0 && wal_sender_shutdown_timeout > 0)
2951 : : {
2952 : : long shutdown_sleeptime;
2953 : :
2954 : 4 : wakeup_time = TimestampTzPlusMilliseconds(shutdown_request_timestamp,
2955 : : wal_sender_shutdown_timeout);
2956 : :
2957 : 4 : shutdown_sleeptime = TimestampDifferenceMilliseconds(now, wakeup_time);
2958 : :
2959 : : /* Choose the earliest wakeup. */
2960 [ + - ]: 4 : if (shutdown_sleeptime < sleeptime)
2961 : 4 : sleeptime = shutdown_sleeptime;
2962 : : }
2963 : :
2964 : 106511 : return sleeptime;
2965 : : }
2966 : :
2967 : : /*
2968 : : * Check whether there have been responses by the client within
2969 : : * wal_sender_timeout and shutdown if not. Using last_processing as the
2970 : : * reference point avoids counting server-side stalls against the client.
2971 : : * However, a long server-side stall can make WalSndKeepaliveIfNecessary()
2972 : : * postdate last_processing by more than wal_sender_timeout. If that happens,
2973 : : * the client must reply almost immediately to avoid a timeout. This rarely
2974 : : * affects the default configuration, under which clients spontaneously send a
2975 : : * message every standby_message_timeout = wal_sender_timeout/6 = 10s. We
2976 : : * could eliminate that problem by recognizing timeout expiration at
2977 : : * wal_sender_timeout/2 after the keepalive.
2978 : : */
2979 : : static void
2980 : 1167867 : WalSndCheckTimeOut(void)
2981 : : {
2982 : : TimestampTz timeout;
2983 : :
2984 : : /* don't bail out if we're doing something that doesn't require timeouts */
2985 [ + + ]: 1167867 : if (last_reply_timestamp <= 0)
2986 : 29 : return;
2987 : :
2988 : 1167838 : timeout = TimestampTzPlusMilliseconds(last_reply_timestamp,
2989 : : wal_sender_timeout);
2990 : :
2991 [ + - - + ]: 1167838 : if (wal_sender_timeout > 0 && last_processing >= timeout)
2992 : : {
2993 : : /*
2994 : : * Since typically expiration of replication timeout means
2995 : : * communication problem, we don't send the error message to the
2996 : : * standby.
2997 : : */
2998 [ # # ]: 0 : ereport(COMMERROR,
2999 : : (errmsg("terminating walsender process due to replication timeout")));
3000 : :
3001 : 0 : WalSndShutdown();
3002 : : }
3003 : : }
3004 : :
3005 : : /*
3006 : : * Check whether the walsender process should terminate due to the expiration
3007 : : * of wal_sender_shutdown_timeout after the receipt of a shutdown request.
3008 : : */
3009 : : static void
3010 : 1167955 : WalSndCheckShutdownTimeout(void)
3011 : : {
3012 : : TimestampTz now;
3013 : :
3014 : : /* Do nothing if shutdown has not been requested yet */
3015 [ + + + - ]: 1167955 : if (!(got_STOPPING || got_SIGUSR2))
3016 : 1162059 : return;
3017 : :
3018 : : /* Terminate immediately if the timeout is set to 0 */
3019 [ - + ]: 5896 : if (wal_sender_shutdown_timeout == 0)
3020 : 0 : WalSndDoneImmediate();
3021 : :
3022 : : /*
3023 : : * Record the shutdown request timestamp even if
3024 : : * wal_sender_shutdown_timeout is disabled (-1), since the setting may
3025 : : * change during shutdown and the timestamp will be needed in that case.
3026 : : */
3027 [ + + ]: 5896 : if (shutdown_request_timestamp == 0)
3028 : : {
3029 : 48 : shutdown_request_timestamp = GetCurrentTimestamp();
3030 : 48 : return;
3031 : : }
3032 : :
3033 : : /* Do not check the timeout if it's disabled */
3034 [ + + ]: 5848 : if (wal_sender_shutdown_timeout == -1)
3035 : 5432 : return;
3036 : :
3037 : : /* Terminate immediately if the timeout expires */
3038 : 416 : now = GetCurrentTimestamp();
3039 [ + + ]: 416 : if (TimestampDifferenceExceeds(shutdown_request_timestamp, now,
3040 : : wal_sender_shutdown_timeout))
3041 : 3 : WalSndDoneImmediate();
3042 : : }
3043 : :
3044 : : /* Main loop of walsender process that streams the WAL over Copy messages. */
3045 : : static void
3046 : 781 : WalSndLoop(WalSndSendDataCallback send_data)
3047 : : {
3048 : 781 : TimestampTz last_flush = 0;
3049 : :
3050 : : /*
3051 : : * Initialize the last reply timestamp. That enables timeout processing
3052 : : * from hereon.
3053 : : */
3054 : 781 : last_reply_timestamp = GetCurrentTimestamp();
3055 : 781 : waiting_for_ping_response = false;
3056 : :
3057 : : /*
3058 : : * Loop until we reach the end of this timeline or the client requests to
3059 : : * stop streaming.
3060 : : */
3061 : : for (;;)
3062 : : {
3063 : : /* Clear any already-pending wakeups */
3064 : 1153945 : ResetLatch(MyLatch);
3065 : :
3066 [ + + ]: 1153945 : CHECK_FOR_INTERRUPTS();
3067 : :
3068 : : /* Process any requests or signals received recently */
3069 : 1153942 : WalSndHandleConfigReload();
3070 : :
3071 : : /* Check for input from the client */
3072 : 1153942 : ProcessRepliesIfAny();
3073 : :
3074 : : /*
3075 : : * If we have received CopyDone from the client, sent CopyDone
3076 : : * ourselves, and the output buffer is empty, it's time to exit
3077 : : * streaming.
3078 : : */
3079 [ + + + - ]: 1153833 : if (streamingDoneReceiving && streamingDoneSending &&
3080 [ + + ]: 596 : !pq_is_send_pending())
3081 : 380 : break;
3082 : :
3083 : : /*
3084 : : * If we don't have any pending data in the output buffer, try to send
3085 : : * some more. If there is some, we don't bother to call send_data
3086 : : * again until we've flushed it ... but we'd better assume we are not
3087 : : * caught up.
3088 : : */
3089 [ + + ]: 1153453 : if (!pq_is_send_pending())
3090 : 1111381 : send_data();
3091 : : else
3092 : 42072 : WalSndCaughtUp = false;
3093 : :
3094 : : /* Try to flush pending output to the client */
3095 [ - + ]: 1153210 : if (pq_flush_if_writable() != 0)
3096 : 0 : WalSndShutdown();
3097 : :
3098 : : /* If nothing remains to be sent right now ... */
3099 [ + + + + ]: 1153210 : if (WalSndCaughtUp && !pq_is_send_pending())
3100 : : {
3101 : : /*
3102 : : * If we're in catchup state, move to streaming. This is an
3103 : : * important state change for users to know about, since before
3104 : : * this point data loss might occur if the primary dies and we
3105 : : * need to failover to the standby. The state change is also
3106 : : * important for synchronous replication, since commits that
3107 : : * started to wait at that point might wait for some time.
3108 : : */
3109 [ + + ]: 89954 : if (MyWalSnd->state == WALSNDSTATE_CATCHUP)
3110 : : {
3111 [ + + ]: 731 : ereport(DEBUG1,
3112 : : (errmsg_internal("\"%s\" has now caught up with upstream server",
3113 : : application_name)));
3114 : 731 : WalSndSetState(WALSNDSTATE_STREAMING);
3115 : : }
3116 : :
3117 : : /*
3118 : : * When SIGUSR2 arrives, we send any outstanding logs up to the
3119 : : * shutdown checkpoint record (i.e., the latest record), wait for
3120 : : * them to be replicated to the standby, and exit. This may be a
3121 : : * normal termination at shutdown, or a promotion, the walsender
3122 : : * is not sure which.
3123 : : */
3124 [ + + ]: 89954 : if (got_SIGUSR2)
3125 : 4368 : WalSndDone(send_data);
3126 : : }
3127 : :
3128 : : /* Check for replication timeout. */
3129 : 1153166 : WalSndCheckTimeOut();
3130 : :
3131 : : /*
3132 : : * During shutdown, die if the shutdown timeout expires. Call this
3133 : : * before WalSndComputeSleeptime() so the timeout is considered when
3134 : : * computing sleep time.
3135 : : */
3136 : 1153166 : WalSndCheckShutdownTimeout();
3137 : :
3138 : : /* Send keepalive if the time has come */
3139 : 1153164 : WalSndKeepaliveIfNecessary();
3140 : :
3141 : : /*
3142 : : * Block if we have unsent data. XXX For logical replication, let
3143 : : * WalSndWaitForWal() handle any other blocking; idle receivers need
3144 : : * its additional actions. For physical replication, also block if
3145 : : * caught up; its send_data does not block.
3146 : : *
3147 : : * The IO statistics are reported in WalSndWaitForWal() for the
3148 : : * logical WAL senders.
3149 : : */
3150 [ + + + + ]: 1153164 : if ((WalSndCaughtUp && send_data != XLogSendLogical &&
3151 [ + + + + ]: 1186724 : !streamingDoneSending) ||
3152 : 1100061 : pq_is_send_pending())
3153 : : {
3154 : : long sleeptime;
3155 : : int wakeEvents;
3156 : : TimestampTz now;
3157 : :
3158 [ + + ]: 92300 : if (!streamingDoneReceiving)
3159 : 92279 : wakeEvents = WL_SOCKET_READABLE;
3160 : : else
3161 : 21 : wakeEvents = 0;
3162 : :
3163 : : /*
3164 : : * Use fresh timestamp, not last_processing, to reduce the chance
3165 : : * of reaching wal_sender_timeout before sending a keepalive.
3166 : : */
3167 : 92300 : now = GetCurrentTimestamp();
3168 : 92300 : sleeptime = WalSndComputeSleeptime(now);
3169 : :
3170 [ + + ]: 92300 : if (pq_is_send_pending())
3171 : 42016 : wakeEvents |= WL_SOCKET_WRITEABLE;
3172 : :
3173 : : /* Report IO statistics, if needed */
3174 [ + + ]: 92300 : if (TimestampDifferenceExceeds(last_flush, now,
3175 : : WALSENDER_STATS_FLUSH_INTERVAL))
3176 : : {
3177 : 590 : pgstat_flush_io(false);
3178 : 590 : (void) pgstat_flush_backend(false, PGSTAT_BACKEND_FLUSH_IO);
3179 : 590 : last_flush = now;
3180 : : }
3181 : :
3182 : : /* Sleep until something happens or we time out */
3183 : 92300 : WalSndWait(wakeEvents, sleeptime, WAIT_EVENT_WAL_SENDER_MAIN);
3184 : : }
3185 : : }
3186 : 380 : }
3187 : :
3188 : : /* Initialize a per-walsender data structure for this walsender process */
3189 : : static void
3190 : 1327 : InitWalSenderSlot(void)
3191 : : {
3192 : : int i;
3193 : :
3194 : : /*
3195 : : * WalSndCtl should be set up already (we inherit this by fork() or
3196 : : * EXEC_BACKEND mechanism from the postmaster).
3197 : : */
3198 : : Assert(WalSndCtl != NULL);
3199 : : Assert(MyWalSnd == NULL);
3200 : :
3201 : : /*
3202 : : * Find a free walsender slot and reserve it. This must not fail due to
3203 : : * the prior check for free WAL senders in InitProcess().
3204 : : */
3205 [ + - ]: 1951 : for (i = 0; i < max_wal_senders; i++)
3206 : : {
3207 : 1951 : WalSnd *walsnd = &WalSndCtl->walsnds[i];
3208 : :
3209 : 1951 : SpinLockAcquire(&walsnd->mutex);
3210 : :
3211 [ + + ]: 1951 : if (walsnd->pid != 0)
3212 : : {
3213 : 624 : SpinLockRelease(&walsnd->mutex);
3214 : 624 : continue;
3215 : : }
3216 : : else
3217 : : {
3218 : : /*
3219 : : * Found a free slot. Reserve it for us.
3220 : : */
3221 : 1327 : walsnd->pid = MyProcPid;
3222 : 1327 : walsnd->state = WALSNDSTATE_STARTUP;
3223 : 1327 : walsnd->sentPtr = InvalidXLogRecPtr;
3224 : 1327 : walsnd->needreload = false;
3225 : 1327 : walsnd->write = InvalidXLogRecPtr;
3226 : 1327 : walsnd->flush = InvalidXLogRecPtr;
3227 : 1327 : walsnd->apply = InvalidXLogRecPtr;
3228 : 1327 : walsnd->writeLag = -1;
3229 : 1327 : walsnd->flushLag = -1;
3230 : 1327 : walsnd->applyLag = -1;
3231 : 1327 : walsnd->sync_standby_priority = 0;
3232 : 1327 : walsnd->replyTime = 0;
3233 : :
3234 : : /*
3235 : : * The kind assignment is done here and not in StartReplication()
3236 : : * and StartLogicalReplication(). Indeed, the logical walsender
3237 : : * needs to read WAL records (like snapshot of running
3238 : : * transactions) during the slot creation. So it needs to be woken
3239 : : * up based on its kind.
3240 : : *
3241 : : * The kind assignment could also be done in StartReplication(),
3242 : : * StartLogicalReplication() and CREATE_REPLICATION_SLOT but it
3243 : : * seems better to set it on one place.
3244 : : */
3245 [ + + ]: 1327 : if (MyDatabaseId == InvalidOid)
3246 : 516 : walsnd->kind = REPLICATION_KIND_PHYSICAL;
3247 : : else
3248 : 811 : walsnd->kind = REPLICATION_KIND_LOGICAL;
3249 : :
3250 : 1327 : SpinLockRelease(&walsnd->mutex);
3251 : : /* don't need the lock anymore */
3252 : 1327 : MyWalSnd = walsnd;
3253 : :
3254 : 1327 : break;
3255 : : }
3256 : : }
3257 : :
3258 : : Assert(MyWalSnd != NULL);
3259 : :
3260 : : /* Arrange to clean up at walsender exit */
3261 : 1327 : on_shmem_exit(WalSndKill, 0);
3262 : 1327 : }
3263 : :
3264 : : /* Destroy the per-walsender data structure for this walsender process */
3265 : : static void
3266 : 1327 : WalSndKill(int code, Datum arg)
3267 : : {
3268 : 1327 : WalSnd *walsnd = MyWalSnd;
3269 : :
3270 : : Assert(walsnd != NULL);
3271 : :
3272 : 1327 : MyWalSnd = NULL;
3273 : :
3274 : 1327 : SpinLockAcquire(&walsnd->mutex);
3275 : : /* Mark WalSnd struct as no longer being in use. */
3276 : 1327 : walsnd->pid = 0;
3277 : 1327 : SpinLockRelease(&walsnd->mutex);
3278 : 1327 : }
3279 : :
3280 : : /* XLogReaderRoutine->segment_open callback */
3281 : : static void
3282 : 7102 : WalSndSegmentOpen(XLogReaderState *state, XLogSegNo nextSegNo,
3283 : : TimeLineID *tli_p)
3284 : : {
3285 : : char path[MAXPGPATH];
3286 : :
3287 : : /*-------
3288 : : * When reading from a historic timeline, and there is a timeline switch
3289 : : * within this segment, read from the WAL segment belonging to the new
3290 : : * timeline.
3291 : : *
3292 : : * For example, imagine that this server is currently on timeline 5, and
3293 : : * we're streaming timeline 4. The switch from timeline 4 to 5 happened at
3294 : : * 0/13002088. In pg_wal, we have these files:
3295 : : *
3296 : : * ...
3297 : : * 000000040000000000000012
3298 : : * 000000040000000000000013
3299 : : * 000000050000000000000013
3300 : : * 000000050000000000000014
3301 : : * ...
3302 : : *
3303 : : * In this situation, when requested to send the WAL from segment 0x13, on
3304 : : * timeline 4, we read the WAL from file 000000050000000000000013. Archive
3305 : : * recovery prefers files from newer timelines, so if the segment was
3306 : : * restored from the archive on this server, the file belonging to the old
3307 : : * timeline, 000000040000000000000013, might not exist. Their contents are
3308 : : * equal up to the switchpoint, because at a timeline switch, the used
3309 : : * portion of the old segment is copied to the new file.
3310 : : */
3311 : 7102 : *tli_p = sendTimeLine;
3312 [ + + ]: 7102 : if (sendTimeLineIsHistoric)
3313 : : {
3314 : : XLogSegNo endSegNo;
3315 : :
3316 : 592 : XLByteToSeg(sendTimeLineValidUpto, endSegNo, state->segcxt.ws_segsize);
3317 [ + + ]: 592 : if (nextSegNo == endSegNo)
3318 : 8 : *tli_p = sendTimeLineNextTLI;
3319 : : }
3320 : :
3321 : 7102 : XLogFilePath(path, *tli_p, nextSegNo, state->segcxt.ws_segsize);
3322 : 7102 : state->seg.ws_file = BasicOpenFile(path, O_RDONLY | PG_BINARY);
3323 [ + + ]: 7102 : if (state->seg.ws_file >= 0)
3324 : 7101 : return;
3325 : :
3326 : : /*
3327 : : * If the file is not found, assume it's because the standby asked for a
3328 : : * too old WAL segment that has already been removed or recycled.
3329 : : */
3330 [ + - ]: 1 : if (errno == ENOENT)
3331 : : {
3332 : : char xlogfname[MAXFNAMELEN];
3333 : 1 : int save_errno = errno;
3334 : :
3335 : 1 : XLogFileName(xlogfname, *tli_p, nextSegNo, wal_segment_size);
3336 : 1 : errno = save_errno;
3337 [ + - ]: 1 : ereport(ERROR,
3338 : : (errcode_for_file_access(),
3339 : : errmsg("requested WAL segment %s has already been removed",
3340 : : xlogfname)));
3341 : : }
3342 : : else
3343 [ # # ]: 0 : ereport(ERROR,
3344 : : (errcode_for_file_access(),
3345 : : errmsg("could not open file \"%s\": %m",
3346 : : path)));
3347 : : }
3348 : :
3349 : : /*
3350 : : * Send out the WAL in its normal physical/stored form.
3351 : : *
3352 : : * Read up to MAX_SEND_SIZE bytes of WAL that's been flushed to disk,
3353 : : * but not yet sent to the client, and buffer it in the libpq output
3354 : : * buffer.
3355 : : *
3356 : : * If there is no unsent WAL remaining, WalSndCaughtUp is set to true,
3357 : : * otherwise WalSndCaughtUp is set to false.
3358 : : */
3359 : : static void
3360 : 178081 : XLogSendPhysical(void)
3361 : : {
3362 : : XLogRecPtr SendRqstPtr;
3363 : : XLogRecPtr startptr;
3364 : : XLogRecPtr endptr;
3365 : : Size nbytes;
3366 : : XLogSegNo segno;
3367 : : WALReadError errinfo;
3368 : : Size rbytes;
3369 : :
3370 : : /* If requested switch the WAL sender to the stopping state. */
3371 [ + + ]: 178081 : if (got_STOPPING)
3372 : 4365 : WalSndSetState(WALSNDSTATE_STOPPING);
3373 : :
3374 [ + + ]: 178081 : if (streamingDoneSending)
3375 : : {
3376 : 33548 : WalSndCaughtUp = true;
3377 : 68932 : return;
3378 : : }
3379 : :
3380 : : /* Figure out how far we can safely send the WAL. */
3381 [ + + ]: 144533 : if (sendTimeLineIsHistoric)
3382 : : {
3383 : : /*
3384 : : * Streaming an old timeline that's in this server's history, but is
3385 : : * not the one we're currently inserting or replaying. It can be
3386 : : * streamed up to the point where we switched off that timeline.
3387 : : */
3388 : 33 : SendRqstPtr = sendTimeLineValidUpto;
3389 : : }
3390 [ + + ]: 144500 : else if (am_cascading_walsender)
3391 : : {
3392 : : TimeLineID SendRqstTLI;
3393 : :
3394 : : /*
3395 : : * Streaming the latest timeline on a standby.
3396 : : *
3397 : : * Attempt to send all WAL that has already been replayed, so that we
3398 : : * know it's valid. If we're receiving WAL through streaming
3399 : : * replication, it's also OK to send any WAL that has been received
3400 : : * but not replayed.
3401 : : *
3402 : : * The timeline we're recovering from can change, or we can be
3403 : : * promoted. In either case, the current timeline becomes historic. We
3404 : : * need to detect that so that we don't try to stream past the point
3405 : : * where we switched to another timeline. We check for promotion or
3406 : : * timeline switch after calculating FlushPtr, to avoid a race
3407 : : * condition: if the timeline becomes historic just after we checked
3408 : : * that it was still current, it's still be OK to stream it up to the
3409 : : * FlushPtr that was calculated before it became historic.
3410 : : */
3411 : 1021 : bool becameHistoric = false;
3412 : :
3413 : 1021 : SendRqstPtr = GetStandbyFlushRecPtr(&SendRqstTLI);
3414 : :
3415 [ + + ]: 1021 : if (!RecoveryInProgress())
3416 : : {
3417 : : /* We have been promoted. */
3418 : 3 : SendRqstTLI = GetWALInsertionTimeLine();
3419 : 3 : am_cascading_walsender = false;
3420 : 3 : becameHistoric = true;
3421 : : }
3422 : : else
3423 : : {
3424 : : /*
3425 : : * Still a cascading standby. But is the timeline we're sending
3426 : : * still the one recovery is recovering from?
3427 : : */
3428 [ - + ]: 1018 : if (sendTimeLine != SendRqstTLI)
3429 : 0 : becameHistoric = true;
3430 : : }
3431 : :
3432 [ + + ]: 1021 : if (becameHistoric)
3433 : : {
3434 : : /*
3435 : : * The timeline we were sending has become historic. Read the
3436 : : * timeline history file of the new timeline to see where exactly
3437 : : * we forked off from the timeline we were sending.
3438 : : */
3439 : : List *history;
3440 : :
3441 : 3 : history = readTimeLineHistory(SendRqstTLI);
3442 : 3 : sendTimeLineValidUpto = tliSwitchPoint(sendTimeLine, history, &sendTimeLineNextTLI);
3443 : :
3444 : : Assert(sendTimeLine < sendTimeLineNextTLI);
3445 : 3 : list_free_deep(history);
3446 : :
3447 : 3 : sendTimeLineIsHistoric = true;
3448 : :
3449 : 3 : SendRqstPtr = sendTimeLineValidUpto;
3450 : : }
3451 : : }
3452 : : else
3453 : : {
3454 : : /*
3455 : : * Streaming the current timeline on a primary.
3456 : : *
3457 : : * Attempt to send all data that's already been written out and
3458 : : * fsync'd to disk. We cannot go further than what's been written out
3459 : : * given the current implementation of WALRead(). And in any case
3460 : : * it's unsafe to send WAL that is not securely down to disk on the
3461 : : * primary: if the primary subsequently crashes and restarts, standbys
3462 : : * must not have applied any WAL that got lost on the primary.
3463 : : */
3464 : 143479 : SendRqstPtr = GetFlushRecPtr(NULL);
3465 : : }
3466 : :
3467 : : /*
3468 : : * Record the current system time as an approximation of the time at which
3469 : : * this WAL location was written for the purposes of lag tracking.
3470 : : *
3471 : : * In theory we could make XLogFlush() record a time in shmem whenever WAL
3472 : : * is flushed and we could get that time as well as the LSN when we call
3473 : : * GetFlushRecPtr() above (and likewise for the cascading standby
3474 : : * equivalent), but rather than putting any new code into the hot WAL path
3475 : : * it seems good enough to capture the time here. We should reach this
3476 : : * after XLogFlush() runs WalSndWakeupProcessRequests(), and although that
3477 : : * may take some time, we read the WAL flush pointer and take the time
3478 : : * very close to together here so that we'll get a later position if it is
3479 : : * still moving.
3480 : : *
3481 : : * Because LagTrackerWrite ignores samples when the LSN hasn't advanced,
3482 : : * this gives us a cheap approximation for the WAL flush time for this
3483 : : * LSN.
3484 : : *
3485 : : * Note that the LSN is not necessarily the LSN for the data contained in
3486 : : * the present message; it's the end of the WAL, which might be further
3487 : : * ahead. All the lag tracking machinery cares about is finding out when
3488 : : * that arbitrary LSN is eventually reported as written, flushed and
3489 : : * applied, so that it can measure the elapsed time.
3490 : : */
3491 : 144533 : LagTrackerWrite(SendRqstPtr, GetCurrentTimestamp());
3492 : :
3493 : : /*
3494 : : * If this is a historic timeline and we've reached the point where we
3495 : : * forked to the next timeline, stop streaming.
3496 : : *
3497 : : * Note: We might already have sent WAL > sendTimeLineValidUpto. The
3498 : : * startup process will normally replay all WAL that has been received
3499 : : * from the primary, before promoting, but if the WAL streaming is
3500 : : * terminated at a WAL page boundary, the valid portion of the timeline
3501 : : * might end in the middle of a WAL record. We might've already sent the
3502 : : * first half of that partial WAL record to the cascading standby, so that
3503 : : * sentPtr > sendTimeLineValidUpto. That's OK; the cascading standby can't
3504 : : * replay the partial WAL record either, so it can still follow our
3505 : : * timeline switch.
3506 : : */
3507 [ + + + + ]: 144533 : if (sendTimeLineIsHistoric && sendTimeLineValidUpto <= sentPtr)
3508 : : {
3509 : : /* close the current file. */
3510 [ + - ]: 12 : if (xlogreader->seg.ws_file >= 0)
3511 : 12 : wal_segment_close(xlogreader);
3512 : :
3513 : : /* Send CopyDone */
3514 : 12 : pq_putmessage_noblock(PqMsg_CopyDone, NULL, 0);
3515 : 12 : streamingDoneSending = true;
3516 : :
3517 : 12 : WalSndCaughtUp = true;
3518 : :
3519 [ + + ]: 12 : elog(DEBUG1, "walsender reached end of timeline at %X/%08X (sent up to %X/%08X)",
3520 : : LSN_FORMAT_ARGS(sendTimeLineValidUpto),
3521 : : LSN_FORMAT_ARGS(sentPtr));
3522 : 12 : return;
3523 : : }
3524 : :
3525 : : /* Do we have any work to do? */
3526 : : Assert(sentPtr <= SendRqstPtr);
3527 [ + + ]: 144521 : if (SendRqstPtr <= sentPtr)
3528 : : {
3529 : 35372 : WalSndCaughtUp = true;
3530 : 35372 : return;
3531 : : }
3532 : :
3533 : : /*
3534 : : * Figure out how much to send in one message. If there's no more than
3535 : : * MAX_SEND_SIZE bytes to send, send everything. Otherwise send
3536 : : * MAX_SEND_SIZE bytes, but round back to logfile or page boundary.
3537 : : *
3538 : : * The rounding is not only for performance reasons. Walreceiver relies on
3539 : : * the fact that we never split a WAL record across two messages. Since a
3540 : : * long WAL record is split at page boundary into continuation records,
3541 : : * page boundary is always a safe cut-off point. We also assume that
3542 : : * SendRqstPtr never points to the middle of a WAL record.
3543 : : */
3544 : 109149 : startptr = sentPtr;
3545 : 109149 : endptr = startptr;
3546 : 109149 : endptr += MAX_SEND_SIZE;
3547 : :
3548 : : /* if we went beyond SendRqstPtr, back off */
3549 [ + + ]: 109149 : if (SendRqstPtr <= endptr)
3550 : : {
3551 : 19799 : endptr = SendRqstPtr;
3552 [ + + ]: 19799 : if (sendTimeLineIsHistoric)
3553 : 9 : WalSndCaughtUp = false;
3554 : : else
3555 : 19790 : WalSndCaughtUp = true;
3556 : : }
3557 : : else
3558 : : {
3559 : : /* round down to page boundary. */
3560 : 89350 : endptr -= (endptr % XLOG_BLCKSZ);
3561 : 89350 : WalSndCaughtUp = false;
3562 : : }
3563 : :
3564 : 109149 : nbytes = endptr - startptr;
3565 : : Assert(nbytes <= MAX_SEND_SIZE);
3566 : :
3567 : : /*
3568 : : * OK to read and send the slice.
3569 : : */
3570 : 109149 : resetStringInfo(&output_message);
3571 : 109149 : pq_sendbyte(&output_message, PqReplMsg_WALData);
3572 : :
3573 : 109149 : pq_sendint64(&output_message, startptr); /* dataStart */
3574 : 109149 : pq_sendint64(&output_message, SendRqstPtr); /* walEnd */
3575 : 109149 : pq_sendint64(&output_message, 0); /* sendtime, filled in last */
3576 : :
3577 : : /*
3578 : : * Read the log directly into the output buffer to avoid extra memcpy
3579 : : * calls.
3580 : : */
3581 : 109149 : enlargeStringInfo(&output_message, nbytes);
3582 : :
3583 : 109149 : retry:
3584 : : /* attempt to read WAL from WAL buffers first */
3585 : 109149 : rbytes = WALReadFromBuffers(&output_message.data[output_message.len],
3586 : 109149 : startptr, nbytes, xlogreader->seg.ws_tli);
3587 : 109149 : output_message.len += rbytes;
3588 : 109149 : startptr += rbytes;
3589 : 109149 : nbytes -= rbytes;
3590 : :
3591 : : /* now read the remaining WAL from WAL file */
3592 [ + + ]: 109149 : if (nbytes > 0 &&
3593 [ - + ]: 100098 : !WALRead(xlogreader,
3594 : 100099 : &output_message.data[output_message.len],
3595 : : startptr,
3596 : : nbytes,
3597 : 100099 : xlogreader->seg.ws_tli, /* Pass the current TLI because
3598 : : * only WalSndSegmentOpen controls
3599 : : * whether new TLI is needed. */
3600 : : &errinfo))
3601 : 0 : WALReadRaiseError(&errinfo);
3602 : :
3603 : : /* See logical_read_xlog_page(). */
3604 : 109148 : XLByteToSeg(startptr, segno, xlogreader->segcxt.ws_segsize);
3605 : 109148 : CheckXLogRemoved(segno, xlogreader->seg.ws_tli);
3606 : :
3607 : : /*
3608 : : * During recovery, the currently-open WAL file might be replaced with the
3609 : : * file of the same name retrieved from archive. So we always need to
3610 : : * check what we read was valid after reading into the buffer. If it's
3611 : : * invalid, we try to open and read the file again.
3612 : : */
3613 [ + + ]: 109148 : if (am_cascading_walsender)
3614 : : {
3615 : 814 : WalSnd *walsnd = MyWalSnd;
3616 : : bool reload;
3617 : :
3618 : 814 : SpinLockAcquire(&walsnd->mutex);
3619 : 814 : reload = walsnd->needreload;
3620 : 814 : walsnd->needreload = false;
3621 : 814 : SpinLockRelease(&walsnd->mutex);
3622 : :
3623 [ - + - - ]: 814 : if (reload && xlogreader->seg.ws_file >= 0)
3624 : : {
3625 : 0 : wal_segment_close(xlogreader);
3626 : :
3627 : 0 : goto retry;
3628 : : }
3629 : : }
3630 : :
3631 : 109148 : output_message.len += nbytes;
3632 : 109148 : output_message.data[output_message.len] = '\0';
3633 : :
3634 : : /*
3635 : : * Fill the send timestamp last, so that it is taken as late as possible.
3636 : : */
3637 : 109148 : resetStringInfo(&tmpbuf);
3638 : 109148 : pq_sendint64(&tmpbuf, GetCurrentTimestamp());
3639 : 109148 : memcpy(&output_message.data[1 + sizeof(int64) + sizeof(int64)],
3640 : 109148 : tmpbuf.data, sizeof(int64));
3641 : :
3642 : 109148 : pq_putmessage_noblock(PqMsg_CopyData, output_message.data, output_message.len);
3643 : :
3644 : 109148 : sentPtr = endptr;
3645 : :
3646 : : /* Update shared memory status */
3647 : : {
3648 : 109148 : WalSnd *walsnd = MyWalSnd;
3649 : :
3650 : 109148 : SpinLockAcquire(&walsnd->mutex);
3651 : 109148 : walsnd->sentPtr = sentPtr;
3652 : 109148 : SpinLockRelease(&walsnd->mutex);
3653 : : }
3654 : :
3655 : : /* Report progress of XLOG streaming in PS display */
3656 [ + - ]: 109148 : if (update_process_title)
3657 : : {
3658 : : char activitymsg[50];
3659 : :
3660 : 109148 : snprintf(activitymsg, sizeof(activitymsg), "streaming %X/%08X",
3661 : 109148 : LSN_FORMAT_ARGS(sentPtr));
3662 : 109148 : set_ps_display(activitymsg);
3663 : : }
3664 : : }
3665 : :
3666 : : /*
3667 : : * Stream out logically decoded data.
3668 : : */
3669 : : static void
3670 : 937668 : XLogSendLogical(void)
3671 : : {
3672 : : XLogRecord *record;
3673 : : char *errm;
3674 : :
3675 : : /*
3676 : : * We'll use the current flush point to determine whether we've caught up.
3677 : : * This variable is static in order to cache it across calls. Caching is
3678 : : * helpful because GetFlushRecPtr() needs to acquire a heavily-contended
3679 : : * spinlock.
3680 : : */
3681 : : static XLogRecPtr flushPtr = InvalidXLogRecPtr;
3682 : :
3683 : : /*
3684 : : * Don't know whether we've caught up yet. We'll set WalSndCaughtUp to
3685 : : * true in WalSndWaitForWal, if we're actually waiting. We also set to
3686 : : * true if XLogReadRecord() had to stop reading but WalSndWaitForWal
3687 : : * didn't wait - i.e. when we're shutting down.
3688 : : */
3689 : 937668 : WalSndCaughtUp = false;
3690 : :
3691 : 937668 : record = XLogReadRecord(logical_decoding_ctx->reader, &errm);
3692 : :
3693 : : /* xlog record was invalid */
3694 [ - + ]: 937433 : if (errm != NULL)
3695 [ # # ]: 0 : elog(ERROR, "could not find record while sending logically-decoded data: %s",
3696 : : errm);
3697 : :
3698 [ + + ]: 937433 : if (record != NULL)
3699 : : {
3700 : : /*
3701 : : * Note the lack of any call to LagTrackerWrite() which is handled by
3702 : : * WalSndUpdateProgress which is called by output plugin through
3703 : : * logical decoding write api.
3704 : : */
3705 : 932577 : LogicalDecodingProcessRecord(logical_decoding_ctx, logical_decoding_ctx->reader);
3706 : :
3707 : 932570 : sentPtr = logical_decoding_ctx->reader->EndRecPtr;
3708 : : }
3709 : :
3710 : : /*
3711 : : * If first time through in this session, initialize flushPtr. Otherwise,
3712 : : * we only need to update flushPtr if EndRecPtr is past it.
3713 : : */
3714 [ + + ]: 937426 : if (!XLogRecPtrIsValid(flushPtr) ||
3715 [ + + ]: 936992 : logical_decoding_ctx->reader->EndRecPtr >= flushPtr)
3716 : : {
3717 : : /*
3718 : : * For cascading logical WAL senders, we use the replay LSN instead of
3719 : : * the flush LSN, since logical decoding on a standby only processes
3720 : : * WAL that has been replayed. This distinction becomes particularly
3721 : : * important during shutdown, as new WAL is no longer replayed and the
3722 : : * last replayed LSN marks the furthest point up to which decoding can
3723 : : * proceed.
3724 : : */
3725 [ + + ]: 7644 : if (am_cascading_walsender)
3726 : 1558 : flushPtr = GetXLogReplayRecPtr(NULL);
3727 : : else
3728 : 6086 : flushPtr = GetFlushRecPtr(NULL);
3729 : : }
3730 : :
3731 : : /* If EndRecPtr is still past our flushPtr, it means we caught up. */
3732 [ + + ]: 937426 : if (logical_decoding_ctx->reader->EndRecPtr >= flushPtr)
3733 : 6502 : WalSndCaughtUp = true;
3734 : :
3735 : : /*
3736 : : * If we're caught up and have been requested to stop, have WalSndLoop()
3737 : : * terminate the connection in an orderly manner, after writing out all
3738 : : * the pending data.
3739 : : */
3740 [ + + + + ]: 937426 : if (WalSndCaughtUp && got_STOPPING)
3741 : 4685 : got_SIGUSR2 = true;
3742 : :
3743 : : /* Update shared memory status */
3744 : : {
3745 : 937426 : WalSnd *walsnd = MyWalSnd;
3746 : :
3747 : 937426 : SpinLockAcquire(&walsnd->mutex);
3748 : 937426 : walsnd->sentPtr = sentPtr;
3749 : 937426 : SpinLockRelease(&walsnd->mutex);
3750 : : }
3751 : 937426 : }
3752 : :
3753 : : /*
3754 : : * Forced shutdown of walsender if wal_sender_shutdown_timeout has expired.
3755 : : */
3756 : : static void
3757 : 3 : WalSndDoneImmediate(void)
3758 : : {
3759 : 3 : WalSndState state = MyWalSnd->state;
3760 : :
3761 [ + - + + ]: 3 : if ((state == WALSNDSTATE_CATCHUP ||
3762 [ + - ]: 1 : state == WALSNDSTATE_STREAMING ||
3763 : 3 : state == WALSNDSTATE_STOPPING) &&
3764 [ + - ]: 3 : !shutdown_stream_done_queued)
3765 : : {
3766 : : QueryCompletion qc;
3767 : :
3768 : : /* Try to inform receiver that XLOG streaming is done */
3769 : 3 : SetQueryCompletion(&qc, CMDTAG_COPY, 0);
3770 : 3 : EndCommandExtended(&qc, DestRemote, false, true);
3771 : 3 : shutdown_stream_done_queued = true;
3772 : :
3773 : : /*
3774 : : * Note that the output buffer may be full during the forced shutdown
3775 : : * of walsender. If pq_flush() is called at that time, the walsender
3776 : : * process will be stuck. Therefore, call pq_flush_if_writable()
3777 : : * instead. Successful reception of the done message with the
3778 : : * walsender forced into a shutdown is not guaranteed.
3779 : : */
3780 : 3 : pq_flush_if_writable();
3781 : : }
3782 : :
3783 : : /*
3784 : : * Prevent ereport from attempting to send any more messages to the
3785 : : * standby. Otherwise, it can cause the process to get stuck if the output
3786 : : * buffers are full.
3787 : : */
3788 [ + - ]: 3 : if (whereToSendOutput == DestRemote)
3789 : 3 : whereToSendOutput = DestNone;
3790 : :
3791 [ + - ]: 3 : ereport(WARNING,
3792 : : (errmsg("terminating walsender process due to replication shutdown timeout"),
3793 : : errdetail("Walsender process might have been terminated before all WAL data was replicated to the receiver.")));
3794 : :
3795 : 3 : proc_exit(0);
3796 : : }
3797 : :
3798 : : /*
3799 : : * Shutdown if the sender is caught up.
3800 : : *
3801 : : * NB: This should only be called when the shutdown signal has been received
3802 : : * from postmaster.
3803 : : *
3804 : : * Note that if we determine that there's still more data to send, this
3805 : : * function will return control to the caller.
3806 : : */
3807 : : static void
3808 : 4368 : WalSndDone(WalSndSendDataCallback send_data)
3809 : : {
3810 : : XLogRecPtr replicatedPtr;
3811 : :
3812 : : /* ... let's just be real sure we're caught up ... */
3813 : 4368 : send_data();
3814 : :
3815 : : /*
3816 : : * To figure out whether all WAL has successfully been replicated, check
3817 : : * flush location if valid, write otherwise. Tools like pg_receivewal will
3818 : : * usually (unless in synchronous mode) return an invalid flush location.
3819 : : */
3820 : 8736 : replicatedPtr = XLogRecPtrIsValid(MyWalSnd->flush) ?
3821 [ + + ]: 4368 : MyWalSnd->flush : MyWalSnd->write;
3822 : :
3823 [ + + + + ]: 4368 : if (WalSndCaughtUp && sentPtr == replicatedPtr &&
3824 [ + - ]: 44 : !pq_is_send_pending())
3825 : : {
3826 : : QueryCompletion qc;
3827 : :
3828 : : Assert(!shutdown_stream_done_queued);
3829 : :
3830 : : /* Inform the standby that XLOG streaming is done */
3831 : 44 : SetQueryCompletion(&qc, CMDTAG_COPY, 0);
3832 : 44 : EndCommandExtended(&qc, DestRemote, false, true);
3833 : 44 : shutdown_stream_done_queued = true;
3834 : :
3835 : : /*
3836 : : * Reset last_reply_timestamp so subsequent WalSndComputeSleeptime()
3837 : : * calls ignore wal_sender_timeout during shutdown.
3838 : : */
3839 : 44 : last_reply_timestamp = 0;
3840 : :
3841 : : /*
3842 : : * Do not call pq_flush() here, since it can block indefinitely while
3843 : : * waiting for the socket to become writable, preventing
3844 : : * wal_sender_shutdown_timeout from being enforced. Instead, use the
3845 : : * walsender nonblocking flush path so the shutdown timeout continues
3846 : : * to be checked while the send buffer drains.
3847 : : */
3848 : : for (;;)
3849 : 44 : {
3850 : : long sleeptime;
3851 : :
3852 : : /*
3853 : : * During shutdown, die if the shutdown timeout expires. Call this
3854 : : * before WalSndComputeSleeptime() so the timeout is considered
3855 : : * when computing sleep time.
3856 : : */
3857 : 88 : WalSndCheckShutdownTimeout();
3858 : :
3859 [ + + ]: 88 : if (!pq_is_send_pending())
3860 : 44 : break;
3861 : :
3862 : 44 : sleeptime = WalSndComputeSleeptime(GetCurrentTimestamp());
3863 : :
3864 : : /* Sleep until something happens or we time out */
3865 : 44 : WalSndWait(WL_SOCKET_WRITEABLE, sleeptime,
3866 : : WAIT_EVENT_WAL_SENDER_WRITE_DATA);
3867 : :
3868 : : /* Clear any already-pending wakeups */
3869 : 44 : ResetLatch(MyLatch);
3870 : :
3871 [ - + ]: 44 : CHECK_FOR_INTERRUPTS();
3872 : :
3873 : : /* Try to flush pending output to the client */
3874 [ - + ]: 44 : if (pq_flush_if_writable() != 0)
3875 : 0 : WalSndShutdown();
3876 : : }
3877 : :
3878 : 44 : proc_exit(0);
3879 : : }
3880 [ + + ]: 4324 : if (!waiting_for_ping_response)
3881 : 1004 : WalSndKeepalive(true, InvalidXLogRecPtr);
3882 : 4324 : }
3883 : :
3884 : : /*
3885 : : * Returns the latest point in WAL that has been safely flushed to disk.
3886 : : * This should only be called when in recovery.
3887 : : *
3888 : : * This is called either by cascading walsender to find WAL position to be sent
3889 : : * to a cascaded standby or by slot synchronization operation to validate remote
3890 : : * slot's lsn before syncing it locally.
3891 : : *
3892 : : * As a side-effect, *tli is updated to the TLI of the last
3893 : : * replayed WAL record.
3894 : : */
3895 : : XLogRecPtr
3896 : 1166 : GetStandbyFlushRecPtr(TimeLineID *tli)
3897 : : {
3898 : : XLogRecPtr replayPtr;
3899 : : TimeLineID replayTLI;
3900 : : XLogRecPtr receivePtr;
3901 : : TimeLineID receiveTLI;
3902 : : XLogRecPtr result;
3903 : :
3904 : : Assert(am_cascading_walsender || IsSyncingReplicationSlots());
3905 : :
3906 : : /*
3907 : : * We can safely send what's already been replayed. Also, if walreceiver
3908 : : * is streaming WAL from the same timeline, we can send anything that it
3909 : : * has streamed, but hasn't been replayed yet.
3910 : : */
3911 : :
3912 : 1166 : receivePtr = GetWalRcvFlushRecPtr(NULL, &receiveTLI);
3913 : 1166 : replayPtr = GetXLogReplayRecPtr(&replayTLI);
3914 : :
3915 [ + + ]: 1166 : if (tli)
3916 : 1107 : *tli = replayTLI;
3917 : :
3918 : 1166 : result = replayPtr;
3919 [ + - + + ]: 1166 : if (receiveTLI == replayTLI && receivePtr > replayPtr)
3920 : 97 : result = receivePtr;
3921 : :
3922 : 1166 : return result;
3923 : : }
3924 : :
3925 : : /*
3926 : : * Request walsenders to reload the currently-open WAL file
3927 : : */
3928 : : void
3929 : 30 : WalSndRqstFileReload(void)
3930 : : {
3931 : : int i;
3932 : :
3933 [ + + ]: 306 : for (i = 0; i < max_wal_senders; i++)
3934 : : {
3935 : 276 : WalSnd *walsnd = &WalSndCtl->walsnds[i];
3936 : :
3937 : 276 : SpinLockAcquire(&walsnd->mutex);
3938 [ + - ]: 276 : if (walsnd->pid == 0)
3939 : : {
3940 : 276 : SpinLockRelease(&walsnd->mutex);
3941 : 276 : continue;
3942 : : }
3943 : 0 : walsnd->needreload = true;
3944 : 0 : SpinLockRelease(&walsnd->mutex);
3945 : : }
3946 : 30 : }
3947 : :
3948 : : /*
3949 : : * Handle PROCSIG_WALSND_INIT_STOPPING signal.
3950 : : */
3951 : : void
3952 : 48 : HandleWalSndInitStopping(void)
3953 : : {
3954 : : Assert(am_walsender);
3955 : :
3956 : : /*
3957 : : * If replication has not yet started, die like with SIGTERM. If
3958 : : * replication is active, only set a flag and wake up the main loop. It
3959 : : * will send any outstanding WAL, wait for it to be replicated to the
3960 : : * standby, and then exit gracefully.
3961 : : */
3962 [ - + ]: 48 : if (!replication_active)
3963 : 0 : kill(MyProcPid, SIGTERM);
3964 : : else
3965 : 48 : got_STOPPING = true;
3966 : :
3967 : : /* latch will be set by procsignal_sigusr1_handler */
3968 : 48 : }
3969 : :
3970 : : /*
3971 : : * SIGUSR2: set flag to do a last cycle and shut down afterwards. The WAL
3972 : : * sender should already have been switched to WALSNDSTATE_STOPPING at
3973 : : * this point.
3974 : : */
3975 : : static void
3976 : 48 : WalSndLastCycleHandler(SIGNAL_ARGS)
3977 : : {
3978 : 48 : got_SIGUSR2 = true;
3979 : 48 : SetLatch(MyLatch);
3980 : 48 : }
3981 : :
3982 : : /* Set up signal handlers */
3983 : : void
3984 : 1327 : WalSndSignals(void)
3985 : : {
3986 : : /* Set up signal handlers */
3987 : 1327 : pqsignal(SIGHUP, SignalHandlerForConfigReload);
3988 : 1327 : pqsignal(SIGINT, StatementCancelHandler); /* query cancel */
3989 : 1327 : pqsignal(SIGTERM, die); /* request shutdown */
3990 : : /* SIGQUIT handler was already set up by InitPostmasterChild */
3991 : 1327 : InitializeTimeouts(); /* establishes SIGALRM handler */
3992 : 1327 : pqsignal(SIGPIPE, PG_SIG_IGN);
3993 : 1327 : pqsignal(SIGUSR1, procsignal_sigusr1_handler);
3994 : 1327 : pqsignal(SIGUSR2, WalSndLastCycleHandler); /* request a last cycle and
3995 : : * shutdown */
3996 : :
3997 : : /* Reset some signals that are accepted by postmaster but not here */
3998 : 1327 : pqsignal(SIGCHLD, PG_SIG_DFL);
3999 : 1327 : }
4000 : :
4001 : : /* Register shared-memory space needed by walsender */
4002 : : static void
4003 : 1260 : WalSndShmemRequest(void *arg)
4004 : : {
4005 : : Size size;
4006 : :
4007 : 1260 : size = offsetof(WalSndCtlData, walsnds);
4008 : 1260 : size = add_size(size, mul_size(max_wal_senders, sizeof(WalSnd)));
4009 : 1260 : ShmemRequestStruct(.name = "Wal Sender Ctl",
4010 : : .size = size,
4011 : : .ptr = (void **) &WalSndCtl,
4012 : : );
4013 : 1260 : }
4014 : :
4015 : : /* Initialize walsender-related shared memory */
4016 : : static void
4017 : 1257 : WalSndShmemInit(void *arg)
4018 : : {
4019 [ + + ]: 5028 : for (int i = 0; i < NUM_SYNC_REP_WAIT_MODE; i++)
4020 : 3771 : dlist_init(&(WalSndCtl->SyncRepQueue[i]));
4021 : :
4022 [ + + ]: 9349 : for (int i = 0; i < max_wal_senders; i++)
4023 : : {
4024 : 8092 : WalSnd *walsnd = &WalSndCtl->walsnds[i];
4025 : :
4026 : 8092 : SpinLockInit(&walsnd->mutex);
4027 : : }
4028 : :
4029 : 1257 : ConditionVariableInit(&WalSndCtl->wal_flush_cv);
4030 : 1257 : ConditionVariableInit(&WalSndCtl->wal_replay_cv);
4031 : 1257 : ConditionVariableInit(&WalSndCtl->wal_confirm_rcv_cv);
4032 : 1257 : }
4033 : :
4034 : : /*
4035 : : * Wake up physical, logical or both kinds of walsenders
4036 : : *
4037 : : * The distinction between physical and logical walsenders is done, because:
4038 : : * - physical walsenders can't send data until it's been flushed
4039 : : * - logical walsenders on standby can't decode and send data until it's been
4040 : : * applied
4041 : : *
4042 : : * For cascading replication we need to wake up physical walsenders separately
4043 : : * from logical walsenders (see the comment before calling WalSndWakeup() in
4044 : : * ApplyWalRecord() for more details).
4045 : : *
4046 : : * This will be called inside critical sections, so throwing an error is not
4047 : : * advisable.
4048 : : */
4049 : : void
4050 : 2874187 : WalSndWakeup(bool physical, bool logical)
4051 : : {
4052 : : /*
4053 : : * Wake up all the walsenders waiting on WAL being flushed or replayed
4054 : : * respectively. Note that waiting walsender would have prepared to sleep
4055 : : * on the CV (i.e., added itself to the CV's waitlist) in WalSndWait()
4056 : : * before actually waiting.
4057 : : */
4058 [ + + ]: 2874187 : if (physical)
4059 : 158526 : ConditionVariableBroadcast(&WalSndCtl->wal_flush_cv);
4060 : :
4061 [ + + ]: 2874187 : if (logical)
4062 : 2830260 : ConditionVariableBroadcast(&WalSndCtl->wal_replay_cv);
4063 : 2874187 : }
4064 : :
4065 : : /*
4066 : : * Wait for readiness on the FeBe socket, or a timeout. The mask should be
4067 : : * composed of optional WL_SOCKET_WRITEABLE and WL_SOCKET_READABLE flags. Exit
4068 : : * on postmaster death.
4069 : : */
4070 : : static void
4071 : 106511 : WalSndWait(uint32 socket_events, long timeout, uint32 wait_event)
4072 : : {
4073 : : WaitEvent event;
4074 : :
4075 : 106511 : ModifyWaitEvent(FeBeWaitSet, FeBeWaitSetSocketPos, socket_events, NULL);
4076 : :
4077 : : /*
4078 : : * We use a condition variable to efficiently wake up walsenders in
4079 : : * WalSndWakeup().
4080 : : *
4081 : : * Every walsender prepares to sleep on a shared memory CV. Note that it
4082 : : * just prepares to sleep on the CV (i.e., adds itself to the CV's
4083 : : * waitlist), but does not actually wait on the CV (IOW, it never calls
4084 : : * ConditionVariableSleep()). It still uses WaitEventSetWait() for
4085 : : * waiting, because we also need to wait for socket events. The processes
4086 : : * (startup process, walreceiver etc.) wanting to wake up walsenders use
4087 : : * ConditionVariableBroadcast(), which in turn calls SetLatch(), helping
4088 : : * walsenders come out of WaitEventSetWait().
4089 : : *
4090 : : * This approach is simple and efficient because, one doesn't have to loop
4091 : : * through all the walsenders slots, with a spinlock acquisition and
4092 : : * release for every iteration, just to wake up only the waiting
4093 : : * walsenders. It makes WalSndWakeup() callers' life easy.
4094 : : *
4095 : : * XXX: A desirable future improvement would be to add support for CVs
4096 : : * into WaitEventSetWait().
4097 : : *
4098 : : * And, we use separate shared memory CVs for physical and logical
4099 : : * walsenders for selective wake ups, see WalSndWakeup() for more details.
4100 : : *
4101 : : * If the wait event is WAIT_FOR_STANDBY_CONFIRMATION, wait on another CV
4102 : : * until awakened by physical walsenders after the walreceiver confirms
4103 : : * the receipt of the LSN.
4104 : : */
4105 [ + + ]: 106511 : if (wait_event == WAIT_EVENT_WAIT_FOR_STANDBY_CONFIRMATION)
4106 : 11 : ConditionVariablePrepareToSleep(&WalSndCtl->wal_confirm_rcv_cv);
4107 [ + + ]: 106500 : else if (MyWalSnd->kind == REPLICATION_KIND_PHYSICAL)
4108 : 92328 : ConditionVariablePrepareToSleep(&WalSndCtl->wal_flush_cv);
4109 [ + - ]: 14172 : else if (MyWalSnd->kind == REPLICATION_KIND_LOGICAL)
4110 : 14172 : ConditionVariablePrepareToSleep(&WalSndCtl->wal_replay_cv);
4111 : :
4112 [ + + ]: 106511 : if (WaitEventSetWait(FeBeWaitSet, timeout, &event, 1, wait_event) == 1 &&
4113 [ - + ]: 106508 : (event.events & WL_POSTMASTER_DEATH))
4114 : : {
4115 : 0 : ConditionVariableCancelSleep();
4116 : 0 : proc_exit(1);
4117 : : }
4118 : :
4119 : 106511 : ConditionVariableCancelSleep();
4120 : 106511 : }
4121 : :
4122 : : /*
4123 : : * Signal all walsenders to move to stopping state.
4124 : : *
4125 : : * This will trigger walsenders to move to a state where no further WAL can be
4126 : : * generated. See this file's header for details.
4127 : : */
4128 : : void
4129 : 773 : WalSndInitStopping(void)
4130 : : {
4131 : : int i;
4132 : :
4133 [ + + ]: 5779 : for (i = 0; i < max_wal_senders; i++)
4134 : : {
4135 : 5006 : WalSnd *walsnd = &WalSndCtl->walsnds[i];
4136 : : pid_t pid;
4137 : :
4138 : 5006 : SpinLockAcquire(&walsnd->mutex);
4139 : 5006 : pid = walsnd->pid;
4140 : 5006 : SpinLockRelease(&walsnd->mutex);
4141 : :
4142 [ + + ]: 5006 : if (pid == 0)
4143 : 4958 : continue;
4144 : :
4145 : 48 : SendProcSignal(pid, PROCSIG_WALSND_INIT_STOPPING, INVALID_PROC_NUMBER);
4146 : : }
4147 : 773 : }
4148 : :
4149 : : /*
4150 : : * Wait that all the WAL senders have quit or reached the stopping state. This
4151 : : * is used by the checkpointer to control when the shutdown checkpoint can
4152 : : * safely be performed.
4153 : : */
4154 : : void
4155 : 773 : WalSndWaitStopping(void)
4156 : : {
4157 : : for (;;)
4158 : 44 : {
4159 : : int i;
4160 : 817 : bool all_stopped = true;
4161 : :
4162 [ + + ]: 5825 : for (i = 0; i < max_wal_senders; i++)
4163 : : {
4164 : 5052 : WalSnd *walsnd = &WalSndCtl->walsnds[i];
4165 : :
4166 : 5052 : SpinLockAcquire(&walsnd->mutex);
4167 : :
4168 [ + + ]: 5052 : if (walsnd->pid == 0)
4169 : : {
4170 : 4974 : SpinLockRelease(&walsnd->mutex);
4171 : 4974 : continue;
4172 : : }
4173 : :
4174 [ + + ]: 78 : if (walsnd->state != WALSNDSTATE_STOPPING)
4175 : : {
4176 : 44 : all_stopped = false;
4177 : 44 : SpinLockRelease(&walsnd->mutex);
4178 : 44 : break;
4179 : : }
4180 : 34 : SpinLockRelease(&walsnd->mutex);
4181 : : }
4182 : :
4183 : : /* safe to leave if confirmation is done for all WAL senders */
4184 [ + + ]: 817 : if (all_stopped)
4185 : 773 : return;
4186 : :
4187 : 44 : pg_usleep(10000L); /* wait for 10 msec */
4188 : : }
4189 : : }
4190 : :
4191 : : /* Set state for current walsender (only called in walsender) */
4192 : : void
4193 : 6493 : WalSndSetState(WalSndState state)
4194 : : {
4195 : 6493 : WalSnd *walsnd = MyWalSnd;
4196 : :
4197 : : Assert(am_walsender);
4198 : :
4199 [ + + ]: 6493 : if (walsnd->state == state)
4200 : 4366 : return;
4201 : :
4202 : 2127 : SpinLockAcquire(&walsnd->mutex);
4203 : 2127 : walsnd->state = state;
4204 : 2127 : SpinLockRelease(&walsnd->mutex);
4205 : : }
4206 : :
4207 : : /*
4208 : : * Return a string constant representing the state. This is used
4209 : : * in system views, and should *not* be translated.
4210 : : */
4211 : : static const char *
4212 : 613 : WalSndGetStateString(WalSndState state)
4213 : : {
4214 [ - - + + : 613 : switch (state)
- - ]
4215 : : {
4216 : 0 : case WALSNDSTATE_STARTUP:
4217 : 0 : return "startup";
4218 : 0 : case WALSNDSTATE_BACKUP:
4219 : 0 : return "backup";
4220 : 4 : case WALSNDSTATE_CATCHUP:
4221 : 4 : return "catchup";
4222 : 609 : case WALSNDSTATE_STREAMING:
4223 : 609 : return "streaming";
4224 : 0 : case WALSNDSTATE_STOPPING:
4225 : 0 : return "stopping";
4226 : : }
4227 : 0 : return "UNKNOWN";
4228 : : }
4229 : :
4230 : : static Interval *
4231 : 1452 : offset_to_interval(TimeOffset offset)
4232 : : {
4233 : 1452 : Interval *result = palloc_object(Interval);
4234 : :
4235 : 1452 : result->month = 0;
4236 : 1452 : result->day = 0;
4237 : 1452 : result->time = offset;
4238 : :
4239 : 1452 : return result;
4240 : : }
4241 : :
4242 : : /*
4243 : : * Returns activity of walsenders, including pids and xlog locations sent to
4244 : : * standby servers.
4245 : : */
4246 : : Datum
4247 : 479 : pg_stat_get_wal_senders(PG_FUNCTION_ARGS)
4248 : : {
4249 : : #define PG_STAT_GET_WAL_SENDERS_COLS 12
4250 : 479 : ReturnSetInfo *rsinfo = (ReturnSetInfo *) fcinfo->resultinfo;
4251 : : SyncRepStandbyData *sync_standbys;
4252 : : int num_standbys;
4253 : : int i;
4254 : :
4255 : 479 : InitMaterializedSRF(fcinfo, 0);
4256 : :
4257 : : /*
4258 : : * Get the currently active synchronous standbys. This could be out of
4259 : : * date before we're done, but we'll use the data anyway.
4260 : : */
4261 : 479 : num_standbys = SyncRepGetCandidateStandbys(&sync_standbys);
4262 : :
4263 [ + + ]: 5257 : for (i = 0; i < max_wal_senders; i++)
4264 : : {
4265 : 4778 : WalSnd *walsnd = &WalSndCtl->walsnds[i];
4266 : : XLogRecPtr sent_ptr;
4267 : : XLogRecPtr write;
4268 : : XLogRecPtr flush;
4269 : : XLogRecPtr apply;
4270 : : TimeOffset writeLag;
4271 : : TimeOffset flushLag;
4272 : : TimeOffset applyLag;
4273 : : int priority;
4274 : : int pid;
4275 : : WalSndState state;
4276 : : TimestampTz replyTime;
4277 : : bool is_sync_standby;
4278 : : Datum values[PG_STAT_GET_WAL_SENDERS_COLS];
4279 : 4778 : bool nulls[PG_STAT_GET_WAL_SENDERS_COLS] = {0};
4280 : : int j;
4281 : :
4282 : : /* Collect data from shared memory */
4283 : 4778 : SpinLockAcquire(&walsnd->mutex);
4284 [ + + ]: 4778 : if (walsnd->pid == 0)
4285 : : {
4286 : 4165 : SpinLockRelease(&walsnd->mutex);
4287 : 4165 : continue;
4288 : : }
4289 : 613 : pid = walsnd->pid;
4290 : 613 : sent_ptr = walsnd->sentPtr;
4291 : 613 : state = walsnd->state;
4292 : 613 : write = walsnd->write;
4293 : 613 : flush = walsnd->flush;
4294 : 613 : apply = walsnd->apply;
4295 : 613 : writeLag = walsnd->writeLag;
4296 : 613 : flushLag = walsnd->flushLag;
4297 : 613 : applyLag = walsnd->applyLag;
4298 : 613 : priority = walsnd->sync_standby_priority;
4299 : 613 : replyTime = walsnd->replyTime;
4300 : 613 : SpinLockRelease(&walsnd->mutex);
4301 : :
4302 : : /*
4303 : : * Detect whether walsender is/was considered synchronous. We can
4304 : : * provide some protection against stale data by checking the PID
4305 : : * along with walsnd_index.
4306 : : */
4307 : 613 : is_sync_standby = false;
4308 [ + + ]: 654 : for (j = 0; j < num_standbys; j++)
4309 : : {
4310 [ + + ]: 66 : if (sync_standbys[j].walsnd_index == i &&
4311 [ + - ]: 25 : sync_standbys[j].pid == pid)
4312 : : {
4313 : 25 : is_sync_standby = true;
4314 : 25 : break;
4315 : : }
4316 : : }
4317 : :
4318 : 613 : values[0] = Int32GetDatum(pid);
4319 : :
4320 [ - + ]: 613 : if (!has_privs_of_role(GetUserId(), ROLE_PG_READ_ALL_STATS))
4321 : : {
4322 : : /*
4323 : : * Only superusers and roles with privileges of pg_read_all_stats
4324 : : * can see details. Other users only get the pid value to know
4325 : : * it's a walsender, but no details.
4326 : : */
4327 [ # # # # : 0 : MemSet(&nulls[1], true, PG_STAT_GET_WAL_SENDERS_COLS - 1);
# # # # #
# ]
4328 : : }
4329 : : else
4330 : : {
4331 : 613 : values[1] = CStringGetTextDatum(WalSndGetStateString(state));
4332 : :
4333 [ - + ]: 613 : if (!XLogRecPtrIsValid(sent_ptr))
4334 : 0 : nulls[2] = true;
4335 : 613 : values[2] = LSNGetDatum(sent_ptr);
4336 : :
4337 [ - + ]: 613 : if (!XLogRecPtrIsValid(write))
4338 : 0 : nulls[3] = true;
4339 : 613 : values[3] = LSNGetDatum(write);
4340 : :
4341 [ - + ]: 613 : if (!XLogRecPtrIsValid(flush))
4342 : 0 : nulls[4] = true;
4343 : 613 : values[4] = LSNGetDatum(flush);
4344 : :
4345 [ - + ]: 613 : if (!XLogRecPtrIsValid(apply))
4346 : 0 : nulls[5] = true;
4347 : 613 : values[5] = LSNGetDatum(apply);
4348 : :
4349 : : /*
4350 : : * Treat a standby such as a pg_basebackup background process
4351 : : * which always returns an invalid flush location, as an
4352 : : * asynchronous standby.
4353 : : */
4354 [ + - ]: 613 : priority = XLogRecPtrIsValid(flush) ? priority : 0;
4355 : :
4356 [ + + ]: 613 : if (writeLag < 0)
4357 : 129 : nulls[6] = true;
4358 : : else
4359 : 484 : values[6] = IntervalPGetDatum(offset_to_interval(writeLag));
4360 : :
4361 [ + + ]: 613 : if (flushLag < 0)
4362 : 129 : nulls[7] = true;
4363 : : else
4364 : 484 : values[7] = IntervalPGetDatum(offset_to_interval(flushLag));
4365 : :
4366 [ + + ]: 613 : if (applyLag < 0)
4367 : 129 : nulls[8] = true;
4368 : : else
4369 : 484 : values[8] = IntervalPGetDatum(offset_to_interval(applyLag));
4370 : :
4371 : 613 : values[9] = Int32GetDatum(priority);
4372 : :
4373 : : /*
4374 : : * More easily understood version of standby state. This is purely
4375 : : * informational.
4376 : : *
4377 : : * In quorum-based sync replication, the role of each standby
4378 : : * listed in synchronous_standby_names can be changing very
4379 : : * frequently. Any standbys considered as "sync" at one moment can
4380 : : * be switched to "potential" ones at the next moment. So, it's
4381 : : * basically useless to report "sync" or "potential" as their sync
4382 : : * states. We report just "quorum" for them.
4383 : : */
4384 [ + + ]: 613 : if (priority == 0)
4385 : 577 : values[10] = CStringGetTextDatum("async");
4386 [ + + ]: 36 : else if (is_sync_standby)
4387 : 25 : values[10] = SyncRepConfig->syncrep_method == SYNC_REP_PRIORITY ?
4388 [ + + ]: 25 : CStringGetTextDatum("sync") : CStringGetTextDatum("quorum");
4389 : : else
4390 : 11 : values[10] = CStringGetTextDatum("potential");
4391 : :
4392 [ - + ]: 613 : if (replyTime == 0)
4393 : 0 : nulls[11] = true;
4394 : : else
4395 : 613 : values[11] = TimestampTzGetDatum(replyTime);
4396 : : }
4397 : :
4398 : 613 : tuplestore_putvalues(rsinfo->setResult, rsinfo->setDesc,
4399 : : values, nulls);
4400 : : }
4401 : :
4402 : 479 : return (Datum) 0;
4403 : : }
4404 : :
4405 : : /*
4406 : : * Send a keepalive message to standby.
4407 : : *
4408 : : * If requestReply is set, the message requests the other party to send
4409 : : * a message back to us, for heartbeat purposes. We also set a flag to
4410 : : * let nearby code know that we're waiting for that response, to avoid
4411 : : * repeated requests.
4412 : : *
4413 : : * writePtr is the location up to which the WAL is sent. It is essentially
4414 : : * the same as sentPtr but in some cases, we need to send keep alive before
4415 : : * sentPtr is updated like when skipping empty transactions.
4416 : : */
4417 : : static void
4418 : 3054 : WalSndKeepalive(bool requestReply, XLogRecPtr writePtr)
4419 : : {
4420 [ + + ]: 3054 : elog(DEBUG2, "sending replication keepalive");
4421 : :
4422 : : /* construct the message... */
4423 : 3054 : resetStringInfo(&output_message);
4424 : 3054 : pq_sendbyte(&output_message, PqReplMsg_Keepalive);
4425 [ - + ]: 3054 : pq_sendint64(&output_message, XLogRecPtrIsValid(writePtr) ? writePtr : sentPtr);
4426 : 3054 : pq_sendint64(&output_message, GetCurrentTimestamp());
4427 : 3054 : pq_sendbyte(&output_message, requestReply ? 1 : 0);
4428 : :
4429 : : /* ... and send it wrapped in CopyData */
4430 : 3054 : pq_putmessage_noblock(PqMsg_CopyData, output_message.data, output_message.len);
4431 : :
4432 : : /* Set local flag */
4433 [ + + ]: 3054 : if (requestReply)
4434 : 1004 : waiting_for_ping_response = true;
4435 : 3054 : }
4436 : :
4437 : : /*
4438 : : * Send keepalive message if too much time has elapsed.
4439 : : */
4440 : : static void
4441 : 1167864 : WalSndKeepaliveIfNecessary(void)
4442 : : {
4443 : : TimestampTz ping_time;
4444 : :
4445 : : /*
4446 : : * Don't send keepalive messages if timeouts are globally disabled or
4447 : : * we're doing something not partaking in timeouts.
4448 : : */
4449 [ + - + + ]: 1167864 : if (wal_sender_timeout <= 0 || last_reply_timestamp <= 0)
4450 : 29 : return;
4451 : :
4452 [ + + ]: 1167835 : if (waiting_for_ping_response)
4453 : 5321 : return;
4454 : :
4455 : : /*
4456 : : * If half of wal_sender_timeout has lapsed without receiving any reply
4457 : : * from the standby, send a keep-alive message to the standby requesting
4458 : : * an immediate reply.
4459 : : */
4460 : 1162514 : ping_time = TimestampTzPlusMilliseconds(last_reply_timestamp,
4461 : : wal_sender_timeout / 2);
4462 [ - + ]: 1162514 : if (last_processing >= ping_time)
4463 : : {
4464 : 0 : WalSndKeepalive(true, InvalidXLogRecPtr);
4465 : :
4466 : : /* Try to flush pending output to the client */
4467 [ # # ]: 0 : if (pq_flush_if_writable() != 0)
4468 : 0 : WalSndShutdown();
4469 : : }
4470 : : }
4471 : :
4472 : : /*
4473 : : * Record the end of the WAL and the time it was flushed locally, so that
4474 : : * LagTrackerRead can compute the elapsed time (lag) when this WAL location is
4475 : : * eventually reported to have been written, flushed and applied by the
4476 : : * standby in a reply message.
4477 : : */
4478 : : static void
4479 : 144884 : LagTrackerWrite(XLogRecPtr lsn, TimestampTz local_flush_time)
4480 : : {
4481 : : int new_write_head;
4482 : : int i;
4483 : :
4484 [ - + ]: 144884 : if (!am_walsender)
4485 : 0 : return;
4486 : :
4487 : : /*
4488 : : * If the lsn hasn't advanced since last time, then do nothing. This way
4489 : : * we only record a new sample when new WAL has been written.
4490 : : */
4491 [ + + ]: 144884 : if (lag_tracker->last_lsn == lsn)
4492 : 121239 : return;
4493 : 23645 : lag_tracker->last_lsn = lsn;
4494 : :
4495 : : /*
4496 : : * If advancing the write head of the circular buffer would crash into any
4497 : : * of the read heads, then the buffer is full. In other words, the
4498 : : * slowest reader (presumably apply) is the one that controls the release
4499 : : * of space.
4500 : : */
4501 : 23645 : new_write_head = (lag_tracker->write_head + 1) % LAG_TRACKER_BUFFER_SIZE;
4502 [ + + ]: 94580 : for (i = 0; i < NUM_SYNC_REP_WAIT_MODE; ++i)
4503 : : {
4504 : : /*
4505 : : * If the buffer is full, move the slowest reader to a separate
4506 : : * overflow entry and free its space in the buffer so the write head
4507 : : * can advance.
4508 : : */
4509 [ - + ]: 70935 : if (new_write_head == lag_tracker->read_heads[i])
4510 : : {
4511 : 0 : lag_tracker->overflowed[i] =
4512 : 0 : lag_tracker->buffer[lag_tracker->read_heads[i]];
4513 : 0 : lag_tracker->read_heads[i] = -1;
4514 : : }
4515 : : }
4516 : :
4517 : : /* Store a sample at the current write head position. */
4518 : 23645 : lag_tracker->buffer[lag_tracker->write_head].lsn = lsn;
4519 : 23645 : lag_tracker->buffer[lag_tracker->write_head].time = local_flush_time;
4520 : 23645 : lag_tracker->write_head = new_write_head;
4521 : : }
4522 : :
4523 : : /*
4524 : : * Find out how much time has elapsed between the moment WAL location 'lsn'
4525 : : * (or the highest known earlier LSN) was flushed locally and the time 'now'.
4526 : : * We have a separate read head for each of the reported LSN locations we
4527 : : * receive in replies from standby; 'head' controls which read head is
4528 : : * used. Whenever a read head crosses an LSN which was written into the
4529 : : * lag buffer with LagTrackerWrite, we can use the associated timestamp to
4530 : : * find out the time this LSN (or an earlier one) was flushed locally, and
4531 : : * therefore compute the lag.
4532 : : *
4533 : : * Return -1 if no new sample data is available, and otherwise the elapsed
4534 : : * time in microseconds.
4535 : : */
4536 : : static TimeOffset
4537 : 340731 : LagTrackerRead(int head, XLogRecPtr lsn, TimestampTz now)
4538 : : {
4539 : 340731 : TimestampTz time = 0;
4540 : :
4541 : : /*
4542 : : * If 'lsn' has not passed the WAL position stored in the overflow entry,
4543 : : * return the elapsed time (in microseconds) since the saved local flush
4544 : : * time. If the flush time is in the future (due to clock drift), return
4545 : : * -1 to treat as no valid sample.
4546 : : *
4547 : : * Otherwise, switch back to using the buffer to control the read head and
4548 : : * compute the elapsed time. The read head is then reset to point to the
4549 : : * oldest entry in the buffer.
4550 : : */
4551 [ - + ]: 340731 : if (lag_tracker->read_heads[head] == -1)
4552 : : {
4553 [ # # ]: 0 : if (lag_tracker->overflowed[head].lsn > lsn)
4554 : 0 : return (now >= lag_tracker->overflowed[head].time) ?
4555 [ # # ]: 0 : now - lag_tracker->overflowed[head].time : -1;
4556 : :
4557 : 0 : time = lag_tracker->overflowed[head].time;
4558 : 0 : lag_tracker->last_read[head] = lag_tracker->overflowed[head];
4559 : 0 : lag_tracker->read_heads[head] =
4560 : 0 : (lag_tracker->write_head + 1) % LAG_TRACKER_BUFFER_SIZE;
4561 : : }
4562 : :
4563 : : /* Read all unread samples up to this LSN or end of buffer. */
4564 [ + + ]: 410474 : while (lag_tracker->read_heads[head] != lag_tracker->write_head &&
4565 [ + + ]: 275328 : lag_tracker->buffer[lag_tracker->read_heads[head]].lsn <= lsn)
4566 : : {
4567 : 69743 : time = lag_tracker->buffer[lag_tracker->read_heads[head]].time;
4568 : 69743 : lag_tracker->last_read[head] =
4569 : 69743 : lag_tracker->buffer[lag_tracker->read_heads[head]];
4570 : 69743 : lag_tracker->read_heads[head] =
4571 : 69743 : (lag_tracker->read_heads[head] + 1) % LAG_TRACKER_BUFFER_SIZE;
4572 : : }
4573 : :
4574 : : /*
4575 : : * If the lag tracker is empty, that means the standby has processed
4576 : : * everything we've ever sent so we should now clear 'last_read'. If we
4577 : : * didn't do that, we'd risk using a stale and irrelevant sample for
4578 : : * interpolation at the beginning of the next burst of WAL after a period
4579 : : * of idleness.
4580 : : */
4581 [ + + ]: 340731 : if (lag_tracker->read_heads[head] == lag_tracker->write_head)
4582 : 135146 : lag_tracker->last_read[head].time = 0;
4583 : :
4584 [ - + ]: 340731 : if (time > now)
4585 : : {
4586 : : /* If the clock somehow went backwards, treat as not found. */
4587 : 0 : return -1;
4588 : : }
4589 [ + + ]: 340731 : else if (time == 0)
4590 : : {
4591 : : /*
4592 : : * We didn't cross a time. If there is a future sample that we
4593 : : * haven't reached yet, and we've already reached at least one sample,
4594 : : * let's interpolate the local flushed time. This is mainly useful
4595 : : * for reporting a completely stuck apply position as having
4596 : : * increasing lag, since otherwise we'd have to wait for it to
4597 : : * eventually start moving again and cross one of our samples before
4598 : : * we can show the lag increasing.
4599 : : */
4600 [ + + ]: 285250 : if (lag_tracker->read_heads[head] == lag_tracker->write_head)
4601 : : {
4602 : : /* There are no future samples, so we can't interpolate. */
4603 : 88984 : return -1;
4604 : : }
4605 [ + + ]: 196266 : else if (lag_tracker->last_read[head].time != 0)
4606 : : {
4607 : : /* We can interpolate between last_read and the next sample. */
4608 : : double fraction;
4609 : 78469 : WalTimeSample prev = lag_tracker->last_read[head];
4610 : 78469 : WalTimeSample next = lag_tracker->buffer[lag_tracker->read_heads[head]];
4611 : :
4612 [ - + ]: 78469 : if (lsn < prev.lsn)
4613 : : {
4614 : : /*
4615 : : * Reported LSNs shouldn't normally go backwards, but it's
4616 : : * possible when there is a timeline change. Treat as not
4617 : : * found.
4618 : : */
4619 : 0 : return -1;
4620 : : }
4621 : :
4622 : : Assert(prev.lsn < next.lsn);
4623 : :
4624 [ - + ]: 78469 : if (prev.time > next.time)
4625 : : {
4626 : : /* If the clock somehow went backwards, treat as not found. */
4627 : 0 : return -1;
4628 : : }
4629 : :
4630 : : /* See how far we are between the previous and next samples. */
4631 : 78469 : fraction =
4632 : 78469 : (double) (lsn - prev.lsn) / (double) (next.lsn - prev.lsn);
4633 : :
4634 : : /* Scale the local flush time proportionally. */
4635 : 78469 : time = (TimestampTz)
4636 : 78469 : ((double) prev.time + (next.time - prev.time) * fraction);
4637 : : }
4638 : : else
4639 : : {
4640 : : /*
4641 : : * We have only a future sample, implying that we were entirely
4642 : : * caught up but and now there is a new burst of WAL and the
4643 : : * standby hasn't processed the first sample yet. Until the
4644 : : * standby reaches the future sample the best we can do is report
4645 : : * the hypothetical lag if that sample were to be replayed now.
4646 : : */
4647 : 117797 : time = lag_tracker->buffer[lag_tracker->read_heads[head]].time;
4648 : : }
4649 : : }
4650 : :
4651 : : /* Return the elapsed time since local flush time in microseconds. */
4652 : : Assert(time != 0);
4653 : 251747 : return now - time;
4654 : : }
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