Line data Source code
1 : /*-------------------------------------------------------------------------
2 : *
3 : * autoprewarm.c
4 : * Periodically dump information about the blocks present in
5 : * shared_buffers, and reload them on server restart.
6 : *
7 : * Due to locking considerations, we can't actually begin prewarming
8 : * until the server reaches a consistent state. We need the catalogs
9 : * to be consistent so that we can figure out which relation to lock,
10 : * and we need to lock the relations so that we don't try to prewarm
11 : * pages from a relation that is in the process of being dropped.
12 : *
13 : * While prewarming, autoprewarm will use two workers. There's a
14 : * leader worker that reads and sorts the list of blocks to be
15 : * prewarmed and then launches a per-database worker for each
16 : * relevant database in turn. The former keeps running after the
17 : * initial prewarm is complete to update the dump file periodically.
18 : *
19 : * Copyright (c) 2016-2023, PostgreSQL Global Development Group
20 : *
21 : * IDENTIFICATION
22 : * contrib/pg_prewarm/autoprewarm.c
23 : *
24 : *-------------------------------------------------------------------------
25 : */
26 :
27 : #include "postgres.h"
28 :
29 : #include <unistd.h>
30 :
31 : #include "access/relation.h"
32 : #include "access/xact.h"
33 : #include "catalog/pg_class.h"
34 : #include "catalog/pg_type.h"
35 : #include "miscadmin.h"
36 : #include "pgstat.h"
37 : #include "postmaster/bgworker.h"
38 : #include "postmaster/interrupt.h"
39 : #include "storage/buf_internals.h"
40 : #include "storage/dsm.h"
41 : #include "storage/fd.h"
42 : #include "storage/ipc.h"
43 : #include "storage/latch.h"
44 : #include "storage/lwlock.h"
45 : #include "storage/proc.h"
46 : #include "storage/procsignal.h"
47 : #include "storage/shmem.h"
48 : #include "storage/smgr.h"
49 : #include "tcop/tcopprot.h"
50 : #include "utils/acl.h"
51 : #include "utils/datetime.h"
52 : #include "utils/guc.h"
53 : #include "utils/memutils.h"
54 : #include "utils/rel.h"
55 : #include "utils/relfilenumbermap.h"
56 : #include "utils/resowner.h"
57 :
58 : #define AUTOPREWARM_FILE "autoprewarm.blocks"
59 :
60 : /* Metadata for each block we dump. */
61 : typedef struct BlockInfoRecord
62 : {
63 : Oid database;
64 : Oid tablespace;
65 : RelFileNumber filenumber;
66 : ForkNumber forknum;
67 : BlockNumber blocknum;
68 : } BlockInfoRecord;
69 :
70 : /* Shared state information for autoprewarm bgworker. */
71 : typedef struct AutoPrewarmSharedState
72 : {
73 : LWLock lock; /* mutual exclusion */
74 : pid_t bgworker_pid; /* for main bgworker */
75 : pid_t pid_using_dumpfile; /* for autoprewarm or block dump */
76 :
77 : /* Following items are for communication with per-database worker */
78 : dsm_handle block_info_handle;
79 : Oid database;
80 : int prewarm_start_idx;
81 : int prewarm_stop_idx;
82 : int prewarmed_blocks;
83 : } AutoPrewarmSharedState;
84 :
85 : PGDLLEXPORT void autoprewarm_main(Datum main_arg);
86 : PGDLLEXPORT void autoprewarm_database_main(Datum main_arg);
87 :
88 4 : PG_FUNCTION_INFO_V1(autoprewarm_start_worker);
89 6 : PG_FUNCTION_INFO_V1(autoprewarm_dump_now);
90 :
91 : static void apw_load_buffers(void);
92 : static int apw_dump_now(bool is_bgworker, bool dump_unlogged);
93 : static void apw_start_leader_worker(void);
94 : static void apw_start_database_worker(void);
95 : static bool apw_init_shmem(void);
96 : static void apw_detach_shmem(int code, Datum arg);
97 : static int apw_compare_blockinfo(const void *p, const void *q);
98 : static void autoprewarm_shmem_request(void);
99 : static shmem_request_hook_type prev_shmem_request_hook = NULL;
100 :
101 : /* Pointer to shared-memory state. */
102 : static AutoPrewarmSharedState *apw_state = NULL;
103 :
104 : /* GUC variables. */
105 : static bool autoprewarm = true; /* start worker? */
106 : static int autoprewarm_interval = 300; /* dump interval */
107 :
108 : /*
109 : * Module load callback.
110 : */
111 : void
112 10 : _PG_init(void)
113 : {
114 10 : DefineCustomIntVariable("pg_prewarm.autoprewarm_interval",
115 : "Sets the interval between dumps of shared buffers",
116 : "If set to zero, time-based dumping is disabled.",
117 : &autoprewarm_interval,
118 : 300,
119 : 0, INT_MAX / 1000,
120 : PGC_SIGHUP,
121 : GUC_UNIT_S,
122 : NULL,
123 : NULL,
124 : NULL);
125 :
126 10 : if (!process_shared_preload_libraries_in_progress)
127 6 : return;
128 :
129 : /* can't define PGC_POSTMASTER variable after startup */
130 4 : DefineCustomBoolVariable("pg_prewarm.autoprewarm",
131 : "Starts the autoprewarm worker.",
132 : NULL,
133 : &autoprewarm,
134 : true,
135 : PGC_POSTMASTER,
136 : 0,
137 : NULL,
138 : NULL,
139 : NULL);
140 :
141 4 : MarkGUCPrefixReserved("pg_prewarm");
142 :
143 4 : prev_shmem_request_hook = shmem_request_hook;
144 4 : shmem_request_hook = autoprewarm_shmem_request;
145 :
146 : /* Register autoprewarm worker, if enabled. */
147 4 : if (autoprewarm)
148 4 : apw_start_leader_worker();
149 : }
150 :
151 : /*
152 : * Requests any additional shared memory required for autoprewarm.
153 : */
154 : static void
155 4 : autoprewarm_shmem_request(void)
156 : {
157 4 : if (prev_shmem_request_hook)
158 0 : prev_shmem_request_hook();
159 :
160 4 : RequestAddinShmemSpace(MAXALIGN(sizeof(AutoPrewarmSharedState)));
161 4 : }
162 :
163 : /*
164 : * Main entry point for the leader autoprewarm process. Per-database workers
165 : * have a separate entry point.
166 : */
167 : void
168 4 : autoprewarm_main(Datum main_arg)
169 : {
170 4 : bool first_time = true;
171 4 : bool final_dump_allowed = true;
172 4 : TimestampTz last_dump_time = 0;
173 :
174 : /* Establish signal handlers; once that's done, unblock signals. */
175 4 : pqsignal(SIGTERM, SignalHandlerForShutdownRequest);
176 4 : pqsignal(SIGHUP, SignalHandlerForConfigReload);
177 4 : pqsignal(SIGUSR1, procsignal_sigusr1_handler);
178 4 : BackgroundWorkerUnblockSignals();
179 :
180 : /* Create (if necessary) and attach to our shared memory area. */
181 4 : if (apw_init_shmem())
182 0 : first_time = false;
183 :
184 : /* Set on-detach hook so that our PID will be cleared on exit. */
185 4 : on_shmem_exit(apw_detach_shmem, 0);
186 :
187 : /*
188 : * Store our PID in the shared memory area --- unless there's already
189 : * another worker running, in which case just exit.
190 : */
191 4 : LWLockAcquire(&apw_state->lock, LW_EXCLUSIVE);
192 4 : if (apw_state->bgworker_pid != InvalidPid)
193 : {
194 0 : LWLockRelease(&apw_state->lock);
195 0 : ereport(LOG,
196 : (errmsg("autoprewarm worker is already running under PID %d",
197 : (int) apw_state->bgworker_pid)));
198 0 : return;
199 : }
200 4 : apw_state->bgworker_pid = MyProcPid;
201 4 : LWLockRelease(&apw_state->lock);
202 :
203 : /*
204 : * Preload buffers from the dump file only if we just created the shared
205 : * memory region. Otherwise, it's either already been done or shouldn't
206 : * be done - e.g. because the old dump file has been overwritten since the
207 : * server was started.
208 : *
209 : * There's not much point in performing a dump immediately after we finish
210 : * preloading; so, if we do end up preloading, consider the last dump time
211 : * to be equal to the current time.
212 : *
213 : * If apw_load_buffers() is terminated early by a shutdown request,
214 : * prevent dumping out our state below the loop, because we'd effectively
215 : * just truncate the saved state to however much we'd managed to preload.
216 : */
217 4 : if (first_time)
218 : {
219 4 : apw_load_buffers();
220 4 : final_dump_allowed = !ShutdownRequestPending;
221 4 : last_dump_time = GetCurrentTimestamp();
222 : }
223 :
224 : /* Periodically dump buffers until terminated. */
225 10 : while (!ShutdownRequestPending)
226 : {
227 : /* In case of a SIGHUP, just reload the configuration. */
228 6 : if (ConfigReloadPending)
229 : {
230 0 : ConfigReloadPending = false;
231 0 : ProcessConfigFile(PGC_SIGHUP);
232 : }
233 :
234 6 : if (autoprewarm_interval <= 0)
235 : {
236 : /* We're only dumping at shutdown, so just wait forever. */
237 6 : (void) WaitLatch(MyLatch,
238 : WL_LATCH_SET | WL_EXIT_ON_PM_DEATH,
239 : -1L,
240 : PG_WAIT_EXTENSION);
241 : }
242 : else
243 : {
244 : TimestampTz next_dump_time;
245 : long delay_in_ms;
246 :
247 : /* Compute the next dump time. */
248 0 : next_dump_time =
249 0 : TimestampTzPlusMilliseconds(last_dump_time,
250 : autoprewarm_interval * 1000);
251 : delay_in_ms =
252 0 : TimestampDifferenceMilliseconds(GetCurrentTimestamp(),
253 : next_dump_time);
254 :
255 : /* Perform a dump if it's time. */
256 0 : if (delay_in_ms <= 0)
257 : {
258 0 : last_dump_time = GetCurrentTimestamp();
259 0 : apw_dump_now(true, false);
260 0 : continue;
261 : }
262 :
263 : /* Sleep until the next dump time. */
264 0 : (void) WaitLatch(MyLatch,
265 : WL_LATCH_SET | WL_TIMEOUT | WL_EXIT_ON_PM_DEATH,
266 : delay_in_ms,
267 : PG_WAIT_EXTENSION);
268 : }
269 :
270 : /* Reset the latch, loop. */
271 6 : ResetLatch(MyLatch);
272 : }
273 :
274 : /*
275 : * Dump one last time. We assume this is probably the result of a system
276 : * shutdown, although it's possible that we've merely been terminated.
277 : */
278 4 : if (final_dump_allowed)
279 4 : apw_dump_now(true, true);
280 : }
281 :
282 : /*
283 : * Read the dump file and launch per-database workers one at a time to
284 : * prewarm the buffers found there.
285 : */
286 : static void
287 4 : apw_load_buffers(void)
288 : {
289 4 : FILE *file = NULL;
290 : int num_elements,
291 : i;
292 : BlockInfoRecord *blkinfo;
293 : dsm_segment *seg;
294 :
295 : /*
296 : * Skip the prewarm if the dump file is in use; otherwise, prevent any
297 : * other process from writing it while we're using it.
298 : */
299 4 : LWLockAcquire(&apw_state->lock, LW_EXCLUSIVE);
300 4 : if (apw_state->pid_using_dumpfile == InvalidPid)
301 4 : apw_state->pid_using_dumpfile = MyProcPid;
302 : else
303 : {
304 0 : LWLockRelease(&apw_state->lock);
305 0 : ereport(LOG,
306 : (errmsg("skipping prewarm because block dump file is being written by PID %d",
307 : (int) apw_state->pid_using_dumpfile)));
308 2 : return;
309 : }
310 4 : LWLockRelease(&apw_state->lock);
311 :
312 : /*
313 : * Open the block dump file. Exit quietly if it doesn't exist, but report
314 : * any other error.
315 : */
316 4 : file = AllocateFile(AUTOPREWARM_FILE, "r");
317 4 : if (!file)
318 : {
319 2 : if (errno == ENOENT)
320 : {
321 2 : LWLockAcquire(&apw_state->lock, LW_EXCLUSIVE);
322 2 : apw_state->pid_using_dumpfile = InvalidPid;
323 2 : LWLockRelease(&apw_state->lock);
324 2 : return; /* No file to load. */
325 : }
326 0 : ereport(ERROR,
327 : (errcode_for_file_access(),
328 : errmsg("could not read file \"%s\": %m",
329 : AUTOPREWARM_FILE)));
330 : }
331 :
332 : /* First line of the file is a record count. */
333 2 : if (fscanf(file, "<<%d>>\n", &num_elements) != 1)
334 0 : ereport(ERROR,
335 : (errcode_for_file_access(),
336 : errmsg("could not read from file \"%s\": %m",
337 : AUTOPREWARM_FILE)));
338 :
339 : /* Allocate a dynamic shared memory segment to store the record data. */
340 2 : seg = dsm_create(sizeof(BlockInfoRecord) * num_elements, 0);
341 2 : blkinfo = (BlockInfoRecord *) dsm_segment_address(seg);
342 :
343 : /* Read records, one per line. */
344 358 : for (i = 0; i < num_elements; i++)
345 : {
346 : unsigned forknum;
347 :
348 356 : if (fscanf(file, "%u,%u,%u,%u,%u\n", &blkinfo[i].database,
349 356 : &blkinfo[i].tablespace, &blkinfo[i].filenumber,
350 356 : &forknum, &blkinfo[i].blocknum) != 5)
351 0 : ereport(ERROR,
352 : (errmsg("autoprewarm block dump file is corrupted at line %d",
353 : i + 1)));
354 356 : blkinfo[i].forknum = forknum;
355 : }
356 :
357 2 : FreeFile(file);
358 :
359 : /* Sort the blocks to be loaded. */
360 2 : pg_qsort(blkinfo, num_elements, sizeof(BlockInfoRecord),
361 : apw_compare_blockinfo);
362 :
363 : /* Populate shared memory state. */
364 2 : apw_state->block_info_handle = dsm_segment_handle(seg);
365 2 : apw_state->prewarm_start_idx = apw_state->prewarm_stop_idx = 0;
366 2 : apw_state->prewarmed_blocks = 0;
367 :
368 : /* Get the info position of the first block of the next database. */
369 4 : while (apw_state->prewarm_start_idx < num_elements)
370 : {
371 2 : int j = apw_state->prewarm_start_idx;
372 2 : Oid current_db = blkinfo[j].database;
373 :
374 : /*
375 : * Advance the prewarm_stop_idx to the first BlockInfoRecord that does
376 : * not belong to this database.
377 : */
378 2 : j++;
379 356 : while (j < num_elements)
380 : {
381 354 : if (current_db != blkinfo[j].database)
382 : {
383 : /*
384 : * Combine BlockInfoRecords for global objects with those of
385 : * the database.
386 : */
387 2 : if (current_db != InvalidOid)
388 0 : break;
389 2 : current_db = blkinfo[j].database;
390 : }
391 :
392 354 : j++;
393 : }
394 :
395 : /*
396 : * If we reach this point with current_db == InvalidOid, then only
397 : * BlockInfoRecords belonging to global objects exist. We can't
398 : * prewarm without a database connection, so just bail out.
399 : */
400 2 : if (current_db == InvalidOid)
401 0 : break;
402 :
403 : /* Configure stop point and database for next per-database worker. */
404 2 : apw_state->prewarm_stop_idx = j;
405 2 : apw_state->database = current_db;
406 : Assert(apw_state->prewarm_start_idx < apw_state->prewarm_stop_idx);
407 :
408 : /* If we've run out of free buffers, don't launch another worker. */
409 2 : if (!have_free_buffer())
410 0 : break;
411 :
412 : /*
413 : * Likewise, don't launch if we've already been told to shut down.
414 : * (The launch would fail anyway, but we might as well skip it.)
415 : */
416 2 : if (ShutdownRequestPending)
417 0 : break;
418 :
419 : /*
420 : * Start a per-database worker to load blocks for this database; this
421 : * function will return once the per-database worker exits.
422 : */
423 2 : apw_start_database_worker();
424 :
425 : /* Prepare for next database. */
426 2 : apw_state->prewarm_start_idx = apw_state->prewarm_stop_idx;
427 : }
428 :
429 : /* Clean up. */
430 2 : dsm_detach(seg);
431 2 : LWLockAcquire(&apw_state->lock, LW_EXCLUSIVE);
432 2 : apw_state->block_info_handle = DSM_HANDLE_INVALID;
433 2 : apw_state->pid_using_dumpfile = InvalidPid;
434 2 : LWLockRelease(&apw_state->lock);
435 :
436 : /* Report our success, if we were able to finish. */
437 2 : if (!ShutdownRequestPending)
438 2 : ereport(LOG,
439 : (errmsg("autoprewarm successfully prewarmed %d of %d previously-loaded blocks",
440 : apw_state->prewarmed_blocks, num_elements)));
441 : }
442 :
443 : /*
444 : * Prewarm all blocks for one database (and possibly also global objects, if
445 : * those got grouped with this database).
446 : */
447 : void
448 2 : autoprewarm_database_main(Datum main_arg)
449 : {
450 : int pos;
451 : BlockInfoRecord *block_info;
452 2 : Relation rel = NULL;
453 2 : BlockNumber nblocks = 0;
454 2 : BlockInfoRecord *old_blk = NULL;
455 : dsm_segment *seg;
456 :
457 : /* Establish signal handlers; once that's done, unblock signals. */
458 2 : pqsignal(SIGTERM, die);
459 2 : BackgroundWorkerUnblockSignals();
460 :
461 : /* Connect to correct database and get block information. */
462 2 : apw_init_shmem();
463 2 : seg = dsm_attach(apw_state->block_info_handle);
464 2 : if (seg == NULL)
465 0 : ereport(ERROR,
466 : (errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
467 : errmsg("could not map dynamic shared memory segment")));
468 2 : BackgroundWorkerInitializeConnectionByOid(apw_state->database, InvalidOid, 0);
469 2 : block_info = (BlockInfoRecord *) dsm_segment_address(seg);
470 2 : pos = apw_state->prewarm_start_idx;
471 :
472 : /*
473 : * Loop until we run out of blocks to prewarm or until we run out of free
474 : * buffers.
475 : */
476 358 : while (pos < apw_state->prewarm_stop_idx && have_free_buffer())
477 : {
478 356 : BlockInfoRecord *blk = &block_info[pos++];
479 : Buffer buf;
480 :
481 356 : CHECK_FOR_INTERRUPTS();
482 :
483 : /*
484 : * Quit if we've reached records for another database. If previous
485 : * blocks are of some global objects, then continue pre-warming.
486 : */
487 356 : if (old_blk != NULL && old_blk->database != blk->database &&
488 2 : old_blk->database != 0)
489 0 : break;
490 :
491 : /*
492 : * As soon as we encounter a block of a new relation, close the old
493 : * relation. Note that rel will be NULL if try_relation_open failed
494 : * previously; in that case, there is nothing to close.
495 : */
496 356 : if (old_blk != NULL && old_blk->filenumber != blk->filenumber &&
497 : rel != NULL)
498 : {
499 90 : relation_close(rel, AccessShareLock);
500 90 : rel = NULL;
501 90 : CommitTransactionCommand();
502 : }
503 :
504 : /*
505 : * Try to open each new relation, but only once, when we first
506 : * encounter it. If it's been dropped, skip the associated blocks.
507 : */
508 356 : if (old_blk == NULL || old_blk->filenumber != blk->filenumber)
509 : {
510 : Oid reloid;
511 :
512 : Assert(rel == NULL);
513 92 : StartTransactionCommand();
514 92 : reloid = RelidByRelfilenumber(blk->tablespace, blk->filenumber);
515 92 : if (OidIsValid(reloid))
516 92 : rel = try_relation_open(reloid, AccessShareLock);
517 :
518 92 : if (!rel)
519 0 : CommitTransactionCommand();
520 : }
521 356 : if (!rel)
522 : {
523 0 : old_blk = blk;
524 0 : continue;
525 : }
526 :
527 : /* Once per fork, check for fork existence and size. */
528 356 : if (old_blk == NULL ||
529 354 : old_blk->filenumber != blk->filenumber ||
530 264 : old_blk->forknum != blk->forknum)
531 : {
532 : /*
533 : * smgrexists is not safe for illegal forknum, hence check whether
534 : * the passed forknum is valid before using it in smgrexists.
535 : */
536 120 : if (blk->forknum > InvalidForkNumber &&
537 240 : blk->forknum <= MAX_FORKNUM &&
538 120 : smgrexists(RelationGetSmgr(rel), blk->forknum))
539 120 : nblocks = RelationGetNumberOfBlocksInFork(rel, blk->forknum);
540 : else
541 0 : nblocks = 0;
542 : }
543 :
544 : /* Check whether blocknum is valid and within fork file size. */
545 356 : if (blk->blocknum >= nblocks)
546 : {
547 : /* Move to next forknum. */
548 0 : old_blk = blk;
549 0 : continue;
550 : }
551 :
552 : /* Prewarm buffer. */
553 356 : buf = ReadBufferExtended(rel, blk->forknum, blk->blocknum, RBM_NORMAL,
554 : NULL);
555 356 : if (BufferIsValid(buf))
556 : {
557 356 : apw_state->prewarmed_blocks++;
558 356 : ReleaseBuffer(buf);
559 : }
560 :
561 356 : old_blk = blk;
562 : }
563 :
564 2 : dsm_detach(seg);
565 :
566 : /* Release lock on previous relation. */
567 2 : if (rel)
568 : {
569 2 : relation_close(rel, AccessShareLock);
570 2 : CommitTransactionCommand();
571 : }
572 2 : }
573 :
574 : /*
575 : * Dump information on blocks in shared buffers. We use a text format here
576 : * so that it's easy to understand and even change the file contents if
577 : * necessary.
578 : * Returns the number of blocks dumped.
579 : */
580 : static int
581 6 : apw_dump_now(bool is_bgworker, bool dump_unlogged)
582 : {
583 : int num_blocks;
584 : int i;
585 : int ret;
586 : BlockInfoRecord *block_info_array;
587 : BufferDesc *bufHdr;
588 : FILE *file;
589 : char transient_dump_file_path[MAXPGPATH];
590 : pid_t pid;
591 :
592 6 : LWLockAcquire(&apw_state->lock, LW_EXCLUSIVE);
593 6 : pid = apw_state->pid_using_dumpfile;
594 6 : if (apw_state->pid_using_dumpfile == InvalidPid)
595 6 : apw_state->pid_using_dumpfile = MyProcPid;
596 6 : LWLockRelease(&apw_state->lock);
597 :
598 6 : if (pid != InvalidPid)
599 : {
600 0 : if (!is_bgworker)
601 0 : ereport(ERROR,
602 : (errmsg("could not perform block dump because dump file is being used by PID %d",
603 : (int) apw_state->pid_using_dumpfile)));
604 :
605 0 : ereport(LOG,
606 : (errmsg("skipping block dump because it is already being performed by PID %d",
607 : (int) apw_state->pid_using_dumpfile)));
608 0 : return 0;
609 : }
610 :
611 : block_info_array =
612 6 : (BlockInfoRecord *) palloc(sizeof(BlockInfoRecord) * NBuffers);
613 :
614 98310 : for (num_blocks = 0, i = 0; i < NBuffers; i++)
615 : {
616 : uint32 buf_state;
617 :
618 98304 : CHECK_FOR_INTERRUPTS();
619 :
620 98304 : bufHdr = GetBufferDescriptor(i);
621 :
622 : /* Lock each buffer header before inspecting. */
623 98304 : buf_state = LockBufHdr(bufHdr);
624 :
625 : /*
626 : * Unlogged tables will be automatically truncated after a crash or
627 : * unclean shutdown. In such cases we need not prewarm them. Dump them
628 : * only if requested by caller.
629 : */
630 98304 : if (buf_state & BM_TAG_VALID &&
631 1068 : ((buf_state & BM_PERMANENT) || dump_unlogged))
632 : {
633 1068 : block_info_array[num_blocks].database = bufHdr->tag.dbOid;
634 1068 : block_info_array[num_blocks].tablespace = bufHdr->tag.spcOid;
635 2136 : block_info_array[num_blocks].filenumber =
636 1068 : BufTagGetRelNumber(&bufHdr->tag);
637 2136 : block_info_array[num_blocks].forknum =
638 1068 : BufTagGetForkNum(&bufHdr->tag);
639 1068 : block_info_array[num_blocks].blocknum = bufHdr->tag.blockNum;
640 1068 : ++num_blocks;
641 : }
642 :
643 98304 : UnlockBufHdr(bufHdr, buf_state);
644 : }
645 :
646 6 : snprintf(transient_dump_file_path, MAXPGPATH, "%s.tmp", AUTOPREWARM_FILE);
647 6 : file = AllocateFile(transient_dump_file_path, "w");
648 6 : if (!file)
649 0 : ereport(ERROR,
650 : (errcode_for_file_access(),
651 : errmsg("could not open file \"%s\": %m",
652 : transient_dump_file_path)));
653 :
654 6 : ret = fprintf(file, "<<%d>>\n", num_blocks);
655 6 : if (ret < 0)
656 : {
657 0 : int save_errno = errno;
658 :
659 0 : FreeFile(file);
660 0 : unlink(transient_dump_file_path);
661 0 : errno = save_errno;
662 0 : ereport(ERROR,
663 : (errcode_for_file_access(),
664 : errmsg("could not write to file \"%s\": %m",
665 : transient_dump_file_path)));
666 : }
667 :
668 1074 : for (i = 0; i < num_blocks; i++)
669 : {
670 1068 : CHECK_FOR_INTERRUPTS();
671 :
672 1068 : ret = fprintf(file, "%u,%u,%u,%u,%u\n",
673 1068 : block_info_array[i].database,
674 1068 : block_info_array[i].tablespace,
675 1068 : block_info_array[i].filenumber,
676 1068 : (uint32) block_info_array[i].forknum,
677 1068 : block_info_array[i].blocknum);
678 1068 : if (ret < 0)
679 : {
680 0 : int save_errno = errno;
681 :
682 0 : FreeFile(file);
683 0 : unlink(transient_dump_file_path);
684 0 : errno = save_errno;
685 0 : ereport(ERROR,
686 : (errcode_for_file_access(),
687 : errmsg("could not write to file \"%s\": %m",
688 : transient_dump_file_path)));
689 : }
690 : }
691 :
692 6 : pfree(block_info_array);
693 :
694 : /*
695 : * Rename transient_dump_file_path to AUTOPREWARM_FILE to make things
696 : * permanent.
697 : */
698 6 : ret = FreeFile(file);
699 6 : if (ret != 0)
700 : {
701 0 : int save_errno = errno;
702 :
703 0 : unlink(transient_dump_file_path);
704 0 : errno = save_errno;
705 0 : ereport(ERROR,
706 : (errcode_for_file_access(),
707 : errmsg("could not close file \"%s\": %m",
708 : transient_dump_file_path)));
709 : }
710 :
711 6 : (void) durable_rename(transient_dump_file_path, AUTOPREWARM_FILE, ERROR);
712 6 : apw_state->pid_using_dumpfile = InvalidPid;
713 :
714 6 : ereport(DEBUG1,
715 : (errmsg_internal("wrote block details for %d blocks", num_blocks)));
716 6 : return num_blocks;
717 : }
718 :
719 : /*
720 : * SQL-callable function to launch autoprewarm.
721 : */
722 : Datum
723 0 : autoprewarm_start_worker(PG_FUNCTION_ARGS)
724 : {
725 : pid_t pid;
726 :
727 0 : if (!autoprewarm)
728 0 : ereport(ERROR,
729 : (errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
730 : errmsg("autoprewarm is disabled")));
731 :
732 0 : apw_init_shmem();
733 0 : LWLockAcquire(&apw_state->lock, LW_EXCLUSIVE);
734 0 : pid = apw_state->bgworker_pid;
735 0 : LWLockRelease(&apw_state->lock);
736 :
737 0 : if (pid != InvalidPid)
738 0 : ereport(ERROR,
739 : (errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
740 : errmsg("autoprewarm worker is already running under PID %d",
741 : (int) pid)));
742 :
743 0 : apw_start_leader_worker();
744 :
745 0 : PG_RETURN_VOID();
746 : }
747 :
748 : /*
749 : * SQL-callable function to perform an immediate block dump.
750 : *
751 : * Note: this is declared to return int8, as insurance against some
752 : * very distant day when we might make NBuffers wider than int.
753 : */
754 : Datum
755 2 : autoprewarm_dump_now(PG_FUNCTION_ARGS)
756 : {
757 : int num_blocks;
758 :
759 2 : apw_init_shmem();
760 :
761 2 : PG_ENSURE_ERROR_CLEANUP(apw_detach_shmem, 0);
762 : {
763 2 : num_blocks = apw_dump_now(false, true);
764 : }
765 2 : PG_END_ENSURE_ERROR_CLEANUP(apw_detach_shmem, 0);
766 :
767 2 : PG_RETURN_INT64((int64) num_blocks);
768 : }
769 :
770 : /*
771 : * Allocate and initialize autoprewarm related shared memory, if not already
772 : * done, and set up backend-local pointer to that state. Returns true if an
773 : * existing shared memory segment was found.
774 : */
775 : static bool
776 8 : apw_init_shmem(void)
777 : {
778 : bool found;
779 :
780 8 : LWLockAcquire(AddinShmemInitLock, LW_EXCLUSIVE);
781 8 : apw_state = ShmemInitStruct("autoprewarm",
782 : sizeof(AutoPrewarmSharedState),
783 : &found);
784 8 : if (!found)
785 : {
786 : /* First time through ... */
787 4 : LWLockInitialize(&apw_state->lock, LWLockNewTrancheId());
788 4 : apw_state->bgworker_pid = InvalidPid;
789 4 : apw_state->pid_using_dumpfile = InvalidPid;
790 : }
791 8 : LWLockRelease(AddinShmemInitLock);
792 :
793 8 : LWLockRegisterTranche(apw_state->lock.tranche, "autoprewarm");
794 :
795 8 : return found;
796 : }
797 :
798 : /*
799 : * Clear our PID from autoprewarm shared state.
800 : */
801 : static void
802 4 : apw_detach_shmem(int code, Datum arg)
803 : {
804 4 : LWLockAcquire(&apw_state->lock, LW_EXCLUSIVE);
805 4 : if (apw_state->pid_using_dumpfile == MyProcPid)
806 0 : apw_state->pid_using_dumpfile = InvalidPid;
807 4 : if (apw_state->bgworker_pid == MyProcPid)
808 4 : apw_state->bgworker_pid = InvalidPid;
809 4 : LWLockRelease(&apw_state->lock);
810 4 : }
811 :
812 : /*
813 : * Start autoprewarm leader worker process.
814 : */
815 : static void
816 4 : apw_start_leader_worker(void)
817 : {
818 : BackgroundWorker worker;
819 : BackgroundWorkerHandle *handle;
820 : BgwHandleStatus status;
821 : pid_t pid;
822 :
823 276 : MemSet(&worker, 0, sizeof(BackgroundWorker));
824 4 : worker.bgw_flags = BGWORKER_SHMEM_ACCESS;
825 4 : worker.bgw_start_time = BgWorkerStart_ConsistentState;
826 4 : strcpy(worker.bgw_library_name, "pg_prewarm");
827 4 : strcpy(worker.bgw_function_name, "autoprewarm_main");
828 4 : strcpy(worker.bgw_name, "autoprewarm leader");
829 4 : strcpy(worker.bgw_type, "autoprewarm leader");
830 :
831 4 : if (process_shared_preload_libraries_in_progress)
832 : {
833 4 : RegisterBackgroundWorker(&worker);
834 4 : return;
835 : }
836 :
837 : /* must set notify PID to wait for startup */
838 0 : worker.bgw_notify_pid = MyProcPid;
839 :
840 0 : if (!RegisterDynamicBackgroundWorker(&worker, &handle))
841 0 : ereport(ERROR,
842 : (errcode(ERRCODE_INSUFFICIENT_RESOURCES),
843 : errmsg("could not register background process"),
844 : errhint("You may need to increase max_worker_processes.")));
845 :
846 0 : status = WaitForBackgroundWorkerStartup(handle, &pid);
847 0 : if (status != BGWH_STARTED)
848 0 : ereport(ERROR,
849 : (errcode(ERRCODE_INSUFFICIENT_RESOURCES),
850 : errmsg("could not start background process"),
851 : errhint("More details may be available in the server log.")));
852 : }
853 :
854 : /*
855 : * Start autoprewarm per-database worker process.
856 : */
857 : static void
858 2 : apw_start_database_worker(void)
859 : {
860 : BackgroundWorker worker;
861 : BackgroundWorkerHandle *handle;
862 :
863 138 : MemSet(&worker, 0, sizeof(BackgroundWorker));
864 2 : worker.bgw_flags =
865 : BGWORKER_SHMEM_ACCESS | BGWORKER_BACKEND_DATABASE_CONNECTION;
866 2 : worker.bgw_start_time = BgWorkerStart_ConsistentState;
867 2 : worker.bgw_restart_time = BGW_NEVER_RESTART;
868 2 : strcpy(worker.bgw_library_name, "pg_prewarm");
869 2 : strcpy(worker.bgw_function_name, "autoprewarm_database_main");
870 2 : strcpy(worker.bgw_name, "autoprewarm worker");
871 2 : strcpy(worker.bgw_type, "autoprewarm worker");
872 :
873 : /* must set notify PID to wait for shutdown */
874 2 : worker.bgw_notify_pid = MyProcPid;
875 :
876 2 : if (!RegisterDynamicBackgroundWorker(&worker, &handle))
877 0 : ereport(ERROR,
878 : (errcode(ERRCODE_INSUFFICIENT_RESOURCES),
879 : errmsg("registering dynamic bgworker autoprewarm failed"),
880 : errhint("Consider increasing configuration parameter \"max_worker_processes\".")));
881 :
882 : /*
883 : * Ignore return value; if it fails, postmaster has died, but we have
884 : * checks for that elsewhere.
885 : */
886 2 : WaitForBackgroundWorkerShutdown(handle);
887 2 : }
888 :
889 : /* Compare member elements to check whether they are not equal. */
890 : #define cmp_member_elem(fld) \
891 : do { \
892 : if (a->fld < b->fld) \
893 : return -1; \
894 : else if (a->fld > b->fld) \
895 : return 1; \
896 : } while(0)
897 :
898 : /*
899 : * apw_compare_blockinfo
900 : *
901 : * We depend on all records for a particular database being consecutive
902 : * in the dump file; each per-database worker will preload blocks until
903 : * it sees a block for some other database. Sorting by tablespace,
904 : * filenumber, forknum, and blocknum isn't critical for correctness, but
905 : * helps us get a sequential I/O pattern.
906 : */
907 : static int
908 2740 : apw_compare_blockinfo(const void *p, const void *q)
909 : {
910 2740 : const BlockInfoRecord *a = (const BlockInfoRecord *) p;
911 2740 : const BlockInfoRecord *b = (const BlockInfoRecord *) q;
912 :
913 2740 : cmp_member_elem(database);
914 2610 : cmp_member_elem(tablespace);
915 2610 : cmp_member_elem(filenumber);
916 836 : cmp_member_elem(forknum);
917 698 : cmp_member_elem(blocknum);
918 :
919 0 : return 0;
920 : }
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