Line data Source code
1 : /* ----------
2 : * pgstat.c
3 : * Infrastructure for the cumulative statistics system.
4 : *
5 : * The cumulative statistics system accumulates statistics for different kinds
6 : * of objects. Some kinds of statistics are collected for a fixed number of
7 : * objects (most commonly 1), e.g., checkpointer statistics. Other kinds of
8 : * statistics are collected for a varying number of objects
9 : * (e.g. relations). See PgStat_KindInfo for a list of currently handled
10 : * statistics.
11 : *
12 : * Statistics are loaded from the filesystem during startup (by the startup
13 : * process), unless preceded by a crash, in which case all stats are
14 : * discarded. They are written out by the checkpointer process just before
15 : * shutting down (if the stats kind allows it), except when shutting down in
16 : * immediate mode.
17 : *
18 : * Fixed-numbered stats are stored in plain (non-dynamic) shared memory.
19 : *
20 : * Statistics for variable-numbered objects are stored in dynamic shared
21 : * memory and can be found via a dshash hashtable. The statistics counters are
22 : * not part of the dshash entry (PgStatShared_HashEntry) directly, but are
23 : * separately allocated (PgStatShared_HashEntry->body). The separate
24 : * allocation allows different kinds of statistics to be stored in the same
25 : * hashtable without wasting space in PgStatShared_HashEntry.
26 : *
27 : * Variable-numbered stats are addressed by PgStat_HashKey while running. It
28 : * is not possible to have statistics for an object that cannot be addressed
29 : * that way at runtime. A wider identifier can be used when serializing to
30 : * disk (used for replication slot stats).
31 : *
32 : * To avoid contention on the shared hashtable, each backend has a
33 : * backend-local hashtable (pgStatEntryRefHash) in front of the shared
34 : * hashtable, containing references (PgStat_EntryRef) to shared hashtable
35 : * entries. The shared hashtable only needs to be accessed when no prior
36 : * reference is found in the local hashtable. Besides pointing to the
37 : * shared hashtable entry (PgStatShared_HashEntry) PgStat_EntryRef also
38 : * contains a pointer to the shared statistics data, as a process-local
39 : * address, to reduce access costs.
40 : *
41 : * The names for structs stored in shared memory are prefixed with
42 : * PgStatShared instead of PgStat. Each stats entry in shared memory is
43 : * protected by a dedicated lwlock.
44 : *
45 : * Most stats updates are first accumulated locally in each process as pending
46 : * entries, then later flushed to shared memory (just after commit, or by
47 : * idle-timeout). This practically eliminates contention on individual stats
48 : * entries. For most kinds of variable-numbered pending stats data is stored
49 : * in PgStat_EntryRef->pending. All entries with pending data are in the
50 : * pgStatPending list. Pending statistics updates are flushed out by
51 : * pgstat_report_stat().
52 : *
53 : * It is possible for external modules to define custom statistics kinds,
54 : * that can use the same properties as any built-in stats kinds. Each custom
55 : * stats kind needs to assign a unique ID to ensure that it does not overlap
56 : * with other extensions. In order to reserve a unique stats kind ID, refer
57 : * to https://wiki.postgresql.org/wiki/CustomCumulativeStats.
58 : *
59 : * The behavior of different kinds of statistics is determined by the kind's
60 : * entry in pgstat_kind_builtin_infos for all the built-in statistics kinds
61 : * defined, and pgstat_kind_custom_infos for custom kinds registered at
62 : * startup by pgstat_register_kind(). See PgStat_KindInfo for details.
63 : *
64 : * The consistency of read accesses to statistics can be configured using the
65 : * stats_fetch_consistency GUC (see config.sgml and monitoring.sgml for the
66 : * settings). When using PGSTAT_FETCH_CONSISTENCY_CACHE or
67 : * PGSTAT_FETCH_CONSISTENCY_SNAPSHOT statistics are stored in
68 : * pgStatLocal.snapshot.
69 : *
70 : * To keep things manageable, stats handling is split across several
71 : * files. Infrastructure pieces are in:
72 : * - pgstat.c - this file, to tie it all together
73 : * - pgstat_shmem.c - nearly everything dealing with shared memory, including
74 : * the maintenance of hashtable entries
75 : * - pgstat_xact.c - transactional integration, including the transactional
76 : * creation and dropping of stats entries
77 : *
78 : * Each statistics kind is handled in a dedicated file:
79 : * - pgstat_archiver.c
80 : * - pgstat_backend.c
81 : * - pgstat_bgwriter.c
82 : * - pgstat_checkpointer.c
83 : * - pgstat_database.c
84 : * - pgstat_function.c
85 : * - pgstat_io.c
86 : * - pgstat_relation.c
87 : * - pgstat_replslot.c
88 : * - pgstat_slru.c
89 : * - pgstat_subscription.c
90 : * - pgstat_wal.c
91 : *
92 : * Whenever possible infrastructure files should not contain code related to
93 : * specific kinds of stats.
94 : *
95 : *
96 : * Copyright (c) 2001-2025, PostgreSQL Global Development Group
97 : *
98 : * IDENTIFICATION
99 : * src/backend/utils/activity/pgstat.c
100 : * ----------
101 : */
102 : #include "postgres.h"
103 :
104 : #include <unistd.h>
105 :
106 : #include "access/xact.h"
107 : #include "lib/dshash.h"
108 : #include "pgstat.h"
109 : #include "storage/fd.h"
110 : #include "storage/ipc.h"
111 : #include "storage/lwlock.h"
112 : #include "utils/guc_hooks.h"
113 : #include "utils/memutils.h"
114 : #include "utils/pgstat_internal.h"
115 : #include "utils/timestamp.h"
116 :
117 :
118 : /* ----------
119 : * Timer definitions.
120 : *
121 : * In milliseconds.
122 : * ----------
123 : */
124 :
125 : /* minimum interval non-forced stats flushes.*/
126 : #define PGSTAT_MIN_INTERVAL 1000
127 : /* how long until to block flushing pending stats updates */
128 : #define PGSTAT_MAX_INTERVAL 60000
129 : /* when to call pgstat_report_stat() again, even when idle */
130 : #define PGSTAT_IDLE_INTERVAL 10000
131 :
132 : /* ----------
133 : * Initial size hints for the hash tables used in statistics.
134 : * ----------
135 : */
136 :
137 : #define PGSTAT_SNAPSHOT_HASH_SIZE 512
138 :
139 : /* ---------
140 : * Identifiers in stats file.
141 : * ---------
142 : */
143 : #define PGSTAT_FILE_ENTRY_END 'E' /* end of file */
144 : #define PGSTAT_FILE_ENTRY_FIXED 'F' /* fixed-numbered stats entry */
145 : #define PGSTAT_FILE_ENTRY_NAME 'N' /* stats entry identified by name */
146 : #define PGSTAT_FILE_ENTRY_HASH 'S' /* stats entry identified by
147 : * PgStat_HashKey */
148 :
149 : /* hash table for statistics snapshots entry */
150 : typedef struct PgStat_SnapshotEntry
151 : {
152 : PgStat_HashKey key;
153 : char status; /* for simplehash use */
154 : void *data; /* the stats data itself */
155 : } PgStat_SnapshotEntry;
156 :
157 :
158 : /* ----------
159 : * Backend-local Hash Table Definitions
160 : * ----------
161 : */
162 :
163 : /* for stats snapshot entries */
164 : #define SH_PREFIX pgstat_snapshot
165 : #define SH_ELEMENT_TYPE PgStat_SnapshotEntry
166 : #define SH_KEY_TYPE PgStat_HashKey
167 : #define SH_KEY key
168 : #define SH_HASH_KEY(tb, key) \
169 : pgstat_hash_hash_key(&key, sizeof(PgStat_HashKey), NULL)
170 : #define SH_EQUAL(tb, a, b) \
171 : pgstat_cmp_hash_key(&a, &b, sizeof(PgStat_HashKey), NULL) == 0
172 : #define SH_SCOPE static inline
173 : #define SH_DEFINE
174 : #define SH_DECLARE
175 : #include "lib/simplehash.h"
176 :
177 :
178 : /* ----------
179 : * Local function forward declarations
180 : * ----------
181 : */
182 :
183 : static void pgstat_write_statsfile(void);
184 : static void pgstat_read_statsfile(void);
185 :
186 : static void pgstat_init_snapshot_fixed(void);
187 :
188 : static void pgstat_reset_after_failure(void);
189 :
190 : static bool pgstat_flush_pending_entries(bool nowait);
191 :
192 : static void pgstat_prep_snapshot(void);
193 : static void pgstat_build_snapshot(void);
194 : static void pgstat_build_snapshot_fixed(PgStat_Kind kind);
195 :
196 : static inline bool pgstat_is_kind_valid(PgStat_Kind kind);
197 :
198 :
199 : /* ----------
200 : * GUC parameters
201 : * ----------
202 : */
203 :
204 : bool pgstat_track_counts = false;
205 : int pgstat_fetch_consistency = PGSTAT_FETCH_CONSISTENCY_CACHE;
206 :
207 :
208 : /* ----------
209 : * state shared with pgstat_*.c
210 : * ----------
211 : */
212 :
213 : PgStat_LocalState pgStatLocal;
214 :
215 :
216 : /* ----------
217 : * Local data
218 : *
219 : * NB: There should be only variables related to stats infrastructure here,
220 : * not for specific kinds of stats.
221 : * ----------
222 : */
223 :
224 : /*
225 : * Memory contexts containing the pgStatEntryRefHash table, the
226 : * pgStatSharedRef entries, and pending data respectively. Mostly to make it
227 : * easier to track / attribute memory usage.
228 : */
229 :
230 : static MemoryContext pgStatPendingContext = NULL;
231 :
232 : /*
233 : * Backend local list of PgStat_EntryRef with unflushed pending stats.
234 : *
235 : * Newly pending entries should only ever be added to the end of the list,
236 : * otherwise pgstat_flush_pending_entries() might not see them immediately.
237 : */
238 : static dlist_head pgStatPending = DLIST_STATIC_INIT(pgStatPending);
239 :
240 :
241 : /*
242 : * Force the next stats flush to happen regardless of
243 : * PGSTAT_MIN_INTERVAL. Useful in test scripts.
244 : */
245 : static bool pgStatForceNextFlush = false;
246 :
247 : /*
248 : * Force-clear existing snapshot before next use when stats_fetch_consistency
249 : * is changed.
250 : */
251 : static bool force_stats_snapshot_clear = false;
252 :
253 :
254 : /*
255 : * For assertions that check pgstat is not used before initialization / after
256 : * shutdown.
257 : */
258 : #ifdef USE_ASSERT_CHECKING
259 : static bool pgstat_is_initialized = false;
260 : static bool pgstat_is_shutdown = false;
261 : #endif
262 :
263 :
264 : /*
265 : * The different kinds of built-in statistics.
266 : *
267 : * If reasonably possible, handling specific to one kind of stats should go
268 : * through this abstraction, rather than making more of pgstat.c aware.
269 : *
270 : * See comments for struct PgStat_KindInfo for details about the individual
271 : * fields.
272 : *
273 : * XXX: It'd be nicer to define this outside of this file. But there doesn't
274 : * seem to be a great way of doing that, given the split across multiple
275 : * files.
276 : */
277 : static const PgStat_KindInfo pgstat_kind_builtin_infos[PGSTAT_KIND_BUILTIN_SIZE] = {
278 :
279 : /* stats kinds for variable-numbered objects */
280 :
281 : [PGSTAT_KIND_DATABASE] = {
282 : .name = "database",
283 :
284 : .fixed_amount = false,
285 : .write_to_file = true,
286 : /* so pg_stat_database entries can be seen in all databases */
287 : .accessed_across_databases = true,
288 :
289 : .shared_size = sizeof(PgStatShared_Database),
290 : .shared_data_off = offsetof(PgStatShared_Database, stats),
291 : .shared_data_len = sizeof(((PgStatShared_Database *) 0)->stats),
292 : .pending_size = sizeof(PgStat_StatDBEntry),
293 :
294 : .flush_pending_cb = pgstat_database_flush_cb,
295 : .reset_timestamp_cb = pgstat_database_reset_timestamp_cb,
296 : },
297 :
298 : [PGSTAT_KIND_RELATION] = {
299 : .name = "relation",
300 :
301 : .fixed_amount = false,
302 : .write_to_file = true,
303 :
304 : .shared_size = sizeof(PgStatShared_Relation),
305 : .shared_data_off = offsetof(PgStatShared_Relation, stats),
306 : .shared_data_len = sizeof(((PgStatShared_Relation *) 0)->stats),
307 : .pending_size = sizeof(PgStat_TableStatus),
308 :
309 : .flush_pending_cb = pgstat_relation_flush_cb,
310 : .delete_pending_cb = pgstat_relation_delete_pending_cb,
311 : },
312 :
313 : [PGSTAT_KIND_FUNCTION] = {
314 : .name = "function",
315 :
316 : .fixed_amount = false,
317 : .write_to_file = true,
318 :
319 : .shared_size = sizeof(PgStatShared_Function),
320 : .shared_data_off = offsetof(PgStatShared_Function, stats),
321 : .shared_data_len = sizeof(((PgStatShared_Function *) 0)->stats),
322 : .pending_size = sizeof(PgStat_FunctionCounts),
323 :
324 : .flush_pending_cb = pgstat_function_flush_cb,
325 : },
326 :
327 : [PGSTAT_KIND_REPLSLOT] = {
328 : .name = "replslot",
329 :
330 : .fixed_amount = false,
331 : .write_to_file = true,
332 :
333 : .accessed_across_databases = true,
334 :
335 : .shared_size = sizeof(PgStatShared_ReplSlot),
336 : .shared_data_off = offsetof(PgStatShared_ReplSlot, stats),
337 : .shared_data_len = sizeof(((PgStatShared_ReplSlot *) 0)->stats),
338 :
339 : .reset_timestamp_cb = pgstat_replslot_reset_timestamp_cb,
340 : .to_serialized_name = pgstat_replslot_to_serialized_name_cb,
341 : .from_serialized_name = pgstat_replslot_from_serialized_name_cb,
342 : },
343 :
344 : [PGSTAT_KIND_SUBSCRIPTION] = {
345 : .name = "subscription",
346 :
347 : .fixed_amount = false,
348 : .write_to_file = true,
349 : /* so pg_stat_subscription_stats entries can be seen in all databases */
350 : .accessed_across_databases = true,
351 :
352 : .shared_size = sizeof(PgStatShared_Subscription),
353 : .shared_data_off = offsetof(PgStatShared_Subscription, stats),
354 : .shared_data_len = sizeof(((PgStatShared_Subscription *) 0)->stats),
355 : .pending_size = sizeof(PgStat_BackendSubEntry),
356 :
357 : .flush_pending_cb = pgstat_subscription_flush_cb,
358 : .reset_timestamp_cb = pgstat_subscription_reset_timestamp_cb,
359 : },
360 :
361 : [PGSTAT_KIND_BACKEND] = {
362 : .name = "backend",
363 :
364 : .fixed_amount = false,
365 : .write_to_file = false,
366 :
367 : .accessed_across_databases = true,
368 :
369 : .shared_size = sizeof(PgStatShared_Backend),
370 : .shared_data_off = offsetof(PgStatShared_Backend, stats),
371 : .shared_data_len = sizeof(((PgStatShared_Backend *) 0)->stats),
372 :
373 : .have_static_pending_cb = pgstat_backend_have_pending_cb,
374 : .flush_static_cb = pgstat_backend_flush_cb,
375 : .reset_timestamp_cb = pgstat_backend_reset_timestamp_cb,
376 : },
377 :
378 : /* stats for fixed-numbered (mostly 1) objects */
379 :
380 : [PGSTAT_KIND_ARCHIVER] = {
381 : .name = "archiver",
382 :
383 : .fixed_amount = true,
384 : .write_to_file = true,
385 :
386 : .snapshot_ctl_off = offsetof(PgStat_Snapshot, archiver),
387 : .shared_ctl_off = offsetof(PgStat_ShmemControl, archiver),
388 : .shared_data_off = offsetof(PgStatShared_Archiver, stats),
389 : .shared_data_len = sizeof(((PgStatShared_Archiver *) 0)->stats),
390 :
391 : .init_shmem_cb = pgstat_archiver_init_shmem_cb,
392 : .reset_all_cb = pgstat_archiver_reset_all_cb,
393 : .snapshot_cb = pgstat_archiver_snapshot_cb,
394 : },
395 :
396 : [PGSTAT_KIND_BGWRITER] = {
397 : .name = "bgwriter",
398 :
399 : .fixed_amount = true,
400 : .write_to_file = true,
401 :
402 : .snapshot_ctl_off = offsetof(PgStat_Snapshot, bgwriter),
403 : .shared_ctl_off = offsetof(PgStat_ShmemControl, bgwriter),
404 : .shared_data_off = offsetof(PgStatShared_BgWriter, stats),
405 : .shared_data_len = sizeof(((PgStatShared_BgWriter *) 0)->stats),
406 :
407 : .init_shmem_cb = pgstat_bgwriter_init_shmem_cb,
408 : .reset_all_cb = pgstat_bgwriter_reset_all_cb,
409 : .snapshot_cb = pgstat_bgwriter_snapshot_cb,
410 : },
411 :
412 : [PGSTAT_KIND_CHECKPOINTER] = {
413 : .name = "checkpointer",
414 :
415 : .fixed_amount = true,
416 : .write_to_file = true,
417 :
418 : .snapshot_ctl_off = offsetof(PgStat_Snapshot, checkpointer),
419 : .shared_ctl_off = offsetof(PgStat_ShmemControl, checkpointer),
420 : .shared_data_off = offsetof(PgStatShared_Checkpointer, stats),
421 : .shared_data_len = sizeof(((PgStatShared_Checkpointer *) 0)->stats),
422 :
423 : .init_shmem_cb = pgstat_checkpointer_init_shmem_cb,
424 : .reset_all_cb = pgstat_checkpointer_reset_all_cb,
425 : .snapshot_cb = pgstat_checkpointer_snapshot_cb,
426 : },
427 :
428 : [PGSTAT_KIND_IO] = {
429 : .name = "io",
430 :
431 : .fixed_amount = true,
432 : .write_to_file = true,
433 :
434 : .snapshot_ctl_off = offsetof(PgStat_Snapshot, io),
435 : .shared_ctl_off = offsetof(PgStat_ShmemControl, io),
436 : .shared_data_off = offsetof(PgStatShared_IO, stats),
437 : .shared_data_len = sizeof(((PgStatShared_IO *) 0)->stats),
438 :
439 : .flush_static_cb = pgstat_io_flush_cb,
440 : .have_static_pending_cb = pgstat_io_have_pending_cb,
441 : .init_shmem_cb = pgstat_io_init_shmem_cb,
442 : .reset_all_cb = pgstat_io_reset_all_cb,
443 : .snapshot_cb = pgstat_io_snapshot_cb,
444 : },
445 :
446 : [PGSTAT_KIND_SLRU] = {
447 : .name = "slru",
448 :
449 : .fixed_amount = true,
450 : .write_to_file = true,
451 :
452 : .snapshot_ctl_off = offsetof(PgStat_Snapshot, slru),
453 : .shared_ctl_off = offsetof(PgStat_ShmemControl, slru),
454 : .shared_data_off = offsetof(PgStatShared_SLRU, stats),
455 : .shared_data_len = sizeof(((PgStatShared_SLRU *) 0)->stats),
456 :
457 : .flush_static_cb = pgstat_slru_flush_cb,
458 : .have_static_pending_cb = pgstat_slru_have_pending_cb,
459 : .init_shmem_cb = pgstat_slru_init_shmem_cb,
460 : .reset_all_cb = pgstat_slru_reset_all_cb,
461 : .snapshot_cb = pgstat_slru_snapshot_cb,
462 : },
463 :
464 : [PGSTAT_KIND_WAL] = {
465 : .name = "wal",
466 :
467 : .fixed_amount = true,
468 : .write_to_file = true,
469 :
470 : .snapshot_ctl_off = offsetof(PgStat_Snapshot, wal),
471 : .shared_ctl_off = offsetof(PgStat_ShmemControl, wal),
472 : .shared_data_off = offsetof(PgStatShared_Wal, stats),
473 : .shared_data_len = sizeof(((PgStatShared_Wal *) 0)->stats),
474 :
475 : .init_backend_cb = pgstat_wal_init_backend_cb,
476 : .flush_static_cb = pgstat_wal_flush_cb,
477 : .have_static_pending_cb = pgstat_wal_have_pending_cb,
478 : .init_shmem_cb = pgstat_wal_init_shmem_cb,
479 : .reset_all_cb = pgstat_wal_reset_all_cb,
480 : .snapshot_cb = pgstat_wal_snapshot_cb,
481 : },
482 : };
483 :
484 : /*
485 : * Information about custom statistics kinds.
486 : *
487 : * These are saved in a different array than the built-in kinds to save
488 : * in clarity with the initializations.
489 : *
490 : * Indexed by PGSTAT_KIND_CUSTOM_MIN, of size PGSTAT_KIND_CUSTOM_SIZE.
491 : */
492 : static const PgStat_KindInfo **pgstat_kind_custom_infos = NULL;
493 :
494 : /* ------------------------------------------------------------
495 : * Functions managing the state of the stats system for all backends.
496 : * ------------------------------------------------------------
497 : */
498 :
499 : /*
500 : * Read on-disk stats into memory at server start.
501 : *
502 : * Should only be called by the startup process or in single user mode.
503 : */
504 : void
505 1418 : pgstat_restore_stats(void)
506 : {
507 1418 : pgstat_read_statsfile();
508 1418 : }
509 :
510 : /*
511 : * Remove the stats file. This is currently used only if WAL recovery is
512 : * needed after a crash.
513 : *
514 : * Should only be called by the startup process or in single user mode.
515 : */
516 : void
517 342 : pgstat_discard_stats(void)
518 : {
519 : int ret;
520 :
521 : /* NB: this needs to be done even in single user mode */
522 :
523 342 : ret = unlink(PGSTAT_STAT_PERMANENT_FILENAME);
524 342 : if (ret != 0)
525 : {
526 340 : if (errno == ENOENT)
527 340 : elog(DEBUG2,
528 : "didn't need to unlink permanent stats file \"%s\" - didn't exist",
529 : PGSTAT_STAT_PERMANENT_FILENAME);
530 : else
531 0 : ereport(LOG,
532 : (errcode_for_file_access(),
533 : errmsg("could not unlink permanent statistics file \"%s\": %m",
534 : PGSTAT_STAT_PERMANENT_FILENAME)));
535 : }
536 : else
537 : {
538 2 : ereport(DEBUG2,
539 : (errcode_for_file_access(),
540 : errmsg_internal("unlinked permanent statistics file \"%s\"",
541 : PGSTAT_STAT_PERMANENT_FILENAME)));
542 : }
543 :
544 : /*
545 : * Reset stats contents. This will set reset timestamps of fixed-numbered
546 : * stats to the current time (no variable stats exist).
547 : */
548 342 : pgstat_reset_after_failure();
549 342 : }
550 :
551 : /*
552 : * pgstat_before_server_shutdown() needs to be called by exactly one process
553 : * during regular server shutdowns. Otherwise all stats will be lost.
554 : *
555 : * We currently only write out stats for proc_exit(0). We might want to change
556 : * that at some point... But right now pgstat_discard_stats() would be called
557 : * during the start after a disorderly shutdown, anyway.
558 : */
559 : void
560 1186 : pgstat_before_server_shutdown(int code, Datum arg)
561 : {
562 : Assert(pgStatLocal.shmem != NULL);
563 : Assert(!pgStatLocal.shmem->is_shutdown);
564 :
565 : /*
566 : * Stats should only be reported after pgstat_initialize() and before
567 : * pgstat_shutdown(). This is a convenient point to catch most violations
568 : * of this rule.
569 : */
570 : Assert(pgstat_is_initialized && !pgstat_is_shutdown);
571 :
572 : /* flush out our own pending changes before writing out */
573 1186 : pgstat_report_stat(true);
574 :
575 : /*
576 : * Only write out file during normal shutdown. Don't even signal that
577 : * we've shutdown during irregular shutdowns, because the shutdown
578 : * sequence isn't coordinated to ensure this backend shuts down last.
579 : */
580 1186 : if (code == 0)
581 : {
582 1174 : pgStatLocal.shmem->is_shutdown = true;
583 1174 : pgstat_write_statsfile();
584 : }
585 1186 : }
586 :
587 :
588 : /* ------------------------------------------------------------
589 : * Backend initialization / shutdown functions
590 : * ------------------------------------------------------------
591 : */
592 :
593 : /*
594 : * Shut down a single backend's statistics reporting at process exit.
595 : *
596 : * Flush out any remaining statistics counts. Without this, operations
597 : * triggered during backend exit (such as temp table deletions) won't be
598 : * counted.
599 : */
600 : static void
601 42296 : pgstat_shutdown_hook(int code, Datum arg)
602 : {
603 : Assert(!pgstat_is_shutdown);
604 : Assert(IsUnderPostmaster || !IsPostmasterEnvironment);
605 :
606 : /*
607 : * If we got as far as discovering our own database ID, we can flush out
608 : * what we did so far. Otherwise, we'd be reporting an invalid database
609 : * ID, so forget it. (This means that accesses to pg_database during
610 : * failed backend starts might never get counted.)
611 : */
612 42296 : if (OidIsValid(MyDatabaseId))
613 31836 : pgstat_report_disconnect(MyDatabaseId);
614 :
615 42296 : pgstat_report_stat(true);
616 :
617 : /* there shouldn't be any pending changes left */
618 : Assert(dlist_is_empty(&pgStatPending));
619 42296 : dlist_init(&pgStatPending);
620 :
621 : /* drop the backend stats entry */
622 42296 : if (!pgstat_drop_entry(PGSTAT_KIND_BACKEND, InvalidOid, MyProcNumber))
623 0 : pgstat_request_entry_refs_gc();
624 :
625 42296 : pgstat_detach_shmem();
626 :
627 : #ifdef USE_ASSERT_CHECKING
628 : pgstat_is_shutdown = true;
629 : #endif
630 42296 : }
631 :
632 : /*
633 : * Initialize pgstats state, and set up our on-proc-exit hook. Called from
634 : * BaseInit().
635 : *
636 : * NOTE: MyDatabaseId isn't set yet; so the shutdown hook has to be careful.
637 : */
638 : void
639 42296 : pgstat_initialize(void)
640 : {
641 : Assert(!pgstat_is_initialized);
642 :
643 42296 : pgstat_attach_shmem();
644 :
645 42296 : pgstat_init_snapshot_fixed();
646 :
647 : /* Backend initialization callbacks */
648 10870072 : for (PgStat_Kind kind = PGSTAT_KIND_MIN; kind <= PGSTAT_KIND_MAX; kind++)
649 : {
650 10827776 : const PgStat_KindInfo *kind_info = pgstat_get_kind_info(kind);
651 :
652 10827776 : if (kind_info == NULL || kind_info->init_backend_cb == NULL)
653 10785480 : continue;
654 :
655 42296 : kind_info->init_backend_cb();
656 : }
657 :
658 : /* Set up a process-exit hook to clean up */
659 42296 : before_shmem_exit(pgstat_shutdown_hook, 0);
660 :
661 : #ifdef USE_ASSERT_CHECKING
662 : pgstat_is_initialized = true;
663 : #endif
664 42296 : }
665 :
666 :
667 : /* ------------------------------------------------------------
668 : * Public functions used by backends follow
669 : * ------------------------------------------------------------
670 : */
671 :
672 : /*
673 : * Must be called by processes that performs DML: tcop/postgres.c, logical
674 : * receiver processes, SPI worker, etc. to flush pending statistics updates to
675 : * shared memory.
676 : *
677 : * Unless called with 'force', pending stats updates are flushed happen once
678 : * per PGSTAT_MIN_INTERVAL (1000ms). When not forced, stats flushes do not
679 : * block on lock acquisition, except if stats updates have been pending for
680 : * longer than PGSTAT_MAX_INTERVAL (60000ms).
681 : *
682 : * Whenever pending stats updates remain at the end of pgstat_report_stat() a
683 : * suggested idle timeout is returned. Currently this is always
684 : * PGSTAT_IDLE_INTERVAL (10000ms). Callers can use the returned time to set up
685 : * a timeout after which to call pgstat_report_stat(true), but are not
686 : * required to do so.
687 : *
688 : * Note that this is called only when not within a transaction, so it is fair
689 : * to use transaction stop time as an approximation of current time.
690 : */
691 : long
692 588708 : pgstat_report_stat(bool force)
693 : {
694 : static TimestampTz pending_since = 0;
695 : static TimestampTz last_flush = 0;
696 : bool partial_flush;
697 : TimestampTz now;
698 : bool nowait;
699 :
700 : pgstat_assert_is_up();
701 : Assert(!IsTransactionOrTransactionBlock());
702 :
703 : /* "absorb" the forced flush even if there's nothing to flush */
704 588708 : if (pgStatForceNextFlush)
705 : {
706 428 : force = true;
707 428 : pgStatForceNextFlush = false;
708 : }
709 :
710 : /* Don't expend a clock check if nothing to do */
711 588708 : if (dlist_is_empty(&pgStatPending))
712 : {
713 17186 : bool do_flush = false;
714 :
715 : /* Check for pending stats */
716 3354238 : for (PgStat_Kind kind = PGSTAT_KIND_MIN; kind <= PGSTAT_KIND_MAX; kind++)
717 : {
718 3341340 : const PgStat_KindInfo *kind_info = pgstat_get_kind_info(kind);
719 :
720 3341340 : if (!kind_info)
721 3147040 : continue;
722 194300 : if (!kind_info->have_static_pending_cb)
723 134290 : continue;
724 :
725 60010 : if (kind_info->have_static_pending_cb())
726 : {
727 4288 : do_flush = true;
728 4288 : break;
729 : }
730 : }
731 :
732 17186 : if (!do_flush)
733 : {
734 : Assert(pending_since == 0);
735 12898 : return 0;
736 : }
737 : }
738 :
739 : /*
740 : * There should never be stats to report once stats are shut down. Can't
741 : * assert that before the checks above, as there is an unconditional
742 : * pgstat_report_stat() call in pgstat_shutdown_hook() - which at least
743 : * the process that ran pgstat_before_server_shutdown() will still call.
744 : */
745 : Assert(!pgStatLocal.shmem->is_shutdown);
746 :
747 575810 : if (force)
748 : {
749 : /*
750 : * Stats reports are forced either when it's been too long since stats
751 : * have been reported or in processes that force stats reporting to
752 : * happen at specific points (including shutdown). In the former case
753 : * the transaction stop time might be quite old, in the latter it
754 : * would never get cleared.
755 : */
756 40150 : now = GetCurrentTimestamp();
757 : }
758 : else
759 : {
760 535660 : now = GetCurrentTransactionStopTimestamp();
761 :
762 1016144 : if (pending_since > 0 &&
763 480484 : TimestampDifferenceExceeds(pending_since, now, PGSTAT_MAX_INTERVAL))
764 : {
765 : /* don't keep pending updates longer than PGSTAT_MAX_INTERVAL */
766 0 : force = true;
767 : }
768 535660 : else if (last_flush > 0 &&
769 508960 : !TimestampDifferenceExceeds(last_flush, now, PGSTAT_MIN_INTERVAL))
770 : {
771 : /* don't flush too frequently */
772 507120 : if (pending_since == 0)
773 28208 : pending_since = now;
774 :
775 507120 : return PGSTAT_IDLE_INTERVAL;
776 : }
777 : }
778 :
779 68690 : pgstat_update_dbstats(now);
780 :
781 : /* don't wait for lock acquisition when !force */
782 68690 : nowait = !force;
783 :
784 68690 : partial_flush = false;
785 :
786 : /* flush of variable-numbered stats tracked in pending entries list */
787 68690 : partial_flush |= pgstat_flush_pending_entries(nowait);
788 :
789 : /* flush of other stats kinds */
790 17653330 : for (PgStat_Kind kind = PGSTAT_KIND_MIN; kind <= PGSTAT_KIND_MAX; kind++)
791 : {
792 17584640 : const PgStat_KindInfo *kind_info = pgstat_get_kind_info(kind);
793 :
794 17584640 : if (!kind_info)
795 16760024 : continue;
796 824616 : if (!kind_info->flush_static_cb)
797 549856 : continue;
798 :
799 274760 : partial_flush |= kind_info->flush_static_cb(nowait);
800 : }
801 :
802 68690 : last_flush = now;
803 :
804 : /*
805 : * If some of the pending stats could not be flushed due to lock
806 : * contention, let the caller know when to retry.
807 : */
808 68690 : if (partial_flush)
809 : {
810 : /* force should have prevented us from getting here */
811 : Assert(!force);
812 :
813 : /* remember since when stats have been pending */
814 2 : if (pending_since == 0)
815 2 : pending_since = now;
816 :
817 2 : return PGSTAT_IDLE_INTERVAL;
818 : }
819 :
820 68688 : pending_since = 0;
821 :
822 68688 : return 0;
823 : }
824 :
825 : /*
826 : * Force locally pending stats to be flushed during the next
827 : * pgstat_report_stat() call. This is useful for writing tests.
828 : */
829 : void
830 428 : pgstat_force_next_flush(void)
831 : {
832 428 : pgStatForceNextFlush = true;
833 428 : }
834 :
835 : /*
836 : * Only for use by pgstat_reset_counters()
837 : */
838 : static bool
839 23250 : match_db_entries(PgStatShared_HashEntry *entry, Datum match_data)
840 : {
841 23250 : return entry->key.dboid == DatumGetObjectId(MyDatabaseId);
842 : }
843 :
844 : /*
845 : * Reset counters for our database.
846 : *
847 : * Permission checking for this function is managed through the normal
848 : * GRANT system.
849 : */
850 : void
851 26 : pgstat_reset_counters(void)
852 : {
853 26 : TimestampTz ts = GetCurrentTimestamp();
854 :
855 26 : pgstat_reset_matching_entries(match_db_entries,
856 : ObjectIdGetDatum(MyDatabaseId),
857 : ts);
858 26 : }
859 :
860 : /*
861 : * Reset a single variable-numbered entry.
862 : *
863 : * If the stats kind is within a database, also reset the database's
864 : * stat_reset_timestamp.
865 : *
866 : * Permission checking for this function is managed through the normal
867 : * GRANT system.
868 : */
869 : void
870 44 : pgstat_reset(PgStat_Kind kind, Oid dboid, uint64 objid)
871 : {
872 44 : const PgStat_KindInfo *kind_info = pgstat_get_kind_info(kind);
873 44 : TimestampTz ts = GetCurrentTimestamp();
874 :
875 : /* not needed atm, and doesn't make sense with the current signature */
876 : Assert(!pgstat_get_kind_info(kind)->fixed_amount);
877 :
878 : /* reset the "single counter" */
879 44 : pgstat_reset_entry(kind, dboid, objid, ts);
880 :
881 44 : if (!kind_info->accessed_across_databases)
882 16 : pgstat_reset_database_timestamp(dboid, ts);
883 44 : }
884 :
885 : /*
886 : * Reset stats for all entries of a kind.
887 : *
888 : * Permission checking for this function is managed through the normal
889 : * GRANT system.
890 : */
891 : void
892 54 : pgstat_reset_of_kind(PgStat_Kind kind)
893 : {
894 54 : const PgStat_KindInfo *kind_info = pgstat_get_kind_info(kind);
895 54 : TimestampTz ts = GetCurrentTimestamp();
896 :
897 54 : if (kind_info->fixed_amount)
898 46 : kind_info->reset_all_cb(ts);
899 : else
900 8 : pgstat_reset_entries_of_kind(kind, ts);
901 54 : }
902 :
903 :
904 : /* ------------------------------------------------------------
905 : * Fetching of stats
906 : * ------------------------------------------------------------
907 : */
908 :
909 : /*
910 : * Discard any data collected in the current transaction. Any subsequent
911 : * request will cause new snapshots to be read.
912 : *
913 : * This is also invoked during transaction commit or abort to discard
914 : * the no-longer-wanted snapshot. Updates of stats_fetch_consistency can
915 : * cause this routine to be called.
916 : */
917 : void
918 818734 : pgstat_clear_snapshot(void)
919 : {
920 : pgstat_assert_is_up();
921 :
922 818734 : memset(&pgStatLocal.snapshot.fixed_valid, 0,
923 : sizeof(pgStatLocal.snapshot.fixed_valid));
924 818734 : memset(&pgStatLocal.snapshot.custom_valid, 0,
925 : sizeof(pgStatLocal.snapshot.custom_valid));
926 818734 : pgStatLocal.snapshot.stats = NULL;
927 818734 : pgStatLocal.snapshot.mode = PGSTAT_FETCH_CONSISTENCY_NONE;
928 :
929 : /* Release memory, if any was allocated */
930 818734 : if (pgStatLocal.snapshot.context)
931 : {
932 1012 : MemoryContextDelete(pgStatLocal.snapshot.context);
933 :
934 : /* Reset variables */
935 1012 : pgStatLocal.snapshot.context = NULL;
936 : }
937 :
938 : /*
939 : * Historically the backend_status.c facilities lived in this file, and
940 : * were reset with the same function. For now keep it that way, and
941 : * forward the reset request.
942 : */
943 818734 : pgstat_clear_backend_activity_snapshot();
944 :
945 : /* Reset this flag, as it may be possible that a cleanup was forced. */
946 818734 : force_stats_snapshot_clear = false;
947 818734 : }
948 :
949 : void *
950 373696 : pgstat_fetch_entry(PgStat_Kind kind, Oid dboid, uint64 objid)
951 : {
952 : PgStat_HashKey key;
953 : PgStat_EntryRef *entry_ref;
954 : void *stats_data;
955 373696 : const PgStat_KindInfo *kind_info = pgstat_get_kind_info(kind);
956 :
957 : /* should be called from backends */
958 : Assert(IsUnderPostmaster || !IsPostmasterEnvironment);
959 : Assert(!kind_info->fixed_amount);
960 :
961 373696 : pgstat_prep_snapshot();
962 :
963 : /* clear padding */
964 373696 : memset(&key, 0, sizeof(struct PgStat_HashKey));
965 :
966 373696 : key.kind = kind;
967 373696 : key.dboid = dboid;
968 373696 : key.objid = objid;
969 :
970 : /* if we need to build a full snapshot, do so */
971 373696 : if (pgstat_fetch_consistency == PGSTAT_FETCH_CONSISTENCY_SNAPSHOT)
972 460 : pgstat_build_snapshot();
973 :
974 : /* if caching is desired, look up in cache */
975 373696 : if (pgstat_fetch_consistency > PGSTAT_FETCH_CONSISTENCY_NONE)
976 : {
977 9540 : PgStat_SnapshotEntry *entry = NULL;
978 :
979 9540 : entry = pgstat_snapshot_lookup(pgStatLocal.snapshot.stats, key);
980 :
981 9540 : if (entry)
982 620 : return entry->data;
983 :
984 : /*
985 : * If we built a full snapshot and the key is not in
986 : * pgStatLocal.snapshot.stats, there are no matching stats.
987 : */
988 8920 : if (pgstat_fetch_consistency == PGSTAT_FETCH_CONSISTENCY_SNAPSHOT)
989 28 : return NULL;
990 : }
991 :
992 373048 : pgStatLocal.snapshot.mode = pgstat_fetch_consistency;
993 :
994 373048 : entry_ref = pgstat_get_entry_ref(kind, dboid, objid, false, NULL);
995 :
996 373048 : if (entry_ref == NULL || entry_ref->shared_entry->dropped)
997 : {
998 : /* create empty entry when using PGSTAT_FETCH_CONSISTENCY_CACHE */
999 10512 : if (pgstat_fetch_consistency == PGSTAT_FETCH_CONSISTENCY_CACHE)
1000 : {
1001 1772 : PgStat_SnapshotEntry *entry = NULL;
1002 : bool found;
1003 :
1004 1772 : entry = pgstat_snapshot_insert(pgStatLocal.snapshot.stats, key, &found);
1005 : Assert(!found);
1006 1772 : entry->data = NULL;
1007 : }
1008 10512 : return NULL;
1009 : }
1010 :
1011 : /*
1012 : * Allocate in caller's context for PGSTAT_FETCH_CONSISTENCY_NONE,
1013 : * otherwise we could quickly end up with a fair bit of memory used due to
1014 : * repeated accesses.
1015 : */
1016 362536 : if (pgstat_fetch_consistency == PGSTAT_FETCH_CONSISTENCY_NONE)
1017 355416 : stats_data = palloc(kind_info->shared_data_len);
1018 : else
1019 7120 : stats_data = MemoryContextAlloc(pgStatLocal.snapshot.context,
1020 7120 : kind_info->shared_data_len);
1021 :
1022 362536 : pgstat_lock_entry_shared(entry_ref, false);
1023 725072 : memcpy(stats_data,
1024 362536 : pgstat_get_entry_data(kind, entry_ref->shared_stats),
1025 362536 : kind_info->shared_data_len);
1026 362536 : pgstat_unlock_entry(entry_ref);
1027 :
1028 362536 : if (pgstat_fetch_consistency > PGSTAT_FETCH_CONSISTENCY_NONE)
1029 : {
1030 7120 : PgStat_SnapshotEntry *entry = NULL;
1031 : bool found;
1032 :
1033 7120 : entry = pgstat_snapshot_insert(pgStatLocal.snapshot.stats, key, &found);
1034 7120 : entry->data = stats_data;
1035 : }
1036 :
1037 362536 : return stats_data;
1038 : }
1039 :
1040 : /*
1041 : * If a stats snapshot has been taken, return the timestamp at which that was
1042 : * done, and set *have_snapshot to true. Otherwise *have_snapshot is set to
1043 : * false.
1044 : */
1045 : TimestampTz
1046 60 : pgstat_get_stat_snapshot_timestamp(bool *have_snapshot)
1047 : {
1048 60 : if (force_stats_snapshot_clear)
1049 18 : pgstat_clear_snapshot();
1050 :
1051 60 : if (pgStatLocal.snapshot.mode == PGSTAT_FETCH_CONSISTENCY_SNAPSHOT)
1052 : {
1053 24 : *have_snapshot = true;
1054 24 : return pgStatLocal.snapshot.snapshot_timestamp;
1055 : }
1056 :
1057 36 : *have_snapshot = false;
1058 :
1059 36 : return 0;
1060 : }
1061 :
1062 : bool
1063 160 : pgstat_have_entry(PgStat_Kind kind, Oid dboid, uint64 objid)
1064 : {
1065 : /* fixed-numbered stats always exist */
1066 160 : if (pgstat_get_kind_info(kind)->fixed_amount)
1067 12 : return true;
1068 :
1069 148 : return pgstat_get_entry_ref(kind, dboid, objid, false, NULL) != NULL;
1070 : }
1071 :
1072 : /*
1073 : * Ensure snapshot for fixed-numbered 'kind' exists.
1074 : *
1075 : * Typically used by the pgstat_fetch_* functions for a kind of stats, before
1076 : * massaging the data into the desired format.
1077 : */
1078 : void
1079 458 : pgstat_snapshot_fixed(PgStat_Kind kind)
1080 : {
1081 : Assert(pgstat_is_kind_valid(kind));
1082 : Assert(pgstat_get_kind_info(kind)->fixed_amount);
1083 :
1084 458 : if (force_stats_snapshot_clear)
1085 0 : pgstat_clear_snapshot();
1086 :
1087 458 : if (pgstat_fetch_consistency == PGSTAT_FETCH_CONSISTENCY_SNAPSHOT)
1088 24 : pgstat_build_snapshot();
1089 : else
1090 434 : pgstat_build_snapshot_fixed(kind);
1091 :
1092 458 : if (pgstat_is_kind_builtin(kind))
1093 : Assert(pgStatLocal.snapshot.fixed_valid[kind]);
1094 6 : else if (pgstat_is_kind_custom(kind))
1095 : Assert(pgStatLocal.snapshot.custom_valid[kind - PGSTAT_KIND_CUSTOM_MIN]);
1096 458 : }
1097 :
1098 : static void
1099 42296 : pgstat_init_snapshot_fixed(void)
1100 : {
1101 : /*
1102 : * Initialize fixed-numbered statistics data in snapshots, only for custom
1103 : * stats kinds.
1104 : */
1105 5498480 : for (PgStat_Kind kind = PGSTAT_KIND_CUSTOM_MIN; kind <= PGSTAT_KIND_CUSTOM_MAX; kind++)
1106 : {
1107 5456184 : const PgStat_KindInfo *kind_info = pgstat_get_kind_info(kind);
1108 :
1109 5456184 : if (!kind_info || !kind_info->fixed_amount)
1110 5456058 : continue;
1111 :
1112 126 : pgStatLocal.snapshot.custom_data[kind - PGSTAT_KIND_CUSTOM_MIN] =
1113 126 : MemoryContextAlloc(TopMemoryContext, kind_info->shared_data_len);
1114 : }
1115 42296 : }
1116 :
1117 : static void
1118 373748 : pgstat_prep_snapshot(void)
1119 : {
1120 373748 : if (force_stats_snapshot_clear)
1121 18 : pgstat_clear_snapshot();
1122 :
1123 373748 : if (pgstat_fetch_consistency == PGSTAT_FETCH_CONSISTENCY_NONE ||
1124 9592 : pgStatLocal.snapshot.stats != NULL)
1125 372736 : return;
1126 :
1127 1012 : if (!pgStatLocal.snapshot.context)
1128 1012 : pgStatLocal.snapshot.context = AllocSetContextCreate(TopMemoryContext,
1129 : "PgStat Snapshot",
1130 : ALLOCSET_SMALL_SIZES);
1131 :
1132 1012 : pgStatLocal.snapshot.stats =
1133 1012 : pgstat_snapshot_create(pgStatLocal.snapshot.context,
1134 : PGSTAT_SNAPSHOT_HASH_SIZE,
1135 : NULL);
1136 : }
1137 :
1138 : static void
1139 484 : pgstat_build_snapshot(void)
1140 : {
1141 : dshash_seq_status hstat;
1142 : PgStatShared_HashEntry *p;
1143 :
1144 : /* should only be called when we need a snapshot */
1145 : Assert(pgstat_fetch_consistency == PGSTAT_FETCH_CONSISTENCY_SNAPSHOT);
1146 :
1147 : /* snapshot already built */
1148 484 : if (pgStatLocal.snapshot.mode == PGSTAT_FETCH_CONSISTENCY_SNAPSHOT)
1149 432 : return;
1150 :
1151 52 : pgstat_prep_snapshot();
1152 :
1153 : Assert(pgStatLocal.snapshot.stats->members == 0);
1154 :
1155 52 : pgStatLocal.snapshot.snapshot_timestamp = GetCurrentTimestamp();
1156 :
1157 : /*
1158 : * Snapshot all variable stats.
1159 : */
1160 52 : dshash_seq_init(&hstat, pgStatLocal.shared_hash, false);
1161 54636 : while ((p = dshash_seq_next(&hstat)) != NULL)
1162 : {
1163 54584 : PgStat_Kind kind = p->key.kind;
1164 54584 : const PgStat_KindInfo *kind_info = pgstat_get_kind_info(kind);
1165 : bool found;
1166 : PgStat_SnapshotEntry *entry;
1167 : PgStatShared_Common *stats_data;
1168 :
1169 : /*
1170 : * Check if the stats object should be included in the snapshot.
1171 : * Unless the stats kind can be accessed from all databases (e.g.,
1172 : * database stats themselves), we only include stats for the current
1173 : * database or objects not associated with a database (e.g. shared
1174 : * relations).
1175 : */
1176 54584 : if (p->key.dboid != MyDatabaseId &&
1177 16302 : p->key.dboid != InvalidOid &&
1178 13388 : !kind_info->accessed_across_databases)
1179 13436 : continue;
1180 :
1181 41352 : if (p->dropped)
1182 204 : continue;
1183 :
1184 : Assert(pg_atomic_read_u32(&p->refcount) > 0);
1185 :
1186 41148 : stats_data = dsa_get_address(pgStatLocal.dsa, p->body);
1187 : Assert(stats_data);
1188 :
1189 41148 : entry = pgstat_snapshot_insert(pgStatLocal.snapshot.stats, p->key, &found);
1190 : Assert(!found);
1191 :
1192 82296 : entry->data = MemoryContextAlloc(pgStatLocal.snapshot.context,
1193 41148 : kind_info->shared_size);
1194 :
1195 : /*
1196 : * Acquire the LWLock directly instead of using
1197 : * pg_stat_lock_entry_shared() which requires a reference.
1198 : */
1199 41148 : LWLockAcquire(&stats_data->lock, LW_SHARED);
1200 82296 : memcpy(entry->data,
1201 41148 : pgstat_get_entry_data(kind, stats_data),
1202 41148 : kind_info->shared_size);
1203 41148 : LWLockRelease(&stats_data->lock);
1204 : }
1205 52 : dshash_seq_term(&hstat);
1206 :
1207 : /*
1208 : * Build snapshot of all fixed-numbered stats.
1209 : */
1210 13364 : for (PgStat_Kind kind = PGSTAT_KIND_MIN; kind <= PGSTAT_KIND_MAX; kind++)
1211 : {
1212 13312 : const PgStat_KindInfo *kind_info = pgstat_get_kind_info(kind);
1213 :
1214 13312 : if (!kind_info)
1215 12688 : continue;
1216 624 : if (!kind_info->fixed_amount)
1217 : {
1218 : Assert(kind_info->snapshot_cb == NULL);
1219 312 : continue;
1220 : }
1221 :
1222 312 : pgstat_build_snapshot_fixed(kind);
1223 : }
1224 :
1225 52 : pgStatLocal.snapshot.mode = PGSTAT_FETCH_CONSISTENCY_SNAPSHOT;
1226 : }
1227 :
1228 : static void
1229 7796 : pgstat_build_snapshot_fixed(PgStat_Kind kind)
1230 : {
1231 7796 : const PgStat_KindInfo *kind_info = pgstat_get_kind_info(kind);
1232 : int idx;
1233 : bool *valid;
1234 :
1235 : /* Position in fixed_valid or custom_valid */
1236 7796 : if (pgstat_is_kind_builtin(kind))
1237 : {
1238 7784 : idx = kind;
1239 7784 : valid = pgStatLocal.snapshot.fixed_valid;
1240 : }
1241 : else
1242 : {
1243 12 : idx = kind - PGSTAT_KIND_CUSTOM_MIN;
1244 12 : valid = pgStatLocal.snapshot.custom_valid;
1245 : }
1246 :
1247 : Assert(kind_info->fixed_amount);
1248 : Assert(kind_info->snapshot_cb != NULL);
1249 :
1250 7796 : if (pgstat_fetch_consistency == PGSTAT_FETCH_CONSISTENCY_NONE)
1251 : {
1252 : /* rebuild every time */
1253 7080 : valid[idx] = false;
1254 : }
1255 716 : else if (valid[idx])
1256 : {
1257 : /* in snapshot mode we shouldn't get called again */
1258 : Assert(pgstat_fetch_consistency == PGSTAT_FETCH_CONSISTENCY_CACHE);
1259 12 : return;
1260 : }
1261 :
1262 : Assert(!valid[idx]);
1263 :
1264 7784 : kind_info->snapshot_cb();
1265 :
1266 : Assert(!valid[idx]);
1267 7784 : valid[idx] = true;
1268 : }
1269 :
1270 :
1271 : /* ------------------------------------------------------------
1272 : * Backend-local pending stats infrastructure
1273 : * ------------------------------------------------------------
1274 : */
1275 :
1276 : /*
1277 : * Returns the appropriate PgStat_EntryRef, preparing it to receive pending
1278 : * stats if not already done.
1279 : *
1280 : * If created_entry is non-NULL, it'll be set to true if the entry is newly
1281 : * created, false otherwise.
1282 : */
1283 : PgStat_EntryRef *
1284 3741444 : pgstat_prep_pending_entry(PgStat_Kind kind, Oid dboid, uint64 objid, bool *created_entry)
1285 : {
1286 : PgStat_EntryRef *entry_ref;
1287 :
1288 : /* need to be able to flush out */
1289 : Assert(pgstat_get_kind_info(kind)->flush_pending_cb != NULL);
1290 :
1291 3741444 : if (unlikely(!pgStatPendingContext))
1292 : {
1293 34380 : pgStatPendingContext =
1294 34380 : AllocSetContextCreate(TopMemoryContext,
1295 : "PgStat Pending",
1296 : ALLOCSET_SMALL_SIZES);
1297 : }
1298 :
1299 3741444 : entry_ref = pgstat_get_entry_ref(kind, dboid, objid,
1300 : true, created_entry);
1301 :
1302 3741444 : if (entry_ref->pending == NULL)
1303 : {
1304 1917240 : size_t entrysize = pgstat_get_kind_info(kind)->pending_size;
1305 :
1306 : Assert(entrysize != (size_t) -1);
1307 :
1308 1917240 : entry_ref->pending = MemoryContextAllocZero(pgStatPendingContext, entrysize);
1309 1917240 : dlist_push_tail(&pgStatPending, &entry_ref->pending_node);
1310 : }
1311 :
1312 3741444 : return entry_ref;
1313 : }
1314 :
1315 : /*
1316 : * Return an existing stats entry, or NULL.
1317 : *
1318 : * This should only be used for helper function for pgstatfuncs.c - outside of
1319 : * that it shouldn't be needed.
1320 : */
1321 : PgStat_EntryRef *
1322 84 : pgstat_fetch_pending_entry(PgStat_Kind kind, Oid dboid, uint64 objid)
1323 : {
1324 : PgStat_EntryRef *entry_ref;
1325 :
1326 84 : entry_ref = pgstat_get_entry_ref(kind, dboid, objid, false, NULL);
1327 :
1328 84 : if (entry_ref == NULL || entry_ref->pending == NULL)
1329 30 : return NULL;
1330 :
1331 54 : return entry_ref;
1332 : }
1333 :
1334 : void
1335 1917240 : pgstat_delete_pending_entry(PgStat_EntryRef *entry_ref)
1336 : {
1337 1917240 : PgStat_Kind kind = entry_ref->shared_entry->key.kind;
1338 1917240 : const PgStat_KindInfo *kind_info = pgstat_get_kind_info(kind);
1339 1917240 : void *pending_data = entry_ref->pending;
1340 :
1341 : Assert(pending_data != NULL);
1342 : /* !fixed_amount stats should be handled explicitly */
1343 : Assert(!pgstat_get_kind_info(kind)->fixed_amount);
1344 :
1345 1917240 : if (kind_info->delete_pending_cb)
1346 1802238 : kind_info->delete_pending_cb(entry_ref);
1347 :
1348 1917240 : pfree(pending_data);
1349 1917240 : entry_ref->pending = NULL;
1350 :
1351 1917240 : dlist_delete(&entry_ref->pending_node);
1352 1917240 : }
1353 :
1354 : /*
1355 : * Flush out pending variable-numbered stats.
1356 : */
1357 : static bool
1358 68690 : pgstat_flush_pending_entries(bool nowait)
1359 : {
1360 68690 : bool have_pending = false;
1361 68690 : dlist_node *cur = NULL;
1362 :
1363 : /*
1364 : * Need to be a bit careful iterating over the list of pending entries.
1365 : * Processing a pending entry may queue further pending entries to the end
1366 : * of the list that we want to process, so a simple iteration won't do.
1367 : * Further complicating matters is that we want to delete the current
1368 : * entry in each iteration from the list if we flushed successfully.
1369 : *
1370 : * So we just keep track of the next pointer in each loop iteration.
1371 : */
1372 68690 : if (!dlist_is_empty(&pgStatPending))
1373 64766 : cur = dlist_head_node(&pgStatPending);
1374 :
1375 1922150 : while (cur)
1376 : {
1377 1853460 : PgStat_EntryRef *entry_ref =
1378 1853460 : dlist_container(PgStat_EntryRef, pending_node, cur);
1379 1853460 : PgStat_HashKey key = entry_ref->shared_entry->key;
1380 1853460 : PgStat_Kind kind = key.kind;
1381 1853460 : const PgStat_KindInfo *kind_info = pgstat_get_kind_info(kind);
1382 : bool did_flush;
1383 : dlist_node *next;
1384 :
1385 : Assert(!kind_info->fixed_amount);
1386 : Assert(kind_info->flush_pending_cb != NULL);
1387 :
1388 : /* flush the stats, if possible */
1389 1853460 : did_flush = kind_info->flush_pending_cb(entry_ref, nowait);
1390 :
1391 : Assert(did_flush || nowait);
1392 :
1393 : /* determine next entry, before deleting the pending entry */
1394 1853460 : if (dlist_has_next(&pgStatPending, cur))
1395 1788694 : next = dlist_next_node(&pgStatPending, cur);
1396 : else
1397 64766 : next = NULL;
1398 :
1399 : /* if successfully flushed, remove entry */
1400 1853460 : if (did_flush)
1401 1853460 : pgstat_delete_pending_entry(entry_ref);
1402 : else
1403 0 : have_pending = true;
1404 :
1405 1853460 : cur = next;
1406 : }
1407 :
1408 : Assert(dlist_is_empty(&pgStatPending) == !have_pending);
1409 :
1410 68690 : return have_pending;
1411 : }
1412 :
1413 :
1414 : /* ------------------------------------------------------------
1415 : * Helper / infrastructure functions
1416 : * ------------------------------------------------------------
1417 : */
1418 :
1419 : PgStat_Kind
1420 166 : pgstat_get_kind_from_str(char *kind_str)
1421 : {
1422 494 : for (PgStat_Kind kind = PGSTAT_KIND_BUILTIN_MIN; kind <= PGSTAT_KIND_BUILTIN_MAX; kind++)
1423 : {
1424 488 : if (pg_strcasecmp(kind_str, pgstat_kind_builtin_infos[kind].name) == 0)
1425 160 : return kind;
1426 : }
1427 :
1428 : /* Check the custom set of cumulative stats */
1429 6 : if (pgstat_kind_custom_infos)
1430 : {
1431 0 : for (PgStat_Kind kind = PGSTAT_KIND_CUSTOM_MIN; kind <= PGSTAT_KIND_CUSTOM_MAX; kind++)
1432 : {
1433 0 : uint32 idx = kind - PGSTAT_KIND_CUSTOM_MIN;
1434 :
1435 0 : if (pgstat_kind_custom_infos[idx] &&
1436 0 : pg_strcasecmp(kind_str, pgstat_kind_custom_infos[idx]->name) == 0)
1437 0 : return kind;
1438 : }
1439 : }
1440 :
1441 6 : ereport(ERROR,
1442 : (errcode(ERRCODE_INVALID_PARAMETER_VALUE),
1443 : errmsg("invalid statistics kind: \"%s\"", kind_str)));
1444 : return PGSTAT_KIND_INVALID; /* avoid compiler warnings */
1445 : }
1446 :
1447 : static inline bool
1448 726494 : pgstat_is_kind_valid(PgStat_Kind kind)
1449 : {
1450 726494 : return pgstat_is_kind_builtin(kind) || pgstat_is_kind_custom(kind);
1451 : }
1452 :
1453 : const PgStat_KindInfo *
1454 47878820 : pgstat_get_kind_info(PgStat_Kind kind)
1455 : {
1456 47878820 : if (pgstat_is_kind_builtin(kind))
1457 10540984 : return &pgstat_kind_builtin_infos[kind];
1458 :
1459 37337836 : if (pgstat_is_kind_custom(kind))
1460 : {
1461 22665906 : uint32 idx = kind - PGSTAT_KIND_CUSTOM_MIN;
1462 :
1463 22665906 : if (pgstat_kind_custom_infos == NULL ||
1464 64072 : pgstat_kind_custom_infos[idx] == NULL)
1465 22664826 : return NULL;
1466 1080 : return pgstat_kind_custom_infos[idx];
1467 : }
1468 :
1469 14671930 : return NULL;
1470 : }
1471 :
1472 : /*
1473 : * Register a new stats kind.
1474 : *
1475 : * PgStat_Kinds must be globally unique across all extensions. Refer
1476 : * to https://wiki.postgresql.org/wiki/CustomCumulativeStats to reserve a
1477 : * unique ID for your extension, to avoid conflicts with other extension
1478 : * developers. During development, use PGSTAT_KIND_EXPERIMENTAL to avoid
1479 : * needlessly reserving a new ID.
1480 : */
1481 : void
1482 16 : pgstat_register_kind(PgStat_Kind kind, const PgStat_KindInfo *kind_info)
1483 : {
1484 16 : uint32 idx = kind - PGSTAT_KIND_CUSTOM_MIN;
1485 :
1486 16 : if (kind_info->name == NULL || strlen(kind_info->name) == 0)
1487 0 : ereport(ERROR,
1488 : (errmsg("custom cumulative statistics name is invalid"),
1489 : errhint("Provide a non-empty name for the custom cumulative statistics.")));
1490 :
1491 16 : if (!pgstat_is_kind_custom(kind))
1492 0 : ereport(ERROR, (errmsg("custom cumulative statistics ID %u is out of range", kind),
1493 : errhint("Provide a custom cumulative statistics ID between %u and %u.",
1494 : PGSTAT_KIND_CUSTOM_MIN, PGSTAT_KIND_CUSTOM_MAX)));
1495 :
1496 16 : if (!process_shared_preload_libraries_in_progress)
1497 0 : ereport(ERROR,
1498 : (errmsg("failed to register custom cumulative statistics \"%s\" with ID %u", kind_info->name, kind),
1499 : errdetail("Custom cumulative statistics must be registered while initializing modules in \"shared_preload_libraries\".")));
1500 :
1501 : /*
1502 : * Check some data for fixed-numbered stats.
1503 : */
1504 16 : if (kind_info->fixed_amount)
1505 : {
1506 8 : if (kind_info->shared_size == 0)
1507 0 : ereport(ERROR,
1508 : (errmsg("custom cumulative statistics property is invalid"),
1509 : errhint("Custom cumulative statistics require a shared memory size for fixed-numbered objects.")));
1510 : }
1511 :
1512 : /*
1513 : * If pgstat_kind_custom_infos is not available yet, allocate it.
1514 : */
1515 16 : if (pgstat_kind_custom_infos == NULL)
1516 : {
1517 8 : pgstat_kind_custom_infos = (const PgStat_KindInfo **)
1518 8 : MemoryContextAllocZero(TopMemoryContext,
1519 : sizeof(PgStat_KindInfo *) * PGSTAT_KIND_CUSTOM_SIZE);
1520 : }
1521 :
1522 16 : if (pgstat_kind_custom_infos[idx] != NULL &&
1523 0 : pgstat_kind_custom_infos[idx]->name != NULL)
1524 0 : ereport(ERROR,
1525 : (errmsg("failed to register custom cumulative statistics \"%s\" with ID %u", kind_info->name, kind),
1526 : errdetail("Custom cumulative statistics \"%s\" already registered with the same ID.",
1527 : pgstat_kind_custom_infos[idx]->name)));
1528 :
1529 : /* check for existing custom stats with the same name */
1530 2080 : for (PgStat_Kind existing_kind = PGSTAT_KIND_CUSTOM_MIN; existing_kind <= PGSTAT_KIND_CUSTOM_MAX; existing_kind++)
1531 : {
1532 2064 : uint32 existing_idx = existing_kind - PGSTAT_KIND_CUSTOM_MIN;
1533 :
1534 2064 : if (pgstat_kind_custom_infos[existing_idx] == NULL)
1535 2056 : continue;
1536 8 : if (!pg_strcasecmp(pgstat_kind_custom_infos[existing_idx]->name, kind_info->name))
1537 0 : ereport(ERROR,
1538 : (errmsg("failed to register custom cumulative statistics \"%s\" with ID %u", kind_info->name, kind),
1539 : errdetail("Existing cumulative statistics with ID %u has the same name.", existing_kind)));
1540 : }
1541 :
1542 : /* Register it */
1543 16 : pgstat_kind_custom_infos[idx] = kind_info;
1544 16 : ereport(LOG,
1545 : (errmsg("registered custom cumulative statistics \"%s\" with ID %u",
1546 : kind_info->name, kind)));
1547 16 : }
1548 :
1549 : /*
1550 : * Stats should only be reported after pgstat_initialize() and before
1551 : * pgstat_shutdown(). This check is put in a few central places to catch
1552 : * violations of this rule more easily.
1553 : */
1554 : #ifdef USE_ASSERT_CHECKING
1555 : void
1556 : pgstat_assert_is_up(void)
1557 : {
1558 : Assert(pgstat_is_initialized && !pgstat_is_shutdown);
1559 : }
1560 : #endif
1561 :
1562 :
1563 : /* ------------------------------------------------------------
1564 : * reading and writing of on-disk stats file
1565 : * ------------------------------------------------------------
1566 : */
1567 :
1568 : /* helpers for pgstat_write_statsfile() */
1569 : static void
1570 713264 : write_chunk(FILE *fpout, void *ptr, size_t len)
1571 : {
1572 : int rc;
1573 :
1574 713264 : rc = fwrite(ptr, len, 1, fpout);
1575 :
1576 : /* we'll check for errors with ferror once at the end */
1577 : (void) rc;
1578 713264 : }
1579 :
1580 : #define write_chunk_s(fpout, ptr) write_chunk(fpout, ptr, sizeof(*ptr))
1581 :
1582 : /*
1583 : * This function is called in the last process that is accessing the shared
1584 : * stats so locking is not required.
1585 : */
1586 : static void
1587 1174 : pgstat_write_statsfile(void)
1588 : {
1589 : FILE *fpout;
1590 : int32 format_id;
1591 1174 : const char *tmpfile = PGSTAT_STAT_PERMANENT_TMPFILE;
1592 1174 : const char *statfile = PGSTAT_STAT_PERMANENT_FILENAME;
1593 : dshash_seq_status hstat;
1594 : PgStatShared_HashEntry *ps;
1595 :
1596 : pgstat_assert_is_up();
1597 :
1598 : /* should be called only by the checkpointer or single user mode */
1599 : Assert(!IsUnderPostmaster || MyBackendType == B_CHECKPOINTER);
1600 :
1601 : /* we're shutting down, so it's ok to just override this */
1602 1174 : pgstat_fetch_consistency = PGSTAT_FETCH_CONSISTENCY_NONE;
1603 :
1604 1174 : elog(DEBUG2, "writing stats file \"%s\"", statfile);
1605 :
1606 : /*
1607 : * Open the statistics temp file to write out the current values.
1608 : */
1609 1174 : fpout = AllocateFile(tmpfile, PG_BINARY_W);
1610 1174 : if (fpout == NULL)
1611 : {
1612 0 : ereport(LOG,
1613 : (errcode_for_file_access(),
1614 : errmsg("could not open temporary statistics file \"%s\": %m",
1615 : tmpfile)));
1616 0 : return;
1617 : }
1618 :
1619 : /*
1620 : * Write the file header --- currently just a format ID.
1621 : */
1622 1174 : format_id = PGSTAT_FILE_FORMAT_ID;
1623 1174 : write_chunk_s(fpout, &format_id);
1624 :
1625 : /* Write various stats structs for fixed number of objects */
1626 301718 : for (PgStat_Kind kind = PGSTAT_KIND_MIN; kind <= PGSTAT_KIND_MAX; kind++)
1627 : {
1628 : char *ptr;
1629 300544 : const PgStat_KindInfo *info = pgstat_get_kind_info(kind);
1630 :
1631 300544 : if (!info || !info->fixed_amount)
1632 293494 : continue;
1633 :
1634 7050 : if (pgstat_is_kind_builtin(kind))
1635 : Assert(info->snapshot_ctl_off != 0);
1636 :
1637 : /* skip if no need to write to file */
1638 7050 : if (!info->write_to_file)
1639 0 : continue;
1640 :
1641 7050 : pgstat_build_snapshot_fixed(kind);
1642 7050 : if (pgstat_is_kind_builtin(kind))
1643 7044 : ptr = ((char *) &pgStatLocal.snapshot) + info->snapshot_ctl_off;
1644 : else
1645 6 : ptr = pgStatLocal.snapshot.custom_data[kind - PGSTAT_KIND_CUSTOM_MIN];
1646 :
1647 7050 : fputc(PGSTAT_FILE_ENTRY_FIXED, fpout);
1648 7050 : write_chunk_s(fpout, &kind);
1649 7050 : write_chunk(fpout, ptr, info->shared_data_len);
1650 : }
1651 :
1652 : /*
1653 : * Walk through the stats entries
1654 : */
1655 1174 : dshash_seq_init(&hstat, pgStatLocal.shared_hash, false);
1656 350288 : while ((ps = dshash_seq_next(&hstat)) != NULL)
1657 : {
1658 : PgStatShared_Common *shstats;
1659 349114 : const PgStat_KindInfo *kind_info = NULL;
1660 :
1661 349114 : CHECK_FOR_INTERRUPTS();
1662 :
1663 : /*
1664 : * We should not see any "dropped" entries when writing the stats
1665 : * file, as all backends and auxiliary processes should have cleaned
1666 : * up their references before they terminated.
1667 : *
1668 : * However, since we are already shutting down, it is not worth
1669 : * crashing the server over any potential cleanup issues, so we simply
1670 : * skip such entries if encountered.
1671 : */
1672 : Assert(!ps->dropped);
1673 349114 : if (ps->dropped)
1674 0 : continue;
1675 :
1676 : /*
1677 : * This discards data related to custom stats kinds that are unknown
1678 : * to this process.
1679 : */
1680 349114 : if (!pgstat_is_kind_valid(ps->key.kind))
1681 : {
1682 0 : elog(WARNING, "found unknown stats entry %u/%u/%" PRIu64,
1683 : ps->key.kind, ps->key.dboid,
1684 : ps->key.objid);
1685 0 : continue;
1686 : }
1687 :
1688 349114 : shstats = (PgStatShared_Common *) dsa_get_address(pgStatLocal.dsa, ps->body);
1689 :
1690 349114 : kind_info = pgstat_get_kind_info(ps->key.kind);
1691 :
1692 : /* if not dropped the valid-entry refcount should exist */
1693 : Assert(pg_atomic_read_u32(&ps->refcount) > 0);
1694 :
1695 : /* skip if no need to write to file */
1696 349114 : if (!kind_info->write_to_file)
1697 194 : continue;
1698 :
1699 348920 : if (!kind_info->to_serialized_name)
1700 : {
1701 : /* normal stats entry, identified by PgStat_HashKey */
1702 348770 : fputc(PGSTAT_FILE_ENTRY_HASH, fpout);
1703 348770 : write_chunk_s(fpout, &ps->key);
1704 : }
1705 : else
1706 : {
1707 : /* stats entry identified by name on disk (e.g. slots) */
1708 : NameData name;
1709 :
1710 150 : kind_info->to_serialized_name(&ps->key, shstats, &name);
1711 :
1712 150 : fputc(PGSTAT_FILE_ENTRY_NAME, fpout);
1713 150 : write_chunk_s(fpout, &ps->key.kind);
1714 150 : write_chunk_s(fpout, &name);
1715 : }
1716 :
1717 : /* Write except the header part of the entry */
1718 348920 : write_chunk(fpout,
1719 : pgstat_get_entry_data(ps->key.kind, shstats),
1720 : pgstat_get_entry_len(ps->key.kind));
1721 : }
1722 1174 : dshash_seq_term(&hstat);
1723 :
1724 : /*
1725 : * No more output to be done. Close the temp file and replace the old
1726 : * pgstat.stat with it. The ferror() check replaces testing for error
1727 : * after each individual fputc or fwrite (in write_chunk()) above.
1728 : */
1729 1174 : fputc(PGSTAT_FILE_ENTRY_END, fpout);
1730 :
1731 1174 : if (ferror(fpout))
1732 : {
1733 0 : ereport(LOG,
1734 : (errcode_for_file_access(),
1735 : errmsg("could not write temporary statistics file \"%s\": %m",
1736 : tmpfile)));
1737 0 : FreeFile(fpout);
1738 0 : unlink(tmpfile);
1739 : }
1740 1174 : else if (FreeFile(fpout) < 0)
1741 : {
1742 0 : ereport(LOG,
1743 : (errcode_for_file_access(),
1744 : errmsg("could not close temporary statistics file \"%s\": %m",
1745 : tmpfile)));
1746 0 : unlink(tmpfile);
1747 : }
1748 1174 : else if (durable_rename(tmpfile, statfile, LOG) < 0)
1749 : {
1750 : /* durable_rename already emitted log message */
1751 0 : unlink(tmpfile);
1752 : }
1753 : }
1754 :
1755 : /* helpers for pgstat_read_statsfile() */
1756 : static bool
1757 756180 : read_chunk(FILE *fpin, void *ptr, size_t len)
1758 : {
1759 756180 : return fread(ptr, 1, len, fpin) == len;
1760 : }
1761 :
1762 : #define read_chunk_s(fpin, ptr) read_chunk(fpin, ptr, sizeof(*ptr))
1763 :
1764 : /*
1765 : * Reads in existing statistics file into memory.
1766 : *
1767 : * This function is called in the only process that is accessing the shared
1768 : * stats so locking is not required.
1769 : */
1770 : static void
1771 1418 : pgstat_read_statsfile(void)
1772 : {
1773 : FILE *fpin;
1774 : int32 format_id;
1775 : bool found;
1776 1418 : const char *statfile = PGSTAT_STAT_PERMANENT_FILENAME;
1777 1418 : PgStat_ShmemControl *shmem = pgStatLocal.shmem;
1778 :
1779 : /* shouldn't be called from postmaster */
1780 : Assert(IsUnderPostmaster || !IsPostmasterEnvironment);
1781 :
1782 1418 : elog(DEBUG2, "reading stats file \"%s\"", statfile);
1783 :
1784 : /*
1785 : * Try to open the stats file. If it doesn't exist, the backends simply
1786 : * returns zero for anything and statistics simply starts from scratch
1787 : * with empty counters.
1788 : *
1789 : * ENOENT is a possibility if stats collection was previously disabled or
1790 : * has not yet written the stats file for the first time. Any other
1791 : * failure condition is suspicious.
1792 : */
1793 1418 : if ((fpin = AllocateFile(statfile, PG_BINARY_R)) == NULL)
1794 : {
1795 92 : if (errno != ENOENT)
1796 0 : ereport(LOG,
1797 : (errcode_for_file_access(),
1798 : errmsg("could not open statistics file \"%s\": %m",
1799 : statfile)));
1800 92 : pgstat_reset_after_failure();
1801 92 : return;
1802 : }
1803 :
1804 : /*
1805 : * Verify it's of the expected format.
1806 : */
1807 1326 : if (!read_chunk_s(fpin, &format_id))
1808 : {
1809 0 : elog(WARNING, "could not read format ID");
1810 0 : goto error;
1811 : }
1812 :
1813 1326 : if (format_id != PGSTAT_FILE_FORMAT_ID)
1814 : {
1815 2 : elog(WARNING, "found incorrect format ID %d (expected %d)",
1816 : format_id, PGSTAT_FILE_FORMAT_ID);
1817 2 : goto error;
1818 : }
1819 :
1820 : /*
1821 : * We found an existing statistics file. Read it and put all the stats
1822 : * data into place.
1823 : */
1824 : for (;;)
1825 377378 : {
1826 378702 : int t = fgetc(fpin);
1827 :
1828 378702 : switch (t)
1829 : {
1830 7948 : case PGSTAT_FILE_ENTRY_FIXED:
1831 : {
1832 : PgStat_Kind kind;
1833 : const PgStat_KindInfo *info;
1834 : char *ptr;
1835 :
1836 : /* entry for fixed-numbered stats */
1837 7948 : if (!read_chunk_s(fpin, &kind))
1838 : {
1839 0 : elog(WARNING, "could not read stats kind for entry of type %c", t);
1840 2 : goto error;
1841 : }
1842 :
1843 7948 : if (!pgstat_is_kind_valid(kind))
1844 : {
1845 0 : elog(WARNING, "invalid stats kind %u for entry of type %c",
1846 : kind, t);
1847 0 : goto error;
1848 : }
1849 :
1850 7948 : info = pgstat_get_kind_info(kind);
1851 7948 : if (!info)
1852 : {
1853 2 : elog(WARNING, "could not find information of kind %u for entry of type %c",
1854 : kind, t);
1855 2 : goto error;
1856 : }
1857 :
1858 7946 : if (!info->fixed_amount)
1859 : {
1860 0 : elog(WARNING, "invalid fixed_amount in stats kind %u for entry of type %c",
1861 : kind, t);
1862 0 : goto error;
1863 : }
1864 :
1865 : /* Load back stats into shared memory */
1866 7946 : if (pgstat_is_kind_builtin(kind))
1867 7944 : ptr = ((char *) shmem) + info->shared_ctl_off +
1868 7944 : info->shared_data_off;
1869 : else
1870 : {
1871 2 : int idx = kind - PGSTAT_KIND_CUSTOM_MIN;
1872 :
1873 2 : ptr = ((char *) shmem->custom_data[idx]) +
1874 2 : info->shared_data_off;
1875 : }
1876 :
1877 7946 : if (!read_chunk(fpin, ptr, info->shared_data_len))
1878 : {
1879 0 : elog(WARNING, "could not read data of stats kind %u for entry of type %c with size %u",
1880 : kind, t, info->shared_data_len);
1881 0 : goto error;
1882 : }
1883 :
1884 7946 : break;
1885 : }
1886 369432 : case PGSTAT_FILE_ENTRY_HASH:
1887 : case PGSTAT_FILE_ENTRY_NAME:
1888 : {
1889 : PgStat_HashKey key;
1890 : PgStatShared_HashEntry *p;
1891 : PgStatShared_Common *header;
1892 :
1893 369432 : CHECK_FOR_INTERRUPTS();
1894 :
1895 369432 : if (t == PGSTAT_FILE_ENTRY_HASH)
1896 : {
1897 : /* normal stats entry, identified by PgStat_HashKey */
1898 369334 : if (!read_chunk_s(fpin, &key))
1899 : {
1900 0 : elog(WARNING, "could not read key for entry of type %c", t);
1901 0 : goto error;
1902 : }
1903 :
1904 369334 : if (!pgstat_is_kind_valid(key.kind))
1905 : {
1906 0 : elog(WARNING, "invalid stats kind for entry %u/%u/%" PRIu64 " of type %c",
1907 : key.kind, key.dboid,
1908 : key.objid, t);
1909 0 : goto error;
1910 : }
1911 : }
1912 : else
1913 : {
1914 : /* stats entry identified by name on disk (e.g. slots) */
1915 98 : const PgStat_KindInfo *kind_info = NULL;
1916 : PgStat_Kind kind;
1917 : NameData name;
1918 :
1919 98 : if (!read_chunk_s(fpin, &kind))
1920 : {
1921 0 : elog(WARNING, "could not read stats kind for entry of type %c", t);
1922 0 : goto error;
1923 : }
1924 98 : if (!read_chunk_s(fpin, &name))
1925 : {
1926 0 : elog(WARNING, "could not read name of stats kind %u for entry of type %c",
1927 : kind, t);
1928 0 : goto error;
1929 : }
1930 98 : if (!pgstat_is_kind_valid(kind))
1931 : {
1932 0 : elog(WARNING, "invalid stats kind %u for entry of type %c",
1933 : kind, t);
1934 0 : goto error;
1935 : }
1936 :
1937 98 : kind_info = pgstat_get_kind_info(kind);
1938 98 : if (!kind_info)
1939 : {
1940 0 : elog(WARNING, "could not find information of kind %u for entry of type %c",
1941 : kind, t);
1942 0 : goto error;
1943 : }
1944 :
1945 98 : if (!kind_info->from_serialized_name)
1946 : {
1947 0 : elog(WARNING, "invalid from_serialized_name in stats kind %u for entry of type %c",
1948 : kind, t);
1949 0 : goto error;
1950 : }
1951 :
1952 98 : if (!kind_info->from_serialized_name(&name, &key))
1953 : {
1954 : /* skip over data for entry we don't care about */
1955 2 : if (fseek(fpin, pgstat_get_entry_len(kind), SEEK_CUR) != 0)
1956 : {
1957 0 : elog(WARNING, "could not seek \"%s\" of stats kind %u for entry of type %c",
1958 : NameStr(name), kind, t);
1959 0 : goto error;
1960 : }
1961 :
1962 2 : continue;
1963 : }
1964 :
1965 : Assert(key.kind == kind);
1966 : }
1967 :
1968 : /*
1969 : * This intentionally doesn't use pgstat_get_entry_ref() -
1970 : * putting all stats into checkpointer's
1971 : * pgStatEntryRefHash would be wasted effort and memory.
1972 : */
1973 369430 : p = dshash_find_or_insert(pgStatLocal.shared_hash, &key, &found);
1974 :
1975 : /* don't allow duplicate entries */
1976 369430 : if (found)
1977 : {
1978 0 : dshash_release_lock(pgStatLocal.shared_hash, p);
1979 0 : elog(WARNING, "found duplicate stats entry %u/%u/%" PRIu64 " of type %c",
1980 : key.kind, key.dboid,
1981 : key.objid, t);
1982 0 : goto error;
1983 : }
1984 :
1985 369430 : header = pgstat_init_entry(key.kind, p);
1986 369430 : dshash_release_lock(pgStatLocal.shared_hash, p);
1987 :
1988 369430 : if (!read_chunk(fpin,
1989 : pgstat_get_entry_data(key.kind, header),
1990 : pgstat_get_entry_len(key.kind)))
1991 : {
1992 0 : elog(WARNING, "could not read data for entry %u/%u/%" PRIu64 " of type %c",
1993 : key.kind, key.dboid,
1994 : key.objid, t);
1995 0 : goto error;
1996 : }
1997 :
1998 369430 : break;
1999 : }
2000 1322 : case PGSTAT_FILE_ENTRY_END:
2001 :
2002 : /*
2003 : * check that PGSTAT_FILE_ENTRY_END actually signals end of
2004 : * file
2005 : */
2006 1322 : if (fgetc(fpin) != EOF)
2007 : {
2008 2 : elog(WARNING, "could not read end-of-file");
2009 2 : goto error;
2010 : }
2011 :
2012 1320 : goto done;
2013 :
2014 0 : default:
2015 0 : elog(WARNING, "could not read entry of type %c", t);
2016 0 : goto error;
2017 : }
2018 : }
2019 :
2020 1326 : done:
2021 1326 : FreeFile(fpin);
2022 :
2023 1326 : elog(DEBUG2, "removing permanent stats file \"%s\"", statfile);
2024 1326 : unlink(statfile);
2025 :
2026 1326 : return;
2027 :
2028 6 : error:
2029 6 : ereport(LOG,
2030 : (errmsg("corrupted statistics file \"%s\"", statfile)));
2031 :
2032 6 : pgstat_reset_after_failure();
2033 :
2034 6 : goto done;
2035 : }
2036 :
2037 : /*
2038 : * Helper to reset / drop stats after a crash or after restoring stats from
2039 : * disk failed, potentially after already loading parts.
2040 : */
2041 : static void
2042 440 : pgstat_reset_after_failure(void)
2043 : {
2044 440 : TimestampTz ts = GetCurrentTimestamp();
2045 :
2046 : /* reset fixed-numbered stats */
2047 113080 : for (PgStat_Kind kind = PGSTAT_KIND_MIN; kind <= PGSTAT_KIND_MAX; kind++)
2048 : {
2049 112640 : const PgStat_KindInfo *kind_info = pgstat_get_kind_info(kind);
2050 :
2051 112640 : if (!kind_info || !kind_info->fixed_amount)
2052 109998 : continue;
2053 :
2054 2642 : kind_info->reset_all_cb(ts);
2055 : }
2056 :
2057 : /* and drop variable-numbered ones */
2058 440 : pgstat_drop_all_entries();
2059 440 : }
2060 :
2061 : /*
2062 : * GUC assign_hook for stats_fetch_consistency.
2063 : */
2064 : void
2065 5544 : assign_stats_fetch_consistency(int newval, void *extra)
2066 : {
2067 : /*
2068 : * Changing this value in a transaction may cause snapshot state
2069 : * inconsistencies, so force a clear of the current snapshot on the next
2070 : * snapshot build attempt.
2071 : */
2072 5544 : if (pgstat_fetch_consistency != newval)
2073 3232 : force_stats_snapshot_clear = true;
2074 5544 : }
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