Line data Source code
1 : /* ----------
2 : * pgstat_internal.h
3 : *
4 : * Definitions for the PostgreSQL cumulative statistics system that should
5 : * only be needed by files implementing statistics support (rather than ones
6 : * reporting / querying stats).
7 : *
8 : * Copyright (c) 2001-2025, PostgreSQL Global Development Group
9 : *
10 : * src/include/utils/pgstat_internal.h
11 : * ----------
12 : */
13 : #ifndef PGSTAT_INTERNAL_H
14 : #define PGSTAT_INTERNAL_H
15 :
16 :
17 : #include "common/hashfn_unstable.h"
18 : #include "lib/dshash.h"
19 : #include "lib/ilist.h"
20 : #include "pgstat.h"
21 : #include "storage/lwlock.h"
22 : #include "utils/dsa.h"
23 :
24 :
25 : /*
26 : * Types related to shared memory storage of statistics.
27 : *
28 : * Per-object statistics are stored in the "shared stats" hashtable. That
29 : * table's entries (PgStatShared_HashEntry) contain a pointer to the actual stats
30 : * data for the object (the size of the stats data varies depending on the
31 : * kind of stats). The table is keyed by PgStat_HashKey.
32 : *
33 : * Once a backend has a reference to a shared stats entry, it increments the
34 : * entry's refcount. Even after stats data is dropped (e.g., due to a DROP
35 : * TABLE), the entry itself can only be deleted once all references have been
36 : * released.
37 : *
38 : * These refcounts, in combination with a backend local hashtable
39 : * (pgStatEntryRefHash, with entries pointing to PgStat_EntryRef) in front of
40 : * the shared hash table, mean that most stats work can happen without
41 : * touching the shared hash table, reducing contention.
42 : *
43 : * Once there are pending stats updates for a table PgStat_EntryRef->pending
44 : * is allocated to contain a working space for as-of-yet-unapplied stats
45 : * updates. Once the stats are flushed, PgStat_EntryRef->pending is freed.
46 : *
47 : * Each stat kind in the shared hash table has a fixed member
48 : * PgStatShared_Common as the first element.
49 : */
50 :
51 : /* struct for shared statistics hash entry key. */
52 : typedef struct PgStat_HashKey
53 : {
54 : PgStat_Kind kind; /* statistics entry kind */
55 : Oid dboid; /* database ID. InvalidOid for shared objects. */
56 : uint64 objid; /* object ID (table, function, etc.), or
57 : * identifier. */
58 : } PgStat_HashKey;
59 :
60 : /*
61 : * Shared statistics hash entry. Doesn't itself contain any stats, but points
62 : * to them (with ->body). That allows the stats entries themselves to be of
63 : * variable size.
64 : */
65 : typedef struct PgStatShared_HashEntry
66 : {
67 : PgStat_HashKey key; /* hash key */
68 :
69 : /*
70 : * If dropped is set, backends need to release their references so that
71 : * the memory for the entry can be freed. No new references may be made
72 : * once marked as dropped.
73 : */
74 : bool dropped;
75 :
76 : /*
77 : * Refcount managing lifetime of the entry itself (as opposed to the
78 : * dshash entry pointing to it). The stats lifetime has to be separate
79 : * from the hash table entry lifetime because we allow backends to point
80 : * to a stats entry without holding a hash table lock (and some other
81 : * reasons).
82 : *
83 : * As long as the entry is not dropped, 1 is added to the refcount
84 : * representing that the entry should not be dropped. In addition each
85 : * backend that has a reference to the entry needs to increment the
86 : * refcount as long as it does.
87 : *
88 : * May only be incremented / decremented while holding at least a shared
89 : * lock on the dshash partition containing the entry. It needs to be an
90 : * atomic variable because multiple backends can increment the refcount
91 : * with just a shared lock.
92 : *
93 : * When the refcount reaches 0 the entry needs to be freed.
94 : */
95 : pg_atomic_uint32 refcount;
96 :
97 : /*
98 : * Counter tracking the number of times the entry has been reused.
99 : *
100 : * Set to 0 when the entry is created, and incremented by one each time
101 : * the shared entry is reinitialized with pgstat_reinit_entry().
102 : *
103 : * May only be incremented / decremented while holding at least a shared
104 : * lock on the dshash partition containing the entry. Like refcount, it
105 : * needs to be an atomic variable because multiple backends can increment
106 : * the generation with just a shared lock.
107 : */
108 : pg_atomic_uint32 generation;
109 :
110 : /*
111 : * Pointer to shared stats. The stats entry always starts with
112 : * PgStatShared_Common, embedded in a larger struct containing the
113 : * PgStat_Kind specific stats fields.
114 : */
115 : dsa_pointer body;
116 : } PgStatShared_HashEntry;
117 :
118 : /*
119 : * Common header struct for PgStatShared_*.
120 : */
121 : typedef struct PgStatShared_Common
122 : {
123 : uint32 magic; /* just a validity cross-check */
124 : /* lock protecting stats contents (i.e. data following the header) */
125 : LWLock lock;
126 : } PgStatShared_Common;
127 :
128 : /*
129 : * A backend local reference to a shared stats entry. As long as at least one
130 : * such reference exists, the shared stats entry will not be released.
131 : *
132 : * If there are pending stats update to the shared stats, these are stored in
133 : * ->pending.
134 : */
135 : typedef struct PgStat_EntryRef
136 : {
137 : /*
138 : * Pointer to the PgStatShared_HashEntry entry in the shared stats
139 : * hashtable.
140 : */
141 : PgStatShared_HashEntry *shared_entry;
142 :
143 : /*
144 : * Pointer to the stats data (i.e. PgStatShared_HashEntry->body), resolved
145 : * as a local pointer, to avoid repeated dsa_get_address() calls.
146 : */
147 : PgStatShared_Common *shared_stats;
148 :
149 : /*
150 : * Copy of PgStatShared_HashEntry->generation, keeping locally track of
151 : * the shared stats entry "generation" retrieved (number of times reused).
152 : */
153 : uint32 generation;
154 :
155 : /*
156 : * Pending statistics data that will need to be flushed to shared memory
157 : * stats eventually. Each stats kind utilizing pending data defines what
158 : * format its pending data has and needs to provide a
159 : * PgStat_KindInfo->flush_pending_cb callback to merge pending entries
160 : * into the shared stats hash table.
161 : */
162 : void *pending;
163 : dlist_node pending_node; /* membership in pgStatPending list */
164 : } PgStat_EntryRef;
165 :
166 :
167 : /*
168 : * Some stats changes are transactional. To maintain those, a stack of
169 : * PgStat_SubXactStatus entries is maintained, which contain data pertaining
170 : * to the current transaction and its active subtransactions.
171 : */
172 : typedef struct PgStat_SubXactStatus
173 : {
174 : int nest_level; /* subtransaction nest level */
175 :
176 : struct PgStat_SubXactStatus *prev; /* higher-level subxact if any */
177 :
178 : /*
179 : * Statistics for transactionally dropped objects need to be
180 : * transactionally dropped as well. Collect the stats dropped in the
181 : * current (sub-)transaction and only execute the stats drop when we know
182 : * if the transaction commits/aborts. To handle replicas and crashes,
183 : * stats drops are included in commit / abort records.
184 : */
185 : dclist_head pending_drops;
186 :
187 : /*
188 : * Tuple insertion/deletion counts for an open transaction can't be
189 : * propagated into PgStat_TableStatus counters until we know if it is
190 : * going to commit or abort. Hence, we keep these counts in per-subxact
191 : * structs that live in TopTransactionContext. This data structure is
192 : * designed on the assumption that subxacts won't usually modify very many
193 : * tables.
194 : */
195 : PgStat_TableXactStatus *first; /* head of list for this subxact */
196 : } PgStat_SubXactStatus;
197 :
198 :
199 : /*
200 : * Metadata for a specific kind of statistics.
201 : */
202 : typedef struct PgStat_KindInfo
203 : {
204 : /*
205 : * Do a fixed number of stats objects exist for this kind of stats (e.g.
206 : * bgwriter stats) or not (e.g. tables).
207 : */
208 : bool fixed_amount:1;
209 :
210 : /*
211 : * Can stats of this kind be accessed from another database? Determines
212 : * whether a stats object gets included in stats snapshots.
213 : */
214 : bool accessed_across_databases:1;
215 :
216 : /* Should stats be written to the on-disk stats file? */
217 : bool write_to_file:1;
218 :
219 : /*
220 : * The size of an entry in the shared stats hash table (pointed to by
221 : * PgStatShared_HashEntry->body). For fixed-numbered statistics, this is
222 : * the size of an entry in PgStat_ShmemControl->custom_data.
223 : */
224 : uint32 shared_size;
225 :
226 : /*
227 : * The offset of the statistics struct in the cached statistics snapshot
228 : * PgStat_Snapshot, for fixed-numbered statistics.
229 : */
230 : uint32 snapshot_ctl_off;
231 :
232 : /*
233 : * The offset of the statistics struct in the containing shared memory
234 : * control structure PgStat_ShmemControl, for fixed-numbered statistics.
235 : */
236 : uint32 shared_ctl_off;
237 :
238 : /*
239 : * The offset/size of statistics inside the shared stats entry. Used when
240 : * [de-]serializing statistics to / from disk respectively. Separate from
241 : * shared_size because [de-]serialization may not include in-memory state
242 : * like lwlocks.
243 : */
244 : uint32 shared_data_off;
245 : uint32 shared_data_len;
246 :
247 : /*
248 : * The size of the pending data for this kind. E.g. how large
249 : * PgStat_EntryRef->pending is. Used for allocations.
250 : *
251 : * 0 signals that an entry of this kind should never have a pending entry.
252 : */
253 : uint32 pending_size;
254 :
255 : /*
256 : * Perform custom actions when initializing a backend (standalone or under
257 : * postmaster). Optional.
258 : */
259 : void (*init_backend_cb) (void);
260 :
261 : /*
262 : * For variable-numbered stats: flush pending stats. Required if pending
263 : * data is used. See flush_static_cb when dealing with stats data that
264 : * that cannot use PgStat_EntryRef->pending.
265 : */
266 : bool (*flush_pending_cb) (PgStat_EntryRef *sr, bool nowait);
267 :
268 : /*
269 : * For variable-numbered stats: delete pending stats. Optional.
270 : */
271 : void (*delete_pending_cb) (PgStat_EntryRef *sr);
272 :
273 : /*
274 : * For variable-numbered stats: reset the reset timestamp. Optional.
275 : */
276 : void (*reset_timestamp_cb) (PgStatShared_Common *header, TimestampTz ts);
277 :
278 : /*
279 : * For variable-numbered stats. Optional.
280 : */
281 : void (*to_serialized_name) (const PgStat_HashKey *key,
282 : const PgStatShared_Common *header, NameData *name);
283 : bool (*from_serialized_name) (const NameData *name, PgStat_HashKey *key);
284 :
285 : /*
286 : * For fixed-numbered statistics: Initialize shared memory state.
287 : *
288 : * "stats" is the pointer to the allocated shared memory area.
289 : */
290 : void (*init_shmem_cb) (void *stats);
291 :
292 : /*
293 : * For fixed-numbered or variable-numbered statistics: Flush pending stats
294 : * entries, for stats kinds that do not use PgStat_EntryRef->pending.
295 : *
296 : * Returns true if some of the stats could not be flushed, due to lock
297 : * contention for example. Optional.
298 : *
299 : * "pgstat_report_fixed" needs to be set to trigger the flush of pending
300 : * stats.
301 : */
302 : bool (*flush_static_cb) (bool nowait);
303 :
304 : /*
305 : * For fixed-numbered statistics: Reset All.
306 : */
307 : void (*reset_all_cb) (TimestampTz ts);
308 :
309 : /*
310 : * For fixed-numbered statistics: Build snapshot for entry
311 : */
312 : void (*snapshot_cb) (void);
313 :
314 : /* name of the kind of stats */
315 : const char *const name;
316 : } PgStat_KindInfo;
317 :
318 :
319 : /*
320 : * List of SLRU names that we keep stats for. There is no central registry of
321 : * SLRUs, so we use this fixed list instead. The "other" entry is used for
322 : * all SLRUs without an explicit entry (e.g. SLRUs in extensions).
323 : *
324 : * This is only defined here so that SLRU_NUM_ELEMENTS is known for later type
325 : * definitions.
326 : */
327 : static const char *const slru_names[] = {
328 : "commit_timestamp",
329 : "multixact_member",
330 : "multixact_offset",
331 : "notify",
332 : "serializable",
333 : "subtransaction",
334 : "transaction",
335 : "other" /* has to be last */
336 : };
337 :
338 : #define SLRU_NUM_ELEMENTS lengthof(slru_names)
339 :
340 :
341 : /* ----------
342 : * Types and definitions for different kinds of fixed-amount stats.
343 : *
344 : * Single-writer stats use the changecount mechanism to achieve low-overhead
345 : * writes - they're obviously more performance critical than reads. Check the
346 : * definition of struct PgBackendStatus for some explanation of the
347 : * changecount mechanism.
348 : *
349 : * Because the obvious implementation of resetting single-writer stats isn't
350 : * compatible with that (another backend needs to write), we don't scribble on
351 : * shared stats while resetting. Instead, just record the current counter
352 : * values in a copy of the stats data, which is protected by ->lock. See
353 : * pgstat_fetch_stat_(archiver|bgwriter|checkpointer) for the reader side.
354 : *
355 : * The only exception to that is the stat_reset_timestamp in these structs,
356 : * which is protected by ->lock, because it has to be written by another
357 : * backend while resetting.
358 : * ----------
359 : */
360 :
361 : typedef struct PgStatShared_Archiver
362 : {
363 : /* lock protects ->reset_offset as well as stats->stat_reset_timestamp */
364 : LWLock lock;
365 : uint32 changecount;
366 : PgStat_ArchiverStats stats;
367 : PgStat_ArchiverStats reset_offset;
368 : } PgStatShared_Archiver;
369 :
370 : typedef struct PgStatShared_BgWriter
371 : {
372 : /* lock protects ->reset_offset as well as stats->stat_reset_timestamp */
373 : LWLock lock;
374 : uint32 changecount;
375 : PgStat_BgWriterStats stats;
376 : PgStat_BgWriterStats reset_offset;
377 : } PgStatShared_BgWriter;
378 :
379 : typedef struct PgStatShared_Checkpointer
380 : {
381 : /* lock protects ->reset_offset as well as stats->stat_reset_timestamp */
382 : LWLock lock;
383 : uint32 changecount;
384 : PgStat_CheckpointerStats stats;
385 : PgStat_CheckpointerStats reset_offset;
386 : } PgStatShared_Checkpointer;
387 :
388 : /* Shared-memory ready PgStat_IO */
389 : typedef struct PgStatShared_IO
390 : {
391 : /*
392 : * locks[i] protects stats.stats[i]. locks[0] also protects
393 : * stats.stat_reset_timestamp.
394 : */
395 : LWLock locks[BACKEND_NUM_TYPES];
396 : PgStat_IO stats;
397 : } PgStatShared_IO;
398 :
399 : typedef struct PgStatShared_SLRU
400 : {
401 : /* lock protects ->stats */
402 : LWLock lock;
403 : PgStat_SLRUStats stats[SLRU_NUM_ELEMENTS];
404 : } PgStatShared_SLRU;
405 :
406 : typedef struct PgStatShared_Wal
407 : {
408 : /* lock protects ->stats */
409 : LWLock lock;
410 : PgStat_WalStats stats;
411 : } PgStatShared_Wal;
412 :
413 :
414 :
415 : /* ----------
416 : * Types and definitions for different kinds of variable-amount stats.
417 : *
418 : * Each struct has to start with PgStatShared_Common, containing information
419 : * common across the different types of stats. Kind-specific data follows.
420 : * ----------
421 : */
422 :
423 : typedef struct PgStatShared_Database
424 : {
425 : PgStatShared_Common header;
426 : PgStat_StatDBEntry stats;
427 : } PgStatShared_Database;
428 :
429 : typedef struct PgStatShared_Relation
430 : {
431 : PgStatShared_Common header;
432 : PgStat_StatTabEntry stats;
433 : } PgStatShared_Relation;
434 :
435 : typedef struct PgStatShared_Function
436 : {
437 : PgStatShared_Common header;
438 : PgStat_StatFuncEntry stats;
439 : } PgStatShared_Function;
440 :
441 : typedef struct PgStatShared_Subscription
442 : {
443 : PgStatShared_Common header;
444 : PgStat_StatSubEntry stats;
445 : } PgStatShared_Subscription;
446 :
447 : typedef struct PgStatShared_ReplSlot
448 : {
449 : PgStatShared_Common header;
450 : PgStat_StatReplSlotEntry stats;
451 : } PgStatShared_ReplSlot;
452 :
453 : typedef struct PgStatShared_Backend
454 : {
455 : PgStatShared_Common header;
456 : PgStat_Backend stats;
457 : } PgStatShared_Backend;
458 :
459 : /*
460 : * Central shared memory entry for the cumulative stats system.
461 : *
462 : * Fixed amount stats, the dynamic shared memory hash table for
463 : * non-fixed-amount stats, as well as remaining bits and pieces are all
464 : * reached from here.
465 : */
466 : typedef struct PgStat_ShmemControl
467 : {
468 : void *raw_dsa_area;
469 :
470 : /*
471 : * Stats for variable-numbered objects are kept in this shared hash table.
472 : * See comment above PgStat_Kind for details.
473 : */
474 : dshash_table_handle hash_handle; /* shared dbstat hash */
475 :
476 : /* Has the stats system already been shut down? Just a debugging check. */
477 : bool is_shutdown;
478 :
479 : /*
480 : * Whenever statistics for dropped objects could not be freed - because
481 : * backends still have references - the dropping backend calls
482 : * pgstat_request_entry_refs_gc() incrementing this counter. Eventually
483 : * that causes backends to run pgstat_gc_entry_refs(), allowing memory to
484 : * be reclaimed.
485 : */
486 : pg_atomic_uint64 gc_request_count;
487 :
488 : /*
489 : * Stats data for fixed-numbered objects.
490 : */
491 : PgStatShared_Archiver archiver;
492 : PgStatShared_BgWriter bgwriter;
493 : PgStatShared_Checkpointer checkpointer;
494 : PgStatShared_IO io;
495 : PgStatShared_SLRU slru;
496 : PgStatShared_Wal wal;
497 :
498 : /*
499 : * Custom stats data with fixed-numbered objects, indexed by (PgStat_Kind
500 : * - PGSTAT_KIND_CUSTOM_MIN).
501 : */
502 : void *custom_data[PGSTAT_KIND_CUSTOM_SIZE];
503 :
504 : } PgStat_ShmemControl;
505 :
506 :
507 : /*
508 : * Cached statistics snapshot
509 : */
510 : typedef struct PgStat_Snapshot
511 : {
512 : PgStat_FetchConsistency mode;
513 :
514 : /* time at which snapshot was taken */
515 : TimestampTz snapshot_timestamp;
516 :
517 : bool fixed_valid[PGSTAT_KIND_BUILTIN_SIZE];
518 :
519 : PgStat_ArchiverStats archiver;
520 :
521 : PgStat_BgWriterStats bgwriter;
522 :
523 : PgStat_CheckpointerStats checkpointer;
524 :
525 : PgStat_IO io;
526 :
527 : PgStat_SLRUStats slru[SLRU_NUM_ELEMENTS];
528 :
529 : PgStat_WalStats wal;
530 :
531 : /*
532 : * Data in snapshot for custom fixed-numbered statistics, indexed by
533 : * (PgStat_Kind - PGSTAT_KIND_CUSTOM_MIN). Each entry is allocated in
534 : * TopMemoryContext, for a size of PgStat_KindInfo->shared_data_len.
535 : */
536 : bool custom_valid[PGSTAT_KIND_CUSTOM_SIZE];
537 : void *custom_data[PGSTAT_KIND_CUSTOM_SIZE];
538 :
539 : /* to free snapshot in bulk */
540 : MemoryContext context;
541 : struct pgstat_snapshot_hash *stats;
542 : } PgStat_Snapshot;
543 :
544 :
545 : /*
546 : * Collection of backend-local stats state.
547 : */
548 : typedef struct PgStat_LocalState
549 : {
550 : PgStat_ShmemControl *shmem;
551 : dsa_area *dsa;
552 : dshash_table *shared_hash;
553 :
554 : /* the current statistics snapshot */
555 : PgStat_Snapshot snapshot;
556 : } PgStat_LocalState;
557 :
558 :
559 : /*
560 : * Inline functions defined further below.
561 : */
562 :
563 : static inline void pgstat_begin_changecount_write(uint32 *cc);
564 : static inline void pgstat_end_changecount_write(uint32 *cc);
565 : static inline uint32 pgstat_begin_changecount_read(uint32 *cc);
566 : static inline bool pgstat_end_changecount_read(uint32 *cc, uint32 cc_before);
567 :
568 : static inline void pgstat_copy_changecounted_stats(void *dst, void *src, size_t len,
569 : uint32 *cc);
570 :
571 : static inline int pgstat_cmp_hash_key(const void *a, const void *b, size_t size, void *arg);
572 : static inline uint32 pgstat_hash_hash_key(const void *d, size_t size, void *arg);
573 : static inline size_t pgstat_get_entry_len(PgStat_Kind kind);
574 : static inline void *pgstat_get_entry_data(PgStat_Kind kind, PgStatShared_Common *entry);
575 : static inline void *pgstat_get_custom_shmem_data(PgStat_Kind kind);
576 : static inline void *pgstat_get_custom_snapshot_data(PgStat_Kind kind);
577 :
578 :
579 : /*
580 : * Functions in pgstat.c
581 : */
582 :
583 : extern const PgStat_KindInfo *pgstat_get_kind_info(PgStat_Kind kind);
584 : extern void pgstat_register_kind(PgStat_Kind kind,
585 : const PgStat_KindInfo *kind_info);
586 :
587 : #ifdef USE_ASSERT_CHECKING
588 : extern void pgstat_assert_is_up(void);
589 : #else
590 : #define pgstat_assert_is_up() ((void)true)
591 : #endif
592 :
593 : extern void pgstat_delete_pending_entry(PgStat_EntryRef *entry_ref);
594 : extern PgStat_EntryRef *pgstat_prep_pending_entry(PgStat_Kind kind, Oid dboid,
595 : uint64 objid,
596 : bool *created_entry);
597 : extern PgStat_EntryRef *pgstat_fetch_pending_entry(PgStat_Kind kind,
598 : Oid dboid, uint64 objid);
599 :
600 : extern void *pgstat_fetch_entry(PgStat_Kind kind, Oid dboid, uint64 objid);
601 : extern void pgstat_snapshot_fixed(PgStat_Kind kind);
602 :
603 :
604 : /*
605 : * Functions in pgstat_archiver.c
606 : */
607 :
608 : extern void pgstat_archiver_init_shmem_cb(void *stats);
609 : extern void pgstat_archiver_reset_all_cb(TimestampTz ts);
610 : extern void pgstat_archiver_snapshot_cb(void);
611 :
612 : /*
613 : * Functions in pgstat_backend.c
614 : */
615 :
616 : /* flags for pgstat_flush_backend() */
617 : #define PGSTAT_BACKEND_FLUSH_IO (1 << 0) /* Flush I/O statistics */
618 : #define PGSTAT_BACKEND_FLUSH_WAL (1 << 1) /* Flush WAL statistics */
619 : #define PGSTAT_BACKEND_FLUSH_ALL (PGSTAT_BACKEND_FLUSH_IO | PGSTAT_BACKEND_FLUSH_WAL)
620 :
621 : extern bool pgstat_flush_backend(bool nowait, bits32 flags);
622 : extern bool pgstat_backend_flush_cb(bool nowait);
623 : extern void pgstat_backend_reset_timestamp_cb(PgStatShared_Common *header,
624 : TimestampTz ts);
625 :
626 : /*
627 : * Functions in pgstat_bgwriter.c
628 : */
629 :
630 : extern void pgstat_bgwriter_init_shmem_cb(void *stats);
631 : extern void pgstat_bgwriter_reset_all_cb(TimestampTz ts);
632 : extern void pgstat_bgwriter_snapshot_cb(void);
633 :
634 :
635 : /*
636 : * Functions in pgstat_checkpointer.c
637 : */
638 :
639 : extern void pgstat_checkpointer_init_shmem_cb(void *stats);
640 : extern void pgstat_checkpointer_reset_all_cb(TimestampTz ts);
641 : extern void pgstat_checkpointer_snapshot_cb(void);
642 :
643 :
644 : /*
645 : * Functions in pgstat_database.c
646 : */
647 :
648 : extern void pgstat_report_disconnect(Oid dboid);
649 : extern void pgstat_update_dbstats(TimestampTz ts);
650 : extern void AtEOXact_PgStat_Database(bool isCommit, bool parallel);
651 :
652 : extern PgStat_StatDBEntry *pgstat_prep_database_pending(Oid dboid);
653 : extern void pgstat_reset_database_timestamp(Oid dboid, TimestampTz ts);
654 : extern bool pgstat_database_flush_cb(PgStat_EntryRef *entry_ref, bool nowait);
655 : extern void pgstat_database_reset_timestamp_cb(PgStatShared_Common *header, TimestampTz ts);
656 :
657 :
658 : /*
659 : * Functions in pgstat_function.c
660 : */
661 :
662 : extern bool pgstat_function_flush_cb(PgStat_EntryRef *entry_ref, bool nowait);
663 :
664 :
665 : /*
666 : * Functions in pgstat_io.c
667 : */
668 :
669 : extern void pgstat_flush_io(bool nowait);
670 :
671 : extern bool pgstat_io_flush_cb(bool nowait);
672 : extern void pgstat_io_init_shmem_cb(void *stats);
673 : extern void pgstat_io_reset_all_cb(TimestampTz ts);
674 : extern void pgstat_io_snapshot_cb(void);
675 :
676 :
677 : /*
678 : * Functions in pgstat_relation.c
679 : */
680 :
681 : extern void AtEOXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit);
682 : extern void AtEOSubXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit, int nestDepth);
683 : extern void AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state);
684 : extern void PostPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state);
685 :
686 : extern bool pgstat_relation_flush_cb(PgStat_EntryRef *entry_ref, bool nowait);
687 : extern void pgstat_relation_delete_pending_cb(PgStat_EntryRef *entry_ref);
688 :
689 :
690 : /*
691 : * Functions in pgstat_replslot.c
692 : */
693 :
694 : extern void pgstat_replslot_reset_timestamp_cb(PgStatShared_Common *header, TimestampTz ts);
695 : extern void pgstat_replslot_to_serialized_name_cb(const PgStat_HashKey *key, const PgStatShared_Common *header, NameData *name);
696 : extern bool pgstat_replslot_from_serialized_name_cb(const NameData *name, PgStat_HashKey *key);
697 :
698 :
699 : /*
700 : * Functions in pgstat_shmem.c
701 : */
702 :
703 : extern void pgstat_attach_shmem(void);
704 : extern void pgstat_detach_shmem(void);
705 :
706 : extern PgStat_EntryRef *pgstat_get_entry_ref(PgStat_Kind kind, Oid dboid, uint64 objid,
707 : bool create, bool *created_entry);
708 : extern bool pgstat_lock_entry(PgStat_EntryRef *entry_ref, bool nowait);
709 : extern bool pgstat_lock_entry_shared(PgStat_EntryRef *entry_ref, bool nowait);
710 : extern void pgstat_unlock_entry(PgStat_EntryRef *entry_ref);
711 : extern bool pgstat_drop_entry(PgStat_Kind kind, Oid dboid, uint64 objid);
712 : extern void pgstat_drop_all_entries(void);
713 : extern void pgstat_drop_matching_entries(bool (*do_drop) (PgStatShared_HashEntry *, Datum),
714 : Datum match_data);
715 : extern PgStat_EntryRef *pgstat_get_entry_ref_locked(PgStat_Kind kind, Oid dboid, uint64 objid,
716 : bool nowait);
717 : extern void pgstat_reset_entry(PgStat_Kind kind, Oid dboid, uint64 objid, TimestampTz ts);
718 : extern void pgstat_reset_entries_of_kind(PgStat_Kind kind, TimestampTz ts);
719 : extern void pgstat_reset_matching_entries(bool (*do_reset) (PgStatShared_HashEntry *, Datum),
720 : Datum match_data,
721 : TimestampTz ts);
722 :
723 : extern void pgstat_request_entry_refs_gc(void);
724 : extern PgStatShared_Common *pgstat_init_entry(PgStat_Kind kind,
725 : PgStatShared_HashEntry *shhashent);
726 :
727 :
728 : /*
729 : * Functions in pgstat_slru.c
730 : */
731 :
732 : extern bool pgstat_slru_flush_cb(bool nowait);
733 : extern void pgstat_slru_init_shmem_cb(void *stats);
734 : extern void pgstat_slru_reset_all_cb(TimestampTz ts);
735 : extern void pgstat_slru_snapshot_cb(void);
736 :
737 :
738 : /*
739 : * Functions in pgstat_wal.c
740 : */
741 :
742 : extern void pgstat_wal_init_backend_cb(void);
743 : extern bool pgstat_wal_flush_cb(bool nowait);
744 : extern void pgstat_wal_init_shmem_cb(void *stats);
745 : extern void pgstat_wal_reset_all_cb(TimestampTz ts);
746 : extern void pgstat_wal_snapshot_cb(void);
747 :
748 :
749 : /*
750 : * Functions in pgstat_subscription.c
751 : */
752 :
753 : extern bool pgstat_subscription_flush_cb(PgStat_EntryRef *entry_ref, bool nowait);
754 : extern void pgstat_subscription_reset_timestamp_cb(PgStatShared_Common *header, TimestampTz ts);
755 :
756 :
757 : /*
758 : * Functions in pgstat_xact.c
759 : */
760 :
761 : extern PgStat_SubXactStatus *pgstat_get_xact_stack_level(int nest_level);
762 : extern void pgstat_drop_transactional(PgStat_Kind kind, Oid dboid, uint64 objid);
763 : extern void pgstat_create_transactional(PgStat_Kind kind, Oid dboid, uint64 objid);
764 :
765 :
766 : /*
767 : * Variables in pgstat.c
768 : */
769 :
770 : /*
771 : * Track if *any* pending fixed-numbered statistics should be flushed to
772 : * shared memory.
773 : *
774 : * This flag can be switched to true by fixed-numbered statistics to let
775 : * pgstat_report_stat() know if it needs to go through one round of
776 : * reports, calling flush_static_cb for each fixed-numbered statistics
777 : * kind. When this flag is not set, pgstat_report_stat() is able to do
778 : * a fast exit, knowing that there are no pending fixed-numbered statistics.
779 : *
780 : * Statistics callbacks should never reset this flag; pgstat_report_stat()
781 : * is in charge of doing that.
782 : */
783 : extern PGDLLIMPORT bool pgstat_report_fixed;
784 :
785 : /* Backend-local stats state */
786 : extern PGDLLIMPORT PgStat_LocalState pgStatLocal;
787 :
788 : /*
789 : * Implementation of inline functions declared above.
790 : */
791 :
792 : /*
793 : * Helpers for changecount manipulation. See comments around struct
794 : * PgBackendStatus for details.
795 : */
796 :
797 : static inline void
798 26028 : pgstat_begin_changecount_write(uint32 *cc)
799 : {
800 : Assert((*cc & 1) == 0);
801 :
802 26028 : START_CRIT_SECTION();
803 26028 : (*cc)++;
804 26028 : pg_write_barrier();
805 26028 : }
806 :
807 : static inline void
808 26028 : pgstat_end_changecount_write(uint32 *cc)
809 : {
810 : Assert((*cc & 1) == 1);
811 :
812 26028 : pg_write_barrier();
813 :
814 26028 : (*cc)++;
815 :
816 26028 : END_CRIT_SECTION();
817 26028 : }
818 :
819 : static inline uint32
820 5392 : pgstat_begin_changecount_read(uint32 *cc)
821 : {
822 5392 : uint32 before_cc = *cc;
823 :
824 5392 : CHECK_FOR_INTERRUPTS();
825 :
826 5392 : pg_read_barrier();
827 :
828 5392 : return before_cc;
829 : }
830 :
831 : /*
832 : * Returns true if the read succeeded, false if it needs to be repeated.
833 : */
834 : static inline bool
835 5392 : pgstat_end_changecount_read(uint32 *cc, uint32 before_cc)
836 : {
837 : uint32 after_cc;
838 :
839 5392 : pg_read_barrier();
840 :
841 5392 : after_cc = *cc;
842 :
843 : /* was a write in progress when we started? */
844 5392 : if (before_cc & 1)
845 0 : return false;
846 :
847 : /* did writes start and complete while we read? */
848 5392 : return before_cc == after_cc;
849 : }
850 :
851 :
852 : /*
853 : * helper function for PgStat_KindInfo->snapshot_cb
854 : * PgStat_KindInfo->reset_all_cb callbacks.
855 : *
856 : * Copies out the specified memory area following change-count protocol.
857 : */
858 : static inline void
859 5392 : pgstat_copy_changecounted_stats(void *dst, void *src, size_t len,
860 : uint32 *cc)
861 : {
862 : uint32 cc_before;
863 :
864 : do
865 : {
866 5392 : cc_before = pgstat_begin_changecount_read(cc);
867 :
868 5392 : memcpy(dst, src, len);
869 : }
870 5392 : while (!pgstat_end_changecount_read(cc, cc_before));
871 5392 : }
872 :
873 : /* helpers for dshash / simplehash hashtables */
874 : static inline int
875 14233254 : pgstat_cmp_hash_key(const void *a, const void *b, size_t size, void *arg)
876 : {
877 : Assert(size == sizeof(PgStat_HashKey) && arg == NULL);
878 14233254 : return memcmp(a, b, sizeof(PgStat_HashKey));
879 : }
880 :
881 : static inline uint32
882 17078942 : pgstat_hash_hash_key(const void *d, size_t size, void *arg)
883 : {
884 17078942 : const char *key = (const char *) d;
885 :
886 : Assert(size == sizeof(PgStat_HashKey) && arg == NULL);
887 17078942 : return fasthash32(key, size, 0);
888 : }
889 :
890 : /*
891 : * The length of the data portion of a shared memory stats entry (i.e. without
892 : * transient data such as refcounts, lwlocks, ...).
893 : */
894 : static inline size_t
895 856328 : pgstat_get_entry_len(PgStat_Kind kind)
896 : {
897 856328 : return pgstat_get_kind_info(kind)->shared_data_len;
898 : }
899 :
900 : /*
901 : * Returns a pointer to the data portion of a shared memory stats entry.
902 : */
903 : static inline void *
904 1414796 : pgstat_get_entry_data(PgStat_Kind kind, PgStatShared_Common *entry)
905 : {
906 1414796 : size_t off = pgstat_get_kind_info(kind)->shared_data_off;
907 :
908 : Assert(off != 0 && off < PG_UINT32_MAX);
909 :
910 1414796 : return ((char *) (entry)) + off;
911 : }
912 :
913 : /*
914 : * Returns a pointer to the shared memory area of custom stats for
915 : * fixed-numbered statistics.
916 : */
917 : static inline void *
918 30 : pgstat_get_custom_shmem_data(PgStat_Kind kind)
919 : {
920 30 : int idx = kind - PGSTAT_KIND_CUSTOM_MIN;
921 :
922 : Assert(pgstat_is_kind_custom(kind));
923 : Assert(pgstat_get_kind_info(kind)->fixed_amount);
924 :
925 30 : return pgStatLocal.shmem->custom_data[idx];
926 : }
927 :
928 : /*
929 : * Returns a pointer to the portion of custom data for fixed-numbered
930 : * statistics in the current snapshot.
931 : */
932 : static inline void *
933 18 : pgstat_get_custom_snapshot_data(PgStat_Kind kind)
934 : {
935 18 : int idx = kind - PGSTAT_KIND_CUSTOM_MIN;
936 :
937 : Assert(pgstat_is_kind_custom(kind));
938 : Assert(pgstat_get_kind_info(kind)->fixed_amount);
939 :
940 18 : return pgStatLocal.snapshot.custom_data[idx];
941 : }
942 :
943 : #endif /* PGSTAT_INTERNAL_H */
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