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) 2001-2026, 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 : /*
52 : * Struct for shared statistics hash entry key.
53 : *
54 : * NB: We assume that this struct contains no padding. Also, 8 bytes
55 : * allocated for the object ID are good enough to ensure the uniqueness
56 : * of the hash key, hence the addition of new fields is not recommended.
57 : */
58 : typedef struct PgStat_HashKey
59 : {
60 : PgStat_Kind kind; /* statistics entry kind */
61 : Oid dboid; /* database ID. InvalidOid for shared objects. */
62 : uint64 objid; /* object ID (table, function, etc.), or
63 : * identifier. */
64 : } PgStat_HashKey;
65 :
66 : /*
67 : * Tracks if the stats file is being read, written or discarded, used in
68 : * combination with the finish callback.
69 : *
70 : * These states allow plugins that create auxiliary data files to determine
71 : * the current operation and perform any necessary file cleanup.
72 : */
73 : typedef enum PgStat_StatsFileOp
74 : {
75 : STATS_WRITE,
76 : STATS_READ,
77 : STATS_DISCARD,
78 : } PgStat_StatsFileOp;
79 :
80 : /*
81 : * PgStat_HashKey should not have any padding. Checking that the structure
82 : * size matches with the sum of each field is a check simple enough to
83 : * enforce this policy.
84 : */
85 : StaticAssertDecl((sizeof(PgStat_Kind) + sizeof(uint64) + sizeof(Oid)) ==
86 : sizeof(PgStat_HashKey),
87 : "PgStat_HashKey should have no padding");
88 :
89 : /*
90 : * Shared statistics hash entry. Doesn't itself contain any stats, but points
91 : * to them (with ->body). That allows the stats entries themselves to be of
92 : * variable size.
93 : */
94 : typedef struct PgStatShared_HashEntry
95 : {
96 : PgStat_HashKey key; /* hash key */
97 :
98 : /*
99 : * If dropped is set, backends need to release their references so that
100 : * the memory for the entry can be freed. No new references may be made
101 : * once marked as dropped.
102 : */
103 : bool dropped;
104 :
105 : /*
106 : * Refcount managing lifetime of the entry itself (as opposed to the
107 : * dshash entry pointing to it). The stats lifetime has to be separate
108 : * from the hash table entry lifetime because we allow backends to point
109 : * to a stats entry without holding a hash table lock (and some other
110 : * reasons).
111 : *
112 : * As long as the entry is not dropped, 1 is added to the refcount
113 : * representing that the entry should not be dropped. In addition each
114 : * backend that has a reference to the entry needs to increment the
115 : * refcount as long as it does.
116 : *
117 : * May only be incremented / decremented while holding at least a shared
118 : * lock on the dshash partition containing the entry. It needs to be an
119 : * atomic variable because multiple backends can increment the refcount
120 : * with just a shared lock.
121 : *
122 : * When the refcount reaches 0 the entry needs to be freed.
123 : */
124 : pg_atomic_uint32 refcount;
125 :
126 : /*
127 : * Counter tracking the number of times the entry has been reused.
128 : *
129 : * Set to 0 when the entry is created, and incremented by one each time
130 : * the shared entry is reinitialized with pgstat_reinit_entry().
131 : *
132 : * May only be incremented / decremented while holding at least a shared
133 : * lock on the dshash partition containing the entry. Like refcount, it
134 : * needs to be an atomic variable because multiple backends can increment
135 : * the generation with just a shared lock.
136 : */
137 : pg_atomic_uint32 generation;
138 :
139 : /*
140 : * Pointer to shared stats. The stats entry always starts with
141 : * PgStatShared_Common, embedded in a larger struct containing the
142 : * PgStat_Kind specific stats fields.
143 : */
144 : dsa_pointer body;
145 : } PgStatShared_HashEntry;
146 :
147 : /*
148 : * Common header struct for PgStatShared_*.
149 : */
150 : typedef struct PgStatShared_Common
151 : {
152 : uint32 magic; /* just a validity cross-check */
153 : /* lock protecting stats contents (i.e. data following the header) */
154 : LWLock lock;
155 : } PgStatShared_Common;
156 :
157 : /*
158 : * A backend local reference to a shared stats entry. As long as at least one
159 : * such reference exists, the shared stats entry will not be released.
160 : *
161 : * If there are pending stats update to the shared stats, these are stored in
162 : * ->pending.
163 : */
164 : typedef struct PgStat_EntryRef
165 : {
166 : /*
167 : * Pointer to the PgStatShared_HashEntry entry in the shared stats
168 : * hashtable.
169 : */
170 : PgStatShared_HashEntry *shared_entry;
171 :
172 : /*
173 : * Pointer to the stats data (i.e. PgStatShared_HashEntry->body), resolved
174 : * as a local pointer, to avoid repeated dsa_get_address() calls.
175 : */
176 : PgStatShared_Common *shared_stats;
177 :
178 : /*
179 : * Copy of PgStatShared_HashEntry->generation, keeping locally track of
180 : * the shared stats entry "generation" retrieved (number of times reused).
181 : */
182 : uint32 generation;
183 :
184 : /*
185 : * Pending statistics data that will need to be flushed to shared memory
186 : * stats eventually. Each stats kind utilizing pending data defines what
187 : * format its pending data has and needs to provide a
188 : * PgStat_KindInfo->flush_pending_cb callback to merge pending entries
189 : * into the shared stats hash table.
190 : */
191 : void *pending;
192 : dlist_node pending_node; /* membership in pgStatPending list */
193 : } PgStat_EntryRef;
194 :
195 :
196 : /*
197 : * Some stats changes are transactional. To maintain those, a stack of
198 : * PgStat_SubXactStatus entries is maintained, which contain data pertaining
199 : * to the current transaction and its active subtransactions.
200 : */
201 : typedef struct PgStat_SubXactStatus
202 : {
203 : int nest_level; /* subtransaction nest level */
204 :
205 : struct PgStat_SubXactStatus *prev; /* higher-level subxact if any */
206 :
207 : /*
208 : * Statistics for transactionally dropped objects need to be
209 : * transactionally dropped as well. Collect the stats dropped in the
210 : * current (sub-)transaction and only execute the stats drop when we know
211 : * if the transaction commits/aborts. To handle replicas and crashes,
212 : * stats drops are included in commit / abort records.
213 : */
214 : dclist_head pending_drops;
215 :
216 : /*
217 : * Tuple insertion/deletion counts for an open transaction can't be
218 : * propagated into PgStat_TableStatus counters until we know if it is
219 : * going to commit or abort. Hence, we keep these counts in per-subxact
220 : * structs that live in TopTransactionContext. This data structure is
221 : * designed on the assumption that subxacts won't usually modify very many
222 : * tables.
223 : */
224 : PgStat_TableXactStatus *first; /* head of list for this subxact */
225 : } PgStat_SubXactStatus;
226 :
227 :
228 : /*
229 : * Metadata for a specific kind of statistics.
230 : */
231 : typedef struct PgStat_KindInfo
232 : {
233 : /*
234 : * Do a fixed number of stats objects exist for this kind of stats (e.g.
235 : * bgwriter stats) or not (e.g. tables).
236 : */
237 : bool fixed_amount:1;
238 :
239 : /*
240 : * Can stats of this kind be accessed from another database? Determines
241 : * whether a stats object gets included in stats snapshots.
242 : */
243 : bool accessed_across_databases:1;
244 :
245 : /* Should stats be written to the on-disk stats file? */
246 : bool write_to_file:1;
247 :
248 : /*
249 : * Should the number of entries be tracked? For variable-numbered stats,
250 : * to update its PgStat_ShmemControl.entry_counts.
251 : */
252 : bool track_entry_count:1;
253 :
254 : /*
255 : * The size of an entry in the shared stats hash table (pointed to by
256 : * PgStatShared_HashEntry->body). For fixed-numbered statistics, this is
257 : * the size of an entry in PgStat_ShmemControl->custom_data.
258 : */
259 : uint32 shared_size;
260 :
261 : /*
262 : * The offset of the statistics struct in the cached statistics snapshot
263 : * PgStat_Snapshot, for fixed-numbered statistics.
264 : */
265 : uint32 snapshot_ctl_off;
266 :
267 : /*
268 : * The offset of the statistics struct in the containing shared memory
269 : * control structure PgStat_ShmemControl, for fixed-numbered statistics.
270 : */
271 : uint32 shared_ctl_off;
272 :
273 : /*
274 : * The offset/size of statistics inside the shared stats entry. Used when
275 : * [de-]serializing statistics to / from disk respectively. Separate from
276 : * shared_size because [de-]serialization may not include in-memory state
277 : * like lwlocks.
278 : */
279 : uint32 shared_data_off;
280 : uint32 shared_data_len;
281 :
282 : /*
283 : * The size of the pending data for this kind. E.g. how large
284 : * PgStat_EntryRef->pending is. Used for allocations.
285 : *
286 : * 0 signals that an entry of this kind should never have a pending entry.
287 : */
288 : uint32 pending_size;
289 :
290 : /*
291 : * Perform custom actions when initializing a backend (standalone or under
292 : * postmaster). Optional.
293 : */
294 : void (*init_backend_cb) (void);
295 :
296 : /*
297 : * For variable-numbered stats: flush pending stats. Required if pending
298 : * data is used. See flush_static_cb when dealing with stats data that
299 : * that cannot use PgStat_EntryRef->pending.
300 : */
301 : bool (*flush_pending_cb) (PgStat_EntryRef *sr, bool nowait);
302 :
303 : /*
304 : * For variable-numbered stats: delete pending stats. Optional.
305 : */
306 : void (*delete_pending_cb) (PgStat_EntryRef *sr);
307 :
308 : /*
309 : * For variable-numbered stats: reset the reset timestamp. Optional.
310 : */
311 : void (*reset_timestamp_cb) (PgStatShared_Common *header, TimestampTz ts);
312 :
313 : /*
314 : * For variable-numbered stats. Optional.
315 : */
316 : void (*to_serialized_name) (const PgStat_HashKey *key,
317 : const PgStatShared_Common *header, NameData *name);
318 : bool (*from_serialized_name) (const NameData *name, PgStat_HashKey *key);
319 :
320 : /*
321 : * For variable-numbered stats: read or write additional data related to
322 : * an entry, in the stats file or optionally in a different file.
323 : * Optional.
324 : *
325 : * to_serialized_data: write auxiliary data for an entry.
326 : *
327 : * from_serialized_data: read auxiliary data for an entry. Returns true
328 : * on success, false on read error.
329 : *
330 : * "statfile" is a pointer to the on-disk stats file, named
331 : * PGSTAT_STAT_PERMANENT_FILENAME. "key" is the hash key of the entry
332 : * just written or read. "header" is a pointer to the stats data; it may
333 : * be modified only in from_serialized_data to reconstruct an entry.
334 : */
335 : void (*to_serialized_data) (const PgStat_HashKey *key,
336 : const PgStatShared_Common *header,
337 : FILE *statfile);
338 : bool (*from_serialized_data) (const PgStat_HashKey *key,
339 : PgStatShared_Common *header,
340 : FILE *statfile);
341 :
342 : /*
343 : * For fixed-numbered or variable-numbered statistics.
344 : *
345 : * Perform custom actions when done processing the on-disk stats file
346 : * after all the stats entries have been processed. Optional.
347 : *
348 : * "status" tracks the operation done for the on-disk stats file (read,
349 : * write, discard).
350 : */
351 : void (*finish) (PgStat_StatsFileOp status);
352 :
353 : /*
354 : * For fixed-numbered statistics: Initialize shared memory state.
355 : *
356 : * "stats" is the pointer to the allocated shared memory area.
357 : */
358 : void (*init_shmem_cb) (void *stats);
359 :
360 : /*
361 : * For fixed-numbered or variable-numbered statistics: Flush pending stats
362 : * entries, for stats kinds that do not use PgStat_EntryRef->pending.
363 : *
364 : * Returns true if some of the stats could not be flushed, due to lock
365 : * contention for example. Optional.
366 : *
367 : * "pgstat_report_fixed" needs to be set to trigger the flush of pending
368 : * stats.
369 : */
370 : bool (*flush_static_cb) (bool nowait);
371 :
372 : /*
373 : * For fixed-numbered statistics: Reset All.
374 : */
375 : void (*reset_all_cb) (TimestampTz ts);
376 :
377 : /*
378 : * For fixed-numbered statistics: Build snapshot for entry
379 : */
380 : void (*snapshot_cb) (void);
381 :
382 : /* name of the kind of stats */
383 : const char *const name;
384 : } PgStat_KindInfo;
385 :
386 :
387 : /*
388 : * List of SLRU names that we keep stats for. There is no central registry of
389 : * SLRUs, so we use this fixed list instead. The "other" entry is used for
390 : * all SLRUs without an explicit entry (e.g. SLRUs in extensions).
391 : *
392 : * This is only defined here so that SLRU_NUM_ELEMENTS is known for later type
393 : * definitions.
394 : */
395 : static const char *const slru_names[] = {
396 : "commit_timestamp",
397 : "multixact_member",
398 : "multixact_offset",
399 : "notify",
400 : "serializable",
401 : "subtransaction",
402 : "transaction",
403 : "other" /* has to be last */
404 : };
405 :
406 : #define SLRU_NUM_ELEMENTS lengthof(slru_names)
407 :
408 :
409 : /* ----------
410 : * Types and definitions for different kinds of fixed-amount stats.
411 : *
412 : * Single-writer stats use the changecount mechanism to achieve low-overhead
413 : * writes - they're obviously more performance critical than reads. Check the
414 : * definition of struct PgBackendStatus for some explanation of the
415 : * changecount mechanism.
416 : *
417 : * Because the obvious implementation of resetting single-writer stats isn't
418 : * compatible with that (another backend needs to write), we don't scribble on
419 : * shared stats while resetting. Instead, just record the current counter
420 : * values in a copy of the stats data, which is protected by ->lock. See
421 : * pgstat_fetch_stat_(archiver|bgwriter|checkpointer) for the reader side.
422 : *
423 : * The only exception to that is the stat_reset_timestamp in these structs,
424 : * which is protected by ->lock, because it has to be written by another
425 : * backend while resetting.
426 : * ----------
427 : */
428 :
429 : typedef struct PgStatShared_Archiver
430 : {
431 : /* lock protects ->reset_offset as well as stats->stat_reset_timestamp */
432 : LWLock lock;
433 : uint32 changecount;
434 : PgStat_ArchiverStats stats;
435 : PgStat_ArchiverStats reset_offset;
436 : } PgStatShared_Archiver;
437 :
438 : typedef struct PgStatShared_BgWriter
439 : {
440 : /* lock protects ->reset_offset as well as stats->stat_reset_timestamp */
441 : LWLock lock;
442 : uint32 changecount;
443 : PgStat_BgWriterStats stats;
444 : PgStat_BgWriterStats reset_offset;
445 : } PgStatShared_BgWriter;
446 :
447 : typedef struct PgStatShared_Checkpointer
448 : {
449 : /* lock protects ->reset_offset as well as stats->stat_reset_timestamp */
450 : LWLock lock;
451 : uint32 changecount;
452 : PgStat_CheckpointerStats stats;
453 : PgStat_CheckpointerStats reset_offset;
454 : } PgStatShared_Checkpointer;
455 :
456 : /* Shared-memory ready PgStat_IO */
457 : typedef struct PgStatShared_IO
458 : {
459 : /*
460 : * locks[i] protects stats.stats[i]. locks[0] also protects
461 : * stats.stat_reset_timestamp.
462 : */
463 : LWLock locks[BACKEND_NUM_TYPES];
464 : PgStat_IO stats;
465 : } PgStatShared_IO;
466 :
467 : typedef struct PgStatShared_Lock
468 : {
469 : /* lock protects ->stats */
470 : LWLock lock;
471 : PgStat_Lock stats;
472 : } PgStatShared_Lock;
473 :
474 : typedef struct PgStatShared_SLRU
475 : {
476 : /* lock protects ->stats */
477 : LWLock lock;
478 : PgStat_SLRUStats stats[SLRU_NUM_ELEMENTS];
479 : } PgStatShared_SLRU;
480 :
481 : typedef struct PgStatShared_Wal
482 : {
483 : /* lock protects ->stats */
484 : LWLock lock;
485 : PgStat_WalStats stats;
486 : } PgStatShared_Wal;
487 :
488 :
489 :
490 : /* ----------
491 : * Types and definitions for different kinds of variable-amount stats.
492 : *
493 : * Each struct has to start with PgStatShared_Common, containing information
494 : * common across the different types of stats. Kind-specific data follows.
495 : * ----------
496 : */
497 :
498 : typedef struct PgStatShared_Database
499 : {
500 : PgStatShared_Common header;
501 : PgStat_StatDBEntry stats;
502 : } PgStatShared_Database;
503 :
504 : typedef struct PgStatShared_Relation
505 : {
506 : PgStatShared_Common header;
507 : PgStat_StatTabEntry stats;
508 : } PgStatShared_Relation;
509 :
510 : typedef struct PgStatShared_Function
511 : {
512 : PgStatShared_Common header;
513 : PgStat_StatFuncEntry stats;
514 : } PgStatShared_Function;
515 :
516 : typedef struct PgStatShared_Subscription
517 : {
518 : PgStatShared_Common header;
519 : PgStat_StatSubEntry stats;
520 : } PgStatShared_Subscription;
521 :
522 : typedef struct PgStatShared_ReplSlot
523 : {
524 : PgStatShared_Common header;
525 : PgStat_StatReplSlotEntry stats;
526 : } PgStatShared_ReplSlot;
527 :
528 : typedef struct PgStatShared_Backend
529 : {
530 : PgStatShared_Common header;
531 : PgStat_Backend stats;
532 : } PgStatShared_Backend;
533 :
534 : /*
535 : * Central shared memory entry for the cumulative stats system.
536 : *
537 : * Fixed amount stats, the dynamic shared memory hash table for
538 : * non-fixed-amount stats, as well as remaining bits and pieces are all
539 : * reached from here.
540 : */
541 : typedef struct PgStat_ShmemControl
542 : {
543 : void *raw_dsa_area;
544 :
545 : /*
546 : * Stats for variable-numbered objects are kept in this shared hash table.
547 : * See comment above PgStat_Kind for details.
548 : */
549 : dshash_table_handle hash_handle; /* shared dbstat hash */
550 :
551 : /* Has the stats system already been shut down? Just a debugging check. */
552 : bool is_shutdown;
553 :
554 : /*
555 : * Whenever statistics for dropped objects could not be freed - because
556 : * backends still have references - the dropping backend calls
557 : * pgstat_request_entry_refs_gc() incrementing this counter. Eventually
558 : * that causes backends to run pgstat_gc_entry_refs(), allowing memory to
559 : * be reclaimed.
560 : */
561 : pg_atomic_uint64 gc_request_count;
562 :
563 : /*
564 : * Counters for the number of entries associated to a single stats kind
565 : * that uses variable-numbered objects stored in the shared hash table.
566 : * These counters can be enabled on a per-kind basis, when
567 : * track_entry_count is set. This counter is incremented each time a new
568 : * entry is created (not reused) in the shared hash table, and is
569 : * decremented each time an entry is freed from the shared hash table.
570 : */
571 : pg_atomic_uint64 entry_counts[PGSTAT_KIND_MAX];
572 :
573 : /*
574 : * Stats data for fixed-numbered objects.
575 : */
576 : PgStatShared_Archiver archiver;
577 : PgStatShared_BgWriter bgwriter;
578 : PgStatShared_Checkpointer checkpointer;
579 : PgStatShared_IO io;
580 : PgStatShared_Lock lock;
581 : PgStatShared_SLRU slru;
582 : PgStatShared_Wal wal;
583 :
584 : /*
585 : * Custom stats data with fixed-numbered objects, indexed by (PgStat_Kind
586 : * - PGSTAT_KIND_CUSTOM_MIN).
587 : */
588 : void *custom_data[PGSTAT_KIND_CUSTOM_SIZE];
589 :
590 : } PgStat_ShmemControl;
591 :
592 :
593 : /*
594 : * Cached statistics snapshot
595 : */
596 : typedef struct PgStat_Snapshot
597 : {
598 : PgStat_FetchConsistency mode;
599 :
600 : /* time at which snapshot was taken */
601 : TimestampTz snapshot_timestamp;
602 :
603 : bool fixed_valid[PGSTAT_KIND_BUILTIN_SIZE];
604 :
605 : PgStat_ArchiverStats archiver;
606 :
607 : PgStat_BgWriterStats bgwriter;
608 :
609 : PgStat_CheckpointerStats checkpointer;
610 :
611 : PgStat_IO io;
612 :
613 : PgStat_Lock lock;
614 :
615 : PgStat_SLRUStats slru[SLRU_NUM_ELEMENTS];
616 :
617 : PgStat_WalStats wal;
618 :
619 : /*
620 : * Data in snapshot for custom fixed-numbered statistics, indexed by
621 : * (PgStat_Kind - PGSTAT_KIND_CUSTOM_MIN). Each entry is allocated in
622 : * TopMemoryContext, for a size of PgStat_KindInfo->shared_data_len.
623 : */
624 : bool custom_valid[PGSTAT_KIND_CUSTOM_SIZE];
625 : void *custom_data[PGSTAT_KIND_CUSTOM_SIZE];
626 :
627 : /* to free snapshot in bulk */
628 : MemoryContext context;
629 : struct pgstat_snapshot_hash *stats;
630 : } PgStat_Snapshot;
631 :
632 :
633 : /*
634 : * Collection of backend-local stats state.
635 : */
636 : typedef struct PgStat_LocalState
637 : {
638 : PgStat_ShmemControl *shmem;
639 : dsa_area *dsa;
640 : dshash_table *shared_hash;
641 :
642 : /* the current statistics snapshot */
643 : PgStat_Snapshot snapshot;
644 : } PgStat_LocalState;
645 :
646 :
647 : /*
648 : * Inline functions defined further below.
649 : */
650 :
651 : static inline void pgstat_begin_changecount_write(uint32 *cc);
652 : static inline void pgstat_end_changecount_write(uint32 *cc);
653 : static inline uint32 pgstat_begin_changecount_read(uint32 *cc);
654 : static inline bool pgstat_end_changecount_read(uint32 *cc, uint32 cc_before);
655 :
656 : static inline void pgstat_copy_changecounted_stats(void *dst, void *src, size_t len,
657 : uint32 *cc);
658 :
659 : static inline int pgstat_cmp_hash_key(const void *a, const void *b, size_t size, void *arg);
660 : static inline uint32 pgstat_hash_hash_key(const void *d, size_t size, void *arg);
661 : static inline size_t pgstat_get_entry_len(PgStat_Kind kind);
662 : static inline void *pgstat_get_entry_data(PgStat_Kind kind, PgStatShared_Common *entry);
663 : static inline void *pgstat_get_custom_shmem_data(PgStat_Kind kind);
664 : static inline void *pgstat_get_custom_snapshot_data(PgStat_Kind kind);
665 :
666 :
667 : /*
668 : * Functions in pgstat.c
669 : */
670 :
671 : extern const PgStat_KindInfo *pgstat_get_kind_info(PgStat_Kind kind);
672 : extern void pgstat_register_kind(PgStat_Kind kind,
673 : const PgStat_KindInfo *kind_info);
674 :
675 : #ifdef USE_ASSERT_CHECKING
676 : extern void pgstat_assert_is_up(void);
677 : #else
678 : #define pgstat_assert_is_up() ((void)true)
679 : #endif
680 :
681 : extern void pgstat_delete_pending_entry(PgStat_EntryRef *entry_ref);
682 : extern PgStat_EntryRef *pgstat_prep_pending_entry(PgStat_Kind kind, Oid dboid,
683 : uint64 objid,
684 : bool *created_entry);
685 : extern PgStat_EntryRef *pgstat_fetch_pending_entry(PgStat_Kind kind,
686 : Oid dboid, uint64 objid);
687 :
688 : extern void *pgstat_fetch_entry(PgStat_Kind kind, Oid dboid, uint64 objid);
689 : extern void pgstat_snapshot_fixed(PgStat_Kind kind);
690 :
691 :
692 : /*
693 : * Functions in pgstat_archiver.c
694 : */
695 :
696 : extern void pgstat_archiver_init_shmem_cb(void *stats);
697 : extern void pgstat_archiver_reset_all_cb(TimestampTz ts);
698 : extern void pgstat_archiver_snapshot_cb(void);
699 :
700 : /*
701 : * Functions in pgstat_backend.c
702 : */
703 :
704 : /* flags for pgstat_flush_backend() */
705 : #define PGSTAT_BACKEND_FLUSH_IO (1 << 0) /* Flush I/O statistics */
706 : #define PGSTAT_BACKEND_FLUSH_WAL (1 << 1) /* Flush WAL statistics */
707 : #define PGSTAT_BACKEND_FLUSH_ALL (PGSTAT_BACKEND_FLUSH_IO | PGSTAT_BACKEND_FLUSH_WAL)
708 :
709 : extern bool pgstat_flush_backend(bool nowait, uint32 flags);
710 : extern bool pgstat_backend_flush_cb(bool nowait);
711 : extern void pgstat_backend_reset_timestamp_cb(PgStatShared_Common *header,
712 : TimestampTz ts);
713 :
714 : /*
715 : * Functions in pgstat_bgwriter.c
716 : */
717 :
718 : extern void pgstat_bgwriter_init_shmem_cb(void *stats);
719 : extern void pgstat_bgwriter_reset_all_cb(TimestampTz ts);
720 : extern void pgstat_bgwriter_snapshot_cb(void);
721 :
722 :
723 : /*
724 : * Functions in pgstat_checkpointer.c
725 : */
726 :
727 : extern void pgstat_checkpointer_init_shmem_cb(void *stats);
728 : extern void pgstat_checkpointer_reset_all_cb(TimestampTz ts);
729 : extern void pgstat_checkpointer_snapshot_cb(void);
730 :
731 :
732 : /*
733 : * Functions in pgstat_database.c
734 : */
735 :
736 : extern void pgstat_report_disconnect(Oid dboid);
737 : extern void pgstat_update_dbstats(TimestampTz ts);
738 : extern void AtEOXact_PgStat_Database(bool isCommit, bool parallel);
739 :
740 : extern PgStat_StatDBEntry *pgstat_prep_database_pending(Oid dboid);
741 : extern void pgstat_reset_database_timestamp(Oid dboid, TimestampTz ts);
742 : extern bool pgstat_database_flush_cb(PgStat_EntryRef *entry_ref, bool nowait);
743 : extern void pgstat_database_reset_timestamp_cb(PgStatShared_Common *header, TimestampTz ts);
744 :
745 :
746 : /*
747 : * Functions in pgstat_function.c
748 : */
749 :
750 : extern bool pgstat_function_flush_cb(PgStat_EntryRef *entry_ref, bool nowait);
751 : extern void pgstat_function_reset_timestamp_cb(PgStatShared_Common *header, TimestampTz ts);
752 :
753 :
754 : /*
755 : * Functions in pgstat_io.c
756 : */
757 :
758 : extern void pgstat_flush_io(bool nowait);
759 :
760 : extern bool pgstat_io_flush_cb(bool nowait);
761 : extern void pgstat_io_init_shmem_cb(void *stats);
762 : extern void pgstat_io_reset_all_cb(TimestampTz ts);
763 : extern void pgstat_io_snapshot_cb(void);
764 :
765 : /*
766 : * Functions in pgstat_lock.c
767 : */
768 :
769 : extern bool pgstat_lock_flush_cb(bool nowait);
770 : extern void pgstat_lock_init_shmem_cb(void *stats);
771 : extern void pgstat_lock_reset_all_cb(TimestampTz ts);
772 : extern void pgstat_lock_snapshot_cb(void);
773 :
774 : /*
775 : * Functions in pgstat_relation.c
776 : */
777 :
778 : extern void AtEOXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit);
779 : extern void AtEOSubXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit, int nestDepth);
780 : extern void AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state);
781 : extern void PostPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state);
782 :
783 : extern bool pgstat_relation_flush_cb(PgStat_EntryRef *entry_ref, bool nowait);
784 : extern void pgstat_relation_delete_pending_cb(PgStat_EntryRef *entry_ref);
785 : extern void pgstat_relation_reset_timestamp_cb(PgStatShared_Common *header, TimestampTz ts);
786 :
787 :
788 : /*
789 : * Functions in pgstat_replslot.c
790 : */
791 :
792 : extern void pgstat_replslot_reset_timestamp_cb(PgStatShared_Common *header, TimestampTz ts);
793 : extern void pgstat_replslot_to_serialized_name_cb(const PgStat_HashKey *key, const PgStatShared_Common *header, NameData *name);
794 : extern bool pgstat_replslot_from_serialized_name_cb(const NameData *name, PgStat_HashKey *key);
795 :
796 :
797 : /*
798 : * Functions in pgstat_shmem.c
799 : */
800 :
801 : extern void pgstat_attach_shmem(void);
802 : extern void pgstat_detach_shmem(void);
803 :
804 : extern PgStat_EntryRef *pgstat_get_entry_ref(PgStat_Kind kind, Oid dboid, uint64 objid,
805 : bool create, bool *created_entry);
806 : extern bool pgstat_lock_entry(PgStat_EntryRef *entry_ref, bool nowait);
807 : extern bool pgstat_lock_entry_shared(PgStat_EntryRef *entry_ref, bool nowait);
808 : extern void pgstat_unlock_entry(PgStat_EntryRef *entry_ref);
809 : extern bool pgstat_drop_entry(PgStat_Kind kind, Oid dboid, uint64 objid);
810 : extern void pgstat_drop_all_entries(void);
811 : extern void pgstat_drop_matching_entries(bool (*do_drop) (PgStatShared_HashEntry *, Datum),
812 : Datum match_data);
813 : extern PgStat_EntryRef *pgstat_get_entry_ref_locked(PgStat_Kind kind, Oid dboid, uint64 objid,
814 : bool nowait);
815 : extern void pgstat_reset_entry(PgStat_Kind kind, Oid dboid, uint64 objid, TimestampTz ts);
816 : extern void pgstat_reset_entries_of_kind(PgStat_Kind kind, TimestampTz ts);
817 : extern void pgstat_reset_matching_entries(bool (*do_reset) (PgStatShared_HashEntry *, Datum),
818 : Datum match_data,
819 : TimestampTz ts);
820 :
821 : extern void pgstat_request_entry_refs_gc(void);
822 : extern PgStatShared_Common *pgstat_init_entry(PgStat_Kind kind,
823 : PgStatShared_HashEntry *shhashent);
824 :
825 :
826 : /*
827 : * Functions in pgstat_slru.c
828 : */
829 :
830 : extern bool pgstat_slru_flush_cb(bool nowait);
831 : extern void pgstat_slru_init_shmem_cb(void *stats);
832 : extern void pgstat_slru_reset_all_cb(TimestampTz ts);
833 : extern void pgstat_slru_snapshot_cb(void);
834 :
835 :
836 : /*
837 : * Functions in pgstat_wal.c
838 : */
839 :
840 : extern void pgstat_wal_init_backend_cb(void);
841 : extern bool pgstat_wal_flush_cb(bool nowait);
842 : extern void pgstat_wal_init_shmem_cb(void *stats);
843 : extern void pgstat_wal_reset_all_cb(TimestampTz ts);
844 : extern void pgstat_wal_snapshot_cb(void);
845 :
846 :
847 : /*
848 : * Functions in pgstat_subscription.c
849 : */
850 :
851 : extern bool pgstat_subscription_flush_cb(PgStat_EntryRef *entry_ref, bool nowait);
852 : extern void pgstat_subscription_reset_timestamp_cb(PgStatShared_Common *header, TimestampTz ts);
853 :
854 :
855 : /*
856 : * Functions in pgstat_xact.c
857 : */
858 :
859 : extern PgStat_SubXactStatus *pgstat_get_xact_stack_level(int nest_level);
860 : extern void pgstat_drop_transactional(PgStat_Kind kind, Oid dboid, uint64 objid);
861 : extern void pgstat_create_transactional(PgStat_Kind kind, Oid dboid, uint64 objid);
862 :
863 :
864 : /*
865 : * Variables in pgstat.c
866 : */
867 :
868 : /*
869 : * Track if *any* pending fixed-numbered statistics should be flushed to
870 : * shared memory.
871 : *
872 : * This flag can be switched to true by fixed-numbered statistics to let
873 : * pgstat_report_stat() know if it needs to go through one round of
874 : * reports, calling flush_static_cb for each fixed-numbered statistics
875 : * kind. When this flag is not set, pgstat_report_stat() is able to do
876 : * a fast exit, knowing that there are no pending fixed-numbered statistics.
877 : *
878 : * Statistics callbacks should never reset this flag; pgstat_report_stat()
879 : * is in charge of doing that.
880 : */
881 : extern PGDLLIMPORT bool pgstat_report_fixed;
882 :
883 : /* Backend-local stats state */
884 : extern PGDLLIMPORT PgStat_LocalState pgStatLocal;
885 :
886 : /* Helper functions for reading and writing of on-disk stats file */
887 : extern void pgstat_write_chunk(FILE *fpout, void *ptr, size_t len);
888 : extern bool pgstat_read_chunk(FILE *fpin, void *ptr, size_t len);
889 : #define pgstat_read_chunk_s(fpin, ptr) pgstat_read_chunk(fpin, ptr, sizeof(*ptr))
890 : #define pgstat_write_chunk_s(fpout, ptr) pgstat_write_chunk(fpout, ptr, sizeof(*ptr))
891 :
892 : /*
893 : * Implementation of inline functions declared above.
894 : */
895 :
896 : /*
897 : * Helpers for changecount manipulation. See comments around struct
898 : * PgBackendStatus for details.
899 : */
900 :
901 : static inline void
902 13568 : pgstat_begin_changecount_write(uint32 *cc)
903 : {
904 : Assert((*cc & 1) == 0);
905 :
906 13568 : START_CRIT_SECTION();
907 13568 : (*cc)++;
908 13568 : pg_write_barrier();
909 13568 : }
910 :
911 : static inline void
912 13568 : pgstat_end_changecount_write(uint32 *cc)
913 : {
914 : Assert((*cc & 1) == 1);
915 :
916 13568 : pg_write_barrier();
917 :
918 13568 : (*cc)++;
919 :
920 13568 : END_CRIT_SECTION();
921 13568 : }
922 :
923 : static inline uint32
924 3171 : pgstat_begin_changecount_read(uint32 *cc)
925 : {
926 3171 : uint32 before_cc = *cc;
927 :
928 3171 : CHECK_FOR_INTERRUPTS();
929 :
930 3171 : pg_read_barrier();
931 :
932 3171 : return before_cc;
933 : }
934 :
935 : /*
936 : * Returns true if the read succeeded, false if it needs to be repeated.
937 : */
938 : static inline bool
939 3171 : pgstat_end_changecount_read(uint32 *cc, uint32 before_cc)
940 : {
941 : uint32 after_cc;
942 :
943 3171 : pg_read_barrier();
944 :
945 3171 : after_cc = *cc;
946 :
947 : /* was a write in progress when we started? */
948 3171 : if (before_cc & 1)
949 0 : return false;
950 :
951 : /* did writes start and complete while we read? */
952 3171 : return before_cc == after_cc;
953 : }
954 :
955 :
956 : /*
957 : * helper function for PgStat_KindInfo->snapshot_cb
958 : * PgStat_KindInfo->reset_all_cb callbacks.
959 : *
960 : * Copies out the specified memory area following change-count protocol.
961 : */
962 : static inline void
963 3171 : pgstat_copy_changecounted_stats(void *dst, void *src, size_t len,
964 : uint32 *cc)
965 : {
966 : uint32 cc_before;
967 :
968 : do
969 : {
970 3171 : cc_before = pgstat_begin_changecount_read(cc);
971 :
972 3171 : memcpy(dst, src, len);
973 : }
974 3171 : while (!pgstat_end_changecount_read(cc, cc_before));
975 3171 : }
976 :
977 : /* helpers for dshash / simplehash hashtables */
978 : static inline int
979 8074491 : pgstat_cmp_hash_key(const void *a, const void *b, size_t size, void *arg)
980 : {
981 : Assert(size == sizeof(PgStat_HashKey) && arg == NULL);
982 8074491 : return memcmp(a, b, sizeof(PgStat_HashKey));
983 : }
984 :
985 : static inline uint32
986 9691974 : pgstat_hash_hash_key(const void *d, size_t size, void *arg)
987 : {
988 9691974 : const char *key = (const char *) d;
989 :
990 : Assert(size == sizeof(PgStat_HashKey) && arg == NULL);
991 9691974 : return fasthash32(key, size, 0);
992 : }
993 :
994 : /*
995 : * The length of the data portion of a shared memory stats entry (i.e. without
996 : * transient data such as refcounts, lwlocks, ...).
997 : */
998 : static inline size_t
999 557550 : pgstat_get_entry_len(PgStat_Kind kind)
1000 : {
1001 557550 : return pgstat_get_kind_info(kind)->shared_data_len;
1002 : }
1003 :
1004 : /*
1005 : * Returns a pointer to the data portion of a shared memory stats entry.
1006 : */
1007 : static inline void *
1008 797689 : pgstat_get_entry_data(PgStat_Kind kind, PgStatShared_Common *entry)
1009 : {
1010 797689 : size_t off = pgstat_get_kind_info(kind)->shared_data_off;
1011 :
1012 : Assert(off != 0 && off < PG_UINT32_MAX);
1013 :
1014 797689 : return ((char *) (entry)) + off;
1015 : }
1016 :
1017 : /*
1018 : * Returns the number of entries counted for a stats kind.
1019 : */
1020 : static inline uint64
1021 : pgstat_get_entry_count(PgStat_Kind kind)
1022 : {
1023 : Assert(pgstat_get_kind_info(kind)->track_entry_count);
1024 :
1025 : return pg_atomic_read_u64(&pgStatLocal.shmem->entry_counts[kind - 1]);
1026 : }
1027 :
1028 : /*
1029 : * Returns a pointer to the shared memory area of custom stats for
1030 : * fixed-numbered statistics.
1031 : */
1032 : static inline void *
1033 12 : pgstat_get_custom_shmem_data(PgStat_Kind kind)
1034 : {
1035 12 : int idx = kind - PGSTAT_KIND_CUSTOM_MIN;
1036 :
1037 : Assert(pgstat_is_kind_custom(kind));
1038 : Assert(pgstat_get_kind_info(kind)->fixed_amount);
1039 :
1040 12 : return pgStatLocal.shmem->custom_data[idx];
1041 : }
1042 :
1043 : /*
1044 : * Returns a pointer to the portion of custom data for fixed-numbered
1045 : * statistics in the current snapshot.
1046 : */
1047 : static inline void *
1048 7 : pgstat_get_custom_snapshot_data(PgStat_Kind kind)
1049 : {
1050 7 : int idx = kind - PGSTAT_KIND_CUSTOM_MIN;
1051 :
1052 : Assert(pgstat_is_kind_custom(kind));
1053 : Assert(pgstat_get_kind_info(kind)->fixed_amount);
1054 :
1055 7 : return pgStatLocal.snapshot.custom_data[idx];
1056 : }
1057 :
1058 : #endif /* PGSTAT_INTERNAL_H */
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