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) 2001-2024, 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 : Oid objoid; /* object ID, either table or function. */
57 : } PgStat_HashKey;
58 :
59 : /*
60 : * Shared statistics hash entry. Doesn't itself contain any stats, but points
61 : * to them (with ->body). That allows the stats entries themselves to be of
62 : * variable size.
63 : */
64 : typedef struct PgStatShared_HashEntry
65 : {
66 : PgStat_HashKey key; /* hash key */
67 :
68 : /*
69 : * If dropped is set, backends need to release their references so that
70 : * the memory for the entry can be freed. No new references may be made
71 : * once marked as dropped.
72 : */
73 : bool dropped;
74 :
75 : /*
76 : * Refcount managing lifetime of the entry itself (as opposed to the
77 : * dshash entry pointing to it). The stats lifetime has to be separate
78 : * from the hash table entry lifetime because we allow backends to point
79 : * to a stats entry without holding a hash table lock (and some other
80 : * reasons).
81 : *
82 : * As long as the entry is not dropped, 1 is added to the refcount
83 : * representing that the entry should not be dropped. In addition each
84 : * backend that has a reference to the entry needs to increment the
85 : * refcount as long as it does.
86 : *
87 : * May only be incremented / decremented while holding at least a shared
88 : * lock on the dshash partition containing the entry. It needs to be an
89 : * atomic variable because multiple backends can increment the refcount
90 : * with just a shared lock.
91 : *
92 : * When the refcount reaches 0 the entry needs to be freed.
93 : */
94 : pg_atomic_uint32 refcount;
95 :
96 : /*
97 : * Pointer to shared stats. The stats entry always starts with
98 : * PgStatShared_Common, embedded in a larger struct containing the
99 : * PgStat_Kind specific stats fields.
100 : */
101 : dsa_pointer body;
102 : } PgStatShared_HashEntry;
103 :
104 : /*
105 : * Common header struct for PgStatShared_*.
106 : */
107 : typedef struct PgStatShared_Common
108 : {
109 : uint32 magic; /* just a validity cross-check */
110 : /* lock protecting stats contents (i.e. data following the header) */
111 : LWLock lock;
112 : } PgStatShared_Common;
113 :
114 : /*
115 : * A backend local reference to a shared stats entry. As long as at least one
116 : * such reference exists, the shared stats entry will not be released.
117 : *
118 : * If there are pending stats update to the shared stats, these are stored in
119 : * ->pending.
120 : */
121 : typedef struct PgStat_EntryRef
122 : {
123 : /*
124 : * Pointer to the PgStatShared_HashEntry entry in the shared stats
125 : * hashtable.
126 : */
127 : PgStatShared_HashEntry *shared_entry;
128 :
129 : /*
130 : * Pointer to the stats data (i.e. PgStatShared_HashEntry->body), resolved
131 : * as a local pointer, to avoid repeated dsa_get_address() calls.
132 : */
133 : PgStatShared_Common *shared_stats;
134 :
135 : /*
136 : * Pending statistics data that will need to be flushed to shared memory
137 : * stats eventually. Each stats kind utilizing pending data defines what
138 : * format its pending data has and needs to provide a
139 : * PgStat_KindInfo->flush_pending_cb callback to merge pending into shared
140 : * stats.
141 : */
142 : void *pending;
143 : dlist_node pending_node; /* membership in pgStatPending list */
144 : } PgStat_EntryRef;
145 :
146 :
147 : /*
148 : * Some stats changes are transactional. To maintain those, a stack of
149 : * PgStat_SubXactStatus entries is maintained, which contain data pertaining
150 : * to the current transaction and its active subtransactions.
151 : */
152 : typedef struct PgStat_SubXactStatus
153 : {
154 : int nest_level; /* subtransaction nest level */
155 :
156 : struct PgStat_SubXactStatus *prev; /* higher-level subxact if any */
157 :
158 : /*
159 : * Statistics for transactionally dropped objects need to be
160 : * transactionally dropped as well. Collect the stats dropped in the
161 : * current (sub-)transaction and only execute the stats drop when we know
162 : * if the transaction commits/aborts. To handle replicas and crashes,
163 : * stats drops are included in commit / abort records.
164 : */
165 : dclist_head pending_drops;
166 :
167 : /*
168 : * Tuple insertion/deletion counts for an open transaction can't be
169 : * propagated into PgStat_TableStatus counters until we know if it is
170 : * going to commit or abort. Hence, we keep these counts in per-subxact
171 : * structs that live in TopTransactionContext. This data structure is
172 : * designed on the assumption that subxacts won't usually modify very many
173 : * tables.
174 : */
175 : PgStat_TableXactStatus *first; /* head of list for this subxact */
176 : } PgStat_SubXactStatus;
177 :
178 :
179 : /*
180 : * Metadata for a specific kind of statistics.
181 : */
182 : typedef struct PgStat_KindInfo
183 : {
184 : /*
185 : * Do a fixed number of stats objects exist for this kind of stats (e.g.
186 : * bgwriter stats) or not (e.g. tables).
187 : */
188 : bool fixed_amount:1;
189 :
190 : /*
191 : * Can stats of this kind be accessed from another database? Determines
192 : * whether a stats object gets included in stats snapshots.
193 : */
194 : bool accessed_across_databases:1;
195 :
196 : /*
197 : * For variable-numbered stats: Identified on-disk using a name, rather
198 : * than PgStat_HashKey. Probably only needed for replication slot stats.
199 : */
200 : bool named_on_disk:1;
201 :
202 : /*
203 : * The size of an entry in the shared stats hash table (pointed to by
204 : * PgStatShared_HashEntry->body).
205 : */
206 : uint32 shared_size;
207 :
208 : /*
209 : * The offset/size of statistics inside the shared stats entry. Used when
210 : * [de-]serializing statistics to / from disk respectively. Separate from
211 : * shared_size because [de-]serialization may not include in-memory state
212 : * like lwlocks.
213 : */
214 : uint32 shared_data_off;
215 : uint32 shared_data_len;
216 :
217 : /*
218 : * The size of the pending data for this kind. E.g. how large
219 : * PgStat_EntryRef->pending is. Used for allocations.
220 : *
221 : * 0 signals that an entry of this kind should never have a pending entry.
222 : */
223 : uint32 pending_size;
224 :
225 : /*
226 : * For variable-numbered stats: flush pending stats. Required if pending
227 : * data is used.
228 : */
229 : bool (*flush_pending_cb) (PgStat_EntryRef *sr, bool nowait);
230 :
231 : /*
232 : * For variable-numbered stats: delete pending stats. Optional.
233 : */
234 : void (*delete_pending_cb) (PgStat_EntryRef *sr);
235 :
236 : /*
237 : * For variable-numbered stats: reset the reset timestamp. Optional.
238 : */
239 : void (*reset_timestamp_cb) (PgStatShared_Common *header, TimestampTz ts);
240 :
241 : /*
242 : * For variable-numbered stats with named_on_disk. Optional.
243 : */
244 : void (*to_serialized_name) (const PgStat_HashKey *key,
245 : const PgStatShared_Common *header, NameData *name);
246 : bool (*from_serialized_name) (const NameData *name, PgStat_HashKey *key);
247 :
248 : /*
249 : * For fixed-numbered statistics: Reset All.
250 : */
251 : void (*reset_all_cb) (TimestampTz ts);
252 :
253 : /*
254 : * For fixed-numbered statistics: Build snapshot for entry
255 : */
256 : void (*snapshot_cb) (void);
257 :
258 : /* name of the kind of stats */
259 : const char *const name;
260 : } PgStat_KindInfo;
261 :
262 :
263 : /*
264 : * List of SLRU names that we keep stats for. There is no central registry of
265 : * SLRUs, so we use this fixed list instead. The "other" entry is used for
266 : * all SLRUs without an explicit entry (e.g. SLRUs in extensions).
267 : *
268 : * This is only defined here so that SLRU_NUM_ELEMENTS is known for later type
269 : * definitions.
270 : */
271 : static const char *const slru_names[] = {
272 : "commit_timestamp",
273 : "multixact_member",
274 : "multixact_offset",
275 : "notify",
276 : "serializable",
277 : "subtransaction",
278 : "transaction",
279 : "other" /* has to be last */
280 : };
281 :
282 : #define SLRU_NUM_ELEMENTS lengthof(slru_names)
283 :
284 :
285 : /* ----------
286 : * Types and definitions for different kinds of fixed-amount stats.
287 : *
288 : * Single-writer stats use the changecount mechanism to achieve low-overhead
289 : * writes - they're obviously more performance critical than reads. Check the
290 : * definition of struct PgBackendStatus for some explanation of the
291 : * changecount mechanism.
292 : *
293 : * Because the obvious implementation of resetting single-writer stats isn't
294 : * compatible with that (another backend needs to write), we don't scribble on
295 : * shared stats while resetting. Instead, just record the current counter
296 : * values in a copy of the stats data, which is protected by ->lock. See
297 : * pgstat_fetch_stat_(archiver|bgwriter|checkpointer) for the reader side.
298 : *
299 : * The only exception to that is the stat_reset_timestamp in these structs,
300 : * which is protected by ->lock, because it has to be written by another
301 : * backend while resetting.
302 : * ----------
303 : */
304 :
305 : typedef struct PgStatShared_Archiver
306 : {
307 : /* lock protects ->reset_offset as well as stats->stat_reset_timestamp */
308 : LWLock lock;
309 : uint32 changecount;
310 : PgStat_ArchiverStats stats;
311 : PgStat_ArchiverStats reset_offset;
312 : } PgStatShared_Archiver;
313 :
314 : typedef struct PgStatShared_BgWriter
315 : {
316 : /* lock protects ->reset_offset as well as stats->stat_reset_timestamp */
317 : LWLock lock;
318 : uint32 changecount;
319 : PgStat_BgWriterStats stats;
320 : PgStat_BgWriterStats reset_offset;
321 : } PgStatShared_BgWriter;
322 :
323 : typedef struct PgStatShared_Checkpointer
324 : {
325 : /* lock protects ->reset_offset as well as stats->stat_reset_timestamp */
326 : LWLock lock;
327 : uint32 changecount;
328 : PgStat_CheckpointerStats stats;
329 : PgStat_CheckpointerStats reset_offset;
330 : } PgStatShared_Checkpointer;
331 :
332 : /* Shared-memory ready PgStat_IO */
333 : typedef struct PgStatShared_IO
334 : {
335 : /*
336 : * locks[i] protects stats.stats[i]. locks[0] also protects
337 : * stats.stat_reset_timestamp.
338 : */
339 : LWLock locks[BACKEND_NUM_TYPES];
340 : PgStat_IO stats;
341 : } PgStatShared_IO;
342 :
343 : typedef struct PgStatShared_SLRU
344 : {
345 : /* lock protects ->stats */
346 : LWLock lock;
347 : PgStat_SLRUStats stats[SLRU_NUM_ELEMENTS];
348 : } PgStatShared_SLRU;
349 :
350 : typedef struct PgStatShared_Wal
351 : {
352 : /* lock protects ->stats */
353 : LWLock lock;
354 : PgStat_WalStats stats;
355 : } PgStatShared_Wal;
356 :
357 :
358 :
359 : /* ----------
360 : * Types and definitions for different kinds of variable-amount stats.
361 : *
362 : * Each struct has to start with PgStatShared_Common, containing information
363 : * common across the different types of stats. Kind-specific data follows.
364 : * ----------
365 : */
366 :
367 : typedef struct PgStatShared_Database
368 : {
369 : PgStatShared_Common header;
370 : PgStat_StatDBEntry stats;
371 : } PgStatShared_Database;
372 :
373 : typedef struct PgStatShared_Relation
374 : {
375 : PgStatShared_Common header;
376 : PgStat_StatTabEntry stats;
377 : } PgStatShared_Relation;
378 :
379 : typedef struct PgStatShared_Function
380 : {
381 : PgStatShared_Common header;
382 : PgStat_StatFuncEntry stats;
383 : } PgStatShared_Function;
384 :
385 : typedef struct PgStatShared_Subscription
386 : {
387 : PgStatShared_Common header;
388 : PgStat_StatSubEntry stats;
389 : } PgStatShared_Subscription;
390 :
391 : typedef struct PgStatShared_ReplSlot
392 : {
393 : PgStatShared_Common header;
394 : PgStat_StatReplSlotEntry stats;
395 : } PgStatShared_ReplSlot;
396 :
397 :
398 : /*
399 : * Central shared memory entry for the cumulative stats system.
400 : *
401 : * Fixed amount stats, the dynamic shared memory hash table for
402 : * non-fixed-amount stats, as well as remaining bits and pieces are all
403 : * reached from here.
404 : */
405 : typedef struct PgStat_ShmemControl
406 : {
407 : void *raw_dsa_area;
408 :
409 : /*
410 : * Stats for variable-numbered objects are kept in this shared hash table.
411 : * See comment above PgStat_Kind for details.
412 : */
413 : dshash_table_handle hash_handle; /* shared dbstat hash */
414 :
415 : /* Has the stats system already been shut down? Just a debugging check. */
416 : bool is_shutdown;
417 :
418 : /*
419 : * Whenever statistics for dropped objects could not be freed - because
420 : * backends still have references - the dropping backend calls
421 : * pgstat_request_entry_refs_gc() incrementing this counter. Eventually
422 : * that causes backends to run pgstat_gc_entry_refs(), allowing memory to
423 : * be reclaimed.
424 : */
425 : pg_atomic_uint64 gc_request_count;
426 :
427 : /*
428 : * Stats data for fixed-numbered objects.
429 : */
430 : PgStatShared_Archiver archiver;
431 : PgStatShared_BgWriter bgwriter;
432 : PgStatShared_Checkpointer checkpointer;
433 : PgStatShared_IO io;
434 : PgStatShared_SLRU slru;
435 : PgStatShared_Wal wal;
436 : } PgStat_ShmemControl;
437 :
438 :
439 : /*
440 : * Cached statistics snapshot
441 : */
442 : typedef struct PgStat_Snapshot
443 : {
444 : PgStat_FetchConsistency mode;
445 :
446 : /* time at which snapshot was taken */
447 : TimestampTz snapshot_timestamp;
448 :
449 : bool fixed_valid[PGSTAT_NUM_KINDS];
450 :
451 : PgStat_ArchiverStats archiver;
452 :
453 : PgStat_BgWriterStats bgwriter;
454 :
455 : PgStat_CheckpointerStats checkpointer;
456 :
457 : PgStat_IO io;
458 :
459 : PgStat_SLRUStats slru[SLRU_NUM_ELEMENTS];
460 :
461 : PgStat_WalStats wal;
462 :
463 : /* to free snapshot in bulk */
464 : MemoryContext context;
465 : struct pgstat_snapshot_hash *stats;
466 : } PgStat_Snapshot;
467 :
468 :
469 : /*
470 : * Collection of backend-local stats state.
471 : */
472 : typedef struct PgStat_LocalState
473 : {
474 : PgStat_ShmemControl *shmem;
475 : dsa_area *dsa;
476 : dshash_table *shared_hash;
477 :
478 : /* the current statistics snapshot */
479 : PgStat_Snapshot snapshot;
480 : } PgStat_LocalState;
481 :
482 :
483 : /*
484 : * Inline functions defined further below.
485 : */
486 :
487 : static inline void pgstat_begin_changecount_write(uint32 *cc);
488 : static inline void pgstat_end_changecount_write(uint32 *cc);
489 : static inline uint32 pgstat_begin_changecount_read(uint32 *cc);
490 : static inline bool pgstat_end_changecount_read(uint32 *cc, uint32 cc_before);
491 :
492 : static inline void pgstat_copy_changecounted_stats(void *dst, void *src, size_t len,
493 : uint32 *cc);
494 :
495 : static inline int pgstat_cmp_hash_key(const void *a, const void *b, size_t size, void *arg);
496 : static inline uint32 pgstat_hash_hash_key(const void *d, size_t size, void *arg);
497 : static inline size_t pgstat_get_entry_len(PgStat_Kind kind);
498 : static inline void *pgstat_get_entry_data(PgStat_Kind kind, PgStatShared_Common *entry);
499 :
500 :
501 : /*
502 : * Functions in pgstat.c
503 : */
504 :
505 : extern const PgStat_KindInfo *pgstat_get_kind_info(PgStat_Kind kind);
506 :
507 : #ifdef USE_ASSERT_CHECKING
508 : extern void pgstat_assert_is_up(void);
509 : #else
510 : #define pgstat_assert_is_up() ((void)true)
511 : #endif
512 :
513 : extern void pgstat_delete_pending_entry(PgStat_EntryRef *entry_ref);
514 : extern PgStat_EntryRef *pgstat_prep_pending_entry(PgStat_Kind kind, Oid dboid, Oid objoid, bool *created_entry);
515 : extern PgStat_EntryRef *pgstat_fetch_pending_entry(PgStat_Kind kind, Oid dboid, Oid objoid);
516 :
517 : extern void *pgstat_fetch_entry(PgStat_Kind kind, Oid dboid, Oid objoid);
518 : extern void pgstat_snapshot_fixed(PgStat_Kind kind);
519 :
520 :
521 : /*
522 : * Functions in pgstat_archiver.c
523 : */
524 :
525 : extern void pgstat_archiver_reset_all_cb(TimestampTz ts);
526 : extern void pgstat_archiver_snapshot_cb(void);
527 :
528 :
529 : /*
530 : * Functions in pgstat_bgwriter.c
531 : */
532 :
533 : extern void pgstat_bgwriter_reset_all_cb(TimestampTz ts);
534 : extern void pgstat_bgwriter_snapshot_cb(void);
535 :
536 :
537 : /*
538 : * Functions in pgstat_checkpointer.c
539 : */
540 :
541 : extern void pgstat_checkpointer_reset_all_cb(TimestampTz ts);
542 : extern void pgstat_checkpointer_snapshot_cb(void);
543 :
544 :
545 : /*
546 : * Functions in pgstat_database.c
547 : */
548 :
549 : extern void pgstat_report_disconnect(Oid dboid);
550 : extern void pgstat_update_dbstats(TimestampTz ts);
551 : extern void AtEOXact_PgStat_Database(bool isCommit, bool parallel);
552 :
553 : extern PgStat_StatDBEntry *pgstat_prep_database_pending(Oid dboid);
554 : extern void pgstat_reset_database_timestamp(Oid dboid, TimestampTz ts);
555 : extern bool pgstat_database_flush_cb(PgStat_EntryRef *entry_ref, bool nowait);
556 : extern void pgstat_database_reset_timestamp_cb(PgStatShared_Common *header, TimestampTz ts);
557 :
558 :
559 : /*
560 : * Functions in pgstat_function.c
561 : */
562 :
563 : extern bool pgstat_function_flush_cb(PgStat_EntryRef *entry_ref, bool nowait);
564 :
565 :
566 : /*
567 : * Functions in pgstat_io.c
568 : */
569 :
570 : extern bool pgstat_flush_io(bool nowait);
571 : extern void pgstat_io_reset_all_cb(TimestampTz ts);
572 : extern void pgstat_io_snapshot_cb(void);
573 :
574 :
575 : /*
576 : * Functions in pgstat_relation.c
577 : */
578 :
579 : extern void AtEOXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit);
580 : extern void AtEOSubXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit, int nestDepth);
581 : extern void AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state);
582 : extern void PostPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state);
583 :
584 : extern bool pgstat_relation_flush_cb(PgStat_EntryRef *entry_ref, bool nowait);
585 : extern void pgstat_relation_delete_pending_cb(PgStat_EntryRef *entry_ref);
586 :
587 :
588 : /*
589 : * Functions in pgstat_replslot.c
590 : */
591 :
592 : extern void pgstat_replslot_reset_timestamp_cb(PgStatShared_Common *header, TimestampTz ts);
593 : extern void pgstat_replslot_to_serialized_name_cb(const PgStat_HashKey *key, const PgStatShared_Common *header, NameData *name);
594 : extern bool pgstat_replslot_from_serialized_name_cb(const NameData *name, PgStat_HashKey *key);
595 :
596 :
597 : /*
598 : * Functions in pgstat_shmem.c
599 : */
600 :
601 : extern void pgstat_attach_shmem(void);
602 : extern void pgstat_detach_shmem(void);
603 :
604 : extern PgStat_EntryRef *pgstat_get_entry_ref(PgStat_Kind kind, Oid dboid, Oid objoid,
605 : bool create, bool *created_entry);
606 : extern bool pgstat_lock_entry(PgStat_EntryRef *entry_ref, bool nowait);
607 : extern bool pgstat_lock_entry_shared(PgStat_EntryRef *entry_ref, bool nowait);
608 : extern void pgstat_unlock_entry(PgStat_EntryRef *entry_ref);
609 : extern bool pgstat_drop_entry(PgStat_Kind kind, Oid dboid, Oid objoid);
610 : extern void pgstat_drop_all_entries(void);
611 : extern PgStat_EntryRef *pgstat_get_entry_ref_locked(PgStat_Kind kind, Oid dboid, Oid objoid,
612 : bool nowait);
613 : extern void pgstat_reset_entry(PgStat_Kind kind, Oid dboid, Oid objoid, TimestampTz ts);
614 : extern void pgstat_reset_entries_of_kind(PgStat_Kind kind, TimestampTz ts);
615 : extern void pgstat_reset_matching_entries(bool (*do_reset) (PgStatShared_HashEntry *, Datum),
616 : Datum match_data,
617 : TimestampTz ts);
618 :
619 : extern void pgstat_request_entry_refs_gc(void);
620 : extern PgStatShared_Common *pgstat_init_entry(PgStat_Kind kind,
621 : PgStatShared_HashEntry *shhashent);
622 :
623 :
624 : /*
625 : * Functions in pgstat_slru.c
626 : */
627 :
628 : extern bool pgstat_slru_flush(bool nowait);
629 : extern void pgstat_slru_reset_all_cb(TimestampTz ts);
630 : extern void pgstat_slru_snapshot_cb(void);
631 :
632 :
633 : /*
634 : * Functions in pgstat_wal.c
635 : */
636 :
637 : extern bool pgstat_flush_wal(bool nowait);
638 : extern void pgstat_init_wal(void);
639 : extern bool pgstat_have_pending_wal(void);
640 :
641 : extern void pgstat_wal_reset_all_cb(TimestampTz ts);
642 : extern void pgstat_wal_snapshot_cb(void);
643 :
644 :
645 : /*
646 : * Functions in pgstat_subscription.c
647 : */
648 :
649 : extern bool pgstat_subscription_flush_cb(PgStat_EntryRef *entry_ref, bool nowait);
650 : extern void pgstat_subscription_reset_timestamp_cb(PgStatShared_Common *header, TimestampTz ts);
651 :
652 :
653 : /*
654 : * Functions in pgstat_xact.c
655 : */
656 :
657 : extern PgStat_SubXactStatus *pgstat_get_xact_stack_level(int nest_level);
658 : extern void pgstat_drop_transactional(PgStat_Kind kind, Oid dboid, Oid objoid);
659 : extern void pgstat_create_transactional(PgStat_Kind kind, Oid dboid, Oid objoid);
660 :
661 :
662 : /*
663 : * Variables in pgstat.c
664 : */
665 :
666 : extern PGDLLIMPORT PgStat_LocalState pgStatLocal;
667 :
668 :
669 : /*
670 : * Variables in pgstat_io.c
671 : */
672 :
673 : extern PGDLLIMPORT bool have_iostats;
674 :
675 :
676 : /*
677 : * Variables in pgstat_slru.c
678 : */
679 :
680 : extern PGDLLIMPORT bool have_slrustats;
681 :
682 :
683 : /*
684 : * Implementation of inline functions declared above.
685 : */
686 :
687 : /*
688 : * Helpers for changecount manipulation. See comments around struct
689 : * PgBackendStatus for details.
690 : */
691 :
692 : static inline void
693 11386 : pgstat_begin_changecount_write(uint32 *cc)
694 : {
695 : Assert((*cc & 1) == 0);
696 :
697 11386 : START_CRIT_SECTION();
698 11386 : (*cc)++;
699 11386 : pg_write_barrier();
700 11386 : }
701 :
702 : static inline void
703 11386 : pgstat_end_changecount_write(uint32 *cc)
704 : {
705 : Assert((*cc & 1) == 1);
706 :
707 11386 : pg_write_barrier();
708 :
709 11386 : (*cc)++;
710 :
711 11386 : END_CRIT_SECTION();
712 11386 : }
713 :
714 : static inline uint32
715 4488 : pgstat_begin_changecount_read(uint32 *cc)
716 : {
717 4488 : uint32 before_cc = *cc;
718 :
719 4488 : CHECK_FOR_INTERRUPTS();
720 :
721 4488 : pg_read_barrier();
722 :
723 4488 : return before_cc;
724 : }
725 :
726 : /*
727 : * Returns true if the read succeeded, false if it needs to be repeated.
728 : */
729 : static inline bool
730 4488 : pgstat_end_changecount_read(uint32 *cc, uint32 before_cc)
731 : {
732 : uint32 after_cc;
733 :
734 4488 : pg_read_barrier();
735 :
736 4488 : after_cc = *cc;
737 :
738 : /* was a write in progress when we started? */
739 4488 : if (before_cc & 1)
740 0 : return false;
741 :
742 : /* did writes start and complete while we read? */
743 4488 : return before_cc == after_cc;
744 : }
745 :
746 :
747 : /*
748 : * helper function for PgStat_KindInfo->snapshot_cb
749 : * PgStat_KindInfo->reset_all_cb callbacks.
750 : *
751 : * Copies out the specified memory area following change-count protocol.
752 : */
753 : static inline void
754 4488 : pgstat_copy_changecounted_stats(void *dst, void *src, size_t len,
755 : uint32 *cc)
756 : {
757 : uint32 cc_before;
758 :
759 : do
760 : {
761 4488 : cc_before = pgstat_begin_changecount_read(cc);
762 :
763 4488 : memcpy(dst, src, len);
764 : }
765 4488 : while (!pgstat_end_changecount_read(cc, cc_before));
766 4488 : }
767 :
768 : /* helpers for dshash / simplehash hashtables */
769 : static inline int
770 5907114 : pgstat_cmp_hash_key(const void *a, const void *b, size_t size, void *arg)
771 : {
772 : Assert(size == sizeof(PgStat_HashKey) && arg == NULL);
773 5907114 : return memcmp(a, b, sizeof(PgStat_HashKey));
774 : }
775 :
776 : static inline uint32
777 7583512 : pgstat_hash_hash_key(const void *d, size_t size, void *arg)
778 : {
779 7583512 : const char *key = (const char *) d;
780 :
781 : Assert(size == sizeof(PgStat_HashKey) && arg == NULL);
782 7583512 : return fasthash32(key, size, 0);
783 : }
784 :
785 : /*
786 : * The length of the data portion of a shared memory stats entry (i.e. without
787 : * transient data such as refcounts, lwlocks, ...).
788 : */
789 : static inline size_t
790 603734 : pgstat_get_entry_len(PgStat_Kind kind)
791 : {
792 603734 : return pgstat_get_kind_info(kind)->shared_data_len;
793 : }
794 :
795 : /*
796 : * Returns a pointer to the data portion of a shared memory stats entry.
797 : */
798 : static inline void *
799 662240 : pgstat_get_entry_data(PgStat_Kind kind, PgStatShared_Common *entry)
800 : {
801 662240 : size_t off = pgstat_get_kind_info(kind)->shared_data_off;
802 :
803 : Assert(off != 0 && off < PG_UINT32_MAX);
804 :
805 662240 : return ((char *) (entry)) + off;
806 : }
807 :
808 : #endif /* PGSTAT_INTERNAL_H */
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