1/*-------------------------------------------------------------------------
2 *
3 * catcache.c
4 * System catalog cache for tuples matching a key.
5 *
6 * Portions Copyright (c) 1996-2019, PostgreSQL Global Development Group
7 * Portions Copyright (c) 1994, Regents of the University of California
8 *
9 *
10 * IDENTIFICATION
11 * src/backend/utils/cache/catcache.c
12 *
13 *-------------------------------------------------------------------------
14 */
15#include "postgres.h"
16
17#include "access/genam.h"
18#include "access/relscan.h"
19#include "access/sysattr.h"
20#include "access/table.h"
21#include "access/tuptoaster.h"
22#include "access/valid.h"
23#include "access/xact.h"
24#include "catalog/pg_collation.h"
25#include "catalog/pg_operator.h"
26#include "catalog/pg_type.h"
27#include "miscadmin.h"
28#ifdef CATCACHE_STATS
29#include "storage/ipc.h" /* for on_proc_exit */
30#endif
31#include "storage/lmgr.h"
32#include "utils/builtins.h"
33#include "utils/datum.h"
34#include "utils/fmgroids.h"
35#include "utils/hashutils.h"
36#include "utils/inval.h"
37#include "utils/memutils.h"
38#include "utils/rel.h"
39#include "utils/resowner_private.h"
40#include "utils/syscache.h"
41
42
43 /* #define CACHEDEBUG */ /* turns DEBUG elogs on */
44
45/*
46 * Given a hash value and the size of the hash table, find the bucket
47 * in which the hash value belongs. Since the hash table must contain
48 * a power-of-2 number of elements, this is a simple bitmask.
49 */
50#define HASH_INDEX(h, sz) ((Index) ((h) & ((sz) - 1)))
51
52
53/*
54 * variables, macros and other stuff
55 */
56
57#ifdef CACHEDEBUG
58#define CACHE_elog(...) elog(__VA_ARGS__)
59#else
60#define CACHE_elog(...)
61#endif
62
63/* Cache management header --- pointer is NULL until created */
64static CatCacheHeader *CacheHdr = NULL;
65
66static inline HeapTuple SearchCatCacheInternal(CatCache *cache,
67 int nkeys,
68 Datum v1, Datum v2,
69 Datum v3, Datum v4);
70
71static pg_noinline HeapTuple SearchCatCacheMiss(CatCache *cache,
72 int nkeys,
73 uint32 hashValue,
74 Index hashIndex,
75 Datum v1, Datum v2,
76 Datum v3, Datum v4);
77
78static uint32 CatalogCacheComputeHashValue(CatCache *cache, int nkeys,
79 Datum v1, Datum v2, Datum v3, Datum v4);
80static uint32 CatalogCacheComputeTupleHashValue(CatCache *cache, int nkeys,
81 HeapTuple tuple);
82static inline bool CatalogCacheCompareTuple(const CatCache *cache, int nkeys,
83 const Datum *cachekeys,
84 const Datum *searchkeys);
85
86#ifdef CATCACHE_STATS
87static void CatCachePrintStats(int code, Datum arg);
88#endif
89static void CatCacheRemoveCTup(CatCache *cache, CatCTup *ct);
90static void CatCacheRemoveCList(CatCache *cache, CatCList *cl);
91static void CatalogCacheInitializeCache(CatCache *cache);
92static CatCTup *CatalogCacheCreateEntry(CatCache *cache, HeapTuple ntp,
93 Datum *arguments,
94 uint32 hashValue, Index hashIndex,
95 bool negative);
96
97static void CatCacheFreeKeys(TupleDesc tupdesc, int nkeys, int *attnos,
98 Datum *keys);
99static void CatCacheCopyKeys(TupleDesc tupdesc, int nkeys, int *attnos,
100 Datum *srckeys, Datum *dstkeys);
101
102
103/*
104 * internal support functions
105 */
106
107/*
108 * Hash and equality functions for system types that are used as cache key
109 * fields. In some cases, we just call the regular SQL-callable functions for
110 * the appropriate data type, but that tends to be a little slow, and the
111 * speed of these functions is performance-critical. Therefore, for data
112 * types that frequently occur as catcache keys, we hard-code the logic here.
113 * Avoiding the overhead of DirectFunctionCallN(...) is a substantial win, and
114 * in certain cases (like int4) we can adopt a faster hash algorithm as well.
115 */
116
117static bool
118chareqfast(Datum a, Datum b)
119{
120 return DatumGetChar(a) == DatumGetChar(b);
121}
122
123static uint32
124charhashfast(Datum datum)
125{
126 return murmurhash32((int32) DatumGetChar(datum));
127}
128
129static bool
130nameeqfast(Datum a, Datum b)
131{
132 char *ca = NameStr(*DatumGetName(a));
133 char *cb = NameStr(*DatumGetName(b));
134
135 return strncmp(ca, cb, NAMEDATALEN) == 0;
136}
137
138static uint32
139namehashfast(Datum datum)
140{
141 char *key = NameStr(*DatumGetName(datum));
142
143 return hash_any((unsigned char *) key, strlen(key));
144}
145
146static bool
147int2eqfast(Datum a, Datum b)
148{
149 return DatumGetInt16(a) == DatumGetInt16(b);
150}
151
152static uint32
153int2hashfast(Datum datum)
154{
155 return murmurhash32((int32) DatumGetInt16(datum));
156}
157
158static bool
159int4eqfast(Datum a, Datum b)
160{
161 return DatumGetInt32(a) == DatumGetInt32(b);
162}
163
164static uint32
165int4hashfast(Datum datum)
166{
167 return murmurhash32((int32) DatumGetInt32(datum));
168}
169
170static bool
171texteqfast(Datum a, Datum b)
172{
173 /*
174 * The use of DEFAULT_COLLATION_OID is fairly arbitrary here. We just
175 * want to take the fast "deterministic" path in texteq().
176 */
177 return DatumGetBool(DirectFunctionCall2Coll(texteq, DEFAULT_COLLATION_OID, a, b));
178}
179
180static uint32
181texthashfast(Datum datum)
182{
183 /* analogously here as in texteqfast() */
184 return DatumGetInt32(DirectFunctionCall1Coll(hashtext, DEFAULT_COLLATION_OID, datum));
185}
186
187static bool
188oidvectoreqfast(Datum a, Datum b)
189{
190 return DatumGetBool(DirectFunctionCall2(oidvectoreq, a, b));
191}
192
193static uint32
194oidvectorhashfast(Datum datum)
195{
196 return DatumGetInt32(DirectFunctionCall1(hashoidvector, datum));
197}
198
199/* Lookup support functions for a type. */
200static void
201GetCCHashEqFuncs(Oid keytype, CCHashFN *hashfunc, RegProcedure *eqfunc, CCFastEqualFN *fasteqfunc)
202{
203 switch (keytype)
204 {
205 case BOOLOID:
206 *hashfunc = charhashfast;
207 *fasteqfunc = chareqfast;
208 *eqfunc = F_BOOLEQ;
209 break;
210 case CHAROID:
211 *hashfunc = charhashfast;
212 *fasteqfunc = chareqfast;
213 *eqfunc = F_CHAREQ;
214 break;
215 case NAMEOID:
216 *hashfunc = namehashfast;
217 *fasteqfunc = nameeqfast;
218 *eqfunc = F_NAMEEQ;
219 break;
220 case INT2OID:
221 *hashfunc = int2hashfast;
222 *fasteqfunc = int2eqfast;
223 *eqfunc = F_INT2EQ;
224 break;
225 case INT4OID:
226 *hashfunc = int4hashfast;
227 *fasteqfunc = int4eqfast;
228 *eqfunc = F_INT4EQ;
229 break;
230 case TEXTOID:
231 *hashfunc = texthashfast;
232 *fasteqfunc = texteqfast;
233 *eqfunc = F_TEXTEQ;
234 break;
235 case OIDOID:
236 case REGPROCOID:
237 case REGPROCEDUREOID:
238 case REGOPEROID:
239 case REGOPERATOROID:
240 case REGCLASSOID:
241 case REGTYPEOID:
242 case REGCONFIGOID:
243 case REGDICTIONARYOID:
244 case REGROLEOID:
245 case REGNAMESPACEOID:
246 *hashfunc = int4hashfast;
247 *fasteqfunc = int4eqfast;
248 *eqfunc = F_OIDEQ;
249 break;
250 case OIDVECTOROID:
251 *hashfunc = oidvectorhashfast;
252 *fasteqfunc = oidvectoreqfast;
253 *eqfunc = F_OIDVECTOREQ;
254 break;
255 default:
256 elog(FATAL, "type %u not supported as catcache key", keytype);
257 *hashfunc = NULL; /* keep compiler quiet */
258
259 *eqfunc = InvalidOid;
260 break;
261 }
262}
263
264/*
265 * CatalogCacheComputeHashValue
266 *
267 * Compute the hash value associated with a given set of lookup keys
268 */
269static uint32
270CatalogCacheComputeHashValue(CatCache *cache, int nkeys,
271 Datum v1, Datum v2, Datum v3, Datum v4)
272{
273 uint32 hashValue = 0;
274 uint32 oneHash;
275 CCHashFN *cc_hashfunc = cache->cc_hashfunc;
276
277 CACHE_elog(DEBUG2, "CatalogCacheComputeHashValue %s %d %p",
278 cache->cc_relname, nkeys, cache);
279
280 switch (nkeys)
281 {
282 case 4:
283 oneHash = (cc_hashfunc[3]) (v4);
284
285 hashValue ^= oneHash << 24;
286 hashValue ^= oneHash >> 8;
287 /* FALLTHROUGH */
288 case 3:
289 oneHash = (cc_hashfunc[2]) (v3);
290
291 hashValue ^= oneHash << 16;
292 hashValue ^= oneHash >> 16;
293 /* FALLTHROUGH */
294 case 2:
295 oneHash = (cc_hashfunc[1]) (v2);
296
297 hashValue ^= oneHash << 8;
298 hashValue ^= oneHash >> 24;
299 /* FALLTHROUGH */
300 case 1:
301 oneHash = (cc_hashfunc[0]) (v1);
302
303 hashValue ^= oneHash;
304 break;
305 default:
306 elog(FATAL, "wrong number of hash keys: %d", nkeys);
307 break;
308 }
309
310 return hashValue;
311}
312
313/*
314 * CatalogCacheComputeTupleHashValue
315 *
316 * Compute the hash value associated with a given tuple to be cached
317 */
318static uint32
319CatalogCacheComputeTupleHashValue(CatCache *cache, int nkeys, HeapTuple tuple)
320{
321 Datum v1 = 0,
322 v2 = 0,
323 v3 = 0,
324 v4 = 0;
325 bool isNull = false;
326 int *cc_keyno = cache->cc_keyno;
327 TupleDesc cc_tupdesc = cache->cc_tupdesc;
328
329 /* Now extract key fields from tuple, insert into scankey */
330 switch (nkeys)
331 {
332 case 4:
333 v4 = fastgetattr(tuple,
334 cc_keyno[3],
335 cc_tupdesc,
336 &isNull);
337 Assert(!isNull);
338 /* FALLTHROUGH */
339 case 3:
340 v3 = fastgetattr(tuple,
341 cc_keyno[2],
342 cc_tupdesc,
343 &isNull);
344 Assert(!isNull);
345 /* FALLTHROUGH */
346 case 2:
347 v2 = fastgetattr(tuple,
348 cc_keyno[1],
349 cc_tupdesc,
350 &isNull);
351 Assert(!isNull);
352 /* FALLTHROUGH */
353 case 1:
354 v1 = fastgetattr(tuple,
355 cc_keyno[0],
356 cc_tupdesc,
357 &isNull);
358 Assert(!isNull);
359 break;
360 default:
361 elog(FATAL, "wrong number of hash keys: %d", nkeys);
362 break;
363 }
364
365 return CatalogCacheComputeHashValue(cache, nkeys, v1, v2, v3, v4);
366}
367
368/*
369 * CatalogCacheCompareTuple
370 *
371 * Compare a tuple to the passed arguments.
372 */
373static inline bool
374CatalogCacheCompareTuple(const CatCache *cache, int nkeys,
375 const Datum *cachekeys,
376 const Datum *searchkeys)
377{
378 const CCFastEqualFN *cc_fastequal = cache->cc_fastequal;
379 int i;
380
381 for (i = 0; i < nkeys; i++)
382 {
383 if (!(cc_fastequal[i]) (cachekeys[i], searchkeys[i]))
384 return false;
385 }
386 return true;
387}
388
389
390#ifdef CATCACHE_STATS
391
392static void
393CatCachePrintStats(int code, Datum arg)
394{
395 slist_iter iter;
396 long cc_searches = 0;
397 long cc_hits = 0;
398 long cc_neg_hits = 0;
399 long cc_newloads = 0;
400 long cc_invals = 0;
401 long cc_lsearches = 0;
402 long cc_lhits = 0;
403
404 slist_foreach(iter, &CacheHdr->ch_caches)
405 {
406 CatCache *cache = slist_container(CatCache, cc_next, iter.cur);
407
408 if (cache->cc_ntup == 0 && cache->cc_searches == 0)
409 continue; /* don't print unused caches */
410 elog(DEBUG2, "catcache %s/%u: %d tup, %ld srch, %ld+%ld=%ld hits, %ld+%ld=%ld loads, %ld invals, %ld lsrch, %ld lhits",
411 cache->cc_relname,
412 cache->cc_indexoid,
413 cache->cc_ntup,
414 cache->cc_searches,
415 cache->cc_hits,
416 cache->cc_neg_hits,
417 cache->cc_hits + cache->cc_neg_hits,
418 cache->cc_newloads,
419 cache->cc_searches - cache->cc_hits - cache->cc_neg_hits - cache->cc_newloads,
420 cache->cc_searches - cache->cc_hits - cache->cc_neg_hits,
421 cache->cc_invals,
422 cache->cc_lsearches,
423 cache->cc_lhits);
424 cc_searches += cache->cc_searches;
425 cc_hits += cache->cc_hits;
426 cc_neg_hits += cache->cc_neg_hits;
427 cc_newloads += cache->cc_newloads;
428 cc_invals += cache->cc_invals;
429 cc_lsearches += cache->cc_lsearches;
430 cc_lhits += cache->cc_lhits;
431 }
432 elog(DEBUG2, "catcache totals: %d tup, %ld srch, %ld+%ld=%ld hits, %ld+%ld=%ld loads, %ld invals, %ld lsrch, %ld lhits",
433 CacheHdr->ch_ntup,
434 cc_searches,
435 cc_hits,
436 cc_neg_hits,
437 cc_hits + cc_neg_hits,
438 cc_newloads,
439 cc_searches - cc_hits - cc_neg_hits - cc_newloads,
440 cc_searches - cc_hits - cc_neg_hits,
441 cc_invals,
442 cc_lsearches,
443 cc_lhits);
444}
445#endif /* CATCACHE_STATS */
446
447
448/*
449 * CatCacheRemoveCTup
450 *
451 * Unlink and delete the given cache entry
452 *
453 * NB: if it is a member of a CatCList, the CatCList is deleted too.
454 * Both the cache entry and the list had better have zero refcount.
455 */
456static void
457CatCacheRemoveCTup(CatCache *cache, CatCTup *ct)
458{
459 Assert(ct->refcount == 0);
460 Assert(ct->my_cache == cache);
461
462 if (ct->c_list)
463 {
464 /*
465 * The cleanest way to handle this is to call CatCacheRemoveCList,
466 * which will recurse back to me, and the recursive call will do the
467 * work. Set the "dead" flag to make sure it does recurse.
468 */
469 ct->dead = true;
470 CatCacheRemoveCList(cache, ct->c_list);
471 return; /* nothing left to do */
472 }
473
474 /* delink from linked list */
475 dlist_delete(&ct->cache_elem);
476
477 /*
478 * Free keys when we're dealing with a negative entry, normal entries just
479 * point into tuple, allocated together with the CatCTup.
480 */
481 if (ct->negative)
482 CatCacheFreeKeys(cache->cc_tupdesc, cache->cc_nkeys,
483 cache->cc_keyno, ct->keys);
484
485 pfree(ct);
486
487 --cache->cc_ntup;
488 --CacheHdr->ch_ntup;
489}
490
491/*
492 * CatCacheRemoveCList
493 *
494 * Unlink and delete the given cache list entry
495 *
496 * NB: any dead member entries that become unreferenced are deleted too.
497 */
498static void
499CatCacheRemoveCList(CatCache *cache, CatCList *cl)
500{
501 int i;
502
503 Assert(cl->refcount == 0);
504 Assert(cl->my_cache == cache);
505
506 /* delink from member tuples */
507 for (i = cl->n_members; --i >= 0;)
508 {
509 CatCTup *ct = cl->members[i];
510
511 Assert(ct->c_list == cl);
512 ct->c_list = NULL;
513 /* if the member is dead and now has no references, remove it */
514 if (
515#ifndef CATCACHE_FORCE_RELEASE
516 ct->dead &&
517#endif
518 ct->refcount == 0)
519 CatCacheRemoveCTup(cache, ct);
520 }
521
522 /* delink from linked list */
523 dlist_delete(&cl->cache_elem);
524
525 /* free associated column data */
526 CatCacheFreeKeys(cache->cc_tupdesc, cl->nkeys,
527 cache->cc_keyno, cl->keys);
528
529 pfree(cl);
530}
531
532
533/*
534 * CatCacheInvalidate
535 *
536 * Invalidate entries in the specified cache, given a hash value.
537 *
538 * We delete cache entries that match the hash value, whether positive
539 * or negative. We don't care whether the invalidation is the result
540 * of a tuple insertion or a deletion.
541 *
542 * We used to try to match positive cache entries by TID, but that is
543 * unsafe after a VACUUM FULL on a system catalog: an inval event could
544 * be queued before VACUUM FULL, and then processed afterwards, when the
545 * target tuple that has to be invalidated has a different TID than it
546 * did when the event was created. So now we just compare hash values and
547 * accept the small risk of unnecessary invalidations due to false matches.
548 *
549 * This routine is only quasi-public: it should only be used by inval.c.
550 */
551void
552CatCacheInvalidate(CatCache *cache, uint32 hashValue)
553{
554 Index hashIndex;
555 dlist_mutable_iter iter;
556
557 CACHE_elog(DEBUG2, "CatCacheInvalidate: called");
558
559 /*
560 * We don't bother to check whether the cache has finished initialization
561 * yet; if not, there will be no entries in it so no problem.
562 */
563
564 /*
565 * Invalidate *all* CatCLists in this cache; it's too hard to tell which
566 * searches might still be correct, so just zap 'em all.
567 */
568 dlist_foreach_modify(iter, &cache->cc_lists)
569 {
570 CatCList *cl = dlist_container(CatCList, cache_elem, iter.cur);
571
572 if (cl->refcount > 0)
573 cl->dead = true;
574 else
575 CatCacheRemoveCList(cache, cl);
576 }
577
578 /*
579 * inspect the proper hash bucket for tuple matches
580 */
581 hashIndex = HASH_INDEX(hashValue, cache->cc_nbuckets);
582 dlist_foreach_modify(iter, &cache->cc_bucket[hashIndex])
583 {
584 CatCTup *ct = dlist_container(CatCTup, cache_elem, iter.cur);
585
586 if (hashValue == ct->hash_value)
587 {
588 if (ct->refcount > 0 ||
589 (ct->c_list && ct->c_list->refcount > 0))
590 {
591 ct->dead = true;
592 /* list, if any, was marked dead above */
593 Assert(ct->c_list == NULL || ct->c_list->dead);
594 }
595 else
596 CatCacheRemoveCTup(cache, ct);
597 CACHE_elog(DEBUG2, "CatCacheInvalidate: invalidated");
598#ifdef CATCACHE_STATS
599 cache->cc_invals++;
600#endif
601 /* could be multiple matches, so keep looking! */
602 }
603 }
604}
605
606/* ----------------------------------------------------------------
607 * public functions
608 * ----------------------------------------------------------------
609 */
610
611
612/*
613 * Standard routine for creating cache context if it doesn't exist yet
614 *
615 * There are a lot of places (probably far more than necessary) that check
616 * whether CacheMemoryContext exists yet and want to create it if not.
617 * We centralize knowledge of exactly how to create it here.
618 */
619void
620CreateCacheMemoryContext(void)
621{
622 /*
623 * Purely for paranoia, check that context doesn't exist; caller probably
624 * did so already.
625 */
626 if (!CacheMemoryContext)
627 CacheMemoryContext = AllocSetContextCreate(TopMemoryContext,
628 "CacheMemoryContext",
629 ALLOCSET_DEFAULT_SIZES);
630}
631
632
633/*
634 * ResetCatalogCache
635 *
636 * Reset one catalog cache to empty.
637 *
638 * This is not very efficient if the target cache is nearly empty.
639 * However, it shouldn't need to be efficient; we don't invoke it often.
640 */
641static void
642ResetCatalogCache(CatCache *cache)
643{
644 dlist_mutable_iter iter;
645 int i;
646
647 /* Remove each list in this cache, or at least mark it dead */
648 dlist_foreach_modify(iter, &cache->cc_lists)
649 {
650 CatCList *cl = dlist_container(CatCList, cache_elem, iter.cur);
651
652 if (cl->refcount > 0)
653 cl->dead = true;
654 else
655 CatCacheRemoveCList(cache, cl);
656 }
657
658 /* Remove each tuple in this cache, or at least mark it dead */
659 for (i = 0; i < cache->cc_nbuckets; i++)
660 {
661 dlist_head *bucket = &cache->cc_bucket[i];
662
663 dlist_foreach_modify(iter, bucket)
664 {
665 CatCTup *ct = dlist_container(CatCTup, cache_elem, iter.cur);
666
667 if (ct->refcount > 0 ||
668 (ct->c_list && ct->c_list->refcount > 0))
669 {
670 ct->dead = true;
671 /* list, if any, was marked dead above */
672 Assert(ct->c_list == NULL || ct->c_list->dead);
673 }
674 else
675 CatCacheRemoveCTup(cache, ct);
676#ifdef CATCACHE_STATS
677 cache->cc_invals++;
678#endif
679 }
680 }
681}
682
683/*
684 * ResetCatalogCaches
685 *
686 * Reset all caches when a shared cache inval event forces it
687 */
688void
689ResetCatalogCaches(void)
690{
691 slist_iter iter;
692
693 CACHE_elog(DEBUG2, "ResetCatalogCaches called");
694
695 slist_foreach(iter, &CacheHdr->ch_caches)
696 {
697 CatCache *cache = slist_container(CatCache, cc_next, iter.cur);
698
699 ResetCatalogCache(cache);
700 }
701
702 CACHE_elog(DEBUG2, "end of ResetCatalogCaches call");
703}
704
705/*
706 * CatalogCacheFlushCatalog
707 *
708 * Flush all catcache entries that came from the specified system catalog.
709 * This is needed after VACUUM FULL/CLUSTER on the catalog, since the
710 * tuples very likely now have different TIDs than before. (At one point
711 * we also tried to force re-execution of CatalogCacheInitializeCache for
712 * the cache(s) on that catalog. This is a bad idea since it leads to all
713 * kinds of trouble if a cache flush occurs while loading cache entries.
714 * We now avoid the need to do it by copying cc_tupdesc out of the relcache,
715 * rather than relying on the relcache to keep a tupdesc for us. Of course
716 * this assumes the tupdesc of a cachable system table will not change...)
717 */
718void
719CatalogCacheFlushCatalog(Oid catId)
720{
721 slist_iter iter;
722
723 CACHE_elog(DEBUG2, "CatalogCacheFlushCatalog called for %u", catId);
724
725 slist_foreach(iter, &CacheHdr->ch_caches)
726 {
727 CatCache *cache = slist_container(CatCache, cc_next, iter.cur);
728
729 /* Does this cache store tuples of the target catalog? */
730 if (cache->cc_reloid == catId)
731 {
732 /* Yes, so flush all its contents */
733 ResetCatalogCache(cache);
734
735 /* Tell inval.c to call syscache callbacks for this cache */
736 CallSyscacheCallbacks(cache->id, 0);
737 }
738 }
739
740 CACHE_elog(DEBUG2, "end of CatalogCacheFlushCatalog call");
741}
742
743/*
744 * InitCatCache
745 *
746 * This allocates and initializes a cache for a system catalog relation.
747 * Actually, the cache is only partially initialized to avoid opening the
748 * relation. The relation will be opened and the rest of the cache
749 * structure initialized on the first access.
750 */
751#ifdef CACHEDEBUG
752#define InitCatCache_DEBUG2 \
753do { \
754 elog(DEBUG2, "InitCatCache: rel=%u ind=%u id=%d nkeys=%d size=%d", \
755 cp->cc_reloid, cp->cc_indexoid, cp->id, \
756 cp->cc_nkeys, cp->cc_nbuckets); \
757} while(0)
758#else
759#define InitCatCache_DEBUG2
760#endif
761
762CatCache *
763InitCatCache(int id,
764 Oid reloid,
765 Oid indexoid,
766 int nkeys,
767 const int *key,
768 int nbuckets)
769{
770 CatCache *cp;
771 MemoryContext oldcxt;
772 size_t sz;
773 int i;
774
775 /*
776 * nbuckets is the initial number of hash buckets to use in this catcache.
777 * It will be enlarged later if it becomes too full.
778 *
779 * nbuckets must be a power of two. We check this via Assert rather than
780 * a full runtime check because the values will be coming from constant
781 * tables.
782 *
783 * If you're confused by the power-of-two check, see comments in
784 * bitmapset.c for an explanation.
785 */
786 Assert(nbuckets > 0 && (nbuckets & -nbuckets) == nbuckets);
787
788 /*
789 * first switch to the cache context so our allocations do not vanish at
790 * the end of a transaction
791 */
792 if (!CacheMemoryContext)
793 CreateCacheMemoryContext();
794
795 oldcxt = MemoryContextSwitchTo(CacheMemoryContext);
796
797 /*
798 * if first time through, initialize the cache group header
799 */
800 if (CacheHdr == NULL)
801 {
802 CacheHdr = (CatCacheHeader *) palloc(sizeof(CatCacheHeader));
803 slist_init(&CacheHdr->ch_caches);
804 CacheHdr->ch_ntup = 0;
805#ifdef CATCACHE_STATS
806 /* set up to dump stats at backend exit */
807 on_proc_exit(CatCachePrintStats, 0);
808#endif
809 }
810
811 /*
812 * Allocate a new cache structure, aligning to a cacheline boundary
813 *
814 * Note: we rely on zeroing to initialize all the dlist headers correctly
815 */
816 sz = sizeof(CatCache) + PG_CACHE_LINE_SIZE;
817 cp = (CatCache *) CACHELINEALIGN(palloc0(sz));
818 cp->cc_bucket = palloc0(nbuckets * sizeof(dlist_head));
819
820 /*
821 * initialize the cache's relation information for the relation
822 * corresponding to this cache, and initialize some of the new cache's
823 * other internal fields. But don't open the relation yet.
824 */
825 cp->id = id;
826 cp->cc_relname = "(not known yet)";
827 cp->cc_reloid = reloid;
828 cp->cc_indexoid = indexoid;
829 cp->cc_relisshared = false; /* temporary */
830 cp->cc_tupdesc = (TupleDesc) NULL;
831 cp->cc_ntup = 0;
832 cp->cc_nbuckets = nbuckets;
833 cp->cc_nkeys = nkeys;
834 for (i = 0; i < nkeys; ++i)
835 cp->cc_keyno[i] = key[i];
836
837 /*
838 * new cache is initialized as far as we can go for now. print some
839 * debugging information, if appropriate.
840 */
841 InitCatCache_DEBUG2;
842
843 /*
844 * add completed cache to top of group header's list
845 */
846 slist_push_head(&CacheHdr->ch_caches, &cp->cc_next);
847
848 /*
849 * back to the old context before we return...
850 */
851 MemoryContextSwitchTo(oldcxt);
852
853 return cp;
854}
855
856/*
857 * Enlarge a catcache, doubling the number of buckets.
858 */
859static void
860RehashCatCache(CatCache *cp)
861{
862 dlist_head *newbucket;
863 int newnbuckets;
864 int i;
865
866 elog(DEBUG1, "rehashing catalog cache id %d for %s; %d tups, %d buckets",
867 cp->id, cp->cc_relname, cp->cc_ntup, cp->cc_nbuckets);
868
869 /* Allocate a new, larger, hash table. */
870 newnbuckets = cp->cc_nbuckets * 2;
871 newbucket = (dlist_head *) MemoryContextAllocZero(CacheMemoryContext, newnbuckets * sizeof(dlist_head));
872
873 /* Move all entries from old hash table to new. */
874 for (i = 0; i < cp->cc_nbuckets; i++)
875 {
876 dlist_mutable_iter iter;
877
878 dlist_foreach_modify(iter, &cp->cc_bucket[i])
879 {
880 CatCTup *ct = dlist_container(CatCTup, cache_elem, iter.cur);
881 int hashIndex = HASH_INDEX(ct->hash_value, newnbuckets);
882
883 dlist_delete(iter.cur);
884 dlist_push_head(&newbucket[hashIndex], &ct->cache_elem);
885 }
886 }
887
888 /* Switch to the new array. */
889 pfree(cp->cc_bucket);
890 cp->cc_nbuckets = newnbuckets;
891 cp->cc_bucket = newbucket;
892}
893
894/*
895 * CatalogCacheInitializeCache
896 *
897 * This function does final initialization of a catcache: obtain the tuple
898 * descriptor and set up the hash and equality function links. We assume
899 * that the relcache entry can be opened at this point!
900 */
901#ifdef CACHEDEBUG
902#define CatalogCacheInitializeCache_DEBUG1 \
903 elog(DEBUG2, "CatalogCacheInitializeCache: cache @%p rel=%u", cache, \
904 cache->cc_reloid)
905
906#define CatalogCacheInitializeCache_DEBUG2 \
907do { \
908 if (cache->cc_keyno[i] > 0) { \
909 elog(DEBUG2, "CatalogCacheInitializeCache: load %d/%d w/%d, %u", \
910 i+1, cache->cc_nkeys, cache->cc_keyno[i], \
911 TupleDescAttr(tupdesc, cache->cc_keyno[i] - 1)->atttypid); \
912 } else { \
913 elog(DEBUG2, "CatalogCacheInitializeCache: load %d/%d w/%d", \
914 i+1, cache->cc_nkeys, cache->cc_keyno[i]); \
915 } \
916} while(0)
917#else
918#define CatalogCacheInitializeCache_DEBUG1
919#define CatalogCacheInitializeCache_DEBUG2
920#endif
921
922static void
923CatalogCacheInitializeCache(CatCache *cache)
924{
925 Relation relation;
926 MemoryContext oldcxt;
927 TupleDesc tupdesc;
928 int i;
929
930 CatalogCacheInitializeCache_DEBUG1;
931
932 relation = table_open(cache->cc_reloid, AccessShareLock);
933
934 /*
935 * switch to the cache context so our allocations do not vanish at the end
936 * of a transaction
937 */
938 Assert(CacheMemoryContext != NULL);
939
940 oldcxt = MemoryContextSwitchTo(CacheMemoryContext);
941
942 /*
943 * copy the relcache's tuple descriptor to permanent cache storage
944 */
945 tupdesc = CreateTupleDescCopyConstr(RelationGetDescr(relation));
946
947 /*
948 * save the relation's name and relisshared flag, too (cc_relname is used
949 * only for debugging purposes)
950 */
951 cache->cc_relname = pstrdup(RelationGetRelationName(relation));
952 cache->cc_relisshared = RelationGetForm(relation)->relisshared;
953
954 /*
955 * return to the caller's memory context and close the rel
956 */
957 MemoryContextSwitchTo(oldcxt);
958
959 table_close(relation, AccessShareLock);
960
961 CACHE_elog(DEBUG2, "CatalogCacheInitializeCache: %s, %d keys",
962 cache->cc_relname, cache->cc_nkeys);
963
964 /*
965 * initialize cache's key information
966 */
967 for (i = 0; i < cache->cc_nkeys; ++i)
968 {
969 Oid keytype;
970 RegProcedure eqfunc;
971
972 CatalogCacheInitializeCache_DEBUG2;
973
974 if (cache->cc_keyno[i] > 0)
975 {
976 Form_pg_attribute attr = TupleDescAttr(tupdesc,
977 cache->cc_keyno[i] - 1);
978
979 keytype = attr->atttypid;
980 /* cache key columns should always be NOT NULL */
981 Assert(attr->attnotnull);
982 }
983 else
984 {
985 if (cache->cc_keyno[i] < 0)
986 elog(FATAL, "sys attributes are not supported in caches");
987 keytype = OIDOID;
988 }
989
990 GetCCHashEqFuncs(keytype,
991 &cache->cc_hashfunc[i],
992 &eqfunc,
993 &cache->cc_fastequal[i]);
994
995 /*
996 * Do equality-function lookup (we assume this won't need a catalog
997 * lookup for any supported type)
998 */
999 fmgr_info_cxt(eqfunc,
1000 &cache->cc_skey[i].sk_func,
1001 CacheMemoryContext);
1002
1003 /* Initialize sk_attno suitably for HeapKeyTest() and heap scans */
1004 cache->cc_skey[i].sk_attno = cache->cc_keyno[i];
1005
1006 /* Fill in sk_strategy as well --- always standard equality */
1007 cache->cc_skey[i].sk_strategy = BTEqualStrategyNumber;
1008 cache->cc_skey[i].sk_subtype = InvalidOid;
1009 /* If a catcache key requires a collation, it must be C collation */
1010 cache->cc_skey[i].sk_collation = C_COLLATION_OID;
1011
1012 CACHE_elog(DEBUG2, "CatalogCacheInitializeCache %s %d %p",
1013 cache->cc_relname, i, cache);
1014 }
1015
1016 /*
1017 * mark this cache fully initialized
1018 */
1019 cache->cc_tupdesc = tupdesc;
1020}
1021
1022/*
1023 * InitCatCachePhase2 -- external interface for CatalogCacheInitializeCache
1024 *
1025 * One reason to call this routine is to ensure that the relcache has
1026 * created entries for all the catalogs and indexes referenced by catcaches.
1027 * Therefore, provide an option to open the index as well as fixing the
1028 * cache itself. An exception is the indexes on pg_am, which we don't use
1029 * (cf. IndexScanOK).
1030 */
1031void
1032InitCatCachePhase2(CatCache *cache, bool touch_index)
1033{
1034 if (cache->cc_tupdesc == NULL)
1035 CatalogCacheInitializeCache(cache);
1036
1037 if (touch_index &&
1038 cache->id != AMOID &&
1039 cache->id != AMNAME)
1040 {
1041 Relation idesc;
1042
1043 /*
1044 * We must lock the underlying catalog before opening the index to
1045 * avoid deadlock, since index_open could possibly result in reading
1046 * this same catalog, and if anyone else is exclusive-locking this
1047 * catalog and index they'll be doing it in that order.
1048 */
1049 LockRelationOid(cache->cc_reloid, AccessShareLock);
1050 idesc = index_open(cache->cc_indexoid, AccessShareLock);
1051
1052 /*
1053 * While we've got the index open, let's check that it's unique (and
1054 * not just deferrable-unique, thank you very much). This is just to
1055 * catch thinkos in definitions of new catcaches, so we don't worry
1056 * about the pg_am indexes not getting tested.
1057 */
1058 Assert(idesc->rd_index->indisunique &&
1059 idesc->rd_index->indimmediate);
1060
1061 index_close(idesc, AccessShareLock);
1062 UnlockRelationOid(cache->cc_reloid, AccessShareLock);
1063 }
1064}
1065
1066
1067/*
1068 * IndexScanOK
1069 *
1070 * This function checks for tuples that will be fetched by
1071 * IndexSupportInitialize() during relcache initialization for
1072 * certain system indexes that support critical syscaches.
1073 * We can't use an indexscan to fetch these, else we'll get into
1074 * infinite recursion. A plain heap scan will work, however.
1075 * Once we have completed relcache initialization (signaled by
1076 * criticalRelcachesBuilt), we don't have to worry anymore.
1077 *
1078 * Similarly, during backend startup we have to be able to use the
1079 * pg_authid and pg_auth_members syscaches for authentication even if
1080 * we don't yet have relcache entries for those catalogs' indexes.
1081 */
1082static bool
1083IndexScanOK(CatCache *cache, ScanKey cur_skey)
1084{
1085 switch (cache->id)
1086 {
1087 case INDEXRELID:
1088
1089 /*
1090 * Rather than tracking exactly which indexes have to be loaded
1091 * before we can use indexscans (which changes from time to time),
1092 * just force all pg_index searches to be heap scans until we've
1093 * built the critical relcaches.
1094 */
1095 if (!criticalRelcachesBuilt)
1096 return false;
1097 break;
1098
1099 case AMOID:
1100 case AMNAME:
1101
1102 /*
1103 * Always do heap scans in pg_am, because it's so small there's
1104 * not much point in an indexscan anyway. We *must* do this when
1105 * initially building critical relcache entries, but we might as
1106 * well just always do it.
1107 */
1108 return false;
1109
1110 case AUTHNAME:
1111 case AUTHOID:
1112 case AUTHMEMMEMROLE:
1113
1114 /*
1115 * Protect authentication lookups occurring before relcache has
1116 * collected entries for shared indexes.
1117 */
1118 if (!criticalSharedRelcachesBuilt)
1119 return false;
1120 break;
1121
1122 default:
1123 break;
1124 }
1125
1126 /* Normal case, allow index scan */
1127 return true;
1128}
1129
1130/*
1131 * SearchCatCacheInternal
1132 *
1133 * This call searches a system cache for a tuple, opening the relation
1134 * if necessary (on the first access to a particular cache).
1135 *
1136 * The result is NULL if not found, or a pointer to a HeapTuple in
1137 * the cache. The caller must not modify the tuple, and must call
1138 * ReleaseCatCache() when done with it.
1139 *
1140 * The search key values should be expressed as Datums of the key columns'
1141 * datatype(s). (Pass zeroes for any unused parameters.) As a special
1142 * exception, the passed-in key for a NAME column can be just a C string;
1143 * the caller need not go to the trouble of converting it to a fully
1144 * null-padded NAME.
1145 */
1146HeapTuple
1147SearchCatCache(CatCache *cache,
1148 Datum v1,
1149 Datum v2,
1150 Datum v3,
1151 Datum v4)
1152{
1153 return SearchCatCacheInternal(cache, cache->cc_nkeys, v1, v2, v3, v4);
1154}
1155
1156
1157/*
1158 * SearchCatCacheN() are SearchCatCache() versions for a specific number of
1159 * arguments. The compiler can inline the body and unroll loops, making them a
1160 * bit faster than SearchCatCache().
1161 */
1162
1163HeapTuple
1164SearchCatCache1(CatCache *cache,
1165 Datum v1)
1166{
1167 return SearchCatCacheInternal(cache, 1, v1, 0, 0, 0);
1168}
1169
1170
1171HeapTuple
1172SearchCatCache2(CatCache *cache,
1173 Datum v1, Datum v2)
1174{
1175 return SearchCatCacheInternal(cache, 2, v1, v2, 0, 0);
1176}
1177
1178
1179HeapTuple
1180SearchCatCache3(CatCache *cache,
1181 Datum v1, Datum v2, Datum v3)
1182{
1183 return SearchCatCacheInternal(cache, 3, v1, v2, v3, 0);
1184}
1185
1186
1187HeapTuple
1188SearchCatCache4(CatCache *cache,
1189 Datum v1, Datum v2, Datum v3, Datum v4)
1190{
1191 return SearchCatCacheInternal(cache, 4, v1, v2, v3, v4);
1192}
1193
1194/*
1195 * Work-horse for SearchCatCache/SearchCatCacheN.
1196 */
1197static inline HeapTuple
1198SearchCatCacheInternal(CatCache *cache,
1199 int nkeys,
1200 Datum v1,
1201 Datum v2,
1202 Datum v3,
1203 Datum v4)
1204{
1205 Datum arguments[CATCACHE_MAXKEYS];
1206 uint32 hashValue;
1207 Index hashIndex;
1208 dlist_iter iter;
1209 dlist_head *bucket;
1210 CatCTup *ct;
1211
1212 /* Make sure we're in an xact, even if this ends up being a cache hit */
1213 Assert(IsTransactionState());
1214
1215 Assert(cache->cc_nkeys == nkeys);
1216
1217 /*
1218 * one-time startup overhead for each cache
1219 */
1220 if (unlikely(cache->cc_tupdesc == NULL))
1221 CatalogCacheInitializeCache(cache);
1222
1223#ifdef CATCACHE_STATS
1224 cache->cc_searches++;
1225#endif
1226
1227 /* Initialize local parameter array */
1228 arguments[0] = v1;
1229 arguments[1] = v2;
1230 arguments[2] = v3;
1231 arguments[3] = v4;
1232
1233 /*
1234 * find the hash bucket in which to look for the tuple
1235 */
1236 hashValue = CatalogCacheComputeHashValue(cache, nkeys, v1, v2, v3, v4);
1237 hashIndex = HASH_INDEX(hashValue, cache->cc_nbuckets);
1238
1239 /*
1240 * scan the hash bucket until we find a match or exhaust our tuples
1241 *
1242 * Note: it's okay to use dlist_foreach here, even though we modify the
1243 * dlist within the loop, because we don't continue the loop afterwards.
1244 */
1245 bucket = &cache->cc_bucket[hashIndex];
1246 dlist_foreach(iter, bucket)
1247 {
1248 ct = dlist_container(CatCTup, cache_elem, iter.cur);
1249
1250 if (ct->dead)
1251 continue; /* ignore dead entries */
1252
1253 if (ct->hash_value != hashValue)
1254 continue; /* quickly skip entry if wrong hash val */
1255
1256 if (!CatalogCacheCompareTuple(cache, nkeys, ct->keys, arguments))
1257 continue;
1258
1259 /*
1260 * We found a match in the cache. Move it to the front of the list
1261 * for its hashbucket, in order to speed subsequent searches. (The
1262 * most frequently accessed elements in any hashbucket will tend to be
1263 * near the front of the hashbucket's list.)
1264 */
1265 dlist_move_head(bucket, &ct->cache_elem);
1266
1267 /*
1268 * If it's a positive entry, bump its refcount and return it. If it's
1269 * negative, we can report failure to the caller.
1270 */
1271 if (!ct->negative)
1272 {
1273 ResourceOwnerEnlargeCatCacheRefs(CurrentResourceOwner);
1274 ct->refcount++;
1275 ResourceOwnerRememberCatCacheRef(CurrentResourceOwner, &ct->tuple);
1276
1277 CACHE_elog(DEBUG2, "SearchCatCache(%s): found in bucket %d",
1278 cache->cc_relname, hashIndex);
1279
1280#ifdef CATCACHE_STATS
1281 cache->cc_hits++;
1282#endif
1283
1284 return &ct->tuple;
1285 }
1286 else
1287 {
1288 CACHE_elog(DEBUG2, "SearchCatCache(%s): found neg entry in bucket %d",
1289 cache->cc_relname, hashIndex);
1290
1291#ifdef CATCACHE_STATS
1292 cache->cc_neg_hits++;
1293#endif
1294
1295 return NULL;
1296 }
1297 }
1298
1299 return SearchCatCacheMiss(cache, nkeys, hashValue, hashIndex, v1, v2, v3, v4);
1300}
1301
1302/*
1303 * Search the actual catalogs, rather than the cache.
1304 *
1305 * This is kept separate from SearchCatCacheInternal() to keep the fast-path
1306 * as small as possible. To avoid that effort being undone by a helpful
1307 * compiler, try to explicitly forbid inlining.
1308 */
1309static pg_noinline HeapTuple
1310SearchCatCacheMiss(CatCache *cache,
1311 int nkeys,
1312 uint32 hashValue,
1313 Index hashIndex,
1314 Datum v1,
1315 Datum v2,
1316 Datum v3,
1317 Datum v4)
1318{
1319 ScanKeyData cur_skey[CATCACHE_MAXKEYS];
1320 Relation relation;
1321 SysScanDesc scandesc;
1322 HeapTuple ntp;
1323 CatCTup *ct;
1324 Datum arguments[CATCACHE_MAXKEYS];
1325
1326 /* Initialize local parameter array */
1327 arguments[0] = v1;
1328 arguments[1] = v2;
1329 arguments[2] = v3;
1330 arguments[3] = v4;
1331
1332 /*
1333 * Ok, need to make a lookup in the relation, copy the scankey and fill
1334 * out any per-call fields.
1335 */
1336 memcpy(cur_skey, cache->cc_skey, sizeof(ScanKeyData) * nkeys);
1337 cur_skey[0].sk_argument = v1;
1338 cur_skey[1].sk_argument = v2;
1339 cur_skey[2].sk_argument = v3;
1340 cur_skey[3].sk_argument = v4;
1341
1342 /*
1343 * Tuple was not found in cache, so we have to try to retrieve it directly
1344 * from the relation. If found, we will add it to the cache; if not
1345 * found, we will add a negative cache entry instead.
1346 *
1347 * NOTE: it is possible for recursive cache lookups to occur while reading
1348 * the relation --- for example, due to shared-cache-inval messages being
1349 * processed during table_open(). This is OK. It's even possible for one
1350 * of those lookups to find and enter the very same tuple we are trying to
1351 * fetch here. If that happens, we will enter a second copy of the tuple
1352 * into the cache. The first copy will never be referenced again, and
1353 * will eventually age out of the cache, so there's no functional problem.
1354 * This case is rare enough that it's not worth expending extra cycles to
1355 * detect.
1356 */
1357 relation = table_open(cache->cc_reloid, AccessShareLock);
1358
1359 scandesc = systable_beginscan(relation,
1360 cache->cc_indexoid,
1361 IndexScanOK(cache, cur_skey),
1362 NULL,
1363 nkeys,
1364 cur_skey);
1365
1366 ct = NULL;
1367
1368 while (HeapTupleIsValid(ntp = systable_getnext(scandesc)))
1369 {
1370 ct = CatalogCacheCreateEntry(cache, ntp, arguments,
1371 hashValue, hashIndex,
1372 false);
1373 /* immediately set the refcount to 1 */
1374 ResourceOwnerEnlargeCatCacheRefs(CurrentResourceOwner);
1375 ct->refcount++;
1376 ResourceOwnerRememberCatCacheRef(CurrentResourceOwner, &ct->tuple);
1377 break; /* assume only one match */
1378 }
1379
1380 systable_endscan(scandesc);
1381
1382 table_close(relation, AccessShareLock);
1383
1384 /*
1385 * If tuple was not found, we need to build a negative cache entry
1386 * containing a fake tuple. The fake tuple has the correct key columns,
1387 * but nulls everywhere else.
1388 *
1389 * In bootstrap mode, we don't build negative entries, because the cache
1390 * invalidation mechanism isn't alive and can't clear them if the tuple
1391 * gets created later. (Bootstrap doesn't do UPDATEs, so it doesn't need
1392 * cache inval for that.)
1393 */
1394 if (ct == NULL)
1395 {
1396 if (IsBootstrapProcessingMode())
1397 return NULL;
1398
1399 ct = CatalogCacheCreateEntry(cache, NULL, arguments,
1400 hashValue, hashIndex,
1401 true);
1402
1403 CACHE_elog(DEBUG2, "SearchCatCache(%s): Contains %d/%d tuples",
1404 cache->cc_relname, cache->cc_ntup, CacheHdr->ch_ntup);
1405 CACHE_elog(DEBUG2, "SearchCatCache(%s): put neg entry in bucket %d",
1406 cache->cc_relname, hashIndex);
1407
1408 /*
1409 * We are not returning the negative entry to the caller, so leave its
1410 * refcount zero.
1411 */
1412
1413 return NULL;
1414 }
1415
1416 CACHE_elog(DEBUG2, "SearchCatCache(%s): Contains %d/%d tuples",
1417 cache->cc_relname, cache->cc_ntup, CacheHdr->ch_ntup);
1418 CACHE_elog(DEBUG2, "SearchCatCache(%s): put in bucket %d",
1419 cache->cc_relname, hashIndex);
1420
1421#ifdef CATCACHE_STATS
1422 cache->cc_newloads++;
1423#endif
1424
1425 return &ct->tuple;
1426}
1427
1428/*
1429 * ReleaseCatCache
1430 *
1431 * Decrement the reference count of a catcache entry (releasing the
1432 * hold grabbed by a successful SearchCatCache).
1433 *
1434 * NOTE: if compiled with -DCATCACHE_FORCE_RELEASE then catcache entries
1435 * will be freed as soon as their refcount goes to zero. In combination
1436 * with aset.c's CLOBBER_FREED_MEMORY option, this provides a good test
1437 * to catch references to already-released catcache entries.
1438 */
1439void
1440ReleaseCatCache(HeapTuple tuple)
1441{
1442 CatCTup *ct = (CatCTup *) (((char *) tuple) -
1443 offsetof(CatCTup, tuple));
1444
1445 /* Safety checks to ensure we were handed a cache entry */
1446 Assert(ct->ct_magic == CT_MAGIC);
1447 Assert(ct->refcount > 0);
1448
1449 ct->refcount--;
1450 ResourceOwnerForgetCatCacheRef(CurrentResourceOwner, &ct->tuple);
1451
1452 if (
1453#ifndef CATCACHE_FORCE_RELEASE
1454 ct->dead &&
1455#endif
1456 ct->refcount == 0 &&
1457 (ct->c_list == NULL || ct->c_list->refcount == 0))
1458 CatCacheRemoveCTup(ct->my_cache, ct);
1459}
1460
1461
1462/*
1463 * GetCatCacheHashValue
1464 *
1465 * Compute the hash value for a given set of search keys.
1466 *
1467 * The reason for exposing this as part of the API is that the hash value is
1468 * exposed in cache invalidation operations, so there are places outside the
1469 * catcache code that need to be able to compute the hash values.
1470 */
1471uint32
1472GetCatCacheHashValue(CatCache *cache,
1473 Datum v1,
1474 Datum v2,
1475 Datum v3,
1476 Datum v4)
1477{
1478 /*
1479 * one-time startup overhead for each cache
1480 */
1481 if (cache->cc_tupdesc == NULL)
1482 CatalogCacheInitializeCache(cache);
1483
1484 /*
1485 * calculate the hash value
1486 */
1487 return CatalogCacheComputeHashValue(cache, cache->cc_nkeys, v1, v2, v3, v4);
1488}
1489
1490
1491/*
1492 * SearchCatCacheList
1493 *
1494 * Generate a list of all tuples matching a partial key (that is,
1495 * a key specifying just the first K of the cache's N key columns).
1496 *
1497 * It doesn't make any sense to specify all of the cache's key columns
1498 * here: since the key is unique, there could be at most one match, so
1499 * you ought to use SearchCatCache() instead. Hence this function takes
1500 * one less Datum argument than SearchCatCache() does.
1501 *
1502 * The caller must not modify the list object or the pointed-to tuples,
1503 * and must call ReleaseCatCacheList() when done with the list.
1504 */
1505CatCList *
1506SearchCatCacheList(CatCache *cache,
1507 int nkeys,
1508 Datum v1,
1509 Datum v2,
1510 Datum v3)
1511{
1512 Datum v4 = 0; /* dummy last-column value */
1513 Datum arguments[CATCACHE_MAXKEYS];
1514 uint32 lHashValue;
1515 dlist_iter iter;
1516 CatCList *cl;
1517 CatCTup *ct;
1518 List *volatile ctlist;
1519 ListCell *ctlist_item;
1520 int nmembers;
1521 bool ordered;
1522 HeapTuple ntp;
1523 MemoryContext oldcxt;
1524 int i;
1525
1526 /*
1527 * one-time startup overhead for each cache
1528 */
1529 if (cache->cc_tupdesc == NULL)
1530 CatalogCacheInitializeCache(cache);
1531
1532 Assert(nkeys > 0 && nkeys < cache->cc_nkeys);
1533
1534#ifdef CATCACHE_STATS
1535 cache->cc_lsearches++;
1536#endif
1537
1538 /* Initialize local parameter array */
1539 arguments[0] = v1;
1540 arguments[1] = v2;
1541 arguments[2] = v3;
1542 arguments[3] = v4;
1543
1544 /*
1545 * compute a hash value of the given keys for faster search. We don't
1546 * presently divide the CatCList items into buckets, but this still lets
1547 * us skip non-matching items quickly most of the time.
1548 */
1549 lHashValue = CatalogCacheComputeHashValue(cache, nkeys, v1, v2, v3, v4);
1550
1551 /*
1552 * scan the items until we find a match or exhaust our list
1553 *
1554 * Note: it's okay to use dlist_foreach here, even though we modify the
1555 * dlist within the loop, because we don't continue the loop afterwards.
1556 */
1557 dlist_foreach(iter, &cache->cc_lists)
1558 {
1559 cl = dlist_container(CatCList, cache_elem, iter.cur);
1560
1561 if (cl->dead)
1562 continue; /* ignore dead entries */
1563
1564 if (cl->hash_value != lHashValue)
1565 continue; /* quickly skip entry if wrong hash val */
1566
1567 /*
1568 * see if the cached list matches our key.
1569 */
1570 if (cl->nkeys != nkeys)
1571 continue;
1572
1573 if (!CatalogCacheCompareTuple(cache, nkeys, cl->keys, arguments))
1574 continue;
1575
1576 /*
1577 * We found a matching list. Move the list to the front of the
1578 * cache's list-of-lists, to speed subsequent searches. (We do not
1579 * move the members to the fronts of their hashbucket lists, however,
1580 * since there's no point in that unless they are searched for
1581 * individually.)
1582 */
1583 dlist_move_head(&cache->cc_lists, &cl->cache_elem);
1584
1585 /* Bump the list's refcount and return it */
1586 ResourceOwnerEnlargeCatCacheListRefs(CurrentResourceOwner);
1587 cl->refcount++;
1588 ResourceOwnerRememberCatCacheListRef(CurrentResourceOwner, cl);
1589
1590 CACHE_elog(DEBUG2, "SearchCatCacheList(%s): found list",
1591 cache->cc_relname);
1592
1593#ifdef CATCACHE_STATS
1594 cache->cc_lhits++;
1595#endif
1596
1597 return cl;
1598 }
1599
1600 /*
1601 * List was not found in cache, so we have to build it by reading the
1602 * relation. For each matching tuple found in the relation, use an
1603 * existing cache entry if possible, else build a new one.
1604 *
1605 * We have to bump the member refcounts temporarily to ensure they won't
1606 * get dropped from the cache while loading other members. We use a PG_TRY
1607 * block to ensure we can undo those refcounts if we get an error before
1608 * we finish constructing the CatCList.
1609 */
1610 ResourceOwnerEnlargeCatCacheListRefs(CurrentResourceOwner);
1611
1612 ctlist = NIL;
1613
1614 PG_TRY();
1615 {
1616 ScanKeyData cur_skey[CATCACHE_MAXKEYS];
1617 Relation relation;
1618 SysScanDesc scandesc;
1619
1620 /*
1621 * Ok, need to make a lookup in the relation, copy the scankey and
1622 * fill out any per-call fields.
1623 */
1624 memcpy(cur_skey, cache->cc_skey, sizeof(ScanKeyData) * cache->cc_nkeys);
1625 cur_skey[0].sk_argument = v1;
1626 cur_skey[1].sk_argument = v2;
1627 cur_skey[2].sk_argument = v3;
1628 cur_skey[3].sk_argument = v4;
1629
1630 relation = table_open(cache->cc_reloid, AccessShareLock);
1631
1632 scandesc = systable_beginscan(relation,
1633 cache->cc_indexoid,
1634 IndexScanOK(cache, cur_skey),
1635 NULL,
1636 nkeys,
1637 cur_skey);
1638
1639 /* The list will be ordered iff we are doing an index scan */
1640 ordered = (scandesc->irel != NULL);
1641
1642 while (HeapTupleIsValid(ntp = systable_getnext(scandesc)))
1643 {
1644 uint32 hashValue;
1645 Index hashIndex;
1646 bool found = false;
1647 dlist_head *bucket;
1648
1649 /*
1650 * See if there's an entry for this tuple already.
1651 */
1652 ct = NULL;
1653 hashValue = CatalogCacheComputeTupleHashValue(cache, cache->cc_nkeys, ntp);
1654 hashIndex = HASH_INDEX(hashValue, cache->cc_nbuckets);
1655
1656 bucket = &cache->cc_bucket[hashIndex];
1657 dlist_foreach(iter, bucket)
1658 {
1659 ct = dlist_container(CatCTup, cache_elem, iter.cur);
1660
1661 if (ct->dead || ct->negative)
1662 continue; /* ignore dead and negative entries */
1663
1664 if (ct->hash_value != hashValue)
1665 continue; /* quickly skip entry if wrong hash val */
1666
1667 if (!ItemPointerEquals(&(ct->tuple.t_self), &(ntp->t_self)))
1668 continue; /* not same tuple */
1669
1670 /*
1671 * Found a match, but can't use it if it belongs to another
1672 * list already
1673 */
1674 if (ct->c_list)
1675 continue;
1676
1677 found = true;
1678 break; /* A-OK */
1679 }
1680
1681 if (!found)
1682 {
1683 /* We didn't find a usable entry, so make a new one */
1684 ct = CatalogCacheCreateEntry(cache, ntp, arguments,
1685 hashValue, hashIndex,
1686 false);
1687 }
1688
1689 /* Careful here: add entry to ctlist, then bump its refcount */
1690 /* This way leaves state correct if lappend runs out of memory */
1691 ctlist = lappend(ctlist, ct);
1692 ct->refcount++;
1693 }
1694
1695 systable_endscan(scandesc);
1696
1697 table_close(relation, AccessShareLock);
1698
1699 /* Now we can build the CatCList entry. */
1700 oldcxt = MemoryContextSwitchTo(CacheMemoryContext);
1701 nmembers = list_length(ctlist);
1702 cl = (CatCList *)
1703 palloc(offsetof(CatCList, members) + nmembers * sizeof(CatCTup *));
1704
1705 /* Extract key values */
1706 CatCacheCopyKeys(cache->cc_tupdesc, nkeys, cache->cc_keyno,
1707 arguments, cl->keys);
1708 MemoryContextSwitchTo(oldcxt);
1709
1710 /*
1711 * We are now past the last thing that could trigger an elog before we
1712 * have finished building the CatCList and remembering it in the
1713 * resource owner. So it's OK to fall out of the PG_TRY, and indeed
1714 * we'd better do so before we start marking the members as belonging
1715 * to the list.
1716 */
1717
1718 }
1719 PG_CATCH();
1720 {
1721 foreach(ctlist_item, ctlist)
1722 {
1723 ct = (CatCTup *) lfirst(ctlist_item);
1724 Assert(ct->c_list == NULL);
1725 Assert(ct->refcount > 0);
1726 ct->refcount--;
1727 if (
1728#ifndef CATCACHE_FORCE_RELEASE
1729 ct->dead &&
1730#endif
1731 ct->refcount == 0 &&
1732 (ct->c_list == NULL || ct->c_list->refcount == 0))
1733 CatCacheRemoveCTup(cache, ct);
1734 }
1735
1736 PG_RE_THROW();
1737 }
1738 PG_END_TRY();
1739
1740 cl->cl_magic = CL_MAGIC;
1741 cl->my_cache = cache;
1742 cl->refcount = 0; /* for the moment */
1743 cl->dead = false;
1744 cl->ordered = ordered;
1745 cl->nkeys = nkeys;
1746 cl->hash_value = lHashValue;
1747 cl->n_members = nmembers;
1748
1749 i = 0;
1750 foreach(ctlist_item, ctlist)
1751 {
1752 cl->members[i++] = ct = (CatCTup *) lfirst(ctlist_item);
1753 Assert(ct->c_list == NULL);
1754 ct->c_list = cl;
1755 /* release the temporary refcount on the member */
1756 Assert(ct->refcount > 0);
1757 ct->refcount--;
1758 /* mark list dead if any members already dead */
1759 if (ct->dead)
1760 cl->dead = true;
1761 }
1762 Assert(i == nmembers);
1763
1764 dlist_push_head(&cache->cc_lists, &cl->cache_elem);
1765
1766 /* Finally, bump the list's refcount and return it */
1767 cl->refcount++;
1768 ResourceOwnerRememberCatCacheListRef(CurrentResourceOwner, cl);
1769
1770 CACHE_elog(DEBUG2, "SearchCatCacheList(%s): made list of %d members",
1771 cache->cc_relname, nmembers);
1772
1773 return cl;
1774}
1775
1776/*
1777 * ReleaseCatCacheList
1778 *
1779 * Decrement the reference count of a catcache list.
1780 */
1781void
1782ReleaseCatCacheList(CatCList *list)
1783{
1784 /* Safety checks to ensure we were handed a cache entry */
1785 Assert(list->cl_magic == CL_MAGIC);
1786 Assert(list->refcount > 0);
1787 list->refcount--;
1788 ResourceOwnerForgetCatCacheListRef(CurrentResourceOwner, list);
1789
1790 if (
1791#ifndef CATCACHE_FORCE_RELEASE
1792 list->dead &&
1793#endif
1794 list->refcount == 0)
1795 CatCacheRemoveCList(list->my_cache, list);
1796}
1797
1798
1799/*
1800 * CatalogCacheCreateEntry
1801 * Create a new CatCTup entry, copying the given HeapTuple and other
1802 * supplied data into it. The new entry initially has refcount 0.
1803 */
1804static CatCTup *
1805CatalogCacheCreateEntry(CatCache *cache, HeapTuple ntp, Datum *arguments,
1806 uint32 hashValue, Index hashIndex,
1807 bool negative)
1808{
1809 CatCTup *ct;
1810 HeapTuple dtp;
1811 MemoryContext oldcxt;
1812
1813 /* negative entries have no tuple associated */
1814 if (ntp)
1815 {
1816 int i;
1817
1818 Assert(!negative);
1819
1820 /*
1821 * If there are any out-of-line toasted fields in the tuple, expand
1822 * them in-line. This saves cycles during later use of the catcache
1823 * entry, and also protects us against the possibility of the toast
1824 * tuples being freed before we attempt to fetch them, in case of
1825 * something using a slightly stale catcache entry.
1826 */
1827 if (HeapTupleHasExternal(ntp))
1828 dtp = toast_flatten_tuple(ntp, cache->cc_tupdesc);
1829 else
1830 dtp = ntp;
1831
1832 /* Allocate memory for CatCTup and the cached tuple in one go */
1833 oldcxt = MemoryContextSwitchTo(CacheMemoryContext);
1834
1835 ct = (CatCTup *) palloc(sizeof(CatCTup) +
1836 MAXIMUM_ALIGNOF + dtp->t_len);
1837 ct->tuple.t_len = dtp->t_len;
1838 ct->tuple.t_self = dtp->t_self;
1839 ct->tuple.t_tableOid = dtp->t_tableOid;
1840 ct->tuple.t_data = (HeapTupleHeader)
1841 MAXALIGN(((char *) ct) + sizeof(CatCTup));
1842 /* copy tuple contents */
1843 memcpy((char *) ct->tuple.t_data,
1844 (const char *) dtp->t_data,
1845 dtp->t_len);
1846 MemoryContextSwitchTo(oldcxt);
1847
1848 if (dtp != ntp)
1849 heap_freetuple(dtp);
1850
1851 /* extract keys - they'll point into the tuple if not by-value */
1852 for (i = 0; i < cache->cc_nkeys; i++)
1853 {
1854 Datum atp;
1855 bool isnull;
1856
1857 atp = heap_getattr(&ct->tuple,
1858 cache->cc_keyno[i],
1859 cache->cc_tupdesc,
1860 &isnull);
1861 Assert(!isnull);
1862 ct->keys[i] = atp;
1863 }
1864 }
1865 else
1866 {
1867 Assert(negative);
1868 oldcxt = MemoryContextSwitchTo(CacheMemoryContext);
1869 ct = (CatCTup *) palloc(sizeof(CatCTup));
1870
1871 /*
1872 * Store keys - they'll point into separately allocated memory if not
1873 * by-value.
1874 */
1875 CatCacheCopyKeys(cache->cc_tupdesc, cache->cc_nkeys, cache->cc_keyno,
1876 arguments, ct->keys);
1877 MemoryContextSwitchTo(oldcxt);
1878 }
1879
1880 /*
1881 * Finish initializing the CatCTup header, and add it to the cache's
1882 * linked list and counts.
1883 */
1884 ct->ct_magic = CT_MAGIC;
1885 ct->my_cache = cache;
1886 ct->c_list = NULL;
1887 ct->refcount = 0; /* for the moment */
1888 ct->dead = false;
1889 ct->negative = negative;
1890 ct->hash_value = hashValue;
1891
1892 dlist_push_head(&cache->cc_bucket[hashIndex], &ct->cache_elem);
1893
1894 cache->cc_ntup++;
1895 CacheHdr->ch_ntup++;
1896
1897 /*
1898 * If the hash table has become too full, enlarge the buckets array. Quite
1899 * arbitrarily, we enlarge when fill factor > 2.
1900 */
1901 if (cache->cc_ntup > cache->cc_nbuckets * 2)
1902 RehashCatCache(cache);
1903
1904 return ct;
1905}
1906
1907/*
1908 * Helper routine that frees keys stored in the keys array.
1909 */
1910static void
1911CatCacheFreeKeys(TupleDesc tupdesc, int nkeys, int *attnos, Datum *keys)
1912{
1913 int i;
1914
1915 for (i = 0; i < nkeys; i++)
1916 {
1917 int attnum = attnos[i];
1918 Form_pg_attribute att;
1919
1920 /* system attribute are not supported in caches */
1921 Assert(attnum > 0);
1922
1923 att = TupleDescAttr(tupdesc, attnum - 1);
1924
1925 if (!att->attbyval)
1926 pfree(DatumGetPointer(keys[i]));
1927 }
1928}
1929
1930/*
1931 * Helper routine that copies the keys in the srckeys array into the dstkeys
1932 * one, guaranteeing that the datums are fully allocated in the current memory
1933 * context.
1934 */
1935static void
1936CatCacheCopyKeys(TupleDesc tupdesc, int nkeys, int *attnos,
1937 Datum *srckeys, Datum *dstkeys)
1938{
1939 int i;
1940
1941 /*
1942 * XXX: memory and lookup performance could possibly be improved by
1943 * storing all keys in one allocation.
1944 */
1945
1946 for (i = 0; i < nkeys; i++)
1947 {
1948 int attnum = attnos[i];
1949 Form_pg_attribute att = TupleDescAttr(tupdesc, attnum - 1);
1950 Datum src = srckeys[i];
1951 NameData srcname;
1952
1953 /*
1954 * Must be careful in case the caller passed a C string where a NAME
1955 * is wanted: convert the given argument to a correctly padded NAME.
1956 * Otherwise the memcpy() done by datumCopy() could fall off the end
1957 * of memory.
1958 */
1959 if (att->atttypid == NAMEOID)
1960 {
1961 namestrcpy(&srcname, DatumGetCString(src));
1962 src = NameGetDatum(&srcname);
1963 }
1964
1965 dstkeys[i] = datumCopy(src,
1966 att->attbyval,
1967 att->attlen);
1968 }
1969
1970}
1971
1972/*
1973 * PrepareToInvalidateCacheTuple()
1974 *
1975 * This is part of a rather subtle chain of events, so pay attention:
1976 *
1977 * When a tuple is inserted or deleted, it cannot be flushed from the
1978 * catcaches immediately, for reasons explained at the top of cache/inval.c.
1979 * Instead we have to add entry(s) for the tuple to a list of pending tuple
1980 * invalidations that will be done at the end of the command or transaction.
1981 *
1982 * The lists of tuples that need to be flushed are kept by inval.c. This
1983 * routine is a helper routine for inval.c. Given a tuple belonging to
1984 * the specified relation, find all catcaches it could be in, compute the
1985 * correct hash value for each such catcache, and call the specified
1986 * function to record the cache id and hash value in inval.c's lists.
1987 * SysCacheInvalidate will be called later, if appropriate,
1988 * using the recorded information.
1989 *
1990 * For an insert or delete, tuple is the target tuple and newtuple is NULL.
1991 * For an update, we are called just once, with tuple being the old tuple
1992 * version and newtuple the new version. We should make two list entries
1993 * if the tuple's hash value changed, but only one if it didn't.
1994 *
1995 * Note that it is irrelevant whether the given tuple is actually loaded
1996 * into the catcache at the moment. Even if it's not there now, it might
1997 * be by the end of the command, or there might be a matching negative entry
1998 * to flush --- or other backends' caches might have such entries --- so
1999 * we have to make list entries to flush it later.
2000 *
2001 * Also note that it's not an error if there are no catcaches for the
2002 * specified relation. inval.c doesn't know exactly which rels have
2003 * catcaches --- it will call this routine for any tuple that's in a
2004 * system relation.
2005 */
2006void
2007PrepareToInvalidateCacheTuple(Relation relation,
2008 HeapTuple tuple,
2009 HeapTuple newtuple,
2010 void (*function) (int, uint32, Oid))
2011{
2012 slist_iter iter;
2013 Oid reloid;
2014
2015 CACHE_elog(DEBUG2, "PrepareToInvalidateCacheTuple: called");
2016
2017 /*
2018 * sanity checks
2019 */
2020 Assert(RelationIsValid(relation));
2021 Assert(HeapTupleIsValid(tuple));
2022 Assert(PointerIsValid(function));
2023 Assert(CacheHdr != NULL);
2024
2025 reloid = RelationGetRelid(relation);
2026
2027 /* ----------------
2028 * for each cache
2029 * if the cache contains tuples from the specified relation
2030 * compute the tuple's hash value(s) in this cache,
2031 * and call the passed function to register the information.
2032 * ----------------
2033 */
2034
2035 slist_foreach(iter, &CacheHdr->ch_caches)
2036 {
2037 CatCache *ccp = slist_container(CatCache, cc_next, iter.cur);
2038 uint32 hashvalue;
2039 Oid dbid;
2040
2041 if (ccp->cc_reloid != reloid)
2042 continue;
2043
2044 /* Just in case cache hasn't finished initialization yet... */
2045 if (ccp->cc_tupdesc == NULL)
2046 CatalogCacheInitializeCache(ccp);
2047
2048 hashvalue = CatalogCacheComputeTupleHashValue(ccp, ccp->cc_nkeys, tuple);
2049 dbid = ccp->cc_relisshared ? (Oid) 0 : MyDatabaseId;
2050
2051 (*function) (ccp->id, hashvalue, dbid);
2052
2053 if (newtuple)
2054 {
2055 uint32 newhashvalue;
2056
2057 newhashvalue = CatalogCacheComputeTupleHashValue(ccp, ccp->cc_nkeys, newtuple);
2058
2059 if (newhashvalue != hashvalue)
2060 (*function) (ccp->id, newhashvalue, dbid);
2061 }
2062 }
2063}
2064
2065
2066/*
2067 * Subroutines for warning about reference leaks. These are exported so
2068 * that resowner.c can call them.
2069 */
2070void
2071PrintCatCacheLeakWarning(HeapTuple tuple)
2072{
2073 CatCTup *ct = (CatCTup *) (((char *) tuple) -
2074 offsetof(CatCTup, tuple));
2075
2076 /* Safety check to ensure we were handed a cache entry */
2077 Assert(ct->ct_magic == CT_MAGIC);
2078
2079 elog(WARNING, "cache reference leak: cache %s (%d), tuple %u/%u has count %d",
2080 ct->my_cache->cc_relname, ct->my_cache->id,
2081 ItemPointerGetBlockNumber(&(tuple->t_self)),
2082 ItemPointerGetOffsetNumber(&(tuple->t_self)),
2083 ct->refcount);
2084}
2085
2086void
2087PrintCatCacheListLeakWarning(CatCList *list)
2088{
2089 elog(WARNING, "cache reference leak: cache %s (%d), list %p has count %d",
2090 list->my_cache->cc_relname, list->my_cache->id,
2091 list, list->refcount);
2092}
2093