/*------------------------------------------------------------------------- * * catcache.c * System catalog cache for tuples matching a key. * * Portions Copyright (c) 1996-2011, PostgreSQL Global Development Group * Portions Copyright (c) 1994, Regents of the University of California * * * IDENTIFICATION * src/backend/utils/cache/catcache.c * *------------------------------------------------------------------------- */ #include "postgres.h" #include "access/genam.h" #include "access/hash.h" #include "access/heapam.h" #include "access/relscan.h" #include "access/sysattr.h" #include "access/valid.h" #include "catalog/pg_operator.h" #include "catalog/pg_type.h" #include "miscadmin.h" #ifdef CATCACHE_STATS #include "storage/ipc.h" /* for on_proc_exit */ #endif #include "utils/builtins.h" #include "utils/fmgroids.h" #include "utils/inval.h" #include "utils/memutils.h" #include "utils/rel.h" #include "utils/resowner.h" #include "utils/syscache.h" #include "utils/tqual.h" /* #define CACHEDEBUG */ /* turns DEBUG elogs on */ /* * Given a hash value and the size of the hash table, find the bucket * in which the hash value belongs. Since the hash table must contain * a power-of-2 number of elements, this is a simple bitmask. */ #define HASH_INDEX(h, sz) ((Index) ((h) & ((sz) - 1))) /* * variables, macros and other stuff */ #ifdef CACHEDEBUG #define CACHE1_elog(a,b) elog(a,b) #define CACHE2_elog(a,b,c) elog(a,b,c) #define CACHE3_elog(a,b,c,d) elog(a,b,c,d) #define CACHE4_elog(a,b,c,d,e) elog(a,b,c,d,e) #define CACHE5_elog(a,b,c,d,e,f) elog(a,b,c,d,e,f) #define CACHE6_elog(a,b,c,d,e,f,g) elog(a,b,c,d,e,f,g) #else #define CACHE1_elog(a,b) #define CACHE2_elog(a,b,c) #define CACHE3_elog(a,b,c,d) #define CACHE4_elog(a,b,c,d,e) #define CACHE5_elog(a,b,c,d,e,f) #define CACHE6_elog(a,b,c,d,e,f,g) #endif /* Cache management header --- pointer is NULL until created */ static CatCacheHeader *CacheHdr = NULL; static uint32 CatalogCacheComputeHashValue(CatCache *cache, int nkeys, ScanKey cur_skey); static uint32 CatalogCacheComputeTupleHashValue(CatCache *cache, HeapTuple tuple); #ifdef CATCACHE_STATS static void CatCachePrintStats(int code, Datum arg); #endif static void CatCacheRemoveCTup(CatCache *cache, CatCTup *ct); static void CatCacheRemoveCList(CatCache *cache, CatCList *cl); static void CatalogCacheInitializeCache(CatCache *cache); static CatCTup *CatalogCacheCreateEntry(CatCache *cache, HeapTuple ntp, uint32 hashValue, Index hashIndex, bool negative); static HeapTuple build_dummy_tuple(CatCache *cache, int nkeys, ScanKey skeys); /* * internal support functions */ /* * Look up the hash and equality functions for system types that are used * as cache key fields. * * XXX this should be replaced by catalog lookups, * but that seems to pose considerable risk of circularity... */ static void GetCCHashEqFuncs(Oid keytype, PGFunction *hashfunc, RegProcedure *eqfunc) { switch (keytype) { case BOOLOID: *hashfunc = hashchar; *eqfunc = F_BOOLEQ; break; case CHAROID: *hashfunc = hashchar; *eqfunc = F_CHAREQ; break; case NAMEOID: *hashfunc = hashname; *eqfunc = F_NAMEEQ; break; case INT2OID: *hashfunc = hashint2; *eqfunc = F_INT2EQ; break; case INT2VECTOROID: *hashfunc = hashint2vector; *eqfunc = F_INT2VECTOREQ; break; case INT4OID: *hashfunc = hashint4; *eqfunc = F_INT4EQ; break; case TEXTOID: *hashfunc = hashtext; *eqfunc = F_TEXTEQ; break; case OIDOID: case REGPROCOID: case REGPROCEDUREOID: case REGOPEROID: case REGOPERATOROID: case REGCLASSOID: case REGTYPEOID: case REGCONFIGOID: case REGDICTIONARYOID: *hashfunc = hashoid; *eqfunc = F_OIDEQ; break; case OIDVECTOROID: *hashfunc = hashoidvector; *eqfunc = F_OIDVECTOREQ; break; default: elog(FATAL, "type %u not supported as catcache key", keytype); *hashfunc = NULL; /* keep compiler quiet */ *eqfunc = InvalidOid; break; } } /* * CatalogCacheComputeHashValue * * Compute the hash value associated with a given set of lookup keys */ static uint32 CatalogCacheComputeHashValue(CatCache *cache, int nkeys, ScanKey cur_skey) { uint32 hashValue = 0; uint32 oneHash; CACHE4_elog(DEBUG2, "CatalogCacheComputeHashValue %s %d %p", cache->cc_relname, nkeys, cache); switch (nkeys) { case 4: oneHash = DatumGetUInt32(DirectFunctionCall1(cache->cc_hashfunc[3], cur_skey[3].sk_argument)); hashValue ^= oneHash << 24; hashValue ^= oneHash >> 8; /* FALLTHROUGH */ case 3: oneHash = DatumGetUInt32(DirectFunctionCall1(cache->cc_hashfunc[2], cur_skey[2].sk_argument)); hashValue ^= oneHash << 16; hashValue ^= oneHash >> 16; /* FALLTHROUGH */ case 2: oneHash = DatumGetUInt32(DirectFunctionCall1(cache->cc_hashfunc[1], cur_skey[1].sk_argument)); hashValue ^= oneHash << 8; hashValue ^= oneHash >> 24; /* FALLTHROUGH */ case 1: oneHash = DatumGetUInt32(DirectFunctionCall1(cache->cc_hashfunc[0], cur_skey[0].sk_argument)); hashValue ^= oneHash; break; default: elog(FATAL, "wrong number of hash keys: %d", nkeys); break; } return hashValue; } /* * CatalogCacheComputeTupleHashValue * * Compute the hash value associated with a given tuple to be cached */ static uint32 CatalogCacheComputeTupleHashValue(CatCache *cache, HeapTuple tuple) { ScanKeyData cur_skey[CATCACHE_MAXKEYS]; bool isNull = false; /* Copy pre-initialized overhead data for scankey */ memcpy(cur_skey, cache->cc_skey, sizeof(cur_skey)); /* Now extract key fields from tuple, insert into scankey */ switch (cache->cc_nkeys) { case 4: cur_skey[3].sk_argument = (cache->cc_key[3] == ObjectIdAttributeNumber) ? ObjectIdGetDatum(HeapTupleGetOid(tuple)) : fastgetattr(tuple, cache->cc_key[3], cache->cc_tupdesc, &isNull); Assert(!isNull); /* FALLTHROUGH */ case 3: cur_skey[2].sk_argument = (cache->cc_key[2] == ObjectIdAttributeNumber) ? ObjectIdGetDatum(HeapTupleGetOid(tuple)) : fastgetattr(tuple, cache->cc_key[2], cache->cc_tupdesc, &isNull); Assert(!isNull); /* FALLTHROUGH */ case 2: cur_skey[1].sk_argument = (cache->cc_key[1] == ObjectIdAttributeNumber) ? ObjectIdGetDatum(HeapTupleGetOid(tuple)) : fastgetattr(tuple, cache->cc_key[1], cache->cc_tupdesc, &isNull); Assert(!isNull); /* FALLTHROUGH */ case 1: cur_skey[0].sk_argument = (cache->cc_key[0] == ObjectIdAttributeNumber) ? ObjectIdGetDatum(HeapTupleGetOid(tuple)) : fastgetattr(tuple, cache->cc_key[0], cache->cc_tupdesc, &isNull); Assert(!isNull); break; default: elog(FATAL, "wrong number of hash keys: %d", cache->cc_nkeys); break; } return CatalogCacheComputeHashValue(cache, cache->cc_nkeys, cur_skey); } #ifdef CATCACHE_STATS static void CatCachePrintStats(int code, Datum arg) { CatCache *cache; long cc_searches = 0; long cc_hits = 0; long cc_neg_hits = 0; long cc_newloads = 0; long cc_invals = 0; long cc_lsearches = 0; long cc_lhits = 0; for (cache = CacheHdr->ch_caches; cache; cache = cache->cc_next) { if (cache->cc_ntup == 0 && cache->cc_searches == 0) continue; /* don't print unused caches */ elog(DEBUG2, "catcache %s/%u: %d tup, %ld srch, %ld+%ld=%ld hits, %ld+%ld=%ld loads, %ld invals, %ld lsrch, %ld lhits", cache->cc_relname, cache->cc_indexoid, cache->cc_ntup, cache->cc_searches, cache->cc_hits, cache->cc_neg_hits, cache->cc_hits + cache->cc_neg_hits, cache->cc_newloads, cache->cc_searches - cache->cc_hits - cache->cc_neg_hits - cache->cc_newloads, cache->cc_searches - cache->cc_hits - cache->cc_neg_hits, cache->cc_invals, cache->cc_lsearches, cache->cc_lhits); cc_searches += cache->cc_searches; cc_hits += cache->cc_hits; cc_neg_hits += cache->cc_neg_hits; cc_newloads += cache->cc_newloads; cc_invals += cache->cc_invals; cc_lsearches += cache->cc_lsearches; cc_lhits += cache->cc_lhits; } elog(DEBUG2, "catcache totals: %d tup, %ld srch, %ld+%ld=%ld hits, %ld+%ld=%ld loads, %ld invals, %ld lsrch, %ld lhits", CacheHdr->ch_ntup, cc_searches, cc_hits, cc_neg_hits, cc_hits + cc_neg_hits, cc_newloads, cc_searches - cc_hits - cc_neg_hits - cc_newloads, cc_searches - cc_hits - cc_neg_hits, cc_invals, cc_lsearches, cc_lhits); } #endif /* CATCACHE_STATS */ /* * CatCacheRemoveCTup * * Unlink and delete the given cache entry * * NB: if it is a member of a CatCList, the CatCList is deleted too. * Both the cache entry and the list had better have zero refcount. */ static void CatCacheRemoveCTup(CatCache *cache, CatCTup *ct) { Assert(ct->refcount == 0); Assert(ct->my_cache == cache); if (ct->c_list) { /* * The cleanest way to handle this is to call CatCacheRemoveCList, * which will recurse back to me, and the recursive call will do the * work. Set the "dead" flag to make sure it does recurse. */ ct->dead = true; CatCacheRemoveCList(cache, ct->c_list); return; /* nothing left to do */ } /* delink from linked list */ DLRemove(&ct->cache_elem); /* free associated tuple data */ if (ct->tuple.t_data != NULL) pfree(ct->tuple.t_data); pfree(ct); --cache->cc_ntup; --CacheHdr->ch_ntup; } /* * CatCacheRemoveCList * * Unlink and delete the given cache list entry * * NB: any dead member entries that become unreferenced are deleted too. */ static void CatCacheRemoveCList(CatCache *cache, CatCList *cl) { int i; Assert(cl->refcount == 0); Assert(cl->my_cache == cache); /* delink from member tuples */ for (i = cl->n_members; --i >= 0;) { CatCTup *ct = cl->members[i]; Assert(ct->c_list == cl); ct->c_list = NULL; /* if the member is dead and now has no references, remove it */ if ( #ifndef CATCACHE_FORCE_RELEASE ct->dead && #endif ct->refcount == 0) CatCacheRemoveCTup(cache, ct); } /* delink from linked list */ DLRemove(&cl->cache_elem); /* free associated tuple data */ if (cl->tuple.t_data != NULL) pfree(cl->tuple.t_data); pfree(cl); } /* * CatalogCacheIdInvalidate * * Invalidate entries in the specified cache, given a hash value and * item pointer. Positive entries are deleted if they match the item * pointer. Negative entries must be deleted if they match the hash * value (since we do not have the exact key of the tuple that's being * inserted). But this should only rarely result in loss of a cache * entry that could have been kept. * * Note that it's not very relevant whether the tuple identified by * the item pointer is being inserted or deleted. We don't expect to * find matching positive entries in the one case, and we don't expect * to find matching negative entries in the other; but we will do the * right things in any case. * * This routine is only quasi-public: it should only be used by inval.c. */ void CatalogCacheIdInvalidate(int cacheId, uint32 hashValue, ItemPointer pointer) { CatCache *ccp; /* * sanity checks */ Assert(ItemPointerIsValid(pointer)); CACHE1_elog(DEBUG2, "CatalogCacheIdInvalidate: called"); /* * inspect caches to find the proper cache */ for (ccp = CacheHdr->ch_caches; ccp; ccp = ccp->cc_next) { Index hashIndex; Dlelem *elt, *nextelt; if (cacheId != ccp->id) continue; /* * We don't bother to check whether the cache has finished * initialization yet; if not, there will be no entries in it so no * problem. */ /* * Invalidate *all* CatCLists in this cache; it's too hard to tell * which searches might still be correct, so just zap 'em all. */ for (elt = DLGetHead(&ccp->cc_lists); elt; elt = nextelt) { CatCList *cl = (CatCList *) DLE_VAL(elt); nextelt = DLGetSucc(elt); if (cl->refcount > 0) cl->dead = true; else CatCacheRemoveCList(ccp, cl); } /* * inspect the proper hash bucket for tuple matches */ hashIndex = HASH_INDEX(hashValue, ccp->cc_nbuckets); for (elt = DLGetHead(&ccp->cc_bucket[hashIndex]); elt; elt = nextelt) { CatCTup *ct = (CatCTup *) DLE_VAL(elt); nextelt = DLGetSucc(elt); if (hashValue != ct->hash_value) continue; /* ignore non-matching hash values */ if (ct->negative || ItemPointerEquals(pointer, &ct->tuple.t_self)) { if (ct->refcount > 0 || (ct->c_list && ct->c_list->refcount > 0)) { ct->dead = true; /* list, if any, was marked dead above */ Assert(ct->c_list == NULL || ct->c_list->dead); } else CatCacheRemoveCTup(ccp, ct); CACHE1_elog(DEBUG2, "CatalogCacheIdInvalidate: invalidated"); #ifdef CATCACHE_STATS ccp->cc_invals++; #endif /* could be multiple matches, so keep looking! */ } } break; /* need only search this one cache */ } } /* ---------------------------------------------------------------- * public functions * ---------------------------------------------------------------- */ /* * Standard routine for creating cache context if it doesn't exist yet * * There are a lot of places (probably far more than necessary) that check * whether CacheMemoryContext exists yet and want to create it if not. * We centralize knowledge of exactly how to create it here. */ void CreateCacheMemoryContext(void) { /* * Purely for paranoia, check that context doesn't exist; caller probably * did so already. */ if (!CacheMemoryContext) CacheMemoryContext = AllocSetContextCreate(TopMemoryContext, "CacheMemoryContext", ALLOCSET_DEFAULT_MINSIZE, ALLOCSET_DEFAULT_INITSIZE, ALLOCSET_DEFAULT_MAXSIZE); } /* * AtEOXact_CatCache * * Clean up catcaches at end of main transaction (either commit or abort) * * As of PostgreSQL 8.1, catcache pins should get released by the * ResourceOwner mechanism. This routine is just a debugging * cross-check that no pins remain. */ void AtEOXact_CatCache(bool isCommit) { #ifdef USE_ASSERT_CHECKING if (assert_enabled) { CatCache *ccp; for (ccp = CacheHdr->ch_caches; ccp; ccp = ccp->cc_next) { Dlelem *elt; int i; /* Check CatCLists */ for (elt = DLGetHead(&ccp->cc_lists); elt; elt = DLGetSucc(elt)) { CatCList *cl = (CatCList *) DLE_VAL(elt); Assert(cl->cl_magic == CL_MAGIC); Assert(cl->refcount == 0); Assert(!cl->dead); } /* Check individual tuples */ for (i = 0; i < ccp->cc_nbuckets; i++) { for (elt = DLGetHead(&ccp->cc_bucket[i]); elt; elt = DLGetSucc(elt)) { CatCTup *ct = (CatCTup *) DLE_VAL(elt); Assert(ct->ct_magic == CT_MAGIC); Assert(ct->refcount == 0); Assert(!ct->dead); } } } } #endif } /* * ResetCatalogCache * * Reset one catalog cache to empty. * * This is not very efficient if the target cache is nearly empty. * However, it shouldn't need to be efficient; we don't invoke it often. */ static void ResetCatalogCache(CatCache *cache) { Dlelem *elt, *nextelt; int i; /* Remove each list in this cache, or at least mark it dead */ for (elt = DLGetHead(&cache->cc_lists); elt; elt = nextelt) { CatCList *cl = (CatCList *) DLE_VAL(elt); nextelt = DLGetSucc(elt); if (cl->refcount > 0) cl->dead = true; else CatCacheRemoveCList(cache, cl); } /* Remove each tuple in this cache, or at least mark it dead */ for (i = 0; i < cache->cc_nbuckets; i++) { for (elt = DLGetHead(&cache->cc_bucket[i]); elt; elt = nextelt) { CatCTup *ct = (CatCTup *) DLE_VAL(elt); nextelt = DLGetSucc(elt); if (ct->refcount > 0 || (ct->c_list && ct->c_list->refcount > 0)) { ct->dead = true; /* list, if any, was marked dead above */ Assert(ct->c_list == NULL || ct->c_list->dead); } else CatCacheRemoveCTup(cache, ct); #ifdef CATCACHE_STATS cache->cc_invals++; #endif } } } /* * ResetCatalogCaches * * Reset all caches when a shared cache inval event forces it */ void ResetCatalogCaches(void) { CatCache *cache; CACHE1_elog(DEBUG2, "ResetCatalogCaches called"); for (cache = CacheHdr->ch_caches; cache; cache = cache->cc_next) ResetCatalogCache(cache); CACHE1_elog(DEBUG2, "end of ResetCatalogCaches call"); } /* * CatalogCacheFlushCatalog * * Flush all catcache entries that came from the specified system catalog. * This is needed after VACUUM FULL/CLUSTER on the catalog, since the * tuples very likely now have different TIDs than before. (At one point * we also tried to force re-execution of CatalogCacheInitializeCache for * the cache(s) on that catalog. This is a bad idea since it leads to all * kinds of trouble if a cache flush occurs while loading cache entries. * We now avoid the need to do it by copying cc_tupdesc out of the relcache, * rather than relying on the relcache to keep a tupdesc for us. Of course * this assumes the tupdesc of a cachable system table will not change...) */ void CatalogCacheFlushCatalog(Oid catId) { CatCache *cache; CACHE2_elog(DEBUG2, "CatalogCacheFlushCatalog called for %u", catId); for (cache = CacheHdr->ch_caches; cache; cache = cache->cc_next) { /* We can ignore uninitialized caches, since they must be empty */ if (cache->cc_tupdesc == NULL) continue; /* Does this cache store tuples of the target catalog? */ if (cache->cc_tupdesc->attrs[0]->attrelid == catId) { /* Yes, so flush all its contents */ ResetCatalogCache(cache); /* Tell inval.c to call syscache callbacks for this cache */ CallSyscacheCallbacks(cache->id, NULL); } } CACHE1_elog(DEBUG2, "end of CatalogCacheFlushCatalog call"); } /* * InitCatCache * * This allocates and initializes a cache for a system catalog relation. * Actually, the cache is only partially initialized to avoid opening the * relation. The relation will be opened and the rest of the cache * structure initialized on the first access. */ #ifdef CACHEDEBUG #define InitCatCache_DEBUG2 \ do { \ elog(DEBUG2, "InitCatCache: rel=%u ind=%u id=%d nkeys=%d size=%d", \ cp->cc_reloid, cp->cc_indexoid, cp->id, \ cp->cc_nkeys, cp->cc_nbuckets); \ } while(0) #else #define InitCatCache_DEBUG2 #endif CatCache * InitCatCache(int id, Oid reloid, Oid indexoid, int nkeys, const int *key, int nbuckets) { CatCache *cp; MemoryContext oldcxt; int i; /* * nbuckets is the number of hash buckets to use in this catcache. * Currently we just use a hard-wired estimate of an appropriate size for * each cache; maybe later make them dynamically resizable? * * nbuckets must be a power of two. We check this via Assert rather than * a full runtime check because the values will be coming from constant * tables. * * If you're confused by the power-of-two check, see comments in * bitmapset.c for an explanation. */ Assert(nbuckets > 0 && (nbuckets & -nbuckets) == nbuckets); /* * first switch to the cache context so our allocations do not vanish at * the end of a transaction */ if (!CacheMemoryContext) CreateCacheMemoryContext(); oldcxt = MemoryContextSwitchTo(CacheMemoryContext); /* * if first time through, initialize the cache group header */ if (CacheHdr == NULL) { CacheHdr = (CatCacheHeader *) palloc(sizeof(CatCacheHeader)); CacheHdr->ch_caches = NULL; CacheHdr->ch_ntup = 0; #ifdef CATCACHE_STATS /* set up to dump stats at backend exit */ on_proc_exit(CatCachePrintStats, 0); #endif } /* * allocate a new cache structure * * Note: we assume zeroing initializes the Dllist headers correctly */ cp = (CatCache *) palloc0(sizeof(CatCache) + nbuckets * sizeof(Dllist)); /* * initialize the cache's relation information for the relation * corresponding to this cache, and initialize some of the new cache's * other internal fields. But don't open the relation yet. */ cp->id = id; cp->cc_relname = "(not known yet)"; cp->cc_reloid = reloid; cp->cc_indexoid = indexoid; cp->cc_relisshared = false; /* temporary */ cp->cc_tupdesc = (TupleDesc) NULL; cp->cc_ntup = 0; cp->cc_nbuckets = nbuckets; cp->cc_nkeys = nkeys; for (i = 0; i < nkeys; ++i) cp->cc_key[i] = key[i]; /* * new cache is initialized as far as we can go for now. print some * debugging information, if appropriate. */ InitCatCache_DEBUG2; /* * add completed cache to top of group header's list */ cp->cc_next = CacheHdr->ch_caches; CacheHdr->ch_caches = cp; /* * back to the old context before we return... */ MemoryContextSwitchTo(oldcxt); return cp; } /* * CatalogCacheInitializeCache * * This function does final initialization of a catcache: obtain the tuple * descriptor and set up the hash and equality function links. We assume * that the relcache entry can be opened at this point! */ #ifdef CACHEDEBUG #define CatalogCacheInitializeCache_DEBUG1 \ elog(DEBUG2, "CatalogCacheInitializeCache: cache @%p rel=%u", cache, \ cache->cc_reloid) #define CatalogCacheInitializeCache_DEBUG2 \ do { \ if (cache->cc_key[i] > 0) { \ elog(DEBUG2, "CatalogCacheInitializeCache: load %d/%d w/%d, %u", \ i+1, cache->cc_nkeys, cache->cc_key[i], \ tupdesc->attrs[cache->cc_key[i] - 1]->atttypid); \ } else { \ elog(DEBUG2, "CatalogCacheInitializeCache: load %d/%d w/%d", \ i+1, cache->cc_nkeys, cache->cc_key[i]); \ } \ } while(0) #else #define CatalogCacheInitializeCache_DEBUG1 #define CatalogCacheInitializeCache_DEBUG2 #endif static void CatalogCacheInitializeCache(CatCache *cache) { Relation relation; MemoryContext oldcxt; TupleDesc tupdesc; int i; CatalogCacheInitializeCache_DEBUG1; relation = heap_open(cache->cc_reloid, AccessShareLock); /* * switch to the cache context so our allocations do not vanish at the end * of a transaction */ Assert(CacheMemoryContext != NULL); oldcxt = MemoryContextSwitchTo(CacheMemoryContext); /* * copy the relcache's tuple descriptor to permanent cache storage */ tupdesc = CreateTupleDescCopyConstr(RelationGetDescr(relation)); /* * save the relation's name and relisshared flag, too (cc_relname is used * only for debugging purposes) */ cache->cc_relname = pstrdup(RelationGetRelationName(relation)); cache->cc_relisshared = RelationGetForm(relation)->relisshared; /* * return to the caller's memory context and close the rel */ MemoryContextSwitchTo(oldcxt); heap_close(relation, AccessShareLock); CACHE3_elog(DEBUG2, "CatalogCacheInitializeCache: %s, %d keys", cache->cc_relname, cache->cc_nkeys); /* * initialize cache's key information */ for (i = 0; i < cache->cc_nkeys; ++i) { Oid keytype; RegProcedure eqfunc; CatalogCacheInitializeCache_DEBUG2; if (cache->cc_key[i] > 0) keytype = tupdesc->attrs[cache->cc_key[i] - 1]->atttypid; else { if (cache->cc_key[i] != ObjectIdAttributeNumber) elog(FATAL, "only sys attr supported in caches is OID"); keytype = OIDOID; } GetCCHashEqFuncs(keytype, &cache->cc_hashfunc[i], &eqfunc); cache->cc_isname[i] = (keytype == NAMEOID); /* * Do equality-function lookup (we assume this won't need a catalog * lookup for any supported type) */ fmgr_info_cxt(eqfunc, &cache->cc_skey[i].sk_func, CacheMemoryContext); /* Initialize sk_attno suitably for HeapKeyTest() and heap scans */ cache->cc_skey[i].sk_attno = cache->cc_key[i]; /* Fill in sk_strategy as well --- always standard equality */ cache->cc_skey[i].sk_strategy = BTEqualStrategyNumber; cache->cc_skey[i].sk_subtype = InvalidOid; CACHE4_elog(DEBUG2, "CatalogCacheInitializeCache %s %d %p", cache->cc_relname, i, cache); } /* * mark this cache fully initialized */ cache->cc_tupdesc = tupdesc; } /* * InitCatCachePhase2 -- external interface for CatalogCacheInitializeCache * * One reason to call this routine is to ensure that the relcache has * created entries for all the catalogs and indexes referenced by catcaches. * Therefore, provide an option to open the index as well as fixing the * cache itself. An exception is the indexes on pg_am, which we don't use * (cf. IndexScanOK). */ void InitCatCachePhase2(CatCache *cache, bool touch_index) { if (cache->cc_tupdesc == NULL) CatalogCacheInitializeCache(cache); if (touch_index && cache->id != AMOID && cache->id != AMNAME) { Relation idesc; idesc = index_open(cache->cc_indexoid, AccessShareLock); index_close(idesc, AccessShareLock); } } /* * IndexScanOK * * This function checks for tuples that will be fetched by * IndexSupportInitialize() during relcache initialization for * certain system indexes that support critical syscaches. * We can't use an indexscan to fetch these, else we'll get into * infinite recursion. A plain heap scan will work, however. * Once we have completed relcache initialization (signaled by * criticalRelcachesBuilt), we don't have to worry anymore. * * Similarly, during backend startup we have to be able to use the * pg_authid and pg_auth_members syscaches for authentication even if * we don't yet have relcache entries for those catalogs' indexes. */ static bool IndexScanOK(CatCache *cache, ScanKey cur_skey) { switch (cache->id) { case INDEXRELID: /* * Rather than tracking exactly which indexes have to be loaded * before we can use indexscans (which changes from time to time), * just force all pg_index searches to be heap scans until we've * built the critical relcaches. */ if (!criticalRelcachesBuilt) return false; break; case AMOID: case AMNAME: /* * Always do heap scans in pg_am, because it's so small there's * not much point in an indexscan anyway. We *must* do this when * initially building critical relcache entries, but we might as * well just always do it. */ return false; case AUTHNAME: case AUTHOID: case AUTHMEMMEMROLE: /* * Protect authentication lookups occurring before relcache has * collected entries for shared indexes. */ if (!criticalSharedRelcachesBuilt) return false; break; default: break; } /* Normal case, allow index scan */ return true; } /* * SearchCatCache * * This call searches a system cache for a tuple, opening the relation * if necessary (on the first access to a particular cache). * * The result is NULL if not found, or a pointer to a HeapTuple in * the cache. The caller must not modify the tuple, and must call * ReleaseCatCache() when done with it. * * The search key values should be expressed as Datums of the key columns' * datatype(s). (Pass zeroes for any unused parameters.) As a special * exception, the passed-in key for a NAME column can be just a C string; * the caller need not go to the trouble of converting it to a fully * null-padded NAME. */ HeapTuple SearchCatCache(CatCache *cache, Datum v1, Datum v2, Datum v3, Datum v4) { ScanKeyData cur_skey[CATCACHE_MAXKEYS]; uint32 hashValue; Index hashIndex; Dlelem *elt; CatCTup *ct; Relation relation; SysScanDesc scandesc; HeapTuple ntp; /* * one-time startup overhead for each cache */ if (cache->cc_tupdesc == NULL) CatalogCacheInitializeCache(cache); #ifdef CATCACHE_STATS cache->cc_searches++; #endif /* * initialize the search key information */ memcpy(cur_skey, cache->cc_skey, sizeof(cur_skey)); cur_skey[0].sk_argument = v1; cur_skey[1].sk_argument = v2; cur_skey[2].sk_argument = v3; cur_skey[3].sk_argument = v4; /* * find the hash bucket in which to look for the tuple */ hashValue = CatalogCacheComputeHashValue(cache, cache->cc_nkeys, cur_skey); hashIndex = HASH_INDEX(hashValue, cache->cc_nbuckets); /* * scan the hash bucket until we find a match or exhaust our tuples */ for (elt = DLGetHead(&cache->cc_bucket[hashIndex]); elt; elt = DLGetSucc(elt)) { bool res; ct = (CatCTup *) DLE_VAL(elt); if (ct->dead) continue; /* ignore dead entries */ if (ct->hash_value != hashValue) continue; /* quickly skip entry if wrong hash val */ /* * see if the cached tuple matches our key. */ HeapKeyTest(&ct->tuple, cache->cc_tupdesc, cache->cc_nkeys, cur_skey, res); if (!res) continue; /* * We found a match in the cache. Move it to the front of the list * for its hashbucket, in order to speed subsequent searches. (The * most frequently accessed elements in any hashbucket will tend to be * near the front of the hashbucket's list.) */ DLMoveToFront(&ct->cache_elem); /* * If it's a positive entry, bump its refcount and return it. If it's * negative, we can report failure to the caller. */ if (!ct->negative) { ResourceOwnerEnlargeCatCacheRefs(CurrentResourceOwner); ct->refcount++; ResourceOwnerRememberCatCacheRef(CurrentResourceOwner, &ct->tuple); CACHE3_elog(DEBUG2, "SearchCatCache(%s): found in bucket %d", cache->cc_relname, hashIndex); #ifdef CATCACHE_STATS cache->cc_hits++; #endif return &ct->tuple; } else { CACHE3_elog(DEBUG2, "SearchCatCache(%s): found neg entry in bucket %d", cache->cc_relname, hashIndex); #ifdef CATCACHE_STATS cache->cc_neg_hits++; #endif return NULL; } } /* * Tuple was not found in cache, so we have to try to retrieve it directly * from the relation. If found, we will add it to the cache; if not * found, we will add a negative cache entry instead. * * NOTE: it is possible for recursive cache lookups to occur while reading * the relation --- for example, due to shared-cache-inval messages being * processed during heap_open(). This is OK. It's even possible for one * of those lookups to find and enter the very same tuple we are trying to * fetch here. If that happens, we will enter a second copy of the tuple * into the cache. The first copy will never be referenced again, and * will eventually age out of the cache, so there's no functional problem. * This case is rare enough that it's not worth expending extra cycles to * detect. */ relation = heap_open(cache->cc_reloid, AccessShareLock); scandesc = systable_beginscan(relation, cache->cc_indexoid, IndexScanOK(cache, cur_skey), SnapshotNow, cache->cc_nkeys, cur_skey); ct = NULL; while (HeapTupleIsValid(ntp = systable_getnext(scandesc))) { ct = CatalogCacheCreateEntry(cache, ntp, hashValue, hashIndex, false); /* immediately set the refcount to 1 */ ResourceOwnerEnlargeCatCacheRefs(CurrentResourceOwner); ct->refcount++; ResourceOwnerRememberCatCacheRef(CurrentResourceOwner, &ct->tuple); break; /* assume only one match */ } systable_endscan(scandesc); heap_close(relation, AccessShareLock); /* * If tuple was not found, we need to build a negative cache entry * containing a fake tuple. The fake tuple has the correct key columns, * but nulls everywhere else. * * In bootstrap mode, we don't build negative entries, because the cache * invalidation mechanism isn't alive and can't clear them if the tuple * gets created later. (Bootstrap doesn't do UPDATEs, so it doesn't need * cache inval for that.) */ if (ct == NULL) { if (IsBootstrapProcessingMode()) return NULL; ntp = build_dummy_tuple(cache, cache->cc_nkeys, cur_skey); ct = CatalogCacheCreateEntry(cache, ntp, hashValue, hashIndex, true); heap_freetuple(ntp); CACHE4_elog(DEBUG2, "SearchCatCache(%s): Contains %d/%d tuples", cache->cc_relname, cache->cc_ntup, CacheHdr->ch_ntup); CACHE3_elog(DEBUG2, "SearchCatCache(%s): put neg entry in bucket %d", cache->cc_relname, hashIndex); /* * We are not returning the negative entry to the caller, so leave its * refcount zero. */ return NULL; } CACHE4_elog(DEBUG2, "SearchCatCache(%s): Contains %d/%d tuples", cache->cc_relname, cache->cc_ntup, CacheHdr->ch_ntup); CACHE3_elog(DEBUG2, "SearchCatCache(%s): put in bucket %d", cache->cc_relname, hashIndex); #ifdef CATCACHE_STATS cache->cc_newloads++; #endif return &ct->tuple; } /* * ReleaseCatCache * * Decrement the reference count of a catcache entry (releasing the * hold grabbed by a successful SearchCatCache). * * NOTE: if compiled with -DCATCACHE_FORCE_RELEASE then catcache entries * will be freed as soon as their refcount goes to zero. In combination * with aset.c's CLOBBER_FREED_MEMORY option, this provides a good test * to catch references to already-released catcache entries. */ void ReleaseCatCache(HeapTuple tuple) { CatCTup *ct = (CatCTup *) (((char *) tuple) - offsetof(CatCTup, tuple)); /* Safety checks to ensure we were handed a cache entry */ Assert(ct->ct_magic == CT_MAGIC); Assert(ct->refcount > 0); ct->refcount--; ResourceOwnerForgetCatCacheRef(CurrentResourceOwner, &ct->tuple); if ( #ifndef CATCACHE_FORCE_RELEASE ct->dead && #endif ct->refcount == 0 && (ct->c_list == NULL || ct->c_list->refcount == 0)) CatCacheRemoveCTup(ct->my_cache, ct); } /* * SearchCatCacheList * * Generate a list of all tuples matching a partial key (that is, * a key specifying just the first K of the cache's N key columns). * * The caller must not modify the list object or the pointed-to tuples, * and must call ReleaseCatCacheList() when done with the list. */ CatCList * SearchCatCacheList(CatCache *cache, int nkeys, Datum v1, Datum v2, Datum v3, Datum v4) { ScanKeyData cur_skey[CATCACHE_MAXKEYS]; uint32 lHashValue; Dlelem *elt; CatCList *cl; CatCTup *ct; List *volatile ctlist; ListCell *ctlist_item; int nmembers; bool ordered; HeapTuple ntp; MemoryContext oldcxt; int i; /* * one-time startup overhead for each cache */ if (cache->cc_tupdesc == NULL) CatalogCacheInitializeCache(cache); Assert(nkeys > 0 && nkeys < cache->cc_nkeys); #ifdef CATCACHE_STATS cache->cc_lsearches++; #endif /* * initialize the search key information */ memcpy(cur_skey, cache->cc_skey, sizeof(cur_skey)); cur_skey[0].sk_argument = v1; cur_skey[1].sk_argument = v2; cur_skey[2].sk_argument = v3; cur_skey[3].sk_argument = v4; /* * compute a hash value of the given keys for faster search. We don't * presently divide the CatCList items into buckets, but this still lets * us skip non-matching items quickly most of the time. */ lHashValue = CatalogCacheComputeHashValue(cache, nkeys, cur_skey); /* * scan the items until we find a match or exhaust our list */ for (elt = DLGetHead(&cache->cc_lists); elt; elt = DLGetSucc(elt)) { bool res; cl = (CatCList *) DLE_VAL(elt); if (cl->dead) continue; /* ignore dead entries */ if (cl->hash_value != lHashValue) continue; /* quickly skip entry if wrong hash val */ /* * see if the cached list matches our key. */ if (cl->nkeys != nkeys) continue; HeapKeyTest(&cl->tuple, cache->cc_tupdesc, nkeys, cur_skey, res); if (!res) continue; /* * We found a matching list. Move the list to the front of the * cache's list-of-lists, to speed subsequent searches. (We do not * move the members to the fronts of their hashbucket lists, however, * since there's no point in that unless they are searched for * individually.) */ DLMoveToFront(&cl->cache_elem); /* Bump the list's refcount and return it */ ResourceOwnerEnlargeCatCacheListRefs(CurrentResourceOwner); cl->refcount++; ResourceOwnerRememberCatCacheListRef(CurrentResourceOwner, cl); CACHE2_elog(DEBUG2, "SearchCatCacheList(%s): found list", cache->cc_relname); #ifdef CATCACHE_STATS cache->cc_lhits++; #endif return cl; } /* * List was not found in cache, so we have to build it by reading the * relation. For each matching tuple found in the relation, use an * existing cache entry if possible, else build a new one. * * We have to bump the member refcounts temporarily to ensure they won't * get dropped from the cache while loading other members. We use a PG_TRY * block to ensure we can undo those refcounts if we get an error before * we finish constructing the CatCList. */ ResourceOwnerEnlargeCatCacheListRefs(CurrentResourceOwner); ctlist = NIL; PG_TRY(); { Relation relation; SysScanDesc scandesc; relation = heap_open(cache->cc_reloid, AccessShareLock); scandesc = systable_beginscan(relation, cache->cc_indexoid, IndexScanOK(cache, cur_skey), SnapshotNow, nkeys, cur_skey); /* The list will be ordered iff we are doing an index scan */ ordered = (scandesc->irel != NULL); while (HeapTupleIsValid(ntp = systable_getnext(scandesc))) { uint32 hashValue; Index hashIndex; /* * See if there's an entry for this tuple already. */ ct = NULL; hashValue = CatalogCacheComputeTupleHashValue(cache, ntp); hashIndex = HASH_INDEX(hashValue, cache->cc_nbuckets); for (elt = DLGetHead(&cache->cc_bucket[hashIndex]); elt; elt = DLGetSucc(elt)) { ct = (CatCTup *) DLE_VAL(elt); if (ct->dead || ct->negative) continue; /* ignore dead and negative entries */ if (ct->hash_value != hashValue) continue; /* quickly skip entry if wrong hash val */ if (!ItemPointerEquals(&(ct->tuple.t_self), &(ntp->t_self))) continue; /* not same tuple */ /* * Found a match, but can't use it if it belongs to another * list already */ if (ct->c_list) continue; break; /* A-OK */ } if (elt == NULL) { /* We didn't find a usable entry, so make a new one */ ct = CatalogCacheCreateEntry(cache, ntp, hashValue, hashIndex, false); } /* Careful here: add entry to ctlist, then bump its refcount */ /* This way leaves state correct if lappend runs out of memory */ ctlist = lappend(ctlist, ct); ct->refcount++; } systable_endscan(scandesc); heap_close(relation, AccessShareLock); /* * Now we can build the CatCList entry. First we need a dummy tuple * containing the key values... */ ntp = build_dummy_tuple(cache, nkeys, cur_skey); oldcxt = MemoryContextSwitchTo(CacheMemoryContext); nmembers = list_length(ctlist); cl = (CatCList *) palloc(sizeof(CatCList) + nmembers * sizeof(CatCTup *)); heap_copytuple_with_tuple(ntp, &cl->tuple); MemoryContextSwitchTo(oldcxt); heap_freetuple(ntp); /* * We are now past the last thing that could trigger an elog before we * have finished building the CatCList and remembering it in the * resource owner. So it's OK to fall out of the PG_TRY, and indeed * we'd better do so before we start marking the members as belonging * to the list. */ } PG_CATCH(); { foreach(ctlist_item, ctlist) { ct = (CatCTup *) lfirst(ctlist_item); Assert(ct->c_list == NULL); Assert(ct->refcount > 0); ct->refcount--; if ( #ifndef CATCACHE_FORCE_RELEASE ct->dead && #endif ct->refcount == 0 && (ct->c_list == NULL || ct->c_list->refcount == 0)) CatCacheRemoveCTup(cache, ct); } PG_RE_THROW(); } PG_END_TRY(); cl->cl_magic = CL_MAGIC; cl->my_cache = cache; DLInitElem(&cl->cache_elem, cl); cl->refcount = 0; /* for the moment */ cl->dead = false; cl->ordered = ordered; cl->nkeys = nkeys; cl->hash_value = lHashValue; cl->n_members = nmembers; i = 0; foreach(ctlist_item, ctlist) { cl->members[i++] = ct = (CatCTup *) lfirst(ctlist_item); Assert(ct->c_list == NULL); ct->c_list = cl; /* release the temporary refcount on the member */ Assert(ct->refcount > 0); ct->refcount--; /* mark list dead if any members already dead */ if (ct->dead) cl->dead = true; } Assert(i == nmembers); DLAddHead(&cache->cc_lists, &cl->cache_elem); /* Finally, bump the list's refcount and return it */ cl->refcount++; ResourceOwnerRememberCatCacheListRef(CurrentResourceOwner, cl); CACHE3_elog(DEBUG2, "SearchCatCacheList(%s): made list of %d members", cache->cc_relname, nmembers); return cl; } /* * ReleaseCatCacheList * * Decrement the reference count of a catcache list. */ void ReleaseCatCacheList(CatCList *list) { /* Safety checks to ensure we were handed a cache entry */ Assert(list->cl_magic == CL_MAGIC); Assert(list->refcount > 0); list->refcount--; ResourceOwnerForgetCatCacheListRef(CurrentResourceOwner, list); if ( #ifndef CATCACHE_FORCE_RELEASE list->dead && #endif list->refcount == 0) CatCacheRemoveCList(list->my_cache, list); } /* * CatalogCacheCreateEntry * Create a new CatCTup entry, copying the given HeapTuple and other * supplied data into it. The new entry initially has refcount 0. */ static CatCTup * CatalogCacheCreateEntry(CatCache *cache, HeapTuple ntp, uint32 hashValue, Index hashIndex, bool negative) { CatCTup *ct; MemoryContext oldcxt; /* * Allocate CatCTup header in cache memory, and copy the tuple there too. */ oldcxt = MemoryContextSwitchTo(CacheMemoryContext); ct = (CatCTup *) palloc(sizeof(CatCTup)); heap_copytuple_with_tuple(ntp, &ct->tuple); MemoryContextSwitchTo(oldcxt); /* * Finish initializing the CatCTup header, and add it to the cache's * linked list and counts. */ ct->ct_magic = CT_MAGIC; ct->my_cache = cache; DLInitElem(&ct->cache_elem, (void *) ct); ct->c_list = NULL; ct->refcount = 0; /* for the moment */ ct->dead = false; ct->negative = negative; ct->hash_value = hashValue; DLAddHead(&cache->cc_bucket[hashIndex], &ct->cache_elem); cache->cc_ntup++; CacheHdr->ch_ntup++; return ct; } /* * build_dummy_tuple * Generate a palloc'd HeapTuple that contains the specified key * columns, and NULLs for other columns. * * This is used to store the keys for negative cache entries and CatCList * entries, which don't have real tuples associated with them. */ static HeapTuple build_dummy_tuple(CatCache *cache, int nkeys, ScanKey skeys) { HeapTuple ntp; TupleDesc tupDesc = cache->cc_tupdesc; Datum *values; bool *nulls; Oid tupOid = InvalidOid; NameData tempNames[4]; int i; values = (Datum *) palloc(tupDesc->natts * sizeof(Datum)); nulls = (bool *) palloc(tupDesc->natts * sizeof(bool)); memset(values, 0, tupDesc->natts * sizeof(Datum)); memset(nulls, true, tupDesc->natts * sizeof(bool)); for (i = 0; i < nkeys; i++) { int attindex = cache->cc_key[i]; Datum keyval = skeys[i].sk_argument; if (attindex > 0) { /* * Here we must be careful in case the caller passed a C string * where a NAME is wanted: convert the given argument to a * correctly padded NAME. Otherwise the memcpy() done in * heap_form_tuple could fall off the end of memory. */ if (cache->cc_isname[i]) { Name newval = &tempNames[i]; namestrcpy(newval, DatumGetCString(keyval)); keyval = NameGetDatum(newval); } values[attindex - 1] = keyval; nulls[attindex - 1] = false; } else { Assert(attindex == ObjectIdAttributeNumber); tupOid = DatumGetObjectId(keyval); } } ntp = heap_form_tuple(tupDesc, values, nulls); if (tupOid != InvalidOid) HeapTupleSetOid(ntp, tupOid); pfree(values); pfree(nulls); return ntp; } /* * PrepareToInvalidateCacheTuple() * * This is part of a rather subtle chain of events, so pay attention: * * When a tuple is inserted or deleted, it cannot be flushed from the * catcaches immediately, for reasons explained at the top of cache/inval.c. * Instead we have to add entry(s) for the tuple to a list of pending tuple * invalidations that will be done at the end of the command or transaction. * * The lists of tuples that need to be flushed are kept by inval.c. This * routine is a helper routine for inval.c. Given a tuple belonging to * the specified relation, find all catcaches it could be in, compute the * correct hash value for each such catcache, and call the specified function * to record the cache id, hash value, and tuple ItemPointer in inval.c's * lists. CatalogCacheIdInvalidate will be called later, if appropriate, * using the recorded information. * * Note that it is irrelevant whether the given tuple is actually loaded * into the catcache at the moment. Even if it's not there now, it might * be by the end of the command, or there might be a matching negative entry * to flush --- or other backends' caches might have such entries --- so * we have to make list entries to flush it later. * * Also note that it's not an error if there are no catcaches for the * specified relation. inval.c doesn't know exactly which rels have * catcaches --- it will call this routine for any tuple that's in a * system relation. */ void PrepareToInvalidateCacheTuple(Relation relation, HeapTuple tuple, void (*function) (int, uint32, ItemPointer, Oid)) { CatCache *ccp; Oid reloid; CACHE1_elog(DEBUG2, "PrepareToInvalidateCacheTuple: called"); /* * sanity checks */ Assert(RelationIsValid(relation)); Assert(HeapTupleIsValid(tuple)); Assert(PointerIsValid(function)); Assert(CacheHdr != NULL); reloid = RelationGetRelid(relation); /* ---------------- * for each cache * if the cache contains tuples from the specified relation * compute the tuple's hash value in this cache, * and call the passed function to register the information. * ---------------- */ for (ccp = CacheHdr->ch_caches; ccp; ccp = ccp->cc_next) { if (ccp->cc_reloid != reloid) continue; /* Just in case cache hasn't finished initialization yet... */ if (ccp->cc_tupdesc == NULL) CatalogCacheInitializeCache(ccp); (*function) (ccp->id, CatalogCacheComputeTupleHashValue(ccp, tuple), &tuple->t_self, ccp->cc_relisshared ? (Oid) 0 : MyDatabaseId); } } /* * Subroutines for warning about reference leaks. These are exported so * that resowner.c can call them. */ void PrintCatCacheLeakWarning(HeapTuple tuple) { CatCTup *ct = (CatCTup *) (((char *) tuple) - offsetof(CatCTup, tuple)); /* Safety check to ensure we were handed a cache entry */ Assert(ct->ct_magic == CT_MAGIC); elog(WARNING, "cache reference leak: cache %s (%d), tuple %u/%u has count %d", ct->my_cache->cc_relname, ct->my_cache->id, ItemPointerGetBlockNumber(&(tuple->t_self)), ItemPointerGetOffsetNumber(&(tuple->t_self)), ct->refcount); } void PrintCatCacheListLeakWarning(CatCList *list) { elog(WARNING, "cache reference leak: cache %s (%d), list %p has count %d", list->my_cache->cc_relname, list->my_cache->id, list, list->refcount); }