catcache.c

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/*-------------------------------------------------------------------------
 *
 * catcache.c
 *	  System catalog cache for tuples matching a key.
 *
 * Portions Copyright (c) 1996-2003, PostgreSQL Global Development Group
 * Portions Copyright (c) 1994, Regents of the University of California
 *
 *
 * IDENTIFICATION
 *	  $Header: /cvsroot/pgsql/src/backend/utils/cache/catcache.c,v 1.108 2003/08/04 02:40:06 momjian Exp $
 *
 *-------------------------------------------------------------------------
 */
#include "postgres.h"

#include "access/genam.h"
#include "access/hash.h"
#include "access/heapam.h"
#include "access/valid.h"
#include "catalog/pg_opclass.h"
#include "catalog/pg_operator.h"
#include "catalog/pg_type.h"
#include "catalog/catname.h"
#include "catalog/indexing.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/catcache.h"
#include "utils/relcache.h"
#include "utils/syscache.h"


 /* #define CACHEDEBUG */	/* turns DEBUG elogs on */

/*
 * Constants related to size of the catcache.
 *
 * NCCBUCKETS must be a power of two and must be less than 64K (because
 * SharedInvalCatcacheMsg crams hash indexes into a uint16 field).	In
 * practice it should be a lot less, anyway, to avoid chewing up too much
 * space on hash bucket headers.
 *
 * MAXCCTUPLES could be as small as a few hundred, if per-backend memory
 * consumption is at a premium.
 */
#define NCCBUCKETS 256			/* Hash buckets per CatCache */
#define MAXCCTUPLES 5000		/* Maximum # of tuples in all caches */

/*
 * 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(void);
#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:
			*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);
			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;

	CACHE4_elog(DEBUG2, "CatalogCacheComputeHashValue %s %d %p",
				cache->cc_relname,
				nkeys,
				cache);

	switch (nkeys)
	{
		case 4:
			hashValue ^=
				DatumGetUInt32(DirectFunctionCall1(cache->cc_hashfunc[3],
										  cur_skey[3].sk_argument)) << 9;
			/* FALLTHROUGH */
		case 3:
			hashValue ^=
				DatumGetUInt32(DirectFunctionCall1(cache->cc_hashfunc[2],
										  cur_skey[2].sk_argument)) << 6;
			/* FALLTHROUGH */
		case 2:
			hashValue ^=
				DatumGetUInt32(DirectFunctionCall1(cache->cc_hashfunc[1],
										  cur_skey[1].sk_argument)) << 3;
			/* FALLTHROUGH */
		case 1:
			hashValue ^=
				DatumGetUInt32(DirectFunctionCall1(cache->cc_hashfunc[0],
											   cur_skey[0].sk_argument));
			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[4];
	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(void)
{
	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_discards = 0;
	long		cc_lsearches = 0;
	long		cc_lhits = 0;

	elog(DEBUG2, "catcache stats dump: %d/%d tuples in catcaches",
		 CacheHdr->ch_ntup, CacheHdr->ch_maxtup);

	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/%s: %d tup, %ld srch, %ld+%ld=%ld hits, %ld+%ld=%ld loads, %ld invals, %ld discards, %ld lsrch, %ld lhits",
			 cache->cc_relname,
			 cache->cc_indname,
			 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_discards,
			 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_discards += cache->cc_discards;
		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 discards, %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_discards,
		 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.
 */
static void
CatCacheRemoveCTup(CatCache *cache, CatCTup *ct)
{
	Assert(ct->refcount == 0);
	Assert(ct->my_cache == cache);

	if (ct->c_list)
		CatCacheRemoveCList(cache, ct->c_list);

	/* delink from linked lists */
	DLRemove(&ct->lrulist_elem);
	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
 */
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;
	}

	/* 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->dead = true;
				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 transaction (either commit or abort)
 *
 * We scan the caches to reset refcounts to zero.  This is of course
 * necessary in the abort case, since elog() may have interrupted routines.
 * In the commit case, any nonzero counts indicate failure to call
 * ReleaseSysCache, so we put out a notice for debugging purposes.
 */
void
AtEOXact_CatCache(bool isCommit)
{
	CatCache   *ccp;
	Dlelem	   *elt,
			   *nextelt;

	/*
	 * First clean up CatCLists
	 */
	for (ccp = CacheHdr->ch_caches; ccp; ccp = ccp->cc_next)
	{
		for (elt = DLGetHead(&ccp->cc_lists); elt; elt = nextelt)
		{
			CatCList   *cl = (CatCList *) DLE_VAL(elt);

			nextelt = DLGetSucc(elt);

			if (cl->refcount != 0)
			{
				if (isCommit)
					elog(WARNING, "cache reference leak: cache %s (%d), list %p has count %d",
						 ccp->cc_relname, ccp->id, cl, cl->refcount);
				cl->refcount = 0;
			}

			/* Clean up any now-deletable dead entries */
			if (cl->dead)
				CatCacheRemoveCList(ccp, cl);
		}
	}

	/*
	 * Now clean up tuples; we can scan them all using the global LRU list
	 */
	for (elt = DLGetHead(&CacheHdr->ch_lrulist); elt; elt = nextelt)
	{
		CatCTup    *ct = (CatCTup *) DLE_VAL(elt);

		nextelt = DLGetSucc(elt);

		if (ct->refcount != 0)
		{
			if (isCommit)
				elog(WARNING, "cache reference leak: cache %s (%d), tuple %u has count %d",
					 ct->my_cache->cc_relname, ct->my_cache->id,
					 HeapTupleGetOid(&ct->tuple),
					 ct->refcount);
			ct->refcount = 0;
		}

		/* Clean up any now-deletable dead entries */
		if (ct->dead)
			CatCacheRemoveCTup(ct->my_cache, ct);
	}
}