catcache.c

postgresql8.3.4源码,开源数据库

/*-------------------------------------------------------------------------
 *
 * catcache.c
 *	  System catalog cache for tuples matching a key.
 *
 * Portions Copyright (c) 1996-2008, PostgreSQL Global Development Group
 * Portions Copyright (c) 1994, Regents of the University of California
 *
 *
 * IDENTIFICATION
 *	  $PostgreSQL: pgsql/src/backend/utils/cache/catcache.c,v 1.140.2.1 2008/03/05 17:01:33 tgl Exp $
 *
 *-------------------------------------------------------------------------
 */
#include "postgres.h"

#include "access/genam.h"
#include "access/hash.h"
#include "access/heapam.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/memutils.h"
#include "utils/relcache.h"
#include "utils/resowner.h"
#include "utils/syscache.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[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(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.
		 */

		/*