catcache.c

关系型数据库 Postgresql 6.5.2

/*-------------------------------------------------------------------------
 *
 * catcache.c
 *	  System catalog cache for tuples matching a key.
 *
 * Copyright (c) 1994, Regents of the University of California
 *
 *
 * IDENTIFICATION
 *	  $Header: /usr/local/cvsroot/pgsql/src/backend/utils/cache/catcache.c,v 1.43.2.1 1999/08/02 05:24:59 scrappy Exp $
 *
 *-------------------------------------------------------------------------
 */
#include "postgres.h"
#include "access/genam.h"
#include "access/heapam.h"
#include "access/valid.h"
#include "catalog/pg_type.h"
#include "miscadmin.h"
#include "utils/builtins.h"
#include "utils/catcache.h"

static void CatCacheRemoveCTup(CatCache *cache, Dlelem *e);
static Index CatalogCacheComputeHashIndex(struct catcache * cacheInP);
static Index CatalogCacheComputeTupleHashIndex(struct catcache * cacheInOutP,
								  Relation relation, HeapTuple tuple);
static void CatalogCacheInitializeCache(struct catcache * cache,
							Relation relation);
static long comphash(long l, char *v);

/* ----------------
 *		variables, macros and other stuff
 *
 *	note CCSIZE allocates 51 buckets .. one was already allocated in
 *	the catcache structure.
 * ----------------
 */

#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

static CatCache   *Caches = NULL; /* head of list of caches */

GlobalMemory CacheCxt;			/* context in which caches are allocated */
/* CacheCxt is global because relcache uses it too. */


/* ----------------
 *		EQPROC is used in CatalogCacheInitializeCache
 *		XXX this should be replaced by catalog lookups soon
 * ----------------
 */
static long eqproc[] = {
	F_BOOLEQ, 0l, F_CHAREQ, F_NAMEEQ, 0l,
	F_INT2EQ, F_KEYFIRSTEQ, F_INT4EQ, 0l, F_TEXTEQ,
	F_OIDEQ, 0l, 0l, 0l, F_OID8EQ
};

#define EQPROC(SYSTEMTYPEOID)	eqproc[(SYSTEMTYPEOID)-16]

/* ----------------------------------------------------------------
 *					internal support functions
 * ----------------------------------------------------------------
 */
/* --------------------------------
 *		CatalogCacheInitializeCache
 * --------------------------------
 */
#ifdef CACHEDEBUG
#define CatalogCacheInitializeCache_DEBUG1 \
do { \
	elog(DEBUG, "CatalogCacheInitializeCache: cache @%08lx", cache); \
	if (relation) \
		elog(DEBUG, "CatalogCacheInitializeCache: called w/relation(inval)"); \
	else \
		elog(DEBUG, "CatalogCacheInitializeCache: called w/relname %s", \
			cache->cc_relname) \
} while(0)

#define CatalogCacheInitializeCache_DEBUG2 \
do { \
		if (cache->cc_key[i] > 0) { \
			elog(DEBUG, "CatalogCacheInitializeCache: load %d/%d w/%d, %d", \
				i+1, cache->cc_nkeys, cache->cc_key[i], \
				relation->rd_att->attrs[cache->cc_key[i] - 1]->attlen); \
		} else { \
			elog(DEBUG, "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(struct catcache * cache,
							Relation relation)
{
	MemoryContext oldcxt;
	short		didopen = 0;
	short		i;
	TupleDesc	tupdesc;

	CatalogCacheInitializeCache_DEBUG1;

	/* ----------------
	 *	first switch to the cache context so our allocations
	 *	do not vanish at the end of a transaction
	 * ----------------
	 */
	if (!CacheCxt)
		CacheCxt = CreateGlobalMemory("Cache");
	oldcxt = MemoryContextSwitchTo((MemoryContext) CacheCxt);

	/* ----------------
	 *	If no relation was passed we must open it to get access to
	 *	its fields.  If one of the other caches has already opened
	 *	it we use heap_open() instead of heap_openr()
	 * ----------------
	 */
	if (!RelationIsValid(relation))
	{
		struct catcache *cp;

		/* ----------------
		 *	scan the caches to see if any other cache has opened the relation
		 * ----------------
		 */
		for (cp = Caches; cp; cp = cp->cc_next)
		{
			if (strncmp(cp->cc_relname, cache->cc_relname, NAMEDATALEN) == 0)
			{
				if (cp->relationId != InvalidOid)
					break;
			}
		}

		/* ----------------
		 *	open the relation by name or by id
		 * ----------------
		 */
		if (cp)
			relation = heap_open(cp->relationId);
		else
			relation = heap_openr(cache->cc_relname);

		didopen = 1;
	}

	/* ----------------
	 *	initialize the cache's relation id
	 * ----------------
	 */
	Assert(RelationIsValid(relation));
	cache->relationId = RelationGetRelid(relation);
	tupdesc = cache->cc_tupdesc = RelationGetDescr(relation);

	CACHE3_elog(DEBUG, "CatalogCacheInitializeCache: relid %u, %d keys",
				cache->relationId, cache->cc_nkeys);

	/* ----------------
	 *	initialize cache's key information
	 * ----------------
	 */
	for (i = 0; i < cache->cc_nkeys; ++i)
	{
		CatalogCacheInitializeCache_DEBUG2;

		if (cache->cc_key[i] > 0)
		{

			/*
			 * Yoiks.  The implementation of the hashing code and the
			 * implementation of int28's are at loggerheads.  The right
			 * thing to do is to throw out the implementation of int28's
			 * altogether; until that happens, we do the right thing here
			 * to guarantee that the hash key generator doesn't try to
			 * dereference an int2 by mistake.
			 */

			if (tupdesc->attrs[cache->cc_key[i] - 1]->atttypid == INT28OID)
				cache->cc_klen[i] = sizeof(short);
			else
				cache->cc_klen[i] = tupdesc->attrs[cache->cc_key[i] - 1]->attlen;

			cache->cc_skey[i].sk_procedure = EQPROC(tupdesc->attrs[cache->cc_key[i] - 1]->atttypid);

			fmgr_info(cache->cc_skey[i].sk_procedure,
					  &cache->cc_skey[i].sk_func);
			cache->cc_skey[i].sk_nargs = cache->cc_skey[i].sk_func.fn_nargs;

			CACHE5_elog(DEBUG, "CatalogCacheInit %s %d %d %x",
						&relation->rd_rel->relname,
						i,
						tupdesc->attrs[cache->cc_key[i] - 1]->attlen,
						cache);
		}
	}

	/* ----------------
	 *	close the relation if we opened it
	 * ----------------
	 */
	if (didopen)
		heap_close(relation);

	/* ----------------
	 *	initialize index information for the cache.  this
	 *	should only be done once per cache.
	 * ----------------
	 */
	if (cache->cc_indname != NULL && cache->indexId == InvalidOid)
	{
		if (RelationGetForm(relation)->relhasindex)
		{

			/*
			 * If the index doesn't exist we are in trouble.
			 */
			relation = index_openr(cache->cc_indname);
			Assert(relation);
			cache->indexId = RelationGetRelid(relation);
			index_close(relation);
		}
		else
			cache->cc_indname = NULL;
	}

	/* ----------------
	 *	return to the proper memory context
	 * ----------------
	 */
	MemoryContextSwitchTo(oldcxt);
}

/* --------------------------------
 *		CatalogCacheSetId
 *
 *		XXX temporary function
 * --------------------------------
 */
#ifdef NOT_USED
void
CatalogCacheSetId(CatCache *cacheInOutP, int id)
{
	Assert(id == InvalidCatalogCacheId || id >= 0);
	cacheInOutP->id = id;
}

#endif

/* ----------------
 * comphash
 *		Compute a hash value, somehow.
 *
 * XXX explain algorithm here.
 *
 * l is length of the attribute value, v
 * v is the attribute value ("Datum")
 * ----------------
 */
static long
comphash(long l, char *v)
{
	long		i;
	NameData	n;

	CACHE3_elog(DEBUG, "comphash (%d,%x)", l, v);

	switch (l)
	{
		case 1:
		case 2:
		case 4:
			return (long) v;
	}

	if (l == NAMEDATALEN)
	{

		/*
		 * if it's a name, make sure that the values are null-padded.
		 *
		 * Note that this other fixed-length types can also have the same
		 * typelen so this may break them	  - XXX
		 */
		namestrcpy(&n, v);
		v = n.data;
	}
	else if (l < 0)
		l = VARSIZE(v);

	i = 0;
	while (l--)
		i += *v++;
	return i;
}

/* --------------------------------
 *		CatalogCacheComputeHashIndex
 * --------------------------------
 */
static Index
CatalogCacheComputeHashIndex(struct catcache * cacheInP)
{
	Index		hashIndex;

	hashIndex = 0x0;
	CACHE6_elog(DEBUG, "CatalogCacheComputeHashIndex %s %d %d %d %x",
				cacheInP->cc_relname,
				cacheInP->cc_nkeys,
				cacheInP->cc_klen[0],
				cacheInP->cc_klen[1],
				cacheInP);

	switch (cacheInP->cc_nkeys)
	{
		case 4:
			hashIndex ^= comphash(cacheInP->cc_klen[3],
						 (char *) cacheInP->cc_skey[3].sk_argument) << 9;
			/* FALLTHROUGH */
		case 3:
			hashIndex ^= comphash(cacheInP->cc_klen[2],
						 (char *) cacheInP->cc_skey[2].sk_argument) << 6;
			/* FALLTHROUGH */
		case 2:
			hashIndex ^= comphash(cacheInP->cc_klen[1],
						 (char *) cacheInP->cc_skey[1].sk_argument) << 3;
			/* FALLTHROUGH */
		case 1:
			hashIndex ^= comphash(cacheInP->cc_klen[0],
							  (char *) cacheInP->cc_skey[0].sk_argument);
			break;
		default:
			elog(FATAL, "CCComputeHashIndex: %d cc_nkeys", cacheInP->cc_nkeys);
			break;
	}
	hashIndex %= cacheInP->cc_size;
	return hashIndex;
}

/* --------------------------------
 *		CatalogCacheComputeTupleHashIndex
 * --------------------------------
 */
static Index
CatalogCacheComputeTupleHashIndex(struct catcache * cacheInOutP,
								  Relation relation,
								  HeapTuple tuple)
{
	bool		isNull = '\0';

	if (cacheInOutP->relationId == InvalidOid)
		CatalogCacheInitializeCache(cacheInOutP, relation);
	switch (cacheInOutP->cc_nkeys)
	{
		case 4:
			cacheInOutP->cc_skey[3].sk_argument =
				(cacheInOutP->cc_key[3] == ObjectIdAttributeNumber)
				? (Datum) tuple->t_data->t_oid
				: fastgetattr(tuple,
							  cacheInOutP->cc_key[3],
							  RelationGetDescr(relation),
							  &isNull);
			Assert(!isNull);
			/* FALLTHROUGH */
		case 3:
			cacheInOutP->cc_skey[2].sk_argument =
				(cacheInOutP->cc_key[2] == ObjectIdAttributeNumber)
				? (Datum) tuple->t_data->t_oid
				: fastgetattr(tuple,
							  cacheInOutP->cc_key[2],
							  RelationGetDescr(relation),
							  &isNull);
			Assert(!isNull);
			/* FALLTHROUGH */
		case 2:
			cacheInOutP->cc_skey[1].sk_argument =
				(cacheInOutP->cc_key[1] == ObjectIdAttributeNumber)
				? (Datum) tuple->t_data->t_oid
				: fastgetattr(tuple,
							  cacheInOutP->cc_key[1],
							  RelationGetDescr(relation),
							  &isNull);
			Assert(!isNull);
			/* FALLTHROUGH */
		case 1:
			cacheInOutP->cc_skey[0].sk_argument =
				(cacheInOutP->cc_key[0] == ObjectIdAttributeNumber)
				? (Datum) tuple->t_data->t_oid
				: fastgetattr(tuple,
							  cacheInOutP->cc_key[0],
							  RelationGetDescr(relation),
							  &isNull);
			Assert(!isNull);
			break;
		default:
			elog(FATAL, "CCComputeTupleHashIndex: %d cc_nkeys",
				 cacheInOutP->cc_nkeys
				);
			break;
	}

	return CatalogCacheComputeHashIndex(cacheInOutP);
}

/* --------------------------------
 *		CatCacheRemoveCTup
 * --------------------------------
 */
static void
CatCacheRemoveCTup(CatCache *cache, Dlelem *elt)
{
	CatCTup    *ct;
	CatCTup    *other_ct;
	Dlelem	   *other_elt;

	if (elt)
		ct = (CatCTup *) DLE_VAL(elt);
	else
		return;

	other_elt = ct->ct_node;
	other_ct = (CatCTup *) DLE_VAL(other_elt);
	DLRemove(other_elt);
	DLFreeElem(other_elt);
	free(other_ct);
	DLRemove(elt);
	DLFreeElem(elt);
	free(ct);
	--cache->cc_ntup;
}

/* --------------------------------
 *	CatalogCacheIdInvalidate()
 *
 *	Invalidate a tuple given a cache id.  In this case the id should always
 *	be found (whether the cache has opened its relation or not).  Of course,
 *	if the cache has yet to open its relation, there will be no tuples so
 *	no problem.
 * --------------------------------
 */
void
CatalogCacheIdInvalidate(int cacheId,	/* XXX */
						 Index hashIndex,
						 ItemPointer pointer)
{
	CatCache   *ccp;
	CatCTup    *ct;
	Dlelem	   *elt;
	MemoryContext oldcxt;

	/* ----------------
	 *	sanity checks
	 * ----------------
	 */
	Assert(hashIndex < NCCBUCK);
	Assert(ItemPointerIsValid(pointer));
	CACHE1_elog(DEBUG, "CatalogCacheIdInvalidate: called");

	/* ----------------
	 *	switch to the cache context for our memory allocations
	 * ----------------
	 */
	if (!CacheCxt)
		CacheCxt = CreateGlobalMemory("Cache");
	oldcxt = MemoryContextSwitchTo((MemoryContext) CacheCxt);

	/* ----------------
	 *	inspect every cache that could contain the tuple
	 * ----------------
	 */
	for (ccp = Caches; ccp; ccp = ccp->cc_next)
	{
		if (cacheId != ccp->id)
			continue;
		/* ----------------
		 *	inspect the hash bucket until we find a match or exhaust
		 * ----------------
		 */
		for (elt = DLGetHead(ccp->cc_cache[hashIndex]);
			 elt;
			 elt = DLGetSucc(elt))
		{
			ct = (CatCTup *) DLE_VAL(elt);
			if (ItemPointerEquals(pointer, &ct->ct_tup->t_self))
				break;
		}

		/* ----------------
		 *	if we found a matching tuple, invalidate it.
		 * ----------------
		 */

		if (elt)
		{
			CatCacheRemoveCTup(ccp, elt);

			CACHE1_elog(DEBUG, "CatalogCacheIdInvalidate: invalidated");
		}

		if (cacheId != InvalidCatalogCacheId)
			break;
	}

	/* ----------------
	 *	return to the proper memory context
	 * ----------------
	 */
	MemoryContextSwitchTo(oldcxt);
	/* sendpm('I', "Invalidated tuple"); */
}

/* ----------------------------------------------------------------
 *					   public functions
 *
 *		ResetSystemCache
 *		InitIndexedSysCache
 *		InitSysCache
 *		SearchSysCache
 *		RelationInvalidateCatalogCacheTuple
 * ----------------------------------------------------------------
 */
/* --------------------------------
 *		ResetSystemCache
 * --------------------------------
 */
void
ResetSystemCache()
{
	MemoryContext oldcxt;
	struct catcache *cache;

	CACHE1_elog(DEBUG, "ResetSystemCache called");

	/* ----------------
	 *	first switch to the cache context so our allocations
	 *	do not vanish at the end of a transaction
	 * ----------------
	 */
	if (!CacheCxt)
		CacheCxt = CreateGlobalMemory("Cache");

	oldcxt = MemoryContextSwitchTo((MemoryContext) CacheCxt);

	/* ----------------
	 *	here we purge the contents of all the caches
	 *
	 *	for each system cache
	 *	   for each hash bucket
	 *		   for each tuple in hash bucket
	 *			   remove the tuple
	 * ----------------
	 */
	for (cache = Caches; PointerIsValid(cache); cache = cache->cc_next)
	{
		int			hash;

		for (hash = 0; hash < NCCBUCK; hash += 1)
		{
			Dlelem	   *elt,
					   *nextelt;

			for (elt = DLGetHead(cache->cc_cache[hash]); elt; elt = nextelt)
			{
				nextelt = DLGetSucc(elt);