a933ee38bb
maintained for each cache entry. A cache entry will not be freed until the matching ReleaseSysCache call has been executed. This eliminates worries about cache entries getting dropped while still in use. See my posting to pg-hackers of even date for more info.
103 lines
3.5 KiB
C
103 lines
3.5 KiB
C
/*-------------------------------------------------------------------------
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*
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* catcache.h
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* Low-level catalog cache definitions.
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*
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* NOTE: every catalog cache must have a corresponding unique index on
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* the system table that it caches --- ie, the index must match the keys
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* used to do lookups in this cache. All cache fetches are done with
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* indexscans (under normal conditions). The index should be unique to
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* guarantee that there can only be one matching row for a key combination.
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*
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*
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* Portions Copyright (c) 1996-2000, PostgreSQL, Inc
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* Portions Copyright (c) 1994, Regents of the University of California
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*
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* $Id: catcache.h,v 1.28 2000/11/16 22:30:49 tgl Exp $
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*
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*-------------------------------------------------------------------------
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*/
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#ifndef CATCACHE_H
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#define CATCACHE_H
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/* #define CACHEDEBUG */ /* turns DEBUG elogs on */
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#include "access/htup.h"
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#include "lib/dllist.h"
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/*
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* struct catctup: individual tuple in the cache.
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* struct catcache: information for managing a cache.
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*/
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typedef struct catctup
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{
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int ct_magic; /* for Assert checks */
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#define CT_MAGIC 0x57261502
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/*
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* Each tuple in a cache is a member of two lists: one lists all the
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* elements in that cache in LRU order, and the other lists just the
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* elements in one hashbucket, also in LRU order.
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*
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* A tuple marked "dead" must not be returned by subsequent searches.
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* However, it won't be physically deleted from the cache until its
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* refcount goes to zero.
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*/
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Dlelem lrulist_elem; /* list member of global LRU list */
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Dlelem cache_elem; /* list member of per-bucket list */
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int refcount; /* number of active references */
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bool dead; /* dead but not yet removed? */
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HeapTupleData tuple; /* tuple management header */
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} CatCTup;
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/* voodoo constants */
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#define NCCBUCK 500 /* CatCache buckets */
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#define MAXTUP 500 /* Maximum # of tuples stored per cache */
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typedef struct catcache
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{
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int id; /* cache identifier --- see syscache.h */
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struct catcache *cc_next; /* link to next catcache */
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char *cc_relname; /* name of relation the tuples come from */
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char *cc_indname; /* name of index matching cache keys */
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TupleDesc cc_tupdesc; /* tuple descriptor (copied from reldesc) */
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short cc_ntup; /* # of tuples in this cache */
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short cc_maxtup; /* max # of tuples allowed (LRU) */
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short cc_size; /* # of hash buckets in this cache */
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short cc_nkeys; /* number of keys (1..4) */
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short cc_key[4]; /* AttrNumber of each key */
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PGFunction cc_hashfunc[4]; /* hash function to use for each key */
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ScanKeyData cc_skey[4]; /* precomputed key info for indexscans */
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Dllist cc_lrulist; /* overall LRU list, most recent first */
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Dllist cc_cache[NCCBUCK]; /* hash buckets */
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} CatCache;
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#define InvalidCatalogCacheId (-1)
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/* this extern duplicates utils/memutils.h... */
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extern MemoryContext CacheMemoryContext;
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extern void CreateCacheMemoryContext(void);
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extern void AtEOXact_CatCache(bool isCommit);
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extern CatCache *InitCatCache(int id, char *relname, char *indname,
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int nkeys, int *key);
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extern HeapTuple SearchCatCache(CatCache *cache,
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Datum v1, Datum v2,
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Datum v3, Datum v4);
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extern void ReleaseCatCache(HeapTuple tuple);
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extern void ResetSystemCache(void);
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extern void SystemCacheRelationFlushed(Oid relId);
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extern void CatalogCacheIdInvalidate(int cacheId, Index hashIndex,
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ItemPointer pointer);
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extern void RelationInvalidateCatalogCacheTuple(Relation relation,
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HeapTuple tuple,
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void (*function) (int, Index, ItemPointer));
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#endif /* CATCACHE_H */
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