229 lines
8.3 KiB
C
229 lines
8.3 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) 1996-2023, PostgreSQL Global Development Group
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* Portions Copyright (c) 1994, Regents of the University of California
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*
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* src/include/utils/catcache.h
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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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#include "access/htup.h"
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#include "access/skey.h"
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#include "lib/ilist.h"
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#include "utils/relcache.h"
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/*
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* struct catctup: individual tuple in the cache.
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* struct catclist: list of tuples matching a partial key.
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* struct catcache: information for managing a cache.
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* struct catcacheheader: information for managing all the caches.
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*/
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#define CATCACHE_MAXKEYS 4
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/* function computing a datum's hash */
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typedef uint32 (*CCHashFN) (Datum datum);
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/* function computing equality of two datums */
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typedef bool (*CCFastEqualFN) (Datum a, Datum b);
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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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int cc_nbuckets; /* # of hash buckets in this cache */
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TupleDesc cc_tupdesc; /* tuple descriptor (copied from reldesc) */
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dlist_head *cc_bucket; /* hash buckets */
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CCHashFN cc_hashfunc[CATCACHE_MAXKEYS]; /* hash function for each key */
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CCFastEqualFN cc_fastequal[CATCACHE_MAXKEYS]; /* fast equal function for
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* each key */
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int cc_keyno[CATCACHE_MAXKEYS]; /* AttrNumber of each key */
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dlist_head cc_lists; /* list of CatCList structs */
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int cc_ntup; /* # of tuples currently in this cache */
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int cc_nkeys; /* # of keys (1..CATCACHE_MAXKEYS) */
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const char *cc_relname; /* name of relation the tuples come from */
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Oid cc_reloid; /* OID of relation the tuples come from */
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Oid cc_indexoid; /* OID of index matching cache keys */
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bool cc_relisshared; /* is relation shared across databases? */
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slist_node cc_next; /* list link */
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ScanKeyData cc_skey[CATCACHE_MAXKEYS]; /* precomputed key info for heap
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* scans */
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/*
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* Keep these at the end, so that compiling catcache.c with CATCACHE_STATS
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* doesn't break ABI for other modules
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*/
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#ifdef CATCACHE_STATS
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long cc_searches; /* total # searches against this cache */
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long cc_hits; /* # of matches against existing entry */
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long cc_neg_hits; /* # of matches against negative entry */
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long cc_newloads; /* # of successful loads of new entry */
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/*
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* cc_searches - (cc_hits + cc_neg_hits + cc_newloads) is number of failed
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* searches, each of which will result in loading a negative entry
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*/
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long cc_invals; /* # of entries invalidated from cache */
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long cc_lsearches; /* total # list-searches */
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long cc_lhits; /* # of matches against existing lists */
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#endif
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} CatCache;
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typedef struct catctup
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{
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int ct_magic; /* for identifying CatCTup entries */
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#define CT_MAGIC 0x57261502
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uint32 hash_value; /* hash value for this tuple's keys */
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/*
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* Lookup keys for the entry. By-reference datums point into the tuple for
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* positive cache entries, and are separately allocated for negative ones.
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*/
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Datum keys[CATCACHE_MAXKEYS];
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/*
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* Each tuple in a cache is a member of a dlist that stores the elements
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* of its hash bucket. We keep each dlist in LRU order to speed repeated
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* lookups.
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*/
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dlist_node cache_elem; /* list member of per-bucket list */
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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. (If it's a member of a CatCList, the list's
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* refcount must go to zero, too; also, remember to mark the list dead at
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* the same time the tuple is marked.)
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*
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* A negative cache entry is an assertion that there is no tuple matching
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* a particular key. This is just as useful as a normal entry so far as
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* avoiding catalog searches is concerned. Management of positive and
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* negative entries is identical.
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*/
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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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bool negative; /* negative cache entry? */
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HeapTupleData tuple; /* tuple management header */
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/*
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* The tuple may also be a member of at most one CatCList. (If a single
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* catcache is list-searched with varying numbers of keys, we may have to
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* make multiple entries for the same tuple because of this restriction.
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* Currently, that's not expected to be common, so we accept the potential
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* inefficiency.)
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*/
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struct catclist *c_list; /* containing CatCList, or NULL if none */
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CatCache *my_cache; /* link to owning catcache */
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/* properly aligned tuple data follows, unless a negative entry */
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} CatCTup;
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/*
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* A CatCList describes the result of a partial search, ie, a search using
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* only the first K key columns of an N-key cache. We store the keys used
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* into the keys attribute to represent the stored key set. The CatCList
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* object contains links to cache entries for all the table rows satisfying
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* the partial key. (Note: none of these will be negative cache entries.)
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*
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* A CatCList is only a member of a per-cache list; we do not currently
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* divide them into hash buckets.
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*
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* A list 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. (A list should be marked dead if any of its
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* member entries are dead.)
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*
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* If "ordered" is true then the member tuples appear in the order of the
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* cache's underlying index. This will be true in normal operation, but
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* might not be true during bootstrap or recovery operations. (namespace.c
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* is able to save some cycles when it is true.)
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*/
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typedef struct catclist
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{
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int cl_magic; /* for identifying CatCList entries */
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#define CL_MAGIC 0x52765103
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uint32 hash_value; /* hash value for lookup keys */
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dlist_node cache_elem; /* list member of per-catcache list */
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/*
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* Lookup keys for the entry, with the first nkeys elements being valid.
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* All by-reference are separately allocated.
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*/
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Datum keys[CATCACHE_MAXKEYS];
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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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bool ordered; /* members listed in index order? */
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short nkeys; /* number of lookup keys specified */
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int n_members; /* number of member tuples */
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CatCache *my_cache; /* link to owning catcache */
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CatCTup *members[FLEXIBLE_ARRAY_MEMBER]; /* members */
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} CatCList;
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typedef struct catcacheheader
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{
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slist_head ch_caches; /* head of list of CatCache structs */
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int ch_ntup; /* # of tuples in all caches */
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} CatCacheHeader;
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/* this extern duplicates utils/memutils.h... */
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extern PGDLLIMPORT MemoryContext CacheMemoryContext;
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extern void CreateCacheMemoryContext(void);
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extern CatCache *InitCatCache(int id, Oid reloid, Oid indexoid,
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int nkeys, const int *key,
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int nbuckets);
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extern void InitCatCachePhase2(CatCache *cache, bool touch_index);
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extern HeapTuple SearchCatCache(CatCache *cache,
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Datum v1, Datum v2, Datum v3, Datum v4);
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extern HeapTuple SearchCatCache1(CatCache *cache,
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Datum v1);
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extern HeapTuple SearchCatCache2(CatCache *cache,
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Datum v1, Datum v2);
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extern HeapTuple SearchCatCache3(CatCache *cache,
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Datum v1, Datum v2, Datum v3);
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extern HeapTuple SearchCatCache4(CatCache *cache,
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Datum v1, Datum v2, Datum v3, Datum v4);
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extern void ReleaseCatCache(HeapTuple tuple);
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extern uint32 GetCatCacheHashValue(CatCache *cache,
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Datum v1, Datum v2,
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Datum v3, Datum v4);
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extern CatCList *SearchCatCacheList(CatCache *cache, int nkeys,
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Datum v1, Datum v2,
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Datum v3);
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extern void ReleaseCatCacheList(CatCList *list);
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extern void ResetCatalogCaches(void);
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extern void CatalogCacheFlushCatalog(Oid catId);
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extern void CatCacheInvalidate(CatCache *cache, uint32 hashValue);
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extern void PrepareToInvalidateCacheTuple(Relation relation,
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HeapTuple tuple,
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HeapTuple newtuple,
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void (*function) (int, uint32, Oid));
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#endif /* CATCACHE_H */
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