1 /*------------------------------------------------------------------------- 2 * 3 * catcache.h 4 * Low-level catalog cache definitions. 5 * 6 * NOTE: every catalog cache must have a corresponding unique index on 7 * the system table that it caches --- ie, the index must match the keys 8 * used to do lookups in this cache. All cache fetches are done with 9 * indexscans (under normal conditions). The index should be unique to 10 * guarantee that there can only be one matching row for a key combination. 11 * 12 * 13 * Portions Copyright (c) 1996-2017, PostgreSQL Global Development Group 14 * Portions Copyright (c) 1994, Regents of the University of California 15 * 16 * src/include/utils/catcache.h 17 * 18 *------------------------------------------------------------------------- 19 */ 20 #ifndef CATCACHE_H 21 #define CATCACHE_H 22 23 #include "access/htup.h" 24 #include "access/skey.h" 25 #include "lib/ilist.h" 26 #include "utils/relcache.h" 27 28 /* 29 * struct catctup: individual tuple in the cache. 30 * struct catclist: list of tuples matching a partial key. 31 * struct catcache: information for managing a cache. 32 * struct catcacheheader: information for managing all the caches. 33 */ 34 35 #define CATCACHE_MAXKEYS 4 36 37 typedef struct catcache 38 { 39 int id; /* cache identifier --- see syscache.h */ 40 slist_node cc_next; /* list link */ 41 const char *cc_relname; /* name of relation the tuples come from */ 42 Oid cc_reloid; /* OID of relation the tuples come from */ 43 Oid cc_indexoid; /* OID of index matching cache keys */ 44 bool cc_relisshared; /* is relation shared across databases? */ 45 TupleDesc cc_tupdesc; /* tuple descriptor (copied from reldesc) */ 46 int cc_ntup; /* # of tuples currently in this cache */ 47 int cc_nbuckets; /* # of hash buckets in this cache */ 48 int cc_nkeys; /* # of keys (1..CATCACHE_MAXKEYS) */ 49 int cc_key[CATCACHE_MAXKEYS]; /* AttrNumber of each key */ 50 PGFunction cc_hashfunc[CATCACHE_MAXKEYS]; /* hash function for each key */ 51 ScanKeyData cc_skey[CATCACHE_MAXKEYS]; /* precomputed key info for heap 52 * scans */ 53 bool cc_isname[CATCACHE_MAXKEYS]; /* flag "name" key columns */ 54 dlist_head cc_lists; /* list of CatCList structs */ 55 dlist_head *cc_bucket; /* hash buckets */ 56 57 /* 58 * Keep these at the end, so that compiling catcache.c with CATCACHE_STATS 59 * doesn't break ABI for other modules 60 */ 61 #ifdef CATCACHE_STATS 62 long cc_searches; /* total # searches against this cache */ 63 long cc_hits; /* # of matches against existing entry */ 64 long cc_neg_hits; /* # of matches against negative entry */ 65 long cc_newloads; /* # of successful loads of new entry */ 66 67 /* 68 * cc_searches - (cc_hits + cc_neg_hits + cc_newloads) is number of failed 69 * searches, each of which will result in loading a negative entry 70 */ 71 long cc_invals; /* # of entries invalidated from cache */ 72 long cc_lsearches; /* total # list-searches */ 73 long cc_lhits; /* # of matches against existing lists */ 74 #endif 75 } CatCache; 76 77 78 typedef struct catctup 79 { 80 int ct_magic; /* for identifying CatCTup entries */ 81 #define CT_MAGIC 0x57261502 82 CatCache *my_cache; /* link to owning catcache */ 83 84 /* 85 * Each tuple in a cache is a member of a dlist that stores the elements 86 * of its hash bucket. We keep each dlist in LRU order to speed repeated 87 * lookups. 88 */ 89 dlist_node cache_elem; /* list member of per-bucket list */ 90 91 /* 92 * The tuple may also be a member of at most one CatCList. (If a single 93 * catcache is list-searched with varying numbers of keys, we may have to 94 * make multiple entries for the same tuple because of this restriction. 95 * Currently, that's not expected to be common, so we accept the potential 96 * inefficiency.) 97 */ 98 struct catclist *c_list; /* containing CatCList, or NULL if none */ 99 100 /* 101 * A tuple marked "dead" must not be returned by subsequent searches. 102 * However, it won't be physically deleted from the cache until its 103 * refcount goes to zero. (If it's a member of a CatCList, the list's 104 * refcount must go to zero, too; also, remember to mark the list dead at 105 * the same time the tuple is marked.) 106 * 107 * A negative cache entry is an assertion that there is no tuple matching 108 * a particular key. This is just as useful as a normal entry so far as 109 * avoiding catalog searches is concerned. Management of positive and 110 * negative entries is identical. 111 */ 112 int refcount; /* number of active references */ 113 bool dead; /* dead but not yet removed? */ 114 bool negative; /* negative cache entry? */ 115 uint32 hash_value; /* hash value for this tuple's keys */ 116 HeapTupleData tuple; /* tuple management header */ 117 } CatCTup; 118 119 120 typedef struct catclist 121 { 122 int cl_magic; /* for identifying CatCList entries */ 123 #define CL_MAGIC 0x52765103 124 CatCache *my_cache; /* link to owning catcache */ 125 126 /* 127 * A CatCList describes the result of a partial search, ie, a search using 128 * only the first K key columns of an N-key cache. We form the keys used 129 * into a tuple (with other attributes NULL) to represent the stored key 130 * set. The CatCList object contains links to cache entries for all the 131 * table rows satisfying the partial key. (Note: none of these will be 132 * negative cache entries.) 133 * 134 * A CatCList is only a member of a per-cache list; we do not currently 135 * divide them into hash buckets. 136 * 137 * A list marked "dead" must not be returned by subsequent searches. 138 * However, it won't be physically deleted from the cache until its 139 * refcount goes to zero. (A list should be marked dead if any of its 140 * member entries are dead.) 141 * 142 * If "ordered" is true then the member tuples appear in the order of the 143 * cache's underlying index. This will be true in normal operation, but 144 * might not be true during bootstrap or recovery operations. (namespace.c 145 * is able to save some cycles when it is true.) 146 */ 147 dlist_node cache_elem; /* list member of per-catcache list */ 148 int refcount; /* number of active references */ 149 bool dead; /* dead but not yet removed? */ 150 bool ordered; /* members listed in index order? */ 151 short nkeys; /* number of lookup keys specified */ 152 uint32 hash_value; /* hash value for lookup keys */ 153 HeapTupleData tuple; /* header for tuple holding keys */ 154 int n_members; /* number of member tuples */ 155 CatCTup *members[FLEXIBLE_ARRAY_MEMBER]; /* members */ 156 } CatCList; 157 158 159 typedef struct catcacheheader 160 { 161 slist_head ch_caches; /* head of list of CatCache structs */ 162 int ch_ntup; /* # of tuples in all caches */ 163 } CatCacheHeader; 164 165 166 /* this extern duplicates utils/memutils.h... */ 167 extern PGDLLIMPORT MemoryContext CacheMemoryContext; 168 169 extern void CreateCacheMemoryContext(void); 170 171 extern CatCache *InitCatCache(int id, Oid reloid, Oid indexoid, 172 int nkeys, const int *key, 173 int nbuckets); 174 extern void InitCatCachePhase2(CatCache *cache, bool touch_index); 175 176 extern HeapTuple SearchCatCache(CatCache *cache, 177 Datum v1, Datum v2, 178 Datum v3, Datum v4); 179 extern void ReleaseCatCache(HeapTuple tuple); 180 181 extern uint32 GetCatCacheHashValue(CatCache *cache, 182 Datum v1, Datum v2, 183 Datum v3, Datum v4); 184 185 extern CatCList *SearchCatCacheList(CatCache *cache, int nkeys, 186 Datum v1, Datum v2, 187 Datum v3, Datum v4); 188 extern void ReleaseCatCacheList(CatCList *list); 189 190 extern void ResetCatalogCaches(void); 191 extern void CatalogCacheFlushCatalog(Oid catId); 192 extern void CatCacheInvalidate(CatCache *cache, uint32 hashValue); 193 extern void PrepareToInvalidateCacheTuple(Relation relation, 194 HeapTuple tuple, 195 HeapTuple newtuple, 196 void (*function) (int, uint32, Oid)); 197 198 extern void PrintCatCacheLeakWarning(HeapTuple tuple); 199 extern void PrintCatCacheListLeakWarning(CatCList *list); 200 201 #endif /* CATCACHE_H */ 202