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) 1996-2021, 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 38 /* function computing a datum's hash */ 39 typedef uint32 (*CCHashFN) (Datum datum); 40 41 /* function computing equality of two datums */ 42 typedef bool (*CCFastEqualFN) (Datum a, Datum b); 43 44 typedef struct catcache 45 { 46 int id; /* cache identifier --- see syscache.h */ 47 int cc_nbuckets; /* # of hash buckets in this cache */ 48 TupleDesc cc_tupdesc; /* tuple descriptor (copied from reldesc) */ 49 dlist_head *cc_bucket; /* hash buckets */ 50 CCHashFN cc_hashfunc[CATCACHE_MAXKEYS]; /* hash function for each key */ 51 CCFastEqualFN cc_fastequal[CATCACHE_MAXKEYS]; /* fast equal function for 52 * each key */ 53 int cc_keyno[CATCACHE_MAXKEYS]; /* AttrNumber of each key */ 54 dlist_head cc_lists; /* list of CatCList structs */ 55 int cc_ntup; /* # of tuples currently in this cache */ 56 int cc_nkeys; /* # of keys (1..CATCACHE_MAXKEYS) */ 57 const char *cc_relname; /* name of relation the tuples come from */ 58 Oid cc_reloid; /* OID of relation the tuples come from */ 59 Oid cc_indexoid; /* OID of index matching cache keys */ 60 bool cc_relisshared; /* is relation shared across databases? */ 61 slist_node cc_next; /* list link */ 62 ScanKeyData cc_skey[CATCACHE_MAXKEYS]; /* precomputed key info for heap 63 * scans */ 64 65 /* 66 * Keep these at the end, so that compiling catcache.c with CATCACHE_STATS 67 * doesn't break ABI for other modules 68 */ 69 #ifdef CATCACHE_STATS 70 long cc_searches; /* total # searches against this cache */ 71 long cc_hits; /* # of matches against existing entry */ 72 long cc_neg_hits; /* # of matches against negative entry */ 73 long cc_newloads; /* # of successful loads of new entry */ 74 75 /* 76 * cc_searches - (cc_hits + cc_neg_hits + cc_newloads) is number of failed 77 * searches, each of which will result in loading a negative entry 78 */ 79 long cc_invals; /* # of entries invalidated from cache */ 80 long cc_lsearches; /* total # list-searches */ 81 long cc_lhits; /* # of matches against existing lists */ 82 #endif 83 } CatCache; 84 85 86 typedef struct catctup 87 { 88 int ct_magic; /* for identifying CatCTup entries */ 89 #define CT_MAGIC 0x57261502 90 91 uint32 hash_value; /* hash value for this tuple's keys */ 92 93 /* 94 * Lookup keys for the entry. By-reference datums point into the tuple for 95 * positive cache entries, and are separately allocated for negative ones. 96 */ 97 Datum keys[CATCACHE_MAXKEYS]; 98 99 /* 100 * Each tuple in a cache is a member of a dlist that stores the elements 101 * of its hash bucket. We keep each dlist in LRU order to speed repeated 102 * lookups. 103 */ 104 dlist_node cache_elem; /* list member of per-bucket list */ 105 106 /* 107 * A tuple marked "dead" must not be returned by subsequent searches. 108 * However, it won't be physically deleted from the cache until its 109 * refcount goes to zero. (If it's a member of a CatCList, the list's 110 * refcount must go to zero, too; also, remember to mark the list dead at 111 * the same time the tuple is marked.) 112 * 113 * A negative cache entry is an assertion that there is no tuple matching 114 * a particular key. This is just as useful as a normal entry so far as 115 * avoiding catalog searches is concerned. Management of positive and 116 * negative entries is identical. 117 */ 118 int refcount; /* number of active references */ 119 bool dead; /* dead but not yet removed? */ 120 bool negative; /* negative cache entry? */ 121 HeapTupleData tuple; /* tuple management header */ 122 123 /* 124 * The tuple may also be a member of at most one CatCList. (If a single 125 * catcache is list-searched with varying numbers of keys, we may have to 126 * make multiple entries for the same tuple because of this restriction. 127 * Currently, that's not expected to be common, so we accept the potential 128 * inefficiency.) 129 */ 130 struct catclist *c_list; /* containing CatCList, or NULL if none */ 131 132 CatCache *my_cache; /* link to owning catcache */ 133 /* properly aligned tuple data follows, unless a negative entry */ 134 } CatCTup; 135 136 137 /* 138 * A CatCList describes the result of a partial search, ie, a search using 139 * only the first K key columns of an N-key cache. We store the keys used 140 * into the keys attribute to represent the stored key set. The CatCList 141 * object contains links to cache entries for all the table rows satisfying 142 * the partial key. (Note: none of these will be negative cache entries.) 143 * 144 * A CatCList is only a member of a per-cache list; we do not currently 145 * divide them into hash buckets. 146 * 147 * A list marked "dead" must not be returned by subsequent searches. 148 * However, it won't be physically deleted from the cache until its 149 * refcount goes to zero. (A list should be marked dead if any of its 150 * member entries are dead.) 151 * 152 * If "ordered" is true then the member tuples appear in the order of the 153 * cache's underlying index. This will be true in normal operation, but 154 * might not be true during bootstrap or recovery operations. (namespace.c 155 * is able to save some cycles when it is true.) 156 */ 157 typedef struct catclist 158 { 159 int cl_magic; /* for identifying CatCList entries */ 160 #define CL_MAGIC 0x52765103 161 162 uint32 hash_value; /* hash value for lookup keys */ 163 164 dlist_node cache_elem; /* list member of per-catcache list */ 165 166 /* 167 * Lookup keys for the entry, with the first nkeys elements being valid. 168 * All by-reference are separately allocated. 169 */ 170 Datum keys[CATCACHE_MAXKEYS]; 171 172 int refcount; /* number of active references */ 173 bool dead; /* dead but not yet removed? */ 174 bool ordered; /* members listed in index order? */ 175 short nkeys; /* number of lookup keys specified */ 176 int n_members; /* number of member tuples */ 177 CatCache *my_cache; /* link to owning catcache */ 178 CatCTup *members[FLEXIBLE_ARRAY_MEMBER]; /* members */ 179 } CatCList; 180 181 182 typedef struct catcacheheader 183 { 184 slist_head ch_caches; /* head of list of CatCache structs */ 185 int ch_ntup; /* # of tuples in all caches */ 186 } CatCacheHeader; 187 188 189 /* this extern duplicates utils/memutils.h... */ 190 extern PGDLLIMPORT MemoryContext CacheMemoryContext; 191 192 extern void CreateCacheMemoryContext(void); 193 194 extern CatCache *InitCatCache(int id, Oid reloid, Oid indexoid, 195 int nkeys, const int *key, 196 int nbuckets); 197 extern void InitCatCachePhase2(CatCache *cache, bool touch_index); 198 199 extern HeapTuple SearchCatCache(CatCache *cache, 200 Datum v1, Datum v2, Datum v3, Datum v4); 201 extern HeapTuple SearchCatCache1(CatCache *cache, 202 Datum v1); 203 extern HeapTuple SearchCatCache2(CatCache *cache, 204 Datum v1, Datum v2); 205 extern HeapTuple SearchCatCache3(CatCache *cache, 206 Datum v1, Datum v2, Datum v3); 207 extern HeapTuple SearchCatCache4(CatCache *cache, 208 Datum v1, Datum v2, Datum v3, Datum v4); 209 extern void ReleaseCatCache(HeapTuple tuple); 210 211 extern uint32 GetCatCacheHashValue(CatCache *cache, 212 Datum v1, Datum v2, 213 Datum v3, Datum v4); 214 215 extern CatCList *SearchCatCacheList(CatCache *cache, int nkeys, 216 Datum v1, Datum v2, 217 Datum v3); 218 extern void ReleaseCatCacheList(CatCList *list); 219 220 extern void ResetCatalogCaches(void); 221 extern void CatalogCacheFlushCatalog(Oid catId); 222 extern void CatCacheInvalidate(CatCache *cache, uint32 hashValue); 223 extern void PrepareToInvalidateCacheTuple(Relation relation, 224 HeapTuple tuple, 225 HeapTuple newtuple, 226 void (*function) (int, uint32, Oid)); 227 228 extern void PrintCatCacheLeakWarning(HeapTuple tuple); 229 extern void PrintCatCacheListLeakWarning(CatCList *list); 230 231 #endif /* CATCACHE_H */ 232