Change SearchSysCache coding conventions so that a reference count is

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.

3 files changed, 42 insertions, 18 deletions

diff --git a/src/include/utils/catcache.h b/src/include/utils/catcache.h
index e55b6492d8c..ed78284a478 100644
--- a/src/include/utils/catcache.h
+++ b/src/include/utils/catcache.h
@@ -13,7 +13,7 @@
  * Portions Copyright (c) 1996-2000, PostgreSQL, Inc
  * Portions Copyright (c) 1994, Regents of the University of California
  *
- * $Id: catcache.h,v 1.27 2000/11/10 00:33:12 tgl Exp $
+ * $Id: catcache.h,v 1.28 2000/11/16 22:30:49 tgl Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -32,18 +32,29 @@
 
 typedef struct catctup
 {
-	HeapTuple	ct_tup;			/* A pointer to a tuple */
+	int			ct_magic;		/* for Assert checks */
+#define CT_MAGIC   0x57261502
+
 	/*
-	 * Each tuple in the cache has two catctup items, one in the LRU list
-	 * and one in the hashbucket list for its hash value.  ct_node in each
-	 * one points to the other one.
+	 * Each tuple in a cache is a member of two lists: one lists all the
+	 * elements in that cache in LRU order, and the other lists just the
+	 * elements in one hashbucket, also in LRU order.
+	 *
+	 * A tuple marked "dead" must not be returned by subsequent searches.
+	 * However, it won't be physically deleted from the cache until its
+	 * refcount goes to zero.
 	 */
-	Dlelem	   *ct_node;		/* the other catctup for this tuple */
+	Dlelem		lrulist_elem;	/* list member of global LRU list */
+	Dlelem		cache_elem;		/* list member of per-bucket list */
+	int			refcount;		/* number of active references */
+	bool		dead;			/* dead but not yet removed? */
+	HeapTupleData tuple;		/* tuple management header */
 } CatCTup;
 
+
 /* voodoo constants */
 #define NCCBUCK 500				/* CatCache buckets */
-#define MAXTUP 300				/* Maximum # of tuples stored per cache */
+#define MAXTUP 500				/* Maximum # of tuples stored per cache */
 
 
 typedef struct catcache
@@ -60,8 +71,8 @@ typedef struct catcache
 	short		cc_key[4];		/* AttrNumber of each key */
 	PGFunction	cc_hashfunc[4]; /* hash function to use for each key */
 	ScanKeyData cc_skey[4];		/* precomputed key info for indexscans */
-	Dllist	   *cc_lrulist;		/* LRU list, most recent first */
-	Dllist	   *cc_cache[NCCBUCK + 1];	/* hash buckets */
+	Dllist		cc_lrulist;		/* overall LRU list, most recent first */
+	Dllist		cc_cache[NCCBUCK]; /* hash buckets */
 } CatCache;
 
 #define InvalidCatalogCacheId	(-1)
@@ -70,12 +81,15 @@ typedef struct catcache
 extern MemoryContext CacheMemoryContext;
 
 extern void CreateCacheMemoryContext(void);
+extern void AtEOXact_CatCache(bool isCommit);
 
-extern CatCache *InitSysCache(int id, char *relname, char *indname,
+extern CatCache *InitCatCache(int id, char *relname, char *indname,
 							  int nkeys, int *key);
-extern HeapTuple SearchSysCache(CatCache *cache,
+
+extern HeapTuple SearchCatCache(CatCache *cache,
 								Datum v1, Datum v2,
 								Datum v3, Datum v4);
+extern void ReleaseCatCache(HeapTuple tuple);
 
 extern void ResetSystemCache(void);
 extern void SystemCacheRelationFlushed(Oid relId);
diff --git a/src/include/utils/lsyscache.h b/src/include/utils/lsyscache.h
index 516949d1de9..f8547baa884 100644
--- a/src/include/utils/lsyscache.h
+++ b/src/include/utils/lsyscache.h
@@ -6,7 +6,7 @@
  * Portions Copyright (c) 1996-2000, PostgreSQL, Inc
  * Portions Copyright (c) 1994, Regents of the University of California
  *
- * $Id: lsyscache.h,v 1.26 2000/10/05 19:48:34 momjian Exp $
+ * $Id: lsyscache.h,v 1.27 2000/11/16 22:30:49 tgl Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -29,7 +29,6 @@ extern bool op_mergejoinable(Oid opno, Oid ltype, Oid rtype,
 				 Oid *leftOp, Oid *rightOp);
 extern Oid	op_hashjoinable(Oid opno, Oid ltype, Oid rtype);
 extern bool op_iscachable(Oid opno);
-extern HeapTuple get_operator_tuple(Oid opno);
 extern Oid	get_commutator(Oid opno);
 extern Oid	get_negator(Oid opno);
 extern RegProcedure get_oprrest(Oid opno);
@@ -39,6 +38,7 @@ extern bool func_iscachable(Oid funcid);
 extern char *get_rel_name(Oid relid);
 extern int16 get_typlen(Oid typid);
 extern bool get_typbyval(Oid typid);
+extern void get_typlenbyval(Oid typid, int16 *typlen, bool *typbyval);
 extern Datum get_typdefault(Oid typid);
 
 #endif	 /* LSYSCACHE_H */
diff --git a/src/include/utils/syscache.h b/src/include/utils/syscache.h
index 5d17e8db44c..73abd53e134 100644
--- a/src/include/utils/syscache.h
+++ b/src/include/utils/syscache.h
@@ -9,7 +9,7 @@
  * Portions Copyright (c) 1996-2000, PostgreSQL, Inc
  * Portions Copyright (c) 1994, Regents of the University of California
  *
- * $Id: syscache.h,v 1.26 2000/06/17 04:56:29 tgl Exp $
+ * $Id: syscache.h,v 1.27 2000/11/16 22:30:49 tgl Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -57,12 +57,22 @@
 #define TYPENAME		26
 #define TYPEOID			27
 
-extern void zerocaches(void);
 extern void InitCatalogCache(void);
-extern HeapTuple SearchSysCacheTuple(int cacheId,
+
+extern HeapTuple SearchSysCache(int cacheId,
+					Datum key1, Datum key2, Datum key3, Datum key4);
+extern void ReleaseSysCache(HeapTuple tuple);
+
+/* convenience routines */
+extern HeapTuple SearchSysCacheCopy(int cacheId,
 					Datum key1, Datum key2, Datum key3, Datum key4);
-extern HeapTuple SearchSysCacheTupleCopy(int cacheId,
-						Datum key1, Datum key2, Datum key3, Datum key4);
+extern Oid GetSysCacheOid(int cacheId,
+					Datum key1, Datum key2, Datum key3, Datum key4);
+
+/* macro for just probing for existence of a tuple via the syscache */
+#define SearchSysCacheExists(c,k1,k2,k3,k4)  \
+	OidIsValid(GetSysCacheOid(c,k1,k2,k3,k4))
+
 extern Datum SysCacheGetAttr(int cacheId, HeapTuple tup,
 				AttrNumber attributeNumber, bool *isNull);