diff options
Diffstat (limited to 'src/backend/storage/buffer/buf_table.c')
| -rw-r--r-- | src/backend/storage/buffer/buf_table.c | 44 |
1 files changed, 20 insertions, 24 deletions
diff --git a/src/backend/storage/buffer/buf_table.c b/src/backend/storage/buffer/buf_table.c index 33590b65fdb..3829444195b 100644 --- a/src/backend/storage/buffer/buf_table.c +++ b/src/backend/storage/buffer/buf_table.c @@ -3,46 +3,42 @@ * buf_table.c * routines for finding buffers in the buffer pool. * + * NOTE: these days, what this table actually provides is a mapping from + * BufferTags to CDB indexes, not directly to buffers. The function names + * are thus slight misnomers. + * + * Note: all routines in this file assume that the BufMgrLock is held + * by the caller, so no synchronization is needed. + * + * * Portions Copyright (c) 1996-2003, PostgreSQL Global Development Group * Portions Copyright (c) 1994, Regents of the University of California * * * IDENTIFICATION - * $PostgreSQL: pgsql/src/backend/storage/buffer/buf_table.c,v 1.34 2003/12/14 00:34:47 neilc Exp $ + * $PostgreSQL: pgsql/src/backend/storage/buffer/buf_table.c,v 1.35 2004/04/19 23:27:17 tgl Exp $ * *------------------------------------------------------------------------- */ -/* - * OLD COMMENTS - * - * Data Structures: - * - * Buffers are identified by their BufferTag (buf.h). This - * file contains routines for allocating a shmem hash table to - * map buffer tags to buffer descriptors. - * - * Synchronization: - * - * All routines in this file assume BufMgrLock is held by their caller. - */ - #include "postgres.h" #include "storage/buf_internals.h" #include "storage/bufmgr.h" + static HTAB *SharedBufHash; /* * Initialize shmem hash table for mapping buffers + * size is the desired hash table size (2*NBuffers for ARC algorithm) */ void InitBufTable(int size) { HASHCTL info; - /* assume lock is held */ + /* assume no locking is needed yet */ /* BufferTag maps to Buffer */ info.keysize = sizeof(BufferTag); @@ -60,6 +56,7 @@ InitBufTable(int size) /* * BufTableLookup + * Lookup the given BufferTag; return CDB index, or -1 if not found */ int BufTableLookup(BufferTag *tagPtr) @@ -78,10 +75,11 @@ BufTableLookup(BufferTag *tagPtr) } /* - * BufTableDelete + * BufTableInsert + * Insert a hashtable entry for given tag and CDB index */ -bool -BufTableInsert(BufferTag *tagPtr, Buffer buf_id) +void +BufTableInsert(BufferTag *tagPtr, int cdb_id) { BufferLookupEnt *result; bool found; @@ -97,14 +95,14 @@ BufTableInsert(BufferTag *tagPtr, Buffer buf_id) if (found) /* found something else in the table? */ elog(ERROR, "shared buffer hash table corrupted"); - result->id = buf_id; - return TRUE; + result->id = cdb_id; } /* * BufTableDelete + * Delete the hashtable entry for given tag */ -bool +void BufTableDelete(BufferTag *tagPtr) { BufferLookupEnt *result; @@ -114,6 +112,4 @@ BufTableDelete(BufferTag *tagPtr) if (!result) /* shouldn't happen */ elog(ERROR, "shared buffer hash table corrupted"); - - return TRUE; } |