Split the buffer mapping table into multiple separately lockable
partitions, as per discussion. Passes functionality checks, but I don't have any performance data yet.
This commit is contained in:
Tom Lane
parent
51ee9fa157
commit
10b9ca3d05
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@ -3,7 +3,7 @@
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* pg_buffercache_pages.c
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* display some contents of the buffer cache
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*
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* $PostgreSQL: pgsql/contrib/pg_buffercache/pg_buffercache_pages.c,v 1.7 2006/05/30 22:12:13 tgl Exp $
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* $PostgreSQL: pgsql/contrib/pg_buffercache/pg_buffercache_pages.c,v 1.8 2006/07/23 03:07:57 tgl Exp $
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*-------------------------------------------------------------------------
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*/
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#include "postgres.h"
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@ -74,7 +74,7 @@ pg_buffercache_pages(PG_FUNCTION_ARGS)
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if (SRF_IS_FIRSTCALL())
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{
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uint32 i;
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int i;
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volatile BufferDesc *bufHdr;
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funcctx = SRF_FIRSTCALL_INIT();
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@ -108,7 +108,6 @@ pg_buffercache_pages(PG_FUNCTION_ARGS)
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funcctx->max_calls = NBuffers;
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funcctx->user_fctx = fctx;
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/* Allocate NBuffers worth of BufferCachePagesRec records. */
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fctx->record = (BufferCachePagesRec *) palloc(sizeof(BufferCachePagesRec) * NBuffers);
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@ -120,17 +119,21 @@ pg_buffercache_pages(PG_FUNCTION_ARGS)
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fctx->values[4] = (char *) palloc(3 * sizeof(uint32) + 1);
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fctx->values[5] = (char *) palloc(2);
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/* Return to original context when allocating transient memory */
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MemoryContextSwitchTo(oldcontext);
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/*
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* To get a consistent picture of the buffer state, we must lock
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* all partitions of the buffer map. Needless to say, this is
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* horrible for concurrency...
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*/
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for (i = 0; i < NUM_BUFFER_PARTITIONS; i++)
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LWLockAcquire(FirstBufMappingLock + i, LW_SHARED);
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/*
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* Lock Buffer map and scan though all the buffers, saving the
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* relevant fields in the fctx->record structure.
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* Scan though all the buffers, saving the relevant fields in the
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* fctx->record structure.
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*/
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LWLockAcquire(BufMappingLock, LW_SHARED);
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for (i = 0, bufHdr = BufferDescriptors; i < NBuffers; i++, bufHdr++)
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{
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/* Lock each buffer header before inspecting. */
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@ -157,7 +160,8 @@ pg_buffercache_pages(PG_FUNCTION_ARGS)
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}
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/* Release Buffer map. */
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LWLockRelease(BufMappingLock);
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for (i = 0; i < NUM_BUFFER_PARTITIONS; i++)
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LWLockRelease(FirstBufMappingLock + i);
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}
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funcctx = SRF_PERCALL_SETUP();
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@ -165,7 +169,6 @@ pg_buffercache_pages(PG_FUNCTION_ARGS)
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/* Get the saved state */
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fctx = funcctx->user_fctx;
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if (funcctx->call_cntr < funcctx->max_calls)
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{
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uint32 i = funcctx->call_cntr;
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@ -1,4 +1,4 @@
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$PostgreSQL: pgsql/src/backend/storage/buffer/README,v 1.10 2006/06/08 14:58:33 tgl Exp $
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$PostgreSQL: pgsql/src/backend/storage/buffer/README,v 1.11 2006/07/23 03:07:58 tgl Exp $
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Notes about shared buffer access rules
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--------------------------------------
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@ -114,6 +114,14 @@ operation that needs exclusive lock is reading in a page that was not
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in shared buffers already, which will require at least a kernel call
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and usually a wait for I/O, so it will be slow anyway.
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* As of PG 8.2, the BufMappingLock has been split into NUM_BUFFER_PARTITIONS
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separate locks, each guarding a portion of the buffer tag space. This allows
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further reduction of contention in the normal code paths. The partition
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that a particular buffer tag belongs to is determined from the low-order
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bits of the tag's hash value. The rules stated above apply to each partition
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independently. If it is necessary to lock more than one partition at a time,
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they must be locked in partition-number order to avoid risk of deadlock.
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* A separate system-wide LWLock, the BufFreelistLock, provides mutual
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exclusion for operations that access the buffer free list or select
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buffers for replacement. This is always taken in exclusive mode since
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@ -4,8 +4,10 @@
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* routines for mapping BufferTags to buffer indexes.
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*
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* Note: the routines in this file do no locking of their own. The caller
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* must hold a suitable lock on the BufMappingLock, as specified in the
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* comments.
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* must hold a suitable lock on the appropriate BufMappingLock, as specified
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* in the comments. We can't do the locking inside these functions because
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* in most cases the caller needs to adjust the buffer header contents
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* before the lock is released (see notes in README).
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*
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*
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* Portions Copyright (c) 1996-2006, PostgreSQL Global Development Group
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@ -13,7 +15,7 @@
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*
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*
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* IDENTIFICATION
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* $PostgreSQL: pgsql/src/backend/storage/buffer/buf_table.c,v 1.46 2006/07/14 16:59:19 tgl Exp $
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* $PostgreSQL: pgsql/src/backend/storage/buffer/buf_table.c,v 1.47 2006/07/23 03:07:58 tgl Exp $
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*
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*-------------------------------------------------------------------------
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*/
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@ -58,29 +60,49 @@ InitBufTable(int size)
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info.keysize = sizeof(BufferTag);
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info.entrysize = sizeof(BufferLookupEnt);
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info.hash = tag_hash;
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info.num_partitions = NUM_BUFFER_PARTITIONS;
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SharedBufHash = ShmemInitHash("Shared Buffer Lookup Table",
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size, size,
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&info,
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HASH_ELEM | HASH_FUNCTION);
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HASH_ELEM | HASH_FUNCTION | HASH_PARTITION);
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if (!SharedBufHash)
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elog(FATAL, "could not initialize shared buffer hash table");
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}
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/*
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* BufTableHashCode
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* Compute the hash code associated with a BufferTag
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*
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* This must be passed to the lookup/insert/delete routines along with the
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* tag. We do it like this because the callers need to know the hash code
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* in order to determine which buffer partition to lock, and we don't want
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* to do the hash computation twice (hash_any is a bit slow).
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*/
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uint32
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BufTableHashCode(BufferTag *tagPtr)
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{
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return get_hash_value(SharedBufHash, (void *) tagPtr);
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}
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/*
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* BufTableLookup
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* Lookup the given BufferTag; return buffer ID, or -1 if not found
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*
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* Caller must hold at least share lock on BufMappingLock
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* Caller must hold at least share lock on BufMappingLock for tag's partition
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*/
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int
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BufTableLookup(BufferTag *tagPtr)
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BufTableLookup(BufferTag *tagPtr, uint32 hashcode)
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{
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BufferLookupEnt *result;
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result = (BufferLookupEnt *)
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hash_search(SharedBufHash, (void *) tagPtr, HASH_FIND, NULL);
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hash_search_with_hash_value(SharedBufHash,
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(void *) tagPtr,
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hashcode,
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HASH_FIND,
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NULL);
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if (!result)
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return -1;
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* Returns -1 on successful insertion. If a conflicting entry exists
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* already, returns the buffer ID in that entry.
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*
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* Caller must hold write lock on BufMappingLock
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* Caller must hold exclusive lock on BufMappingLock for tag's partition
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*/
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int
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BufTableInsert(BufferTag *tagPtr, int buf_id)
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BufTableInsert(BufferTag *tagPtr, uint32 hashcode, int buf_id)
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{
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BufferLookupEnt *result;
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bool found;
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@ -108,7 +130,11 @@ BufTableInsert(BufferTag *tagPtr, int buf_id)
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Assert(tagPtr->blockNum != P_NEW); /* invalid tag */
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result = (BufferLookupEnt *)
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hash_search(SharedBufHash, (void *) tagPtr, HASH_ENTER, &found);
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hash_search_with_hash_value(SharedBufHash,
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(void *) tagPtr,
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hashcode,
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HASH_ENTER,
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&found);
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if (found) /* found something already in the table */
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return result->id;
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@ -122,15 +148,19 @@ BufTableInsert(BufferTag *tagPtr, int buf_id)
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* BufTableDelete
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* Delete the hashtable entry for given tag (which must exist)
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*
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* Caller must hold write lock on BufMappingLock
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* Caller must hold exclusive lock on BufMappingLock for tag's partition
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*/
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void
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BufTableDelete(BufferTag *tagPtr)
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BufTableDelete(BufferTag *tagPtr, uint32 hashcode)
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{
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BufferLookupEnt *result;
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result = (BufferLookupEnt *)
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hash_search(SharedBufHash, (void *) tagPtr, HASH_REMOVE, NULL);
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hash_search_with_hash_value(SharedBufHash,
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(void *) tagPtr,
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hashcode,
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HASH_REMOVE,
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NULL);
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if (!result) /* shouldn't happen */
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elog(ERROR, "shared buffer hash table corrupted");
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@ -8,7 +8,7 @@
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*
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*
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* IDENTIFICATION
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* $PostgreSQL: pgsql/src/backend/storage/buffer/bufmgr.c,v 1.208 2006/07/14 14:52:22 momjian Exp $
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* $PostgreSQL: pgsql/src/backend/storage/buffer/bufmgr.c,v 1.209 2006/07/23 03:07:58 tgl Exp $
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*
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*-------------------------------------------------------------------------
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*/
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@ -293,7 +293,11 @@ BufferAlloc(Relation reln,
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bool *foundPtr)
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{
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BufferTag newTag; /* identity of requested block */
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BufferTag oldTag;
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uint32 newHash; /* hash value for newTag */
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LWLockId newPartitionLock; /* buffer partition lock for it */
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BufferTag oldTag; /* previous identity of selected buffer */
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uint32 oldHash; /* hash value for oldTag */
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LWLockId oldPartitionLock; /* buffer partition lock for it */
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BufFlags oldFlags;
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int buf_id;
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volatile BufferDesc *buf;
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@ -302,9 +306,13 @@ BufferAlloc(Relation reln,
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/* create a tag so we can lookup the buffer */
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INIT_BUFFERTAG(newTag, reln, blockNum);
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/* determine its hash code and partition lock ID */
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newHash = BufTableHashCode(&newTag);
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newPartitionLock = BufMappingPartitionLock(newHash);
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/* see if the block is in the buffer pool already */
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LWLockAcquire(BufMappingLock, LW_SHARED);
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buf_id = BufTableLookup(&newTag);
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LWLockAcquire(newPartitionLock, LW_SHARED);
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buf_id = BufTableLookup(&newTag, newHash);
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if (buf_id >= 0)
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{
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/*
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@ -317,7 +325,7 @@ BufferAlloc(Relation reln,
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valid = PinBuffer(buf);
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/* Can release the mapping lock as soon as we've pinned it */
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LWLockRelease(BufMappingLock);
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LWLockRelease(newPartitionLock);
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*foundPtr = TRUE;
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@ -345,9 +353,9 @@ BufferAlloc(Relation reln,
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/*
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* Didn't find it in the buffer pool. We'll have to initialize a new
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* buffer. Remember to unlock BufMappingLock while doing the work.
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* buffer. Remember to unlock the mapping lock while doing the work.
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*/
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LWLockRelease(BufMappingLock);
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LWLockRelease(newPartitionLock);
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/* Loop here in case we have to try another victim buffer */
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for (;;)
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@ -412,10 +420,48 @@ BufferAlloc(Relation reln,
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}
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/*
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* Acquire exclusive mapping lock in preparation for changing the
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* buffer's association.
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* To change the association of a valid buffer, we'll need to have
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* exclusive lock on both the old and new mapping partitions.
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*/
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LWLockAcquire(BufMappingLock, LW_EXCLUSIVE);
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if (oldFlags & BM_TAG_VALID)
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{
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/*
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* Need to compute the old tag's hashcode and partition lock ID.
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* XXX is it worth storing the hashcode in BufferDesc so we need
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* not recompute it here? Probably not.
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*/
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oldTag = buf->tag;
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oldHash = BufTableHashCode(&oldTag);
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oldPartitionLock = BufMappingPartitionLock(oldHash);
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/*
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* Must lock the lower-numbered partition first to avoid
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* deadlocks.
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*/
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if (oldPartitionLock < newPartitionLock)
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{
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LWLockAcquire(oldPartitionLock, LW_EXCLUSIVE);
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LWLockAcquire(newPartitionLock, LW_EXCLUSIVE);
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}
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else if (oldPartitionLock > newPartitionLock)
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{
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LWLockAcquire(newPartitionLock, LW_EXCLUSIVE);
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LWLockAcquire(oldPartitionLock, LW_EXCLUSIVE);
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}
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else
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{
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/* only one partition, only one lock */
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LWLockAcquire(newPartitionLock, LW_EXCLUSIVE);
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}
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}
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else
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{
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/* if it wasn't valid, we need only the new partition */
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LWLockAcquire(newPartitionLock, LW_EXCLUSIVE);
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/* these just keep the compiler quiet about uninit variables */
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oldHash = 0;
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oldPartitionLock = 0;
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}
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/*
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* Try to make a hashtable entry for the buffer under its new tag.
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@ -424,7 +470,7 @@ BufferAlloc(Relation reln,
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* Note that we have not yet removed the hashtable entry for the old
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* tag.
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*/
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buf_id = BufTableInsert(&newTag, buf->buf_id);
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buf_id = BufTableInsert(&newTag, newHash, buf->buf_id);
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if (buf_id >= 0)
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{
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@ -433,10 +479,15 @@ BufferAlloc(Relation reln,
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* do. We'll just handle this as if it were found in the buffer
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* pool in the first place. First, give up the buffer we were
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* planning to use. Don't allow it to be thrown in the free list
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* (we don't want to hold both global locks at once).
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* (we don't want to hold freelist and mapping locks at once).
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*/
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UnpinBuffer(buf, true, false);
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/* Can give up that buffer's mapping partition lock now */
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if ((oldFlags & BM_TAG_VALID) &&
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oldPartitionLock != newPartitionLock)
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LWLockRelease(oldPartitionLock);
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/* remaining code should match code at top of routine */
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buf = &BufferDescriptors[buf_id];
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@ -444,7 +495,7 @@ BufferAlloc(Relation reln,
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valid = PinBuffer(buf);
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/* Can release the mapping lock as soon as we've pinned it */
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LWLockRelease(BufMappingLock);
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LWLockRelease(newPartitionLock);
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*foundPtr = TRUE;
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|
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|
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@ -481,12 +532,16 @@ BufferAlloc(Relation reln,
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* recycle this buffer; we must undo everything we've done and start
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* over with a new victim buffer.
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*/
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if (buf->refcount == 1 && !(buf->flags & BM_DIRTY))
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oldFlags = buf->flags;
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if (buf->refcount == 1 && !(oldFlags & BM_DIRTY))
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break;
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UnlockBufHdr(buf);
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BufTableDelete(&newTag);
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LWLockRelease(BufMappingLock);
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BufTableDelete(&newTag, newHash);
|
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if ((oldFlags & BM_TAG_VALID) &&
|
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oldPartitionLock != newPartitionLock)
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LWLockRelease(oldPartitionLock);
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LWLockRelease(newPartitionLock);
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UnpinBuffer(buf, true, false /* evidently recently used */ );
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}
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|
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|
|
@ -497,8 +552,6 @@ BufferAlloc(Relation reln,
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* paranoia. We also clear the usage_count since any recency of use of
|
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* the old content is no longer relevant.
|
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*/
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oldTag = buf->tag;
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oldFlags = buf->flags;
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buf->tag = newTag;
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buf->flags &= ~(BM_VALID | BM_DIRTY | BM_JUST_DIRTIED | BM_IO_ERROR);
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buf->flags |= BM_TAG_VALID;
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|
|
@ -507,9 +560,13 @@ BufferAlloc(Relation reln,
|
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UnlockBufHdr(buf);
|
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|
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if (oldFlags & BM_TAG_VALID)
|
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BufTableDelete(&oldTag);
|
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{
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BufTableDelete(&oldTag, oldHash);
|
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if (oldPartitionLock != newPartitionLock)
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LWLockRelease(oldPartitionLock);
|
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}
|
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|
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LWLockRelease(BufMappingLock);
|
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LWLockRelease(newPartitionLock);
|
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|
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/*
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* Buffer contents are currently invalid. Try to get the io_in_progress
|
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|
|
@ -545,6 +602,8 @@ static void
|
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InvalidateBuffer(volatile BufferDesc *buf)
|
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{
|
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BufferTag oldTag;
|
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uint32 oldHash; /* hash value for oldTag */
|
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LWLockId oldPartitionLock; /* buffer partition lock for it */
|
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BufFlags oldFlags;
|
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|
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/* Save the original buffer tag before dropping the spinlock */
|
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|
|
@ -552,13 +611,21 @@ InvalidateBuffer(volatile BufferDesc *buf)
|
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|
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UnlockBufHdr(buf);
|
||||
|
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/*
|
||||
* Need to compute the old tag's hashcode and partition lock ID.
|
||||
* XXX is it worth storing the hashcode in BufferDesc so we need
|
||||
* not recompute it here? Probably not.
|
||||
*/
|
||||
oldHash = BufTableHashCode(&oldTag);
|
||||
oldPartitionLock = BufMappingPartitionLock(oldHash);
|
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|
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retry:
|
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|
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/*
|
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* Acquire exclusive mapping lock in preparation for changing the buffer's
|
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* association.
|
||||
*/
|
||||
LWLockAcquire(BufMappingLock, LW_EXCLUSIVE);
|
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LWLockAcquire(oldPartitionLock, LW_EXCLUSIVE);
|
||||
|
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/* Re-lock the buffer header */
|
||||
LockBufHdr(buf);
|
||||
|
|
@ -567,7 +634,7 @@ retry:
|
|||
if (!BUFFERTAGS_EQUAL(buf->tag, oldTag))
|
||||
{
|
||||
UnlockBufHdr(buf);
|
||||
LWLockRelease(BufMappingLock);
|
||||
LWLockRelease(oldPartitionLock);
|
||||
return;
|
||||
}
|
||||
|
||||
|
|
@ -583,7 +650,7 @@ retry:
|
|||
if (buf->refcount != 0)
|
||||
{
|
||||
UnlockBufHdr(buf);
|
||||
LWLockRelease(BufMappingLock);
|
||||
LWLockRelease(oldPartitionLock);
|
||||
/* safety check: should definitely not be our *own* pin */
|
||||
if (PrivateRefCount[buf->buf_id] != 0)
|
||||
elog(ERROR, "buffer is pinned in InvalidateBuffer");
|
||||
|
|
@ -606,7 +673,7 @@ retry:
|
|||
* Remove the buffer from the lookup hashtable, if it was in there.
|
||||
*/
|
||||
if (oldFlags & BM_TAG_VALID)
|
||||
BufTableDelete(&oldTag);
|
||||
BufTableDelete(&oldTag, oldHash);
|
||||
|
||||
/*
|
||||
* Avoid accepting a cancel interrupt when we release the mapping lock;
|
||||
|
|
@ -616,7 +683,7 @@ retry:
|
|||
*/
|
||||
HOLD_INTERRUPTS();
|
||||
|
||||
LWLockRelease(BufMappingLock);
|
||||
LWLockRelease(oldPartitionLock);
|
||||
|
||||
/*
|
||||
* Insert the buffer at the head of the list of free buffers.
|
||||
|
|
|
|||
|
|
@ -15,7 +15,7 @@
|
|||
* Portions Copyright (c) 1994, Regents of the University of California
|
||||
*
|
||||
* IDENTIFICATION
|
||||
* $PostgreSQL: pgsql/src/backend/storage/lmgr/lwlock.c,v 1.40 2006/07/14 14:52:23 momjian Exp $
|
||||
* $PostgreSQL: pgsql/src/backend/storage/lmgr/lwlock.c,v 1.41 2006/07/23 03:07:58 tgl Exp $
|
||||
*
|
||||
*-------------------------------------------------------------------------
|
||||
*/
|
||||
|
|
@ -157,10 +157,7 @@ NumLWLocks(void)
|
|||
*/
|
||||
|
||||
/* Predefined LWLocks */
|
||||
numLocks = (int) FirstLockMgrLock;
|
||||
|
||||
/* lock.c gets the ones starting at FirstLockMgrLock */
|
||||
numLocks += NUM_LOCK_PARTITIONS;
|
||||
numLocks = (int) NumFixedLWLocks;
|
||||
|
||||
/* bufmgr.c needs two for each shared buffer */
|
||||
numLocks += 2 * NBuffers;
|
||||
|
|
@ -239,11 +236,10 @@ CreateLWLocks(void)
|
|||
|
||||
/*
|
||||
* Initialize the dynamic-allocation counter, which is stored just before
|
||||
* the first LWLock. The LWLocks used by lock.c are not dynamically
|
||||
* allocated, it just assumes it has them.
|
||||
* the first LWLock.
|
||||
*/
|
||||
LWLockCounter = (int *) ((char *) LWLockArray - 2 * sizeof(int));
|
||||
LWLockCounter[0] = (int) FirstLockMgrLock + NUM_LOCK_PARTITIONS;
|
||||
LWLockCounter[0] = (int) NumFixedLWLocks;
|
||||
LWLockCounter[1] = numLocks;
|
||||
}
|
||||
|
||||
|
|
|
|||
|
|
@ -8,7 +8,7 @@
|
|||
* Portions Copyright (c) 1996-2006, PostgreSQL Global Development Group
|
||||
* Portions Copyright (c) 1994, Regents of the University of California
|
||||
*
|
||||
* $PostgreSQL: pgsql/src/include/storage/buf_internals.h,v 1.86 2006/03/31 23:32:07 tgl Exp $
|
||||
* $PostgreSQL: pgsql/src/include/storage/buf_internals.h,v 1.87 2006/07/23 03:07:58 tgl Exp $
|
||||
*
|
||||
*-------------------------------------------------------------------------
|
||||
*/
|
||||
|
|
@ -86,6 +86,17 @@ typedef struct buftag
|
|||
(a).blockNum == (b).blockNum \
|
||||
)
|
||||
|
||||
/*
|
||||
* The shared buffer mapping table is partitioned to reduce contention.
|
||||
* To determine which partition lock a given tag requires, compute the tag's
|
||||
* hash code with BufTableHashCode(), then apply BufMappingPartitionLock().
|
||||
* NB: NUM_BUFFER_PARTITIONS must be a power of 2!
|
||||
*/
|
||||
#define BufTableHashPartition(hashcode) \
|
||||
((hashcode) % NUM_BUFFER_PARTITIONS)
|
||||
#define BufMappingPartitionLock(hashcode) \
|
||||
((LWLockId) (FirstBufMappingLock + BufTableHashPartition(hashcode)))
|
||||
|
||||
/*
|
||||
* BufferDesc -- shared descriptor/state data for a single shared buffer.
|
||||
*
|
||||
|
|
@ -182,9 +193,10 @@ extern void StrategyInitialize(bool init);
|
|||
/* buf_table.c */
|
||||
extern Size BufTableShmemSize(int size);
|
||||
extern void InitBufTable(int size);
|
||||
extern int BufTableLookup(BufferTag *tagPtr);
|
||||
extern int BufTableInsert(BufferTag *tagPtr, int buf_id);
|
||||
extern void BufTableDelete(BufferTag *tagPtr);
|
||||
extern uint32 BufTableHashCode(BufferTag *tagPtr);
|
||||
extern int BufTableLookup(BufferTag *tagPtr, uint32 hashcode);
|
||||
extern int BufTableInsert(BufferTag *tagPtr, uint32 hashcode, int buf_id);
|
||||
extern void BufTableDelete(BufferTag *tagPtr, uint32 hashcode);
|
||||
|
||||
/* localbuf.c */
|
||||
extern BufferDesc *LocalBufferAlloc(Relation reln, BlockNumber blockNum,
|
||||
|
|
|
|||
|
|
@ -7,7 +7,7 @@
|
|||
* Portions Copyright (c) 1996-2006, PostgreSQL Global Development Group
|
||||
* Portions Copyright (c) 1994, Regents of the University of California
|
||||
*
|
||||
* $PostgreSQL: pgsql/src/include/storage/lock.h,v 1.94 2006/03/05 15:58:59 momjian Exp $
|
||||
* $PostgreSQL: pgsql/src/include/storage/lock.h,v 1.95 2006/07/23 03:07:58 tgl Exp $
|
||||
*
|
||||
*-------------------------------------------------------------------------
|
||||
*/
|
||||
|
|
@ -19,23 +19,15 @@
|
|||
#include "storage/shmem.h"
|
||||
|
||||
|
||||
/*
|
||||
* Number of partitions the shared lock tables are divided into.
|
||||
*
|
||||
* See LockTagToPartition() if you change this.
|
||||
*/
|
||||
#define NUM_LOCK_PARTITIONS 16
|
||||
/* struct PGPROC is declared in proc.h, but must forward-reference it */
|
||||
typedef struct PGPROC PGPROC;
|
||||
|
||||
/* originally in procq.h */
|
||||
typedef struct PROC_QUEUE
|
||||
{
|
||||
SHM_QUEUE links; /* head of list of PGPROC objects */
|
||||
int size; /* number of entries in list */
|
||||
} PROC_QUEUE;
|
||||
|
||||
/* struct PGPROC is declared in proc.h, but must forward-reference it */
|
||||
typedef struct PGPROC PGPROC;
|
||||
|
||||
/* GUC variables */
|
||||
extern int max_locks_per_xact;
|
||||
|
||||
|
|
|
|||
|
|
@ -7,13 +7,25 @@
|
|||
* Portions Copyright (c) 1996-2006, PostgreSQL Global Development Group
|
||||
* Portions Copyright (c) 1994, Regents of the University of California
|
||||
*
|
||||
* $PostgreSQL: pgsql/src/include/storage/lwlock.h,v 1.28 2006/05/08 00:00:17 tgl Exp $
|
||||
* $PostgreSQL: pgsql/src/include/storage/lwlock.h,v 1.29 2006/07/23 03:07:58 tgl Exp $
|
||||
*
|
||||
*-------------------------------------------------------------------------
|
||||
*/
|
||||
#ifndef LWLOCK_H
|
||||
#define LWLOCK_H
|
||||
|
||||
/*
|
||||
* It's a bit odd to declare NUM_BUFFER_PARTITIONS and NUM_LOCK_PARTITIONS
|
||||
* here, but we need them to set up enum LWLockId correctly, and having
|
||||
* this file include lock.h or bufmgr.h would be backwards.
|
||||
*/
|
||||
|
||||
/* Number of partitions of the shared buffer mapping hashtable */
|
||||
#define NUM_BUFFER_PARTITIONS 16
|
||||
|
||||
/* Number of partitions the shared lock tables are divided into */
|
||||
#define NUM_LOCK_PARTITIONS 16
|
||||
|
||||
/*
|
||||
* We have a number of predefined LWLocks, plus a bunch of LWLocks that are
|
||||
* dynamically assigned (e.g., for shared buffers). The LWLock structures
|
||||
|
|
@ -25,7 +37,6 @@
|
|||
*/
|
||||
typedef enum LWLockId
|
||||
{
|
||||
BufMappingLock,
|
||||
BufFreelistLock,
|
||||
ShmemIndexLock,
|
||||
OidGenLock,
|
||||
|
|
@ -48,7 +59,11 @@ typedef enum LWLockId
|
|||
TwoPhaseStateLock,
|
||||
TablespaceCreateLock,
|
||||
BtreeVacuumLock,
|
||||
FirstLockMgrLock, /* must be last except for MaxDynamicLWLock */
|
||||
FirstBufMappingLock,
|
||||
FirstLockMgrLock = FirstBufMappingLock + NUM_BUFFER_PARTITIONS,
|
||||
|
||||
/* must be last except for MaxDynamicLWLock: */
|
||||
NumFixedLWLocks = FirstLockMgrLock + NUM_LOCK_PARTITIONS,
|
||||
|
||||
MaxDynamicLWLock = 1000000000
|
||||
} LWLockId;
|
||||
|
|
|
|||
Loading…
Reference in New Issue