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290 lines
7.1 KiB
C
290 lines
7.1 KiB
C
/*-------------------------------------------------------------------------
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*
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* localbuf.c--
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* local buffer manager. Fast buffer manager for temporary tables
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* or special cases when the operation is not visible to other backends.
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*
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* When a relation is being created, the descriptor will have rd_islocal
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* set to indicate that the local buffer manager should be used. During
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* the same transaction the relation is being created, any inserts or
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* selects from the newly created relation will use the local buffer
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* pool. rd_islocal is reset at the end of a transaction (commit/abort).
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* This is useful for queries like SELECT INTO TABLE and create index.
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*
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* Copyright (c) 1994-5, Regents of the University of California
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*
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*
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* IDENTIFICATION
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* $Header: /cvsroot/pgsql/src/backend/storage/buffer/localbuf.c,v 1.5 1997/01/16 08:13:14 vadim Exp $
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*
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*-------------------------------------------------------------------------
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*/
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#include <sys/file.h>
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#include <stdio.h>
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#include <string.h>
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#include <math.h>
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#include <signal.h>
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#include "postgres.h"
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/* declarations split between these three files */
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#include "storage/buf.h"
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#include "storage/buf_internals.h"
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#include "storage/bufmgr.h"
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#include "storage/fd.h"
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#include "storage/ipc.h"
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#include "storage/shmem.h"
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#include "storage/spin.h"
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#include "storage/smgr.h"
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#include "storage/lmgr.h"
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#include "storage/buf_internals.h"
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#include "miscadmin.h"
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#include "utils/builtins.h"
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#include "utils/hsearch.h"
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#include "utils/memutils.h"
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#include "utils/relcache.h"
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#include "executor/execdebug.h" /* for NDirectFileRead */
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#include "catalog/catalog.h"
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int NLocBuffer = 64;
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BufferDesc *LocalBufferDescriptors = NULL;
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long *LocalRefCount = NULL;
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static int nextFreeLocalBuf = 0;
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/*#define LBDEBUG*/
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/*
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* LocalBufferAlloc -
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* allocate a local buffer. We do round robin allocation for now.
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*/
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BufferDesc *
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LocalBufferAlloc(Relation reln, BlockNumber blockNum, bool *foundPtr)
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{
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int i;
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BufferDesc *bufHdr = (BufferDesc *) NULL;
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if (blockNum == P_NEW) {
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blockNum = reln->rd_nblocks;
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reln->rd_nblocks++;
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}
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/* a low tech search for now -- not optimized for scans */
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for (i=0; i < NLocBuffer; i++) {
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if (LocalBufferDescriptors[i].tag.relId.relId == reln->rd_id &&
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LocalBufferDescriptors[i].tag.blockNum == blockNum) {
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#ifdef LBDEBUG
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fprintf(stderr, "LB ALLOC (%d,%d) %d\n",
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reln->rd_id, blockNum, -i-1);
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#endif
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LocalRefCount[i]++;
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*foundPtr = TRUE;
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return &LocalBufferDescriptors[i];
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}
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}
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#ifdef LBDEBUG
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fprintf(stderr, "LB ALLOC (%d,%d) %d\n",
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reln->rd_id, blockNum, -nextFreeLocalBuf-1);
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#endif
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/* need to get a new buffer (round robin for now) */
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for(i=0; i < NLocBuffer; i++) {
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int b = (nextFreeLocalBuf + i) % NLocBuffer;
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if (LocalRefCount[b]==0) {
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bufHdr = &LocalBufferDescriptors[b];
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LocalRefCount[b]++;
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nextFreeLocalBuf = (b + 1) % NLocBuffer;
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break;
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}
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}
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if (bufHdr==NULL)
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elog(WARN, "no empty local buffer.");
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/*
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* this buffer is not referenced but it might still be dirty (the
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* last transaction to touch it doesn't need its contents but has
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* not flushed it). if that's the case, write it out before
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* reusing it!
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*/
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if (bufHdr->flags & BM_DIRTY) {
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Relation bufrel = RelationIdCacheGetRelation(bufHdr->tag.relId.relId);
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Assert(bufrel != NULL);
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/* flush this page */
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smgrwrite(bufrel->rd_rel->relsmgr, bufrel, bufHdr->tag.blockNum,
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(char *) MAKE_PTR(bufHdr->data));
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}
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/*
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* it's all ours now.
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*/
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bufHdr->tag.relId.relId = reln->rd_id;
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bufHdr->tag.blockNum = blockNum;
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bufHdr->flags &= ~BM_DIRTY;
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/*
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* lazy memory allocation. (see MAKE_PTR for why we need to do
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* MAKE_OFFSET.)
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*/
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if (bufHdr->data == (SHMEM_OFFSET)0) {
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char *data = (char *)malloc(BLCKSZ);
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bufHdr->data = MAKE_OFFSET(data);
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}
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*foundPtr = FALSE;
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return bufHdr;
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}
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/*
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* WriteLocalBuffer -
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* writes out a local buffer
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*/
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int
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WriteLocalBuffer(Buffer buffer, bool release)
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{
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int bufid;
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Assert(BufferIsLocal(buffer));
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#ifdef LBDEBUG
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fprintf(stderr, "LB WRITE %d\n", buffer);
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#endif
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bufid = - (buffer + 1);
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LocalBufferDescriptors[bufid].flags |= BM_DIRTY;
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if (release) {
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Assert(LocalRefCount[bufid] > 0);
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LocalRefCount[bufid]--;
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}
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return true;
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}
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/*
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* FlushLocalBuffer -
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* flushes a local buffer
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*/
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int
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FlushLocalBuffer(Buffer buffer, bool release)
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{
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int bufid;
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Relation bufrel;
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BufferDesc *bufHdr;
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Assert(BufferIsLocal(buffer));
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#ifdef LBDEBUG
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fprintf(stderr, "LB FLUSH %d\n", buffer);
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#endif
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bufid = - (buffer + 1);
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bufHdr = &LocalBufferDescriptors[bufid];
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bufHdr->flags &= ~BM_DIRTY;
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bufrel = RelationIdCacheGetRelation(bufHdr->tag.relId.relId);
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Assert(bufrel != NULL);
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smgrflush(bufrel->rd_rel->relsmgr, bufrel, bufHdr->tag.blockNum,
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(char *) MAKE_PTR(bufHdr->data));
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Assert(LocalRefCount[bufid] > 0);
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if ( release )
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LocalRefCount[bufid]--;
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return true;
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}
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/*
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* InitLocalBuffer -
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* init the local buffer cache. Since most queries (esp. multi-user ones)
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* don't involve local buffers, we delay allocating memory for actual the
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* buffer until we need it.
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*/
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void
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InitLocalBuffer(void)
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{
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int i;
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/*
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* these aren't going away. I'm not gonna use palloc.
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*/
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LocalBufferDescriptors =
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(BufferDesc *)malloc(sizeof(BufferDesc) * NLocBuffer);
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memset(LocalBufferDescriptors, 0, sizeof(BufferDesc) * NLocBuffer);
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nextFreeLocalBuf = 0;
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for (i = 0; i < NLocBuffer; i++) {
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BufferDesc *buf = &LocalBufferDescriptors[i];
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/*
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* negative to indicate local buffer. This is tricky: shared buffers
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* start with 0. We have to start with -2. (Note that the routine
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* BufferDescriptorGetBuffer adds 1 to buf_id so our first buffer id
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* is -1.)
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*/
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buf->buf_id = - i - 2;
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}
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LocalRefCount =
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(long *)malloc(sizeof(long) * NLocBuffer);
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memset(LocalRefCount, 0, sizeof(long) * NLocBuffer);
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}
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/*
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* LocalBufferSync -
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* flush all dirty buffers in the local buffer cache. Since the buffer
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* cache is only used for keeping relations visible during a transaction,
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* we will not need these buffers again.
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*/
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void
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LocalBufferSync(void)
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{
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int i;
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for (i = 0; i < NLocBuffer; i++) {
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BufferDesc *buf = &LocalBufferDescriptors[i];
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Relation bufrel;
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if (buf->flags & BM_DIRTY) {
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#ifdef LBDEBUG
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fprintf(stderr, "LB SYNC %d\n", -i-1);
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#endif
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bufrel = RelationIdCacheGetRelation(buf->tag.relId.relId);
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Assert(bufrel != NULL);
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smgrwrite(bufrel->rd_rel->relsmgr, bufrel, buf->tag.blockNum,
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(char *) MAKE_PTR(buf->data));
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buf->tag.relId.relId = InvalidOid;
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buf->flags &= ~BM_DIRTY;
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}
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}
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memset(LocalRefCount, 0, sizeof(long) * NLocBuffer);
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}
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void
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ResetLocalBufferPool(void)
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{
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int i;
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memset(LocalBufferDescriptors, 0, sizeof(BufferDesc) * NLocBuffer);
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nextFreeLocalBuf = 0;
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for (i = 0; i < NLocBuffer; i++) {
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BufferDesc *buf = &LocalBufferDescriptors[i];
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/* just like InitLocalBuffer() */
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buf->buf_id = - i - 2;
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}
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memset(LocalRefCount, 0, sizeof(long) * NLocBuffer);
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}
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