Postgres95 1.01 Distribution - Virgin Sources

src/backend/storage/buffer/localbuf.c

@@ -0,0 +1,284 @@
+/*-------------------------------------------------------------------------
+ *
+ * localbuf.c--
+ *    local buffer manager. Fast buffer manager for temporary tables
+ *    or special cases when the operation is not visible to other backends.
+ *
+ *    When a relation is being created, the descriptor will have rd_islocal
+ *    set to indicate that the local buffer manager should be used. During
+ *    the same transaction the relation is being created, any inserts or
+ *    selects from the newly created relation will use the local buffer
+ *    pool. rd_islocal is reset at the end of a transaction (commit/abort).
+ *    This is useful for queries like SELECT INTO TABLE and create index.
+ *
+ * Copyright (c) 1994-5, Regents of the University of California
+ *
+ *
+ * IDENTIFICATION
+ *    $Header: /cvsroot/pgsql/src/backend/storage/buffer/localbuf.c,v 1.1.1.1 1996/07/09 06:21:54 scrappy Exp $
+ *
+ *-------------------------------------------------------------------------
+ */
+#include <sys/file.h>
+#include <stdio.h>
+#include <math.h>
+#include <signal.h>
+
+/* declarations split between these three files */
+#include "storage/buf.h"
+#include "storage/buf_internals.h"
+#include "storage/bufmgr.h"
+
+#include "storage/fd.h"
+#include "storage/ipc.h"
+#include "storage/shmem.h"
+#include "storage/spin.h"
+#include "storage/smgr.h"
+#include "storage/lmgr.h"
+#include "miscadmin.h"
+#include "utils/builtins.h"
+#include "utils/hsearch.h"
+#include "utils/elog.h"
+#include "utils/memutils.h"
+#include "executor/execdebug.h"	/* for NDirectFileRead */
+#include "catalog/catalog.h"
+
+int NLocBuffer = 64;
+BufferDesc *LocalBufferDescriptors = NULL;
+long *LocalRefCount = NULL;
+
+static int nextFreeLocalBuf = 0;
+
+/*#define LBDEBUG*/
+
+/*
+ * LocalBufferAlloc -
+ *    allocate a local buffer. We do round robin allocation for now.
+ */
+BufferDesc *
+LocalBufferAlloc(Relation reln, BlockNumber blockNum, bool *foundPtr)
+{
+    int i;
+    BufferDesc *bufHdr = (BufferDesc *) NULL;
+
+    if (blockNum == P_NEW) {
+	blockNum = reln->rd_nblocks;
+	reln->rd_nblocks++;
+    } 
+
+    /* a low tech search for now -- not optimized for scans */
+    for (i=0; i < NLocBuffer; i++) {
+	if (LocalBufferDescriptors[i].tag.relId.relId == reln->rd_id &&
+	    LocalBufferDescriptors[i].tag.blockNum == blockNum) {
+
+#ifdef LBDEBUG
+	    fprintf(stderr, "LB ALLOC (%d,%d) %d\n",
+		    reln->rd_id, blockNum, -i-1);
+#endif    
+	    LocalRefCount[i]++;
+	    *foundPtr = TRUE;
+	    return &LocalBufferDescriptors[i];
+	}
+    }
+
+#ifdef LBDEBUG
+    fprintf(stderr, "LB ALLOC (%d,%d) %d\n",
+	    reln->rd_id, blockNum, -nextFreeLocalBuf-1);
+#endif    
+    
+    /* need to get a new buffer (round robin for now) */
+    for(i=0; i < NLocBuffer; i++) {
+	int b = (nextFreeLocalBuf + i) % NLocBuffer;
+
+	if (LocalRefCount[b]==0) {
+	    bufHdr = &LocalBufferDescriptors[b];
+	    LocalRefCount[b]++;
+	    nextFreeLocalBuf = (b + 1) % NLocBuffer;
+	    break;
+	}
+    }
+    if (bufHdr==NULL)
+	elog(WARN, "no empty local buffer.");
+
+    /*
+     * this buffer is not referenced but it might still be dirty (the
+     * last transaction to touch it doesn't need its contents but has
+     * not flushed it).  if that's the case, write it out before
+     * reusing it!
+     */
+    if (bufHdr->flags & BM_DIRTY) {
+	Relation bufrel = RelationIdCacheGetRelation(bufHdr->tag.relId.relId);
+
+	Assert(bufrel != NULL);
+	
+	/* flush this page */
+	smgrwrite(bufrel->rd_rel->relsmgr, bufrel, bufHdr->tag.blockNum,
+		  (char *) MAKE_PTR(bufHdr->data));
+    }
+
+    /*
+     * it's all ours now.
+     */
+    bufHdr->tag.relId.relId = reln->rd_id;
+    bufHdr->tag.blockNum = blockNum;
+    bufHdr->flags &= ~BM_DIRTY;
+
+    /*
+     * lazy memory allocation. (see MAKE_PTR for why we need to do 
+     * MAKE_OFFSET.)
+     */
+    if (bufHdr->data == (SHMEM_OFFSET)0) {
+	char *data = (char *)malloc(BLCKSZ);
+
+	bufHdr->data = MAKE_OFFSET(data);
+    }
+    
+    *foundPtr = FALSE;
+    return bufHdr;
+}
+
+/*
+ * WriteLocalBuffer -
+ *    writes out a local buffer
+ */
+int
+WriteLocalBuffer(Buffer buffer, bool release)
+{
+    int bufid;
+
+    Assert(BufferIsLocal(buffer));
+
+#ifdef LBDEBUG
+    fprintf(stderr, "LB WRITE %d\n", buffer);
+#endif    
+    
+    bufid = - (buffer + 1);
+    LocalBufferDescriptors[bufid].flags |= BM_DIRTY;
+
+    if (release) {
+	Assert(LocalRefCount[bufid] > 0);
+	LocalRefCount[bufid]--;
+    }
+
+    return true;
+}
+
+/*
+ * FlushLocalBuffer -
+ *    flushes a local buffer
+ */
+int
+FlushLocalBuffer(Buffer buffer)
+{
+    int bufid;
+    Relation bufrel;
+    BufferDesc *bufHdr;
+
+    Assert(BufferIsLocal(buffer));
+
+#ifdef LBDEBUG
+    fprintf(stderr, "LB FLUSH %d\n", buffer);
+#endif    
+
+    bufid = - (buffer + 1);
+    bufHdr = &LocalBufferDescriptors[bufid];
+    bufHdr->flags &= ~BM_DIRTY;
+    bufrel = RelationIdCacheGetRelation(bufHdr->tag.relId.relId);
+
+    Assert(bufrel != NULL);
+    smgrflush(bufrel->rd_rel->relsmgr, bufrel, bufHdr->tag.blockNum,
+	      (char *) MAKE_PTR(bufHdr->data));
+
+    Assert(LocalRefCount[bufid] > 0);
+    LocalRefCount[bufid]--;
+    
+    return true;
+}
+
+/*
+ * InitLocalBuffer -
+ *    init the local buffer cache. Since most queries (esp. multi-user ones)
+ *    don't involve local buffers, we delay allocating memory for actual the
+ *    buffer until we need it.
+ */
+void
+InitLocalBuffer()
+{
+    int i;
+    
+    /*
+     * these aren't going away. I'm not gonna use palloc.
+     */
+    LocalBufferDescriptors =
+	(BufferDesc *)malloc(sizeof(BufferDesc) * NLocBuffer);
+    memset(LocalBufferDescriptors, 0, sizeof(BufferDesc) * NLocBuffer);
+    nextFreeLocalBuf = 0;
+
+    for (i = 0; i < NLocBuffer; i++) {
+	BufferDesc *buf = &LocalBufferDescriptors[i];
+
+	/*
+	 * negative to indicate local buffer. This is tricky: shared buffers
+	 * start with 0. We have to start with -2. (Note that the routine
+	 * BufferDescriptorGetBuffer adds 1 to buf_id so our first buffer id
+	 * is -1.)
+	 */
+	buf->buf_id = - i - 2;	
+    }
+
+    LocalRefCount =
+	(long *)malloc(sizeof(long) * NLocBuffer);
+    memset(LocalRefCount, 0, sizeof(long) * NLocBuffer);
+}
+
+/*
+ * LocalBufferSync -
+ *    flush all dirty buffers in the local buffer cache. Since the buffer
+ *    cache is only used for keeping relations visible during a transaction,
+ *    we will not need these buffers again.
+ */
+void
+LocalBufferSync()
+{
+    int i;
+    
+    for (i = 0; i < NLocBuffer; i++) {
+	BufferDesc *buf = &LocalBufferDescriptors[i];
+	Relation bufrel;
+
+	if (buf->flags & BM_DIRTY) {
+#ifdef LBDEBUG
+	    fprintf(stderr, "LB SYNC %d\n", -i-1);
+#endif	    
+	    bufrel = RelationIdCacheGetRelation(buf->tag.relId.relId);
+
+	    Assert(bufrel != NULL);
+	    
+	    smgrwrite(bufrel->rd_rel->relsmgr, bufrel, buf->tag.blockNum,
+		      (char *) MAKE_PTR(buf->data));
+
+	    buf->tag.relId.relId = InvalidOid;
+	    buf->flags &= ~BM_DIRTY;
+	}
+    }
+
+    memset(LocalRefCount, 0, sizeof(long) * NLocBuffer);
+}
+
+void
+ResetLocalBufferPool()
+{
+    int i;
+
+    memset(LocalBufferDescriptors, 0, sizeof(BufferDesc) * NLocBuffer);
+    nextFreeLocalBuf = 0;
+
+    for (i = 0; i < NLocBuffer; i++) {
+	BufferDesc *buf = &LocalBufferDescriptors[i];
+
+	/* just like InitLocalBuffer() */
+	buf->buf_id = - i - 2;	
+    }
+
+    memset(LocalRefCount, 0, sizeof(long) * NLocBuffer);
+}