WAL

1 files changed, 274 insertions, 0 deletions

diff --git a/src/backend/storage/buffer/xlog_localbuf.c b/src/backend/storage/buffer/xlog_localbuf.c
new file mode 100644
index 00000000000..cb14a32ed23
--- /dev/null
+++ b/src/backend/storage/buffer/xlog_localbuf.c
@@ -0,0 +1,274 @@
+/*-------------------------------------------------------------------------
+ *
+ * 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.
+ *
+ * Portions Copyright (c) 1996-2000, PostgreSQL, Inc
+ * Portions Copyright (c) 1994-5, Regents of the University of California
+ *
+ *
+ * IDENTIFICATION
+ *	  $Header: /cvsroot/pgsql/src/backend/storage/buffer/Attic/xlog_localbuf.c,v 1.1 2000/10/28 16:20:56 vadim Exp $
+ *
+ *-------------------------------------------------------------------------
+ */
+#include <sys/types.h>
+#include <sys/file.h>
+#include <math.h>
+#include <signal.h>
+
+#include "postgres.h"
+
+#include "executor/execdebug.h"
+#include "storage/smgr.h"
+#include "utils/relcache.h"
+
+extern long int LocalBufferFlushCount;
+
+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.rnode.relNode == 
+			reln->rd_node.relNode &&
+			LocalBufferDescriptors[i].tag.blockNum == blockNum)
+		{
+
+#ifdef LBDEBUG
+			fprintf(stderr, "LB ALLOC (%u,%d) %d\n",
+					RelationGetRelid(reln), blockNum, -i - 1);
+#endif
+			LocalRefCount[i]++;
+			*foundPtr = TRUE;
+			return &LocalBufferDescriptors[i];
+		}
+	}
+
+#ifdef LBDEBUG
+	fprintf(stderr, "LB ALLOC (%u,%d) %d\n",
+			RelationGetRelid(reln), 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(ERROR, "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 || bufHdr->cntxDirty)
+	{
+		Relation	bufrel = RelationNodeCacheGetRelation(bufHdr->tag.rnode);
+
+		Assert(bufrel != NULL);
+
+		/* flush this page */
+		smgrwrite(DEFAULT_SMGR, bufrel, bufHdr->tag.blockNum,
+				  (char *) MAKE_PTR(bufHdr->data));
+		LocalBufferFlushCount++;
+
+		/*
+		 * drop relcache refcount incremented by
+		 * RelationIdCacheGetRelation
+		 */
+		RelationDecrementReferenceCount(bufrel);
+	}
+
+	/*
+	 * it's all ours now.
+	 *
+	 * We need not in tblNode currently but will in future I think,
+	 * when we'll give up rel->rd_fd to fmgr cache.
+	 */
+	bufHdr->tag.rnode = reln->rd_node;
+	bufHdr->tag.blockNum = blockNum;
+	bufHdr->flags &= ~BM_DIRTY;
+	bufHdr->cntxDirty = false;
+
+	/*
+	 * 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;
+}
+
+/*
+ * 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(void)
+{
+	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 at commit time.
+ * Since the buffer cache is only used for keeping relations visible
+ * during a transaction, we will not need these buffers again.
+ *
+ * Note that we have to *flush* local buffers because of them are not
+ * visible to checkpoint makers. But we can skip XLOG flush check.
+ */
+void
+LocalBufferSync(void)
+{
+	int			i;
+
+	for (i = 0; i < NLocBuffer; i++)
+	{
+		BufferDesc *buf = &LocalBufferDescriptors[i];
+		Relation	bufrel;
+
+		if (buf->flags & BM_DIRTY || buf->cntxDirty)
+		{
+#ifdef LBDEBUG
+			fprintf(stderr, "LB SYNC %d\n", -i - 1);
+#endif
+			bufrel = RelationNodeCacheGetRelation(buf->tag.rnode);
+
+			Assert(bufrel != NULL);
+
+			smgrwrite(DEFAULT_SMGR, bufrel, buf->tag.blockNum,
+						(char *) MAKE_PTR(buf->data));
+			smgrmarkdirty(DEFAULT_SMGR, bufrel, buf->tag.blockNum);
+			LocalBufferFlushCount++;
+
+			/* drop relcache refcount from RelationIdCacheGetRelation */
+			RelationDecrementReferenceCount(bufrel);
+
+			buf->flags &= ~BM_DIRTY;
+			buf->cntxDirty = false;
+		}
+	}
+
+	MemSet(LocalRefCount, 0, sizeof(long) * NLocBuffer);
+	nextFreeLocalBuf = 0;
+}
+
+void
+ResetLocalBufferPool(void)
+{
+	int			i;
+
+	for (i = 0; i < NLocBuffer; i++)
+	{
+		BufferDesc *buf = &LocalBufferDescriptors[i];
+
+		buf->tag.rnode.relNode = InvalidOid;
+		buf->flags &= ~BM_DIRTY;
+		buf->cntxDirty = false;
+		buf->buf_id = -i - 2;
+	}
+
+	MemSet(LocalRefCount, 0, sizeof(long) * NLocBuffer);
+	nextFreeLocalBuf = 0;
+}