Postgres95 1.01 Distribution - Virgin SourcesPG95-1_01

1 files changed, 280 insertions, 0 deletions

diff --git a/src/backend/storage/buffer/buf_init.c b/src/backend/storage/buffer/buf_init.c
new file mode 100644
index 00000000000..823bf41eecf
--- /dev/null
+++ b/src/backend/storage/buffer/buf_init.c
@@ -0,0 +1,280 @@
+/*-------------------------------------------------------------------------
+ *
+ * buf_init.c--
+ *    buffer manager initialization routines
+ *
+ * Copyright (c) 1994, Regents of the University of California
+ *
+ *
+ * IDENTIFICATION
+ *    $Header: /cvsroot/pgsql/src/backend/storage/buffer/buf_init.c,v 1.1.1.1 1996/07/09 06:21:53 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"
+
+/*
+ *  if BMTRACE is defined, we trace the last 200 buffer allocations and
+ *  deallocations in a circular buffer in shared memory.
+ */
+#ifdef	BMTRACE
+bmtrace	*TraceBuf;
+long	*CurTraceBuf;
+#define	BMT_LIMIT	200
+#endif /* BMTRACE */
+int ShowPinTrace = 0;
+
+int		NBuffers = NDBUFS;  /* NDBUFS defined in miscadmin.h */
+int		Data_Descriptors;
+int		Free_List_Descriptor;
+int		Lookup_List_Descriptor;
+int		Num_Descriptors;
+
+BufferDesc 	*BufferDescriptors;
+BufferBlock 	BufferBlocks;
+#ifndef HAS_TEST_AND_SET
+long	*NWaitIOBackendP;
+#endif
+
+extern IpcSemaphoreId      WaitIOSemId;
+
+long	*PrivateRefCount;	/* also used in freelist.c */
+long	*LastRefCount;  /* refcounts of last ExecMain level */
+
+/*
+ * Data Structures:
+ *      buffers live in a freelist and a lookup data structure.
+ *	
+ *
+ * Buffer Lookup:
+ *	Two important notes.  First, the buffer has to be
+ *	available for lookup BEFORE an IO begins.  Otherwise
+ *	a second process trying to read the buffer will 
+ *	allocate its own copy and the buffeer pool will 
+ *	become inconsistent.
+ *
+ * Buffer Replacement:
+ *	see freelist.c.  A buffer cannot be replaced while in
+ *	use either by data manager or during IO.
+ *
+ * WriteBufferBack:
+ *	currently, a buffer is only written back at the time
+ *	it is selected for replacement.  It should 
+ *	be done sooner if possible to reduce latency of 
+ *	BufferAlloc().  Maybe there should be a daemon process.
+ *
+ * Synchronization/Locking:
+ *
+ * BufMgrLock lock -- must be acquired before manipulating the 
+ * 	buffer queues (lookup/freelist).  Must be released 
+ * 	before exit and before doing any IO.  
+ *
+ * IO_IN_PROGRESS -- this is a flag in the buffer descriptor.
+ *      It must be set when an IO is initiated and cleared at
+ *      the end of  the IO.  It is there to make sure that one
+ *	process doesn't start to use a buffer while another is
+ *	faulting it in.  see IOWait/IOSignal.
+ *
+ * refcount --  A buffer is pinned during IO and immediately
+ *	after a BufferAlloc().  A buffer is always either pinned
+ *	or on the freelist but never both.  The buffer must be
+ *	released, written, or flushed before the end of 
+ * 	transaction.
+ *
+ * PrivateRefCount -- Each buffer also has a private refcount the keeps
+ *	track of the number of times the buffer is pinned in the current
+ *	processes.  This is used for two purposes, first, if we pin a
+ *	a buffer more than once, we only need to change the shared refcount
+ *	once, thus only lock the buffer pool once, second, when a transaction
+ *	aborts, it should only unpin the buffers exactly the number of times it
+ *	has pinned them, so that it will not blow away buffers of another
+ *	backend.
+ *
+ */
+
+SPINLOCK BufMgrLock;
+
+/* delayed write: TRUE on, FALSE off */
+int LateWrite = TRUE;
+
+int ReadBufferCount;
+int BufferHitCount;
+int BufferFlushCount;
+
+
+/*
+ * Initialize module:
+ *
+ * should calculate size of pool dynamically based on the
+ * amount of available memory.
+ */
+void
+InitBufferPool(IPCKey key)
+{
+    bool foundBufs,foundDescs;
+    int i;
+    
+    Data_Descriptors = NBuffers;
+    Free_List_Descriptor = Data_Descriptors;
+    Lookup_List_Descriptor = Data_Descriptors + 1;
+    Num_Descriptors = Data_Descriptors + 1;
+    
+    SpinAcquire(BufMgrLock);
+    
+#ifdef BMTRACE
+    CurTraceBuf = (long *) ShmemInitStruct("Buffer trace",
+					   (BMT_LIMIT * sizeof(bmtrace)) + sizeof(long),
+					   &foundDescs);
+    if (!foundDescs)
+	memset(CurTraceBuf, 0, (BMT_LIMIT * sizeof(bmtrace)) + sizeof(long));
+    
+    TraceBuf = (bmtrace *) &(CurTraceBuf[1]);
+#endif
+    
+    BufferDescriptors = (BufferDesc *)
+	ShmemInitStruct("Buffer Descriptors",
+			Num_Descriptors*sizeof(BufferDesc),&foundDescs);
+    
+    BufferBlocks = (BufferBlock)
+	ShmemInitStruct("Buffer Blocks",
+			NBuffers*BLCKSZ,&foundBufs);
+    
+#ifndef HAS_TEST_AND_SET
+    {
+	bool foundNWaitIO;
+	
+	NWaitIOBackendP = (long *)ShmemInitStruct("#Backends Waiting IO",
+						  sizeof(long),
+						  &foundNWaitIO);
+	if (!foundNWaitIO)
+	    *NWaitIOBackendP = 0;
+    }
+#endif
+    
+    if (foundDescs || foundBufs) {
+	
+	/* both should be present or neither */
+	Assert(foundDescs && foundBufs);
+	
+    } else {
+	BufferDesc *buf;
+	unsigned long block;
+	
+	buf = BufferDescriptors;
+	block = (unsigned long) BufferBlocks;
+	
+	/*
+	 * link the buffers into a circular, doubly-linked list to
+	 * initialize free list.  Still don't know anything about
+	 * replacement strategy in this file.
+	 */
+	for (i = 0; i < Data_Descriptors; block+=BLCKSZ,buf++,i++) {
+	    Assert(ShmemIsValid((unsigned long)block));
+	    
+	    buf->freeNext = i+1;
+	    buf->freePrev = i-1;
+	    
+	    CLEAR_BUFFERTAG(&(buf->tag));
+	    buf->data = MAKE_OFFSET(block);
+	    buf->flags = (BM_DELETED | BM_FREE | BM_VALID);
+	    buf->refcount = 0;
+	    buf->buf_id = i;
+#ifdef HAS_TEST_AND_SET
+	    S_INIT_LOCK(&(buf->io_in_progress_lock));
+#endif
+	}
+	
+	/* close the circular queue */
+	BufferDescriptors[0].freePrev = Data_Descriptors-1;
+	BufferDescriptors[Data_Descriptors-1].freeNext = 0;
+    }
+    
+    /* Init the rest of the module */
+    InitBufTable();
+    InitFreeList(!foundDescs);
+    
+    SpinRelease(BufMgrLock);
+    
+#ifndef HAS_TEST_AND_SET
+    {
+	int status;
+	WaitIOSemId = IpcSemaphoreCreate(IPCKeyGetWaitIOSemaphoreKey(key),
+					 1, IPCProtection, 0, 1, &status);
+    }
+#endif
+    PrivateRefCount = (long *) calloc(NBuffers, sizeof(long));
+    LastRefCount = (long *) calloc(NBuffers, sizeof(long));
+}
+
+/* -----------------------------------------------------
+ * BufferShmemSize
+ *
+ * compute the size of shared memory for the buffer pool including
+ * data pages, buffer descriptors, hash tables, etc.
+ * ----------------------------------------------------
+ */
+int
+BufferShmemSize()
+{
+    int size = 0;
+    int nbuckets;
+    int nsegs;
+    int tmp;
+    
+    nbuckets = 1 << (int)my_log2((NBuffers - 1) / DEF_FFACTOR + 1);
+    nsegs = 1 << (int)my_log2((nbuckets - 1) / DEF_SEGSIZE + 1);
+    
+    /* size of shmem binding table */
+    size += MAXALIGN(my_log2(BTABLE_SIZE) * sizeof(void *)); /* HTAB->dir */
+    size += MAXALIGN(sizeof(HHDR));			     /* HTAB->hctl */
+    size += MAXALIGN(DEF_SEGSIZE * sizeof(SEGMENT));
+    size += BUCKET_ALLOC_INCR * 
+	(MAXALIGN(sizeof(BUCKET_INDEX)) +
+	 MAXALIGN(BTABLE_KEYSIZE) +
+	 MAXALIGN(BTABLE_DATASIZE));
+    
+    /* size of buffer descriptors */
+    size += MAXALIGN((NBuffers + 1) * sizeof(BufferDesc));
+    
+    /* size of data pages */
+    size += NBuffers * MAXALIGN(BLCKSZ);
+    
+    /* size of buffer hash table */
+    size += MAXALIGN(my_log2(NBuffers) * sizeof(void *)); /* HTAB->dir */
+    size += MAXALIGN(sizeof(HHDR));			  /* HTAB->hctl */
+    size += nsegs * MAXALIGN(DEF_SEGSIZE * sizeof(SEGMENT));
+    tmp = (int)ceil((double)NBuffers/BUCKET_ALLOC_INCR);
+    size += tmp * BUCKET_ALLOC_INCR * 
+	(MAXALIGN(sizeof(BUCKET_INDEX)) +
+	 MAXALIGN(sizeof(BufferTag)) +
+	 MAXALIGN(sizeof(Buffer)));
+    
+#ifdef BMTRACE
+    size += (BMT_LIMIT * sizeof(bmtrace)) + sizeof(long);
+#endif
+    return size;
+}
+
+