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Postgres95 1.01 Distribution - Virgin Sources
This commit is contained in:
Marc G. Fournier
280
src/backend/storage/buffer/buf_init.c
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280
src/backend/storage/buffer/buf_init.c
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/*-------------------------------------------------------------------------
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*
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* buf_init.c--
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* buffer manager initialization routines
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*
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* Copyright (c) 1994, 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/buf_init.c,v 1.1.1.1 1996/07/09 06:21:53 scrappy 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 <math.h>
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#include <signal.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 "miscadmin.h"
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#include "utils/builtins.h"
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#include "utils/hsearch.h"
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#include "utils/elog.h"
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#include "utils/memutils.h"
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#include "executor/execdebug.h" /* for NDirectFileRead */
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#include "catalog/catalog.h"
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/*
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* if BMTRACE is defined, we trace the last 200 buffer allocations and
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* deallocations in a circular buffer in shared memory.
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*/
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#ifdef BMTRACE
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bmtrace *TraceBuf;
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long *CurTraceBuf;
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#define BMT_LIMIT 200
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#endif /* BMTRACE */
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int ShowPinTrace = 0;
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int NBuffers = NDBUFS; /* NDBUFS defined in miscadmin.h */
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int Data_Descriptors;
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int Free_List_Descriptor;
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int Lookup_List_Descriptor;
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int Num_Descriptors;
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BufferDesc *BufferDescriptors;
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BufferBlock BufferBlocks;
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#ifndef HAS_TEST_AND_SET
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long *NWaitIOBackendP;
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#endif
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extern IpcSemaphoreId WaitIOSemId;
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long *PrivateRefCount; /* also used in freelist.c */
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long *LastRefCount; /* refcounts of last ExecMain level */
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/*
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* Data Structures:
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* buffers live in a freelist and a lookup data structure.
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*
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*
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* Buffer Lookup:
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* Two important notes. First, the buffer has to be
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* available for lookup BEFORE an IO begins. Otherwise
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* a second process trying to read the buffer will
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* allocate its own copy and the buffeer pool will
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* become inconsistent.
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*
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* Buffer Replacement:
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* see freelist.c. A buffer cannot be replaced while in
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* use either by data manager or during IO.
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*
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* WriteBufferBack:
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* currently, a buffer is only written back at the time
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* it is selected for replacement. It should
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* be done sooner if possible to reduce latency of
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* BufferAlloc(). Maybe there should be a daemon process.
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*
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* Synchronization/Locking:
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*
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* BufMgrLock lock -- must be acquired before manipulating the
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* buffer queues (lookup/freelist). Must be released
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* before exit and before doing any IO.
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*
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* IO_IN_PROGRESS -- this is a flag in the buffer descriptor.
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* It must be set when an IO is initiated and cleared at
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* the end of the IO. It is there to make sure that one
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* process doesn't start to use a buffer while another is
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* faulting it in. see IOWait/IOSignal.
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*
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* refcount -- A buffer is pinned during IO and immediately
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* after a BufferAlloc(). A buffer is always either pinned
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* or on the freelist but never both. The buffer must be
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* released, written, or flushed before the end of
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* transaction.
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*
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* PrivateRefCount -- Each buffer also has a private refcount the keeps
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* track of the number of times the buffer is pinned in the current
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* processes. This is used for two purposes, first, if we pin a
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* a buffer more than once, we only need to change the shared refcount
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* once, thus only lock the buffer pool once, second, when a transaction
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* aborts, it should only unpin the buffers exactly the number of times it
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* has pinned them, so that it will not blow away buffers of another
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* backend.
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*
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*/
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SPINLOCK BufMgrLock;
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/* delayed write: TRUE on, FALSE off */
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int LateWrite = TRUE;
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int ReadBufferCount;
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int BufferHitCount;
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int BufferFlushCount;
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/*
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* Initialize module:
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*
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* should calculate size of pool dynamically based on the
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* amount of available memory.
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*/
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void
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InitBufferPool(IPCKey key)
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{
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bool foundBufs,foundDescs;
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int i;
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Data_Descriptors = NBuffers;
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Free_List_Descriptor = Data_Descriptors;
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Lookup_List_Descriptor = Data_Descriptors + 1;
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Num_Descriptors = Data_Descriptors + 1;
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SpinAcquire(BufMgrLock);
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#ifdef BMTRACE
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CurTraceBuf = (long *) ShmemInitStruct("Buffer trace",
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(BMT_LIMIT * sizeof(bmtrace)) + sizeof(long),
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&foundDescs);
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if (!foundDescs)
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memset(CurTraceBuf, 0, (BMT_LIMIT * sizeof(bmtrace)) + sizeof(long));
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TraceBuf = (bmtrace *) &(CurTraceBuf[1]);
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#endif
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BufferDescriptors = (BufferDesc *)
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ShmemInitStruct("Buffer Descriptors",
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Num_Descriptors*sizeof(BufferDesc),&foundDescs);
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BufferBlocks = (BufferBlock)
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ShmemInitStruct("Buffer Blocks",
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NBuffers*BLCKSZ,&foundBufs);
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#ifndef HAS_TEST_AND_SET
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{
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bool foundNWaitIO;
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NWaitIOBackendP = (long *)ShmemInitStruct("#Backends Waiting IO",
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sizeof(long),
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&foundNWaitIO);
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if (!foundNWaitIO)
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*NWaitIOBackendP = 0;
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}
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#endif
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if (foundDescs || foundBufs) {
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/* both should be present or neither */
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Assert(foundDescs && foundBufs);
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} else {
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BufferDesc *buf;
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unsigned long block;
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buf = BufferDescriptors;
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block = (unsigned long) BufferBlocks;
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/*
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* link the buffers into a circular, doubly-linked list to
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* initialize free list. Still don't know anything about
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* replacement strategy in this file.
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*/
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for (i = 0; i < Data_Descriptors; block+=BLCKSZ,buf++,i++) {
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Assert(ShmemIsValid((unsigned long)block));
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buf->freeNext = i+1;
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buf->freePrev = i-1;
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CLEAR_BUFFERTAG(&(buf->tag));
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buf->data = MAKE_OFFSET(block);
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buf->flags = (BM_DELETED | BM_FREE | BM_VALID);
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buf->refcount = 0;
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buf->buf_id = i;
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#ifdef HAS_TEST_AND_SET
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S_INIT_LOCK(&(buf->io_in_progress_lock));
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#endif
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}
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/* close the circular queue */
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BufferDescriptors[0].freePrev = Data_Descriptors-1;
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BufferDescriptors[Data_Descriptors-1].freeNext = 0;
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}
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/* Init the rest of the module */
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InitBufTable();
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InitFreeList(!foundDescs);
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SpinRelease(BufMgrLock);
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#ifndef HAS_TEST_AND_SET
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{
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int status;
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WaitIOSemId = IpcSemaphoreCreate(IPCKeyGetWaitIOSemaphoreKey(key),
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1, IPCProtection, 0, 1, &status);
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}
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#endif
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PrivateRefCount = (long *) calloc(NBuffers, sizeof(long));
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LastRefCount = (long *) calloc(NBuffers, sizeof(long));
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}
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/* -----------------------------------------------------
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* BufferShmemSize
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*
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* compute the size of shared memory for the buffer pool including
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* data pages, buffer descriptors, hash tables, etc.
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* ----------------------------------------------------
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*/
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int
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BufferShmemSize()
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{
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int size = 0;
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int nbuckets;
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int nsegs;
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int tmp;
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nbuckets = 1 << (int)my_log2((NBuffers - 1) / DEF_FFACTOR + 1);
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nsegs = 1 << (int)my_log2((nbuckets - 1) / DEF_SEGSIZE + 1);
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/* size of shmem binding table */
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size += MAXALIGN(my_log2(BTABLE_SIZE) * sizeof(void *)); /* HTAB->dir */
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size += MAXALIGN(sizeof(HHDR)); /* HTAB->hctl */
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size += MAXALIGN(DEF_SEGSIZE * sizeof(SEGMENT));
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size += BUCKET_ALLOC_INCR *
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(MAXALIGN(sizeof(BUCKET_INDEX)) +
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MAXALIGN(BTABLE_KEYSIZE) +
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MAXALIGN(BTABLE_DATASIZE));
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/* size of buffer descriptors */
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size += MAXALIGN((NBuffers + 1) * sizeof(BufferDesc));
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/* size of data pages */
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size += NBuffers * MAXALIGN(BLCKSZ);
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/* size of buffer hash table */
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size += MAXALIGN(my_log2(NBuffers) * sizeof(void *)); /* HTAB->dir */
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size += MAXALIGN(sizeof(HHDR)); /* HTAB->hctl */
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size += nsegs * MAXALIGN(DEF_SEGSIZE * sizeof(SEGMENT));
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tmp = (int)ceil((double)NBuffers/BUCKET_ALLOC_INCR);
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size += tmp * BUCKET_ALLOC_INCR *
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(MAXALIGN(sizeof(BUCKET_INDEX)) +
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MAXALIGN(sizeof(BufferTag)) +
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MAXALIGN(sizeof(Buffer)));
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#ifdef BMTRACE
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size += (BMT_LIMIT * sizeof(bmtrace)) + sizeof(long);
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#endif
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return size;
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}
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