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Per previous discussions, get rid of use of sync(2) in favor of

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explicitly fsync'ing every (non-temp) file we have written since the
last checkpoint.  In the vast majority of cases, the burden of the
fsyncs should fall on the bgwriter process not on backends.  (To this
end, we assume that an fsync issued by the bgwriter will force out
blocks written to the same file by other processes using other file
descriptors.  Anyone have a problem with that?)  This makes the world
safe for WIN32, which ain't even got sync(2), and really makes the world
safe for Unixen as well, because sync(2) never had the semantics we need:
it offers no way to wait for the requested I/O to finish.

Along the way, fix a bug I recently introduced in xlog recovery:
file truncation replay failed to clear bufmgr buffers for the dropped
blocks, which could result in 'PANIC:  heap_delete_redo: no block'
later on in xlog replay.
This commit is contained in:
Tom Lane
2004-05-31 03:48:10 +00:00
parent f024086db3
commit 9b178555fc
13 changed files with 779 additions and 250 deletions
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36
src/include/access/slru.h
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@@ -6,26 +6,17 @@
* Portions Copyright (c) 2003, PostgreSQL Global Development Group
* Portions Copyright (c) 1994, Regents of the University of California
*
* $PostgreSQL: pgsql/src/include/access/slru.h,v 1.5 2004/05/28 05:13:17 tgl Exp $
* $PostgreSQL: pgsql/src/include/access/slru.h,v 1.6 2004/05/31 03:48:08 tgl Exp $
*/
#ifndef SLRU_H
#define SLRU_H
#include "access/xlog.h"
#include "storage/lwlock.h"
/* exported because lwlock.c needs it */
#define NUM_CLOG_BUFFERS 8
/*
* Note: the separation between SlruLockData and SlruSharedData is purely
* historical; the structs could be combined.
*/
typedef struct SlruLockData
{
LWLockId ControlLock;
LWLockId BufferLocks[NUM_CLOG_BUFFERS]; /* Per-buffer I/O locks */
} SlruLockData;
typedef SlruLockData *SlruLock;
/* Opaque structs known only in slru.c */
typedef struct SlruSharedData *SlruShared;
typedef struct SlruFlushData *SlruFlush;
/*
* SlruCtlData is an unshared structure that points to the active information
@@ -33,13 +24,13 @@ typedef SlruLockData *SlruLock;
*/
typedef struct SlruCtlData
{
void *shared; /* pointer to SlruSharedData */
SlruLock locks;
SlruShared shared;
LWLockId ControlLock;
/*
* Dir is set during SimpleLruShmemInit and does not change thereafter.
* The value is automatically inherited by backends via fork, and
* doesn't need to be in shared memory.
* Dir is set during SimpleLruInit and does not change thereafter.
* Since it's always the same, it doesn't need to be in shared memory.
*/
char Dir[MAXPGPATH];
@@ -51,13 +42,16 @@ typedef struct SlruCtlData
bool (*PagePrecedes) (int, int);
} SlruCtlData;
typedef SlruCtlData *SlruCtl;
extern int SimpleLruShmemSize(void);
extern void SimpleLruInit(SlruCtl ctl, const char *name, const char *subdir);
extern int SimpleLruZeroPage(SlruCtl ctl, int pageno);
extern char *SimpleLruReadPage(SlruCtl ctl, int pageno, TransactionId xid, bool forwrite);
extern void SimpleLruWritePage(SlruCtl ctl, int slotno);
extern char *SimpleLruReadPage(SlruCtl ctl, int pageno,
TransactionId xid, bool forwrite);
extern void SimpleLruWritePage(SlruCtl ctl, int slotno, SlruFlush fdata);
extern void SimpleLruSetLatestPage(SlruCtl ctl, int pageno);
extern void SimpleLruFlush(SlruCtl ctl, bool checkpoint);
extern void SimpleLruTruncate(SlruCtl ctl, int cutoffPage);