mirror of
https://git.postgresql.org/git/postgresql.git
synced 2024-09-30 21:31:14 +02:00
a1b56090eb
O_FSYNC was a pre-POSIX way of spelling O_SYNC, supported since commit
9d645fd84c for non-conforming operating systems of the time. It's not
needed on any modern system. We can just use standard O_SYNC directly
if it exists (= all targeted systems except Windows), and get rid of our
OPEN_SYNC_FLAG macro.
Similarly for standard O_DSYNC, we can just use that directly if it
exists (= all targeted systems except DragonFlyBSD), and get rid of our
OPEN_DATASYNC_FLAG macro.
We still avoid choosing open_datasync as a default value for
wal_sync_method if O_DSYNC has the same value as O_SYNC (= only
OpenBSD), so there is no change in default behavior.
Discussion: https://postgr.es/m/CA%2BhUKGJE7y92NY7FG2ftUbZUaqohBU65_Ys_7xF5mUHo4wirTQ%40mail.gmail.com
86 lines
2.7 KiB
C
86 lines
2.7 KiB
C
/*
|
|
* xlogdefs.h
|
|
*
|
|
* Postgres write-ahead log manager record pointer and
|
|
* timeline number definitions
|
|
*
|
|
* Portions Copyright (c) 1996-2022, PostgreSQL Global Development Group
|
|
* Portions Copyright (c) 1994, Regents of the University of California
|
|
*
|
|
* src/include/access/xlogdefs.h
|
|
*/
|
|
#ifndef XLOG_DEFS_H
|
|
#define XLOG_DEFS_H
|
|
|
|
#include <fcntl.h> /* need open() flags */
|
|
|
|
/*
|
|
* Pointer to a location in the XLOG. These pointers are 64 bits wide,
|
|
* because we don't want them ever to overflow.
|
|
*/
|
|
typedef uint64 XLogRecPtr;
|
|
|
|
/*
|
|
* Zero is used indicate an invalid pointer. Bootstrap skips the first possible
|
|
* WAL segment, initializing the first WAL page at WAL segment size, so no XLOG
|
|
* record can begin at zero.
|
|
*/
|
|
#define InvalidXLogRecPtr 0
|
|
#define XLogRecPtrIsInvalid(r) ((r) == InvalidXLogRecPtr)
|
|
|
|
/*
|
|
* First LSN to use for "fake" LSNs.
|
|
*
|
|
* Values smaller than this can be used for special per-AM purposes.
|
|
*/
|
|
#define FirstNormalUnloggedLSN ((XLogRecPtr) 1000)
|
|
|
|
/*
|
|
* Handy macro for printing XLogRecPtr in conventional format, e.g.,
|
|
*
|
|
* printf("%X/%X", LSN_FORMAT_ARGS(lsn));
|
|
*/
|
|
#define LSN_FORMAT_ARGS(lsn) (AssertVariableIsOfTypeMacro((lsn), XLogRecPtr), (uint32) ((lsn) >> 32)), ((uint32) (lsn))
|
|
|
|
/*
|
|
* XLogSegNo - physical log file sequence number.
|
|
*/
|
|
typedef uint64 XLogSegNo;
|
|
|
|
/*
|
|
* TimeLineID (TLI) - identifies different database histories to prevent
|
|
* confusion after restoring a prior state of a database installation.
|
|
* TLI does not change in a normal stop/restart of the database (including
|
|
* crash-and-recover cases); but we must assign a new TLI after doing
|
|
* a recovery to a prior state, a/k/a point-in-time recovery. This makes
|
|
* the new WAL logfile sequence we generate distinguishable from the
|
|
* sequence that was generated in the previous incarnation.
|
|
*/
|
|
typedef uint32 TimeLineID;
|
|
|
|
/*
|
|
* Replication origin id - this is located in this file to avoid having to
|
|
* include origin.h in a bunch of xlog related places.
|
|
*/
|
|
typedef uint16 RepOriginId;
|
|
|
|
/*
|
|
* This chunk of hackery attempts to determine which file sync methods
|
|
* are available on the current platform, and to choose an appropriate
|
|
* default method. We assume that fsync() is always available, and that
|
|
* configure determined whether fdatasync() is.
|
|
*
|
|
* Note that we define our own O_DSYNC on Windows, but not O_SYNC.
|
|
*/
|
|
#if defined(PLATFORM_DEFAULT_SYNC_METHOD)
|
|
#define DEFAULT_SYNC_METHOD PLATFORM_DEFAULT_SYNC_METHOD
|
|
#elif defined(O_DSYNC) && (!defined(O_SYNC) || O_DSYNC != O_SYNC)
|
|
#define DEFAULT_SYNC_METHOD SYNC_METHOD_OPEN_DSYNC
|
|
#elif defined(HAVE_FDATASYNC)
|
|
#define DEFAULT_SYNC_METHOD SYNC_METHOD_FDATASYNC
|
|
#else
|
|
#define DEFAULT_SYNC_METHOD SYNC_METHOD_FSYNC
|
|
#endif
|
|
|
|
#endif /* XLOG_DEFS_H */
|