Move fsync method macro defines into /include/access/xlogdefs.h so they

can be used by src/tools/fsync/test_fsync.c.

1 files changed, 72 insertions, 1 deletions

diff --git a/src/include/access/xlogdefs.h b/src/include/access/xlogdefs.h
index 6926bd792ac..ceca7794325 100644
--- a/src/include/access/xlogdefs.h
+++ b/src/include/access/xlogdefs.h
@@ -7,7 +7,7 @@
  * Portions Copyright (c) 1996-2007, PostgreSQL Global Development Group
  * Portions Copyright (c) 1994, Regents of the University of California
  *
- * $PostgreSQL: pgsql/src/include/access/xlogdefs.h,v 1.16 2007/01/05 22:19:51 momjian Exp $
+ * $PostgreSQL: pgsql/src/include/access/xlogdefs.h,v 1.17 2007/02/14 05:00:40 momjian Exp $
  */
 #ifndef XLOG_DEFS_H
 #define XLOG_DEFS_H
@@ -63,4 +63,75 @@ typedef struct XLogRecPtr
  */
 typedef uint32 TimeLineID;
 
+/*
+ *	Because O_DIRECT bypasses the kernel buffers, and because we never
+ *	read those buffers except during crash recovery, it is a win to use
+ *	it in all cases where we sync on each write().	We could allow O_DIRECT
+ *	with fsync(), but because skipping the kernel buffer forces writes out
+ *	quickly, it seems best just to use it for O_SYNC.  It is hard to imagine
+ *	how fsync() could be a win for O_DIRECT compared to O_SYNC and O_DIRECT.
+ *	Also, O_DIRECT is never enough to force data to the drives, it merely
+ *	tries to bypass the kernel cache, so we still need O_SYNC or fsync().
+ */
+#ifdef O_DIRECT
+#define PG_O_DIRECT				O_DIRECT
+#else
+#define PG_O_DIRECT				0
+#endif
+
+/*
+ * 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.
+ */
+#if defined(O_SYNC)
+#define BARE_OPEN_SYNC_FLAG		O_SYNC
+#elif defined(O_FSYNC)
+#define BARE_OPEN_SYNC_FLAG		O_FSYNC
+#endif
+#ifdef BARE_OPEN_SYNC_FLAG
+#define OPEN_SYNC_FLAG			(BARE_OPEN_SYNC_FLAG | PG_O_DIRECT)
+#endif
+
+#if defined(O_DSYNC)
+#if defined(OPEN_SYNC_FLAG)
+/* O_DSYNC is distinct? */
+#if O_DSYNC != BARE_OPEN_SYNC_FLAG
+#define OPEN_DATASYNC_FLAG		(O_DSYNC | PG_O_DIRECT)
+#endif
+#else							/* !defined(OPEN_SYNC_FLAG) */
+/* Win32 only has O_DSYNC */
+#define OPEN_DATASYNC_FLAG		(O_DSYNC | PG_O_DIRECT)
+#endif
+#endif
+
+#if defined(OPEN_DATASYNC_FLAG)
+#define DEFAULT_SYNC_METHOD_STR "open_datasync"
+#define DEFAULT_SYNC_METHOD		SYNC_METHOD_OPEN
+#define DEFAULT_SYNC_FLAGBIT	OPEN_DATASYNC_FLAG
+#elif defined(HAVE_FDATASYNC)
+#define DEFAULT_SYNC_METHOD_STR "fdatasync"
+#define DEFAULT_SYNC_METHOD		SYNC_METHOD_FDATASYNC
+#define DEFAULT_SYNC_FLAGBIT	0
+#elif defined(HAVE_FSYNC_WRITETHROUGH_ONLY)
+#define DEFAULT_SYNC_METHOD_STR "fsync_writethrough"
+#define DEFAULT_SYNC_METHOD		SYNC_METHOD_FSYNC_WRITETHROUGH
+#define DEFAULT_SYNC_FLAGBIT	0
+#else
+#define DEFAULT_SYNC_METHOD_STR "fsync"
+#define DEFAULT_SYNC_METHOD		SYNC_METHOD_FSYNC
+#define DEFAULT_SYNC_FLAGBIT	0
+#endif
+
+/*
+ * Limitation of buffer-alignment for direct IO depends on OS and filesystem,
+ * but XLOG_BLCKSZ is assumed to be enough for it.
+ */
+#ifdef O_DIRECT
+#define ALIGNOF_XLOG_BUFFER		XLOG_BLCKSZ
+#else
+#define ALIGNOF_XLOG_BUFFER		ALIGNOF_BUFFER
+#endif
+
 #endif   /* XLOG_DEFS_H */