Convert wal_sync_method to guc enum.

src/backend/access/transam/xlog.c

@@ -7,7 +7,7 @@
  * Portions Copyright (c) 1996-2008, PostgreSQL Global Development Group
  * Portions Copyright (c) 1994, Regents of the University of California
  *
- * $PostgreSQL: pgsql/src/backend/access/transam/xlog.c,v 1.303 2008/05/12 00:00:46 alvherre Exp $
+ * $PostgreSQL: pgsql/src/backend/access/transam/xlog.c,v 1.304 2008/05/12 08:35:05 mha Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -66,8 +66,6 @@ int			XLOGbuffers = 8;
 int			XLogArchiveTimeout = 0;
 bool		XLogArchiveMode = false;
 char	   *XLogArchiveCommand = NULL;
-char	   *XLOG_sync_method = NULL;
-const char	XLOG_sync_method_default[] = DEFAULT_SYNC_METHOD_STR;
 bool		fullPageWrites = true;
 bool		log_checkpoints = false;
 
@@ -95,6 +93,25 @@ static int	open_sync_bit = DEFAULT_SYNC_FLAGBIT;
 
 #define XLOG_SYNC_BIT  (enableFsync ? open_sync_bit : 0)
 
+/*
+ * GUC support
+ */
+const struct config_enum_entry sync_method_options[] = {
+	{"fsync", SYNC_METHOD_FSYNC},
+#ifdef HAVE_FSYNC_WRITETHROUGH
+	{"fsync_writethrough", SYNC_METHOD_FSYNC_WRITETHROUGH},
+#endif
+#ifdef HAVE_FDATASYNC
+	{"fdatasync", SYNC_METHOD_FDATASYNC},
+#endif
+#ifdef OPEN_SYNC_FLAG
+	{"open_sync", SYNC_METHOD_OPEN},
+#endif
+#ifdef OPEN_DATASYNC_FLAG
+	{"open_datasync", SYNC_METHOD_OPEN_DSYNC},
+#endif
+	{NULL, 0}
+};
 
 /*
  * Statistics for current checkpoint are collected in this global struct.
@@ -1601,7 +1618,7 @@ XLogWrite(XLogwrtRqst WriteRqst, bool flexible, bool xlog_switch)
 		 * have no open file or the wrong one.	However, we do not need to
 		 * fsync more than one file.
 		 */
-		if (sync_method != SYNC_METHOD_OPEN)
+		if (sync_method != SYNC_METHOD_OPEN && sync_method != SYNC_METHOD_OPEN_DSYNC)
 		{
 			if (openLogFile >= 0 &&
 				!XLByteInPrevSeg(LogwrtResult.Write, openLogId, openLogSeg))
@@ -6314,50 +6331,46 @@ xlog_outrec(StringInfo buf, XLogRecord *record)
 /*
  * GUC support
  */
-const char *
-assign_xlog_sync_method(const char *method, bool doit, GucSource source)
+bool
+assign_xlog_sync_method(int new_sync_method, bool doit, GucSource source)
 {
-	int			new_sync_method;
-	int			new_sync_bit;
+	int			new_sync_bit = 0;
 
-	if (pg_strcasecmp(method, "fsync") == 0)
-	{
-		new_sync_method = SYNC_METHOD_FSYNC;
-		new_sync_bit = 0;
-	}
-#ifdef HAVE_FSYNC_WRITETHROUGH
-	else if (pg_strcasecmp(method, "fsync_writethrough") == 0)
-	{
-		new_sync_method = SYNC_METHOD_FSYNC_WRITETHROUGH;
-		new_sync_bit = 0;
-	}
-#endif
-#ifdef HAVE_FDATASYNC
-	else if (pg_strcasecmp(method, "fdatasync") == 0)
+	switch (new_sync_method)
 	{
-		new_sync_method = SYNC_METHOD_FDATASYNC;
-		new_sync_bit = 0;
-	}
-#endif
+		/*
+		 * Values for these sync options are defined even if they are not
+		 * supported on the current platform. They are not included in
+		 * the enum option array, and therefor will never be set if the
+		 * platform doesn't support it.
+		 */
+		case SYNC_METHOD_FSYNC:
+		case SYNC_METHOD_FSYNC_WRITETHROUGH:
+		case SYNC_METHOD_FDATASYNC:
+			new_sync_bit = 0;
+			break;
 #ifdef OPEN_SYNC_FLAG
-	else if (pg_strcasecmp(method, "open_sync") == 0)
-	{
-		new_sync_method = SYNC_METHOD_OPEN;
-		new_sync_bit = OPEN_SYNC_FLAG;
-	}
+		case SYNC_METHOD_OPEN:
+			new_sync_bit = OPEN_SYNC_FLAG;
+			break;
 #endif
 #ifdef OPEN_DATASYNC_FLAG
-	else if (pg_strcasecmp(method, "open_datasync") == 0)
-	{
-		new_sync_method = SYNC_METHOD_OPEN;
-		new_sync_bit = OPEN_DATASYNC_FLAG;
-	}
+		case SYNC_METHOD_OPEN_DSYNC:
+			new_sync_bit = OPEN_DATASYNC_FLAG;
+		break;
 #endif
-	else
-		return NULL;
+		default:
+			/* 
+			 * This "can never happen", since the available values in
+			 * new_sync_method are controlled by the available enum
+			 * options.
+			 */
+			elog(PANIC, "unrecognized wal_sync_method: %d", sync_method);
+			break;
+	}
 
 	if (!doit)
-		return method;
+		return true;
 
 	if (sync_method != new_sync_method || open_sync_bit != new_sync_bit)
 	{
@@ -6381,7 +6394,7 @@ assign_xlog_sync_method(const char *method, bool doit, GucSource source)
 		open_sync_bit = new_sync_bit;
 	}
 
-	return method;
+	return true;
 }
 
 

src/backend/utils/misc/guc.c

@@ -10,7 +10,7 @@
  * Written by Peter Eisentraut <peter_e@gmx.net>.
  *
  * IDENTIFICATION
- *	  $PostgreSQL: pgsql/src/backend/utils/misc/guc.c,v 1.452 2008/05/12 00:00:52 alvherre Exp $
+ *	  $PostgreSQL: pgsql/src/backend/utils/misc/guc.c,v 1.453 2008/05/12 08:35:05 mha Exp $
  *
  *--------------------------------------------------------------------
  */
@@ -270,6 +270,11 @@ static const struct config_enum_entry backslash_quote_options[] = {
 	{NULL, 0}
 };
 
+/*
+ * Options for enum values stored in other modules
+ */
+extern const struct config_enum_entry sync_method_options[];
+
 /*
  * GUC option variables that are exported from this module
  */
@@ -2327,15 +2332,6 @@ static struct config_string ConfigureNamesString[] =
 		"localhost", NULL, NULL
 	},
 
-	{
-		{"wal_sync_method", PGC_SIGHUP, WAL_SETTINGS,
-			gettext_noop("Selects the method used for forcing WAL updates to disk."),
-			NULL
-		},
-		&XLOG_sync_method,
-		XLOG_sync_method_default, assign_xlog_sync_method, NULL
-	},
-
 	{
 		{"custom_variable_classes", PGC_SIGHUP, CUSTOM_OPTIONS,
 			gettext_noop("Sets the list of known custom variable classes."),
@@ -2528,6 +2524,16 @@ static struct config_enum ConfigureNamesEnum[] =
 		assign_session_replication_role, NULL
 	},
 
+	{
+		{"wal_sync_method", PGC_SIGHUP, WAL_SETTINGS,
+			gettext_noop("Selects the method used for forcing WAL updates to disk."),
+			NULL
+		},
+		&sync_method,
+		DEFAULT_SYNC_METHOD, sync_method_options, 
+		assign_xlog_sync_method, NULL
+	},
+
 	{
 		{"xmlbinary", PGC_USERSET, CLIENT_CONN_STATEMENT,
 			gettext_noop("Sets how binary values are to be encoded in XML."),

src/include/access/xlog.h

@@ -6,7 +6,7 @@
  * Portions Copyright (c) 1996-2008, PostgreSQL Global Development Group
  * Portions Copyright (c) 1994, Regents of the University of California
  *
- * $PostgreSQL: pgsql/src/include/access/xlog.h,v 1.87 2008/01/01 19:45:56 momjian Exp $
+ * $PostgreSQL: pgsql/src/include/access/xlog.h,v 1.88 2008/05/12 08:35:05 mha Exp $
  */
 #ifndef XLOG_H
 #define XLOG_H
@@ -88,8 +88,9 @@ typedef struct XLogRecord
 /* Sync methods */
 #define SYNC_METHOD_FSYNC		0
 #define SYNC_METHOD_FDATASYNC	1
-#define SYNC_METHOD_OPEN		2		/* for O_SYNC and O_DSYNC */
+#define SYNC_METHOD_OPEN		2		/* for O_SYNC */
 #define SYNC_METHOD_FSYNC_WRITETHROUGH	3
+#define SYNC_METHOD_OPEN_DSYNC	4		/* for O_DSYNC */
 extern int	sync_method;
 
 /*
@@ -141,8 +142,6 @@ extern int	XLOGbuffers;
 extern bool XLogArchiveMode;
 extern char *XLogArchiveCommand;
 extern int	XLogArchiveTimeout;
-extern char *XLOG_sync_method;
-extern const char XLOG_sync_method_default[];
 extern bool log_checkpoints;
 
 #define XLogArchivingActive()	(XLogArchiveMode)

src/include/access/xlogdefs.h

@@ -7,7 +7,7 @@
  * Portions Copyright (c) 1996-2008, PostgreSQL Global Development Group
  * Portions Copyright (c) 1994, Regents of the University of California
  *
- * $PostgreSQL: pgsql/src/include/access/xlogdefs.h,v 1.19 2008/01/01 19:45:56 momjian Exp $
+ * $PostgreSQL: pgsql/src/include/access/xlogdefs.h,v 1.20 2008/05/12 08:35:05 mha Exp $
  */
 #ifndef XLOG_DEFS_H
 #define XLOG_DEFS_H
@@ -109,19 +109,15 @@ typedef uint32 TimeLineID;
 #endif
 
 #if defined(OPEN_DATASYNC_FLAG)
-#define DEFAULT_SYNC_METHOD_STR "open_datasync"
-#define DEFAULT_SYNC_METHOD		SYNC_METHOD_OPEN
+#define DEFAULT_SYNC_METHOD		SYNC_METHOD_OPEN_DSYNC
 #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

src/include/utils/guc.h

@@ -7,7 +7,7 @@
  * Copyright (c) 2000-2008, PostgreSQL Global Development Group
  * Written by Peter Eisentraut <peter_e@gmx.net>.
  *
- * $PostgreSQL: pgsql/src/include/utils/guc.h,v 1.94 2008/04/18 01:42:17 tgl Exp $
+ * $PostgreSQL: pgsql/src/include/utils/guc.h,v 1.95 2008/05/12 08:35:05 mha Exp $
  *--------------------------------------------------------------------
  */
 #ifndef GUC_H
@@ -267,7 +267,7 @@ extern const char *assign_search_path(const char *newval,
 				   bool doit, GucSource source);
 
 /* in access/transam/xlog.c */
-extern const char *assign_xlog_sync_method(const char *method,
-						bool doit, GucSource source);
+extern bool assign_xlog_sync_method(int newval,
+				bool doit, GucSource source);
 
 #endif   /* GUC_H */