Adjust rename on Win32 to only link to temp name while holding lock,

then release locks and loop over renaming to active file name.

Author: bmomjian

src/backend/commands/user.c

@@ -6,7 +6,7 @@
  * Portions Copyright (c) 1996-2003, PostgreSQL Global Development Group
  * Portions Copyright (c) 1994, Regents of the University of California
  *
- * $PostgreSQL: pgsql/src/backend/commands/user.c,v 1.133 2004/01/26 22:35:32 tgl Exp $
+ * $PostgreSQL: pgsql/src/backend/commands/user.c,v 1.134 2004/02/02 00:17:21 momjian Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -139,7 +139,11 @@ write_group_file(Relation grel)
 	bufsize = strlen(filename) + 12;
 	tempname = (char *) palloc(bufsize);
 	snprintf(tempname, bufsize, "%s.%d", filename, MyProcPid);
-
+#if defined(WIN32) || defined(CYGWIN)
+	filename = repalloc(filename, strlen(filename) + 1 + strlen(".new");
+	strcat(filename, ".new");
+#endif
+	
 	oumask = umask((mode_t) 077);
 	fp = AllocateFile(tempname, "w");
 	umask(oumask);
@@ -286,6 +290,10 @@ write_user_file(Relation urel)
 	bufsize = strlen(filename) + 12;
 	tempname = (char *) palloc(bufsize);
 	snprintf(tempname, bufsize, "%s.%d", filename, MyProcPid);
+#if defined(WIN32) || defined(CYGWIN)
+	filename = repalloc(filename, strlen(filename) + 1 + strlen(".new");
+	strcat(filename, ".new");
+#endif
 
 	oumask = umask((mode_t) 077);
 	fp = AllocateFile(tempname, "w");
@@ -457,13 +465,37 @@ AtEOXact_UpdatePasswordFile(bool isCommit)
 		user_file_update_needed = false;
 		write_user_file(urel);
 		heap_close(urel, NoLock);
+#if defined(WIN32) || defined(CYGWIN)
+		{
+			/* Rename active file while not holding an exclusive lock */
+			char *filename = user_getfilename(), *filename_new;
+
+			filename_new = palloc(strlen(filename) + 1 + strlen(".new")));
+			sprintf(filename_new, "%s.new", filename);
+			rename(filename_new, filename);
+			pfree(filename);
+			pfree(filename_new);
+		}
+#endif
 	}
 
 	if (group_file_update_needed)
 	{
 		group_file_update_needed = false;
 		write_group_file(grel);
 		heap_close(grel, NoLock);
+#if defined(WIN32) || defined(CYGWIN)
+		{
+			/* Rename active file while not holding an exclusive lock */
+			char *filename = group_getfilename(), *filename_new;
+
+			filename_new = palloc(strlen(filename) + 1 + strlen(".new")));
+			sprintf(filename_new, "%s.new", filename);
+			rename(filename_new, filename);
+			pfree(filename);
+			pfree(filename_new);
+		}
+#endif
 	}
 
 	/*

src/backend/utils/cache/relcache.c

@@ -8,7 +8,7 @@
  *
  *
  * IDENTIFICATION
- *	  $PostgreSQL: pgsql/src/backend/utils/cache/relcache.c,v 1.195 2004/01/26 22:35:32 tgl Exp $
+ *	  $PostgreSQL: pgsql/src/backend/utils/cache/relcache.c,v 1.196 2004/02/02 00:17:21 momjian Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -3358,33 +3358,28 @@ write_relcache_init_file(void)
 		/*
 		 * OK, rename the temp file to its final name, deleting any
 		 * previously-existing init file.
-		 *
-		 * Note: a failure here is possible under Cygwin, if some other
-		 * backend is holding open an unlinked-but-not-yet-gone init file.
-		 * So treat this as a noncritical failure.
 		 */
-		if (rename(tempfilename, finalfilename) < 0)
+#if defined(WIN32) || defined(CYGWIN)
+		rename(tempfilename, finalfilename);
+		LWLockRelease(RelCacheInitLock);
+#else
 		{
-			ereport(WARNING,
-					(errcode_for_file_access(),
-				errmsg("could not rename relation-cache initialization file \"%s\" to \"%s\": %m",
-					   tempfilename, finalfilename),
-					 errdetail("Continuing anyway, but there's something wrong.")));
-
-			/*
-			 * If we fail, try to clean up the useless temp file; don't
-			 * bother to complain if this fails too.
-			 */
-			unlink(tempfilename);
+			char		finalfilename_new[MAXPGPATH];
+	
+			snprintf(finalfilename_new, sizeof(finalfilename_new), "%s.new", finalfilename);
+			rename(tempfilename, finalfilename_new);
+			LWLockRelease(RelCacheInitLock);
+			/* Rename to active file after lock is released */
+			rename(finalfilename_new, finalfilename);
 		}
+#endif
 	}
 	else
 	{
 		/* Delete the already-obsolete temp file */
 		unlink(tempfilename);
+		LWLockRelease(RelCacheInitLock);
 	}
-
-	LWLockRelease(RelCacheInitLock);
 }
 
 /*

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 1.182 2004/01/31 05:09:41 neilc Exp $
+ *	  $PostgreSQL: pgsql/src/backend/utils/misc/guc.c,v 1.183 2004/02/02 00:17:21 momjian Exp $
  *
  *--------------------------------------------------------------------
  */
@@ -3981,7 +3981,10 @@ write_nondefault_variables(GucContext context)
 		return;
 	}
 
-	/* Put new file in place, this could delay on Win32 */
+	/*
+	 *	Put new file in place.  This could delay on Win32, but we don't hold
+	 *	any exclusive locks.
+	 */
 	rename(new_filename, filename);
 	free(new_filename);
 	free(filename);

src/include/port.h

@@ -6,7 +6,7 @@
  * Portions Copyright (c) 1996-2003, PostgreSQL Global Development Group
  * Portions Copyright (c) 1994, Regents of the University of California
  *
- * $PostgreSQL: pgsql/src/include/port.h,v 1.16 2004/02/02 00:11:31 momjian Exp $
+ * $PostgreSQL: pgsql/src/include/port.h,v 1.17 2004/02/02 00:17:23 momjian Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -30,18 +30,18 @@ extern int	fseeko(FILE *stream, off_t offset, int whence);
 extern off_t ftello(FILE *stream);
 #endif
 
-#ifdef WIN32
+#if !defined(FRONTEND) && (defined(WIN32) || defined(CYGWIN))
 /*
  * Win32 doesn't have reliable rename/unlink during concurrent access
  */
-#ifndef FRONTEND
 extern int	pgrename(const char *from, const char *to);
 extern int	pgunlink(const char *path);
 
 #define rename(from, to)	pgrename(from, to)
 #define unlink(path)		pgunlink(path)
 #endif
 
+#ifdef WIN32
 extern int	copydir(char *fromdir, char *todir);
 
 /* Missing rand functions */

src/port/dirmod.c

@@ -10,7 +10,7 @@
  *	Win32 (NT, Win2k, XP).	replace() doesn't work on Win95/98/Me.
  *
  * IDENTIFICATION
- *	  $PostgreSQL: pgsql/src/port/dirmod.c,v 1.8 2003/11/29 19:52:13 pgsql Exp $
+ *	  $PostgreSQL: pgsql/src/port/dirmod.c,v 1.9 2004/02/02 00:17:23 momjian Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -27,9 +27,19 @@ pgrename(const char *from, const char *to)
 {
 	int			loops = 0;
 
+#ifdef WIN32
 	while (!MoveFileEx(from, to, MOVEFILE_REPLACE_EXISTING))
+#endif
+#ifdef CYGWIN
+	while (rename(from, to) < 0)
+#endif
 	{
+#ifdef WIN32
 		if (GetLastError() != ERROR_ACCESS_DENIED)
+#endif
+#ifdef CYGWIN
+		if (errno != EACCES)
+#endif
 			/* set errno? */
 			return -1;
 		Sleep(100);				/* ms */