From: Tom Lane <tgl@sss.pgh.pa.us>
Date: Thu, 1 Dec 2005 20:24:49 +0000 (+0000)
Subject: Retry in FileRead and FileWrite if Windows returns ERROR_NO_SYSTEM_RESOURCES.
X-Git-Url: http://git.postgresql.org/gitweb/static/gitweb.js?a=commitdiff_plain;h=071378da5d803ec3af1ab9ca224b6efd5bb0c3e1;p=users%2Fbernd%2Fpostgres.git

Retry in FileRead and FileWrite if Windows returns ERROR_NO_SYSTEM_RESOURCES.
Also add a retry for Unixen returning EINTR, which hasn't been reported
as an issue but at least theoretically could be.  Patch by Qingqing Zhou,
some minor adjustments by me.
---

diff --git a/src/backend/storage/file/fd.c b/src/backend/storage/file/fd.c
index 519386bbf5..272aaef304 100644
--- a/src/backend/storage/file/fd.c
+++ b/src/backend/storage/file/fd.c
@@ -983,11 +983,41 @@ FileRead(File file, char *buffer, int amount)
 	if (returnCode < 0)
 		return returnCode;
 
+retry:
 	returnCode = read(VfdCache[file].fd, buffer, amount);
-	if (returnCode > 0)
+
+	if (returnCode >= 0)
 		VfdCache[file].seekPos += returnCode;
 	else
+	{
+		/*
+		 * Windows may run out of kernel buffers and return "Insufficient
+		 * system resources" error.  Wait a bit and retry to solve it.
+		 *
+		 * It is rumored that EINTR is also possible on some Unix filesystems,
+		 * in which case immediate retry is indicated.
+		 */
+#ifdef WIN32
+		DWORD error = GetLastError();
+
+		switch (error)
+		{
+			case ERROR_NO_SYSTEM_RESOURCES:
+				pg_usleep(1000L);
+				errno = EINTR;
+				break;
+			default:
+				_dosmaperr(error);
+				break;
+		}
+#endif
+		/* OK to retry if interrupted */
+		if (errno == EINTR)
+			goto retry;
+
+		/* Trouble, so assume we don't know the file position anymore */
 		VfdCache[file].seekPos = FileUnknownPos;
+	}
 
 	return returnCode;
 }
@@ -1007,6 +1037,7 @@ FileWrite(File file, char *buffer, int amount)
 	if (returnCode < 0)
 		return returnCode;
 
+retry:
 	errno = 0;
 	returnCode = write(VfdCache[file].fd, buffer, amount);
 
@@ -1014,10 +1045,34 @@ FileWrite(File file, char *buffer, int amount)
 	if (returnCode != amount && errno == 0)
 		errno = ENOSPC;
 
-	if (returnCode > 0)
+	if (returnCode >= 0)
 		VfdCache[file].seekPos += returnCode;
 	else
+	{
+		/*
+		 * See comments in FileRead()
+		 */
+#ifdef WIN32
+		DWORD error = GetLastError();
+
+		switch (error)
+		{
+			case ERROR_NO_SYSTEM_RESOURCES:
+				pg_usleep(1000L);
+				errno = EINTR;
+				break;
+			default:
+				_dosmaperr(error);
+				break;
+		}
+#endif
+		/* OK to retry if interrupted */
+		if (errno == EINTR)
+			goto retry;
+
+		/* Trouble, so assume we don't know the file position anymore */
 		VfdCache[file].seekPos = FileUnknownPos;
+	}
 
 	return returnCode;
 }