Add emulation of non-blocking sockets to the win32 socket/signal layer,

and use this in pq_getbyte_if_available.

It's only a limited implementation which swithes the whole emulation layer
no non-blocking mode, but that's enough as long as non-blocking is only
used during a short period of time, and only one socket is accessed during
this time.

1 files changed, 24 insertions, 1 deletions

diff --git a/src/backend/port/win32/socket.c b/src/backend/port/win32/socket.c
index 8076b8caef..af42576cab 100644
--- a/src/backend/port/win32/socket.c
+++ b/src/backend/port/win32/socket.c
@@ -6,13 +6,26 @@
  * Portions Copyright (c) 1996-2010, PostgreSQL Global Development Group
  *
  * IDENTIFICATION
- *	  $PostgreSQL: pgsql/src/backend/port/win32/socket.c,v 1.23 2010/01/02 16:57:50 momjian Exp $
+ *	  $PostgreSQL: pgsql/src/backend/port/win32/socket.c,v 1.24 2010/02/16 19:26:02 mha Exp $
  *
  *-------------------------------------------------------------------------
  */
 
 #include "postgres.h"
 
+/*
+ * Indicate if pgwin32_recv() should operate in non-blocking mode.
+ *
+ * Since the socket emulation layer always sets the actual socket to
+ * non-blocking mode in order to be able to deliver signals, we must
+ * specify this in a separate flag if we actually need non-blocking
+ * operation.
+ *
+ * This flag changes the behaviour *globally* for all socket operations,
+ * so it should only be set for very short periods of time.
+ */
+int	pgwin32_noblock = 0;
+
 #undef socket
 #undef accept
 #undef connect
@@ -310,6 +323,16 @@ pgwin32_recv(SOCKET s, char *buf, int len, int f)
 		return -1;
 	}
 
+	if (pgwin32_noblock)
+	{
+		/*
+		 * No data received, and we are in "emulated non-blocking mode", so return
+		 * indicating thta we'd block if we were to continue.
+		 */
+		errno = EWOULDBLOCK;
+		return -1;
+	}
+
 	/* No error, zero bytes (win2000+) or error+WSAEWOULDBLOCK (<=nt4) */
 
 	for (n = 0; n < 5; n++)