libpq: Try next host if one of them times out.

If one host in a multi-host connection string times out, move on to
the next specified host instead of giving up entirely.

Takayuki Tsunakawa, reviewed by Michael Paquier.  I added
a minor adjustment to the documentation.

Discussion: http://postgr.es/m/0A3221C70F24FB45833433255569204D1F6F42F5@G01JPEXMBYT05

1 files changed, 4 insertions, 6 deletions

diff --git a/src/interfaces/libpq/fe-misc.c b/src/interfaces/libpq/fe-misc.c
index 756c6d77790..1d6ea93a0a9 100644
--- a/src/interfaces/libpq/fe-misc.c
+++ b/src/interfaces/libpq/fe-misc.c
@@ -991,11 +991,9 @@ pqWait(int forRead, int forWrite, PGconn *conn)
 /*
  * pqWaitTimed: wait, but not past finish_time.
  *
- * If finish_time is exceeded then we return failure (EOF).  This is like
- * the response for a kernel exception because we don't want the caller
- * to try to read/write in that case.
- *
  * finish_time = ((time_t) -1) disables the wait limit.
+ *
+ * Returns -1 on failure, 0 if the socket is readable/writable, 1 if it timed out.
  */
 int
 pqWaitTimed(int forRead, int forWrite, PGconn *conn, time_t finish_time)
@@ -1005,13 +1003,13 @@ pqWaitTimed(int forRead, int forWrite, PGconn *conn, time_t finish_time)
 	result = pqSocketCheck(conn, forRead, forWrite, finish_time);
 
 	if (result < 0)
-		return EOF;				/* errorMessage is already set */
+		return -1;				/* errorMessage is already set */
 
 	if (result == 0)
 	{
 		printfPQExpBuffer(&conn->errorMessage,
 						  libpq_gettext("timeout expired\n"));
-		return EOF;
+		return 1;
 	}
 
 	return 0;