adding timeout parameter to socket writer

socket_writer.go

@@ -14,22 +14,32 @@ type SocketWriter struct {
 	addr        string
 	connSync    *sync.RWMutex
 	restartOnce *sync.Once
+	Timeout     time.Duration
 }
 
 func NewSocketWriter(network, addr string) (*SocketWriter, error) {
 	conn, err := net.Dial(network, addr)
 	if err != nil {
 		return nil, err
 	}
-	return &SocketWriter{conn, network, addr, &sync.RWMutex{}, &sync.Once{}}, nil
+	timeout := 5 * time.Millisecond // logging should be fast
+	return &SocketWriter{conn, network, addr, &sync.RWMutex{}, &sync.Once{}, timeout}, nil
 }
 
 func (sw *SocketWriter) LogWrite(msg string) {
 	sw.connSync.RLock()
+	// Starting with go1.1 (currently tested on go1.1.1)
+	// writing to /dev/log on linux with rsyslog will occasionally
+	// return EAGAIN.  Unfortunately, the go socket code does
+	// a blocking wait which never returns when it gets an EAGAIN,
+	// so a timeout is necessary to unblock. I tested and a reconnect
+	// is not necessary when this happens but I think the code is more
+	// general this way so I'm leaving the reconnect on all errors.
+	sw.conn.SetWriteDeadline(time.Now().Add(sw.Timeout))
 	_, err := sw.conn.Write([]byte(msg))
 	sw.connSync.RUnlock()
 	if err != nil {
-		fmt.Printf("Socket logging error: %v", err)
+		fmt.Printf("Socket logging error: %v\n", err)
 		sw.restartOnce.Do(func() {
 			go sw.reconnect()
 		})