comm/modbus.py: take timeout into account in connect(); raises RuntimeError

exception if connection cannot be established within 'timeout' seconds

bliss/comm/modbus.py

@@ -224,14 +224,15 @@ class ModbusTcp:
             if self._connected:
                 return True
 
-            self._fd = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
-            self._fd.connect((local_host,local_port))
-            self._fd.setsockopt(socket.IPPROTO_TCP, socket.TCP_NODELAY, 1)
-            self._fd.setsockopt(socket.SOL_IP, socket.IP_TOS, 0x10)
-            self._host = local_host
-            self._port = local_port
-            self._raw_read_task = gevent.spawn(self._raw_read,
-                                               weakref.proxy(self), self._fd)
+            with gevent.Timeout(self._timeout, RuntimeError("Cannot connect to %s" % self._host)):
+                self._fd = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
+                self._fd.connect((local_host,local_port))
+                self._fd.setsockopt(socket.IPPROTO_TCP, socket.TCP_NODELAY, 1)
+                self._fd.setsockopt(socket.SOL_IP, socket.IP_TOS, 0x10)
+                self._host = local_host
+                self._port = local_port
+                self._raw_read_task = gevent.spawn(self._raw_read,
+                                                   weakref.proxy(self), self._fd)
             self._connected = True
 
         return True