def __enter__(self):
''' Implement the client with enter block
:returns: The current instance of the client
'''
if not self.connect():
raise ConnectionException("Failed to connect[%s]" %
(self.__str__()))
return self
def execute(self, request=None):
'''
:param request: The request to process
:returns: The result of the request execution
'''
if not self.connect():
raise ConnectionException("Failed to connect[%s]" %
(self.__str__()))
return self.transaction.execute(request)
def _recv(self, size):
''' Reads data from the underlying descriptor
:param size: The number of bytes to read
:return: The bytes read
'''
if not self.socket:
raise ConnectionException(self.__str__())
return self.socket.read(size)
def connectionLost(self, reason):
''' Called upon a client disconnect
:param reason: The reason for the disconnect
'''
_logger.debug("Client disconnected from modbus server: %s" % reason)
self._connected = False
for tid in self.transaction:
self.transaction.getTransaction(tid).errback(Failure(
ConnectionException('Connection lost during request')))
def _send(self, request):
''' Sends data on the underlying socket
:param request: The encoded request to send
:return: The number of bytes written
'''
if not self.socket:
raise ConnectionException(self.__str__())
if request:
return self.socket.write(request)
return 0
def _buildResponse(self, tid):
''' Helper method to return a deferred response
for the current request.
:param tid: The transaction identifier for this response
:returns: A defer linked to the latest request
'''
if not self._connected:
return defer.fail(Failure(
ConnectionException('Client is not connected')))
d = defer.Deferred()
self.transaction.addTransaction(d, tid)
return d