Revert of mojo: Add router for python bindings.

mojo/public/python/mojo/bindings/messaging.py

Index: mojo/public/python/mojo/bindings/messaging.py
diff --git a/mojo/public/python/mojo/bindings/messaging.py b/mojo/public/python/mojo/bindings/messaging.py
index 848c830502cfbb9e1edd666661144eba60172184..a6eb57500fac77ee73fad6ce1cfb30576cbf9a7f 100644
--- a/mojo/public/python/mojo/bindings/messaging.py
+++ b/mojo/public/python/mojo/bindings/messaging.py
@@ -5,112 +5,10 @@
 """Utility classes to handle sending and receiving messages."""
 
 
-import struct
 import weakref
 
 # pylint: disable=F0401
-import mojo.bindings.serialization as serialization
 import mojo.system as system
-
-
-# The flag values for a message header.
-NO_FLAG = 0
-MESSAGE_EXPECTS_RESPONSE_FLAG = 1 << 0
-MESSAGE_IS_RESPONSE_FLAG = 1 << 1
-
-
-class MessageHeader(object):
-  """The header of a mojo message."""
-
-  _SIMPLE_MESSAGE_NUM_FIELDS = 2
-  _SIMPLE_MESSAGE_STRUCT = struct.Struct("=IIII")
-
-  _REQUEST_ID_STRUCT = struct.Struct("=Q")
-  _REQUEST_ID_OFFSET = _SIMPLE_MESSAGE_STRUCT.size
-
-  _MESSAGE_WITH_REQUEST_ID_NUM_FIELDS = 3
-  _MESSAGE_WITH_REQUEST_ID_SIZE = (
-      _SIMPLE_MESSAGE_STRUCT.size + _REQUEST_ID_STRUCT.size)
-
-  def __init__(self, message_type, flags, request_id=0, data=None):
-    self._message_type = message_type
-    self._flags = flags
-    self._request_id = request_id
-    self._data = data
-
-  @classmethod
-  def Deserialize(cls, data):
-    buf = buffer(data)
-    if len(data) < cls._SIMPLE_MESSAGE_STRUCT.size:
-      raise serialization.DeserializationException('Header is too short.')
-    (size, version, message_type, flags) = (
-        cls._SIMPLE_MESSAGE_STRUCT.unpack_from(buf))
-    if (version < cls._SIMPLE_MESSAGE_NUM_FIELDS):
-      raise serialization.DeserializationException('Incorrect version.')
-    request_id = 0
-    if _HasRequestId(flags):
-      if version < cls._MESSAGE_WITH_REQUEST_ID_NUM_FIELDS:
-        raise serialization.DeserializationException('Incorrect version.')
-      if (size < cls._MESSAGE_WITH_REQUEST_ID_SIZE or
-          len(data) < cls._MESSAGE_WITH_REQUEST_ID_SIZE):
-        raise serialization.DeserializationException('Header is too short.')
-      (request_id, ) = cls._REQUEST_ID_STRUCT.unpack_from(
-          buf, cls._REQUEST_ID_OFFSET)
-    return MessageHeader(message_type, flags, request_id, data)
-
-  @property
-  def message_type(self):
-    return self._message_type
-
-  # pylint: disable=E0202
-  @property
-  def request_id(self):
-    assert self.has_request_id
-    return self._request_id
-
-  # pylint: disable=E0202
-  @request_id.setter
-  def request_id(self, request_id):
-    assert self.has_request_id
-    self._request_id = request_id
-    self._REQUEST_ID_STRUCT.pack_into(self._data, self._REQUEST_ID_OFFSET,
-                                      request_id)
-
-  @property
-  def has_request_id(self):
-    return _HasRequestId(self._flags)
-
-  @property
-  def expects_response(self):
-    return self._HasFlag(MESSAGE_EXPECTS_RESPONSE_FLAG)
-
-  @property
-  def is_response(self):
-    return self._HasFlag(MESSAGE_IS_RESPONSE_FLAG)
-
-  @property
-  def size(self):
-    if self.has_request_id:
-      return self._MESSAGE_WITH_REQUEST_ID_SIZE
-    return self._SIMPLE_MESSAGE_STRUCT.size
-
-  def Serialize(self):
-    if not self._data:
-      self._data = bytearray(self.size)
-      version = self._SIMPLE_MESSAGE_NUM_FIELDS
-      size = self._SIMPLE_MESSAGE_STRUCT.size
-      if self.has_request_id:
-        version = self._MESSAGE_WITH_REQUEST_ID_NUM_FIELDS
-        size = self._MESSAGE_WITH_REQUEST_ID_SIZE
-      self._SIMPLE_MESSAGE_STRUCT.pack_into(self._data, 0, size, version,
-                                            self._message_type, self._flags)
-      if self.has_request_id:
-        self._REQUEST_ID_STRUCT.pack_into(self._data, self._REQUEST_ID_OFFSET,
-                                          self._request_id)
-    return self._data
-
-  def _HasFlag(self, flag):
-    return self._flags & flag != 0
 
 
 class Message(object):
@@ -119,26 +17,6 @@
   def __init__(self, data=None, handles=None):
     self.data = data
     self.handles = handles
-    self._header = None
-    self._payload = None
-
-  @property
-  def header(self):
-    if self._header is None:
-      self._header = MessageHeader.Deserialize(self.data)
-    return self._header
-
-  @property
-  def payload(self):
-    if self._payload is None:
-      self._payload = Message(self.data[self.header.size:], self.handles)
-    return self._payload
-
-  def SetRequestId(self, request_id):
-    header = self.header
-    header.request_id = request_id
-    (data, _) = header.Serialize()
-    self.data[:header.Size] = data[:header.Size]
 
 
 class MessageReceiver(object):
@@ -233,12 +111,6 @@
     result = self._handle.WriteMessage(message.data, message.handles)
     return result == system.RESULT_OK
 
-  def Close(self):
-    if self._cancellable:
-      self._cancellable()
-      self._cancellable = None
-    self._handle.Close()
-
   def _OnAsyncWaiterResult(self, result):
     self._cancellable = None
     if result == system.RESULT_OK:
@@ -269,96 +141,6 @@
     self._OnError(result)
 
 
-class Router(MessageReceiverWithResponder):
-  """
-  A Router will handle mojo message and forward those to a Connector. It deals
-  with parsing of headers and adding of request ids in order to be able to match
-  a response to a request.
-  """
-
-  def __init__(self, handle):
-    MessageReceiverWithResponder.__init__(self)
-    self._incoming_message_receiver = None
-    self._next_request_id = 1
-    self._responders = {}
-    self._connector = Connector(handle)
-    self._connector.SetIncomingMessageReceiver(
-        ForwardingMessageReceiver(self._HandleIncomingMessage))
-
-  def Start(self):
-    self._connector.Start()
-
-  def SetIncomingMessageReceiver(self, message_receiver):
-    """
-    Set the MessageReceiver that will receive message from the owned message
-    pipe.
-    """
-    self._incoming_message_receiver = message_receiver
-
-  def SetErrorHandler(self, error_handler):
-    """
-    Set the ConnectionErrorHandler that will be notified of errors on the owned
-    message pipe.
-    """
-    self._connector.SetErrorHandler(error_handler)
-
-  def Accept(self, message):
-    # A message without responder is directly forwarded to the connector.
-    return self._connector.Accept(message)
-
-  def AcceptWithResponder(self, message, responder):
-    # The message must have a header.
-    header = message.header
-    assert header.expects_response
-    request_id = self.NextRequestId()
-    header.request_id = request_id
-    if not self._connector.Accept(message):
-      return False
-    self._responders[request_id] = responder
-    return True
-
-  def Close(self):
-    self._connector.Close()
-
-  def _HandleIncomingMessage(self, message):
-    header = message.header
-    if header.expects_response:
-      if self._incoming_message_receiver:
-        return self._incoming_message_receiver.AcceptWithResponder(
-            message, self)
-      # If we receive a request expecting a response when the client is not
-      # listening, then we have no choice but to tear down the pipe.
-      self.Close()
-      return False
-    if header.is_response:
-      request_id = header.request_id
-      responder = self._responders.pop(request_id, None)
-      if responder is not None:
-        return False
-      return responder.Accept(message)
-    if self._incoming_message_receiver:
-      return self._incoming_message_receiver.Accept(message)
-    # Ok to drop the message
-    return False
-
-  def NextRequestId(self):
-    request_id = self._next_request_id
-    while request_id == 0 or request_id in self._responders:
-      request_id = (request_id + 1) % (1 << 64)
-    self._next_request_id = (request_id + 1) % (1 << 64)
-    return request_id
-
-class ForwardingMessageReceiver(MessageReceiver):
-  """A MessageReceiver that forward calls to |Accept| to a callable."""
-
-  def __init__(self, callback):
-    MessageReceiver.__init__(self)
-    self._callback = callback
-
-  def Accept(self, message):
-    return self._callback(message)
-
-
 def _WeakCallback(callback):
   func = callback.im_func
   self = callback.im_self
@@ -383,5 +165,3 @@
     message_receiver.Accept(Message(data[0], data[1]))
   return result
 
-def _HasRequestId(flags):
-  return flags & (MESSAGE_EXPECTS_RESPONSE_FLAG|MESSAGE_IS_RESPONSE_FLAG) != 0