froofle/protobuf/service_reflection.py - repo - Gitiles

 # Protocol Buffers - Google's data interchange format
 # Copyright 2008 Google Inc.  All rights reserved.
 # http://code.google.com/p/protobuf/
 #
 # Redistribution and use in source and binary forms, with or without
 # modification, are permitted provided that the following conditions are
 # met:
 #
 #     * Redistributions of source code must retain the above copyright
 # notice, this list of conditions and the following disclaimer.
 #     * Redistributions in binary form must reproduce the above
 # copyright notice, this list of conditions and the following disclaimer
 # in the documentation and/or other materials provided with the
 # distribution.
 #     * Neither the name of Google Inc. nor the names of its
 # contributors may be used to endorse or promote products derived from
 # this software without specific prior written permission.
 #
 # THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
 # "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
 # LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
 # A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
 # OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
 # SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
 # LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
 # DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
 # THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
 # (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
 # OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.

 """Contains metaclasses used to create protocol service and service stub
 classes from ServiceDescriptor objects at runtime.

 The GeneratedServiceType and GeneratedServiceStubType metaclasses are used to
 inject all useful functionality into the classes output by the protocol
 compiler at compile-time.
 """

 __author__ = 'petar@google.com (Petar Petrov)'


 class GeneratedServiceType(type):

   """Metaclass for service classes created at runtime from ServiceDescriptors.

   Implementations for all methods described in the Service class are added here
   by this class. We also create properties to allow getting/setting all fields
   in the protocol message.

   The protocol compiler currently uses this metaclass to create protocol service
   classes at runtime. Clients can also manually create their own classes at
   runtime, as in this example:

   mydescriptor = ServiceDescriptor(.....)
   class MyProtoService(service.Service):
     __metaclass__ = GeneratedServiceType
     DESCRIPTOR = mydescriptor
   myservice_instance = MyProtoService()
   ...
   """

   _DESCRIPTOR_KEY = 'DESCRIPTOR'

   def __init__(cls, name, bases, dictionary):
     """Creates a message service class.

     Args:
       name: Name of the class (ignored, but required by the metaclass
         protocol).
       bases: Base classes of the class being constructed.
       dictionary: The class dictionary of the class being constructed.
         dictionary[_DESCRIPTOR_KEY] must contain a ServiceDescriptor object
         describing this protocol service type.
     """
     # Don't do anything if this class doesn't have a descriptor. This happens
     # when a service class is subclassed.
     if GeneratedServiceType._DESCRIPTOR_KEY not in dictionary:
       return
     descriptor = dictionary[GeneratedServiceType._DESCRIPTOR_KEY]
     service_builder = _ServiceBuilder(descriptor)
     service_builder.BuildService(cls)


 class GeneratedServiceStubType(GeneratedServiceType):

   """Metaclass for service stubs created at runtime from ServiceDescriptors.

   This class has similar responsibilities as GeneratedServiceType, except that
   it creates the service stub classes.
   """

   _DESCRIPTOR_KEY = 'DESCRIPTOR'

   def __init__(cls, name, bases, dictionary):
     """Creates a message service stub class.

     Args:
       name: Name of the class (ignored, here).
       bases: Base classes of the class being constructed.
       dictionary: The class dictionary of the class being constructed.
         dictionary[_DESCRIPTOR_KEY] must contain a ServiceDescriptor object
         describing this protocol service type.
     """
     super(GeneratedServiceStubType, cls).__init__(name, bases, dictionary)
     # Don't do anything if this class doesn't have a descriptor. This happens
     # when a service stub is subclassed.
     if GeneratedServiceStubType._DESCRIPTOR_KEY not in dictionary:
       return
     descriptor = dictionary[GeneratedServiceStubType._DESCRIPTOR_KEY]
     service_stub_builder = _ServiceStubBuilder(descriptor)
     service_stub_builder.BuildServiceStub(cls)


 class _ServiceBuilder(object):

   """This class constructs a protocol service class using a service descriptor.

   Given a service descriptor, this class constructs a class that represents
   the specified service descriptor. One service builder instance constructs
   exactly one service class. That means all instances of that class share the
   same builder.
   """

   def __init__(self, service_descriptor):
     """Initializes an instance of the service class builder.

     Args:
       service_descriptor: ServiceDescriptor to use when constructing the
         service class.
     """
     self.descriptor = service_descriptor

   def BuildService(self, cls):
     """Constructs the service class.

     Args:
       cls: The class that will be constructed.
     """

     # CallMethod needs to operate with an instance of the Service class. This
     # internal wrapper function exists only to be able to pass the service
     # instance to the method that does the real CallMethod work.
     def _WrapCallMethod(srvc, method_descriptor,
                         rpc_controller, request, callback):
       self._CallMethod(srvc, method_descriptor,
                        rpc_controller, request, callback)
     self.cls = cls
     cls.CallMethod = _WrapCallMethod
     cls.GetDescriptor = self._GetDescriptor
     cls.GetRequestClass = self._GetRequestClass
     cls.GetResponseClass = self._GetResponseClass
     for method in self.descriptor.methods:
       setattr(cls, method.name, self._GenerateNonImplementedMethod(method))

   def _GetDescriptor(self):
     """Retrieves the service descriptor.

     Returns:
       The descriptor of the service (of type ServiceDescriptor).
     """
     return self.descriptor

   def _CallMethod(self, srvc, method_descriptor,
                   rpc_controller, request, callback):
     """Calls the method described by a given method descriptor.

     Args:
       srvc: Instance of the service for which this method is called.
       method_descriptor: Descriptor that represent the method to call.
       rpc_controller: RPC controller to use for this method's execution.
       request: Request protocol message.
       callback: A callback to invoke after the method has completed.
     """
     if method_descriptor.containing_service != self.descriptor:
       raise RuntimeError(
           'CallMethod() given method descriptor for wrong service type.')
     method = getattr(srvc, method_descriptor.name)
     method(rpc_controller, request, callback)

   def _GetRequestClass(self, method_descriptor):
     """Returns the class of the request protocol message.

     Args:
       method_descriptor: Descriptor of the method for which to return the
         request protocol message class.

     Returns:
       A class that represents the input protocol message of the specified
       method.
     """
     if method_descriptor.containing_service != self.descriptor:
       raise RuntimeError(
           'GetRequestClass() given method descriptor for wrong service type.')
     return method_descriptor.input_type._concrete_class

   def _GetResponseClass(self, method_descriptor):
     """Returns the class of the response protocol message.

     Args:
       method_descriptor: Descriptor of the method for which to return the
         response protocol message class.

     Returns:
       A class that represents the output protocol message of the specified
       method.
     """
     if method_descriptor.containing_service != self.descriptor:
       raise RuntimeError(
           'GetResponseClass() given method descriptor for wrong service type.')
     return method_descriptor.output_type._concrete_class

   def _GenerateNonImplementedMethod(self, method):
     """Generates and returns a method that can be set for a service methods.

     Args:
       method: Descriptor of the service method for which a method is to be
         generated.

     Returns:
       A method that can be added to the service class.
     """
     return lambda inst, rpc_controller, request, callback: (
         self._NonImplementedMethod(method.name, rpc_controller, callback))

   def _NonImplementedMethod(self, method_name, rpc_controller, callback):
     """The body of all methods in the generated service class.

     Args:
       method_name: Name of the method being executed.
       rpc_controller: RPC controller used to execute this method.
       callback: A callback which will be invoked when the method finishes.
     """
     rpc_controller.SetFailed('Method %s not implemented.' % method_name)
     callback(None)


 class _ServiceStubBuilder(object):

   """Constructs a protocol service stub class using a service descriptor.

   Given a service descriptor, this class constructs a suitable stub class.
   A stub is just a type-safe wrapper around an RpcChannel which emulates a
   local implementation of the service.

   One service stub builder instance constructs exactly one class. It means all
   instances of that class share the same service stub builder.
   """

   def __init__(self, service_descriptor):
     """Initializes an instance of the service stub class builder.

     Args:
       service_descriptor: ServiceDescriptor to use when constructing the
         stub class.
     """
     self.descriptor = service_descriptor

   def BuildServiceStub(self, cls):
     """Constructs the stub class.

     Args:
       cls: The class that will be constructed.
     """

     def _ServiceStubInit(stub, rpc_channel):
       stub.rpc_channel = rpc_channel
     self.cls = cls
     cls.__init__ = _ServiceStubInit
     for method in self.descriptor.methods:
       setattr(cls, method.name, self._GenerateStubMethod(method))

   def _GenerateStubMethod(self, method):
     return lambda inst, rpc_controller, request, callback: self._StubMethod(
         inst, method, rpc_controller, request, callback)

   def _StubMethod(self, stub, method_descriptor,
                   rpc_controller, request, callback):
     """The body of all service methods in the generated stub class.

     Args:
       stub: Stub instance.
       method_descriptor: Descriptor of the invoked method.
       rpc_controller: Rpc controller to execute the method.
       request: Request protocol message.
       callback: A callback to execute when the method finishes.
     """
     stub.rpc_channel.CallMethod(
         method_descriptor, rpc_controller, request,
         method_descriptor.output_type._concrete_class, callback)
	# Protocol Buffers - Google's data interchange format
	# Copyright 2008 Google Inc. All rights reserved.
	# http://code.google.com/p/protobuf/
	#
	# Redistribution and use in source and binary forms, with or without
	# modification, are permitted provided that the following conditions are
	# met:
	#
	# * Redistributions of source code must retain the above copyright
	# notice, this list of conditions and the following disclaimer.
	# * Redistributions in binary form must reproduce the above
	# copyright notice, this list of conditions and the following disclaimer
	# in the documentation and/or other materials provided with the
	# distribution.
	# * Neither the name of Google Inc. nor the names of its
	# contributors may be used to endorse or promote products derived from
	# this software without specific prior written permission.
	#
	# THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
	# "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
	# LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
	# A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
	# OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
	# SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
	# LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
	# DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
	# THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
	# (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
	# OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.

	"""Contains metaclasses used to create protocol service and service stub
	classes from ServiceDescriptor objects at runtime.

	The GeneratedServiceType and GeneratedServiceStubType metaclasses are used to
	inject all useful functionality into the classes output by the protocol
	compiler at compile-time.
	"""

	__author__ = 'petar@google.com (Petar Petrov)'


	class GeneratedServiceType(type):

	"""Metaclass for service classes created at runtime from ServiceDescriptors.

	Implementations for all methods described in the Service class are added here
	by this class. We also create properties to allow getting/setting all fields
	in the protocol message.

	The protocol compiler currently uses this metaclass to create protocol service
	classes at runtime. Clients can also manually create their own classes at
	runtime, as in this example:

	mydescriptor = ServiceDescriptor(.....)
	class MyProtoService(service.Service):
	__metaclass__ = GeneratedServiceType
	DESCRIPTOR = mydescriptor
	myservice_instance = MyProtoService()
	...
	"""

	_DESCRIPTOR_KEY = 'DESCRIPTOR'

	def __init__(cls, name, bases, dictionary):
	"""Creates a message service class.

	Args:
	name: Name of the class (ignored, but required by the metaclass
	protocol).
	bases: Base classes of the class being constructed.
	dictionary: The class dictionary of the class being constructed.
	dictionary[_DESCRIPTOR_KEY] must contain a ServiceDescriptor object
	describing this protocol service type.
	"""
	# Don't do anything if this class doesn't have a descriptor. This happens
	# when a service class is subclassed.
	if GeneratedServiceType._DESCRIPTOR_KEY not in dictionary:
	return
	descriptor = dictionary[GeneratedServiceType._DESCRIPTOR_KEY]
	service_builder = _ServiceBuilder(descriptor)
	service_builder.BuildService(cls)


	class GeneratedServiceStubType(GeneratedServiceType):

	"""Metaclass for service stubs created at runtime from ServiceDescriptors.

	This class has similar responsibilities as GeneratedServiceType, except that
	it creates the service stub classes.
	"""

	_DESCRIPTOR_KEY = 'DESCRIPTOR'

	def __init__(cls, name, bases, dictionary):
	"""Creates a message service stub class.

	Args:
	name: Name of the class (ignored, here).
	bases: Base classes of the class being constructed.
	dictionary: The class dictionary of the class being constructed.
	dictionary[_DESCRIPTOR_KEY] must contain a ServiceDescriptor object
	describing this protocol service type.
	"""
	super(GeneratedServiceStubType, cls).__init__(name, bases, dictionary)
	# Don't do anything if this class doesn't have a descriptor. This happens
	# when a service stub is subclassed.
	if GeneratedServiceStubType._DESCRIPTOR_KEY not in dictionary:
	return
	descriptor = dictionary[GeneratedServiceStubType._DESCRIPTOR_KEY]
	service_stub_builder = _ServiceStubBuilder(descriptor)
	service_stub_builder.BuildServiceStub(cls)


	class _ServiceBuilder(object):

	"""This class constructs a protocol service class using a service descriptor.

	Given a service descriptor, this class constructs a class that represents
	the specified service descriptor. One service builder instance constructs
	exactly one service class. That means all instances of that class share the
	same builder.
	"""

	def __init__(self, service_descriptor):
	"""Initializes an instance of the service class builder.

	Args:
	service_descriptor: ServiceDescriptor to use when constructing the
	service class.
	"""
	self.descriptor = service_descriptor

	def BuildService(self, cls):
	"""Constructs the service class.

	Args:
	cls: The class that will be constructed.
	"""

	# CallMethod needs to operate with an instance of the Service class. This
	# internal wrapper function exists only to be able to pass the service
	# instance to the method that does the real CallMethod work.
	def _WrapCallMethod(srvc, method_descriptor,
	rpc_controller, request, callback):
	self._CallMethod(srvc, method_descriptor,
	rpc_controller, request, callback)
	self.cls = cls
	cls.CallMethod = _WrapCallMethod
	cls.GetDescriptor = self._GetDescriptor
	cls.GetRequestClass = self._GetRequestClass
	cls.GetResponseClass = self._GetResponseClass
	for method in self.descriptor.methods:
	setattr(cls, method.name, self._GenerateNonImplementedMethod(method))

	def _GetDescriptor(self):
	"""Retrieves the service descriptor.

	Returns:
	The descriptor of the service (of type ServiceDescriptor).
	"""
	return self.descriptor

	def _CallMethod(self, srvc, method_descriptor,
	rpc_controller, request, callback):
	"""Calls the method described by a given method descriptor.

	Args:
	srvc: Instance of the service for which this method is called.
	method_descriptor: Descriptor that represent the method to call.
	rpc_controller: RPC controller to use for this method's execution.
	request: Request protocol message.
	callback: A callback to invoke after the method has completed.
	"""
	if method_descriptor.containing_service != self.descriptor:
	raise RuntimeError(
	'CallMethod() given method descriptor for wrong service type.')
	method = getattr(srvc, method_descriptor.name)
	method(rpc_controller, request, callback)

	def _GetRequestClass(self, method_descriptor):
	"""Returns the class of the request protocol message.

	Args:
	method_descriptor: Descriptor of the method for which to return the
	request protocol message class.

	Returns:
	A class that represents the input protocol message of the specified
	method.
	"""
	if method_descriptor.containing_service != self.descriptor:
	raise RuntimeError(
	'GetRequestClass() given method descriptor for wrong service type.')
	return method_descriptor.input_type._concrete_class

	def _GetResponseClass(self, method_descriptor):
	"""Returns the class of the response protocol message.

	Args:
	method_descriptor: Descriptor of the method for which to return the
	response protocol message class.

	Returns:
	A class that represents the output protocol message of the specified
	method.
	"""
	if method_descriptor.containing_service != self.descriptor:
	raise RuntimeError(
	'GetResponseClass() given method descriptor for wrong service type.')
	return method_descriptor.output_type._concrete_class

	def _GenerateNonImplementedMethod(self, method):
	"""Generates and returns a method that can be set for a service methods.

	Args:
	method: Descriptor of the service method for which a method is to be
	generated.

	Returns:
	A method that can be added to the service class.
	"""
	return lambda inst, rpc_controller, request, callback: (
	self._NonImplementedMethod(method.name, rpc_controller, callback))

	def _NonImplementedMethod(self, method_name, rpc_controller, callback):
	"""The body of all methods in the generated service class.

	Args:
	method_name: Name of the method being executed.
	rpc_controller: RPC controller used to execute this method.
	callback: A callback which will be invoked when the method finishes.
	"""
	rpc_controller.SetFailed('Method %s not implemented.' % method_name)
	callback(None)


	class _ServiceStubBuilder(object):

	"""Constructs a protocol service stub class using a service descriptor.

	Given a service descriptor, this class constructs a suitable stub class.
	A stub is just a type-safe wrapper around an RpcChannel which emulates a
	local implementation of the service.

	One service stub builder instance constructs exactly one class. It means all
	instances of that class share the same service stub builder.
	"""

	def __init__(self, service_descriptor):
	"""Initializes an instance of the service stub class builder.

	Args:
	service_descriptor: ServiceDescriptor to use when constructing the
	stub class.
	"""
	self.descriptor = service_descriptor

	def BuildServiceStub(self, cls):
	"""Constructs the stub class.

	Args:
	cls: The class that will be constructed.
	"""

	def _ServiceStubInit(stub, rpc_channel):
	stub.rpc_channel = rpc_channel
	self.cls = cls
	cls.__init__ = _ServiceStubInit
	for method in self.descriptor.methods:
	setattr(cls, method.name, self._GenerateStubMethod(method))

	def _GenerateStubMethod(self, method):
	return lambda inst, rpc_controller, request, callback: self._StubMethod(
	inst, method, rpc_controller, request, callback)

	def _StubMethod(self, stub, method_descriptor,
	rpc_controller, request, callback):
	"""The body of all service methods in the generated stub class.

	Args:
	stub: Stub instance.
	method_descriptor: Descriptor of the invoked method.
	rpc_controller: Rpc controller to execute the method.
	request: Request protocol message.
	callback: A callback to execute when the method finishes.
	"""
	stub.rpc_channel.CallMethod(
	method_descriptor, rpc_controller, request,
	method_descriptor.output_type._concrete_class, callback)