Added tools to retrieve CQ builders from a CQ config

third_party/google/protobuf/service_reflection.py

+# 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):
+      return self._CallMethod(srvc, method_descriptor,
+                       rpc_controller, request, callback)
+    self.cls = cls
+    cls.CallMethod = _WrapCallMethod
+    cls.GetDescriptor = staticmethod(lambda: self.descriptor)
+    cls.GetDescriptor.__doc__ = "Returns the service descriptor."
+    cls.GetRequestClass = self._GetRequestClass
+    cls.GetResponseClass = self._GetResponseClass
+    for method in self.descriptor.methods:
+      setattr(cls, method.name, self._GenerateNonImplementedMethod(method))
+
+  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)
+    return 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=None:
+        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.
+    Returns:
+      Response message (in case of blocking call).
+    """
+    return stub.rpc_channel.CallMethod(
+        method_descriptor, rpc_controller, request,
+        method_descriptor.output_type._concrete_class, callback)