Initial checkin of gRPC to third_party/

third_party/grpc/src/python/grpcio/grpc/framework/alpha/interfaces.py

Index: third_party/grpc/src/python/grpcio/grpc/framework/alpha/interfaces.py
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+# Copyright 2015, Google Inc.
+# All rights reserved.
+#
+# 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.
+
+"""Interfaces of GRPC."""
+
+import abc
+import enum
+
+# exceptions is referenced from specification in this module.
+from grpc.framework.alpha import exceptions  # pylint: disable=unused-import
+from grpc.framework.foundation import activated
+from grpc.framework.foundation import future
+
+
+@enum.unique
+class Cardinality(enum.Enum):
+  """Constants for the four cardinalities of RPC."""
+
+  UNARY_UNARY = 'request-unary/response-unary'
+  UNARY_STREAM = 'request-unary/response-streaming'
+  STREAM_UNARY = 'request-streaming/response-unary'
+  STREAM_STREAM = 'request-streaming/response-streaming'
+
+
+@enum.unique
+class Abortion(enum.Enum):
+  """Categories of RPC abortion."""
+
+  CANCELLED = 'cancelled'
+  EXPIRED = 'expired'
+  NETWORK_FAILURE = 'network failure'
+  SERVICED_FAILURE = 'serviced failure'
+  SERVICER_FAILURE = 'servicer failure'
+
+
+class CancellableIterator(object):
+  """Implements the Iterator protocol and affords a cancel method."""
+  __metaclass__ = abc.ABCMeta
+
+  @abc.abstractmethod
+  def __iter__(self):
+    """Returns the self object in accordance with the Iterator protocol."""
+    raise NotImplementedError()
+
+  @abc.abstractmethod
+  def next(self):
+    """Returns a value or raises StopIteration per the Iterator protocol."""
+    raise NotImplementedError()
+
+  @abc.abstractmethod
+  def cancel(self):
+    """Requests cancellation of whatever computation underlies this iterator."""
+    raise NotImplementedError()
+
+
+class RpcContext(object):
+  """Provides RPC-related information and action."""
+  __metaclass__ = abc.ABCMeta
+
+  @abc.abstractmethod
+  def is_active(self):
+    """Describes whether the RPC is active or has terminated."""
+    raise NotImplementedError()
+
+  @abc.abstractmethod
+  def time_remaining(self):
+    """Describes the length of allowed time remaining for the RPC.
+    Returns:
+      A nonnegative float indicating the length of allowed time in seconds
+      remaining for the RPC to complete before it is considered to have timed
+      out.
+    """
+    raise NotImplementedError()
+
+  @abc.abstractmethod
+  def add_abortion_callback(self, abortion_callback):
+    """Registers a callback to be called if the RPC is aborted.
+    Args:
+      abortion_callback: A callable to be called and passed an Abortion value
+        in the event of RPC abortion.
+    """
+    raise NotImplementedError()
+
+
+class UnaryUnarySyncAsync(object):
+  """Affords invoking a unary-unary RPC synchronously or asynchronously.
+  Values implementing this interface are directly callable and present an
+  "async" method. Both calls take a request value and a numeric timeout.
+  Direct invocation of a value of this type invokes its associated RPC and
+  blocks until the RPC's response is available. Calling the "async" method
+  of a value of this type invokes its associated RPC and immediately returns a
+  future.Future bound to the asynchronous execution of the RPC.
+  """
+  __metaclass__ = abc.ABCMeta
+
+  @abc.abstractmethod
+  def __call__(self, request, timeout):
+    """Synchronously invokes the underlying RPC.
+    Args:
+      request: The request value for the RPC.
+      timeout: A duration of time in seconds to allow for the RPC.
+    Returns:
+      The response value for the RPC.
+    Raises:
+      exceptions.RpcError: Indicating that the RPC was aborted.
+    """
+    raise NotImplementedError()
+
+  @abc.abstractmethod
+  def async(self, request, timeout):
+    """Asynchronously invokes the underlying RPC.
+    Args:
+      request: The request value for the RPC.
+      timeout: A duration of time in seconds to allow for the RPC.
+    Returns:
+      A future.Future representing the RPC. In the event of RPC completion, the
+        returned Future's result value will be the response value of the RPC.
+        In the event of RPC abortion, the returned Future's exception value
+        will be an exceptions.RpcError.
+    """
+    raise NotImplementedError()
+
+
+class StreamUnarySyncAsync(object):
+  """Affords invoking a stream-unary RPC synchronously or asynchronously.
+  Values implementing this interface are directly callable and present an
+  "async" method. Both calls take an iterator of request values and a numeric
+  timeout. Direct invocation of a value of this type invokes its associated RPC
+  and blocks until the RPC's response is available. Calling the "async" method
+  of a value of this type invokes its associated RPC and immediately returns a
+  future.Future bound to the asynchronous execution of the RPC.
+  """
+  __metaclass__ = abc.ABCMeta
+
+  @abc.abstractmethod
+  def __call__(self, request_iterator, timeout):
+    """Synchronously invokes the underlying RPC.
+
+    Args:
+      request_iterator: An iterator that yields request values for the RPC.
+      timeout: A duration of time in seconds to allow for the RPC.
+
+    Returns:
+      The response value for the RPC.
+
+    Raises:
+      exceptions.RpcError: Indicating that the RPC was aborted.
+    """
+    raise NotImplementedError()
+
+  @abc.abstractmethod
+  def async(self, request_iterator, timeout):
+    """Asynchronously invokes the underlying RPC.
+
+    Args:
+      request_iterator: An iterator that yields request values for the RPC.
+      timeout: A duration of time in seconds to allow for the RPC.
+
+    Returns:
+      A future.Future representing the RPC. In the event of RPC completion, the
+        returned Future's result value will be the response value of the RPC.
+        In the event of RPC abortion, the returned Future's exception value
+        will be an exceptions.RpcError.
+    """
+    raise NotImplementedError()
+
+
+class RpcMethodDescription(object):
+  """A type for the common aspects of RPC method descriptions."""
+  __metaclass__ = abc.ABCMeta
+
+  @abc.abstractmethod
+  def cardinality(self):
+    """Identifies the cardinality of this RpcMethodDescription.
+
+    Returns:
+      A Cardinality value identifying whether or not this
+        RpcMethodDescription is request-unary or request-streaming and
+        whether or not it is response-unary or response-streaming.
+    """
+    raise NotImplementedError()
+
+
+class RpcMethodInvocationDescription(RpcMethodDescription):
+  """Invocation-side description of an RPC method."""
+  __metaclass__ = abc.ABCMeta
+
+  @abc.abstractmethod
+  def serialize_request(self, request):
+    """Serializes a request value.
+
+    Args:
+      request: A request value appropriate for the RPC method described by this
+        RpcMethodInvocationDescription.
+
+    Returns:
+      The serialization of the given request value as a
+        bytestring.
+    """
+    raise NotImplementedError()
+
+  @abc.abstractmethod
+  def deserialize_response(self, serialized_response):
+    """Deserializes a response value.
+
+    Args:
+      serialized_response: A bytestring that is the serialization of a response
+        value appropriate for the RPC method described by this
+        RpcMethodInvocationDescription.
+
+    Returns:
+      A response value corresponding to the given bytestring.
+    """
+    raise NotImplementedError()
+
+
+class RpcMethodServiceDescription(RpcMethodDescription):
+  """Service-side description of an RPC method."""
+  __metaclass__ = abc.ABCMeta
+
+  @abc.abstractmethod
+  def deserialize_request(self, serialized_request):
+    """Deserializes a request value.
+
+    Args:
+      serialized_request: A bytestring that is the serialization of a request
+        value appropriate for the RPC method described by this
+        RpcMethodServiceDescription.
+
+    Returns:
+      A request value corresponding to the given bytestring.
+    """
+    raise NotImplementedError()
+
+  @abc.abstractmethod
+  def serialize_response(self, response):
+    """Serializes a response value.
+
+    Args:
+      response: A response value appropriate for the RPC method described by
+        this RpcMethodServiceDescription.
+
+    Returns:
+      The serialization of the given response value as a
+        bytestring.
+    """
+    raise NotImplementedError()
+
+  @abc.abstractmethod
+  def service_unary_unary(self, request, context):
+    """Carries out this RPC.
+
+    This method may only be called if the cardinality of this
+    RpcMethodServiceDescription is Cardinality.UNARY_UNARY.
+
+    Args:
+      request: A request value appropriate for the RPC method described by this
+        RpcMethodServiceDescription.
+      context: An RpcContext object for the RPC.
+
+    Returns:
+      A response value appropriate for the RPC method described by this
+        RpcMethodServiceDescription.
+    """
+    raise NotImplementedError()
+
+  @abc.abstractmethod
+  def service_unary_stream(self, request, context):
+    """Carries out this RPC.
+
+    This method may only be called if the cardinality of this
+    RpcMethodServiceDescription is Cardinality.UNARY_STREAM.
+
+    Args:
+      request: A request value appropriate for the RPC method described by this
+        RpcMethodServiceDescription.
+      context: An RpcContext object for the RPC.
+
+    Yields:
+      Zero or more response values appropriate for the RPC method described by
+        this RpcMethodServiceDescription.
+    """
+    raise NotImplementedError()
+
+  @abc.abstractmethod
+  def service_stream_unary(self, request_iterator, context):
+    """Carries out this RPC.
+
+    This method may only be called if the cardinality of this
+    RpcMethodServiceDescription is Cardinality.STREAM_UNARY.
+
+    Args:
+      request_iterator: An iterator of request values appropriate for the RPC
+        method described by this RpcMethodServiceDescription.
+      context: An RpcContext object for the RPC.
+
+    Returns:
+      A response value appropriate for the RPC method described by this
+        RpcMethodServiceDescription.
+    """
+    raise NotImplementedError()
+
+  @abc.abstractmethod
+  def service_stream_stream(self, request_iterator, context):
+    """Carries out this RPC.
+
+    This method may only be called if the cardinality of this
+    RpcMethodServiceDescription is Cardinality.STREAM_STREAM.
+
+    Args:
+      request_iterator: An iterator of request values appropriate for the RPC
+        method described by this RpcMethodServiceDescription.
+      context: An RpcContext object for the RPC.
+
+    Yields:
+      Zero or more response values appropriate for the RPC method described by
+        this RpcMethodServiceDescription.
+    """
+    raise NotImplementedError()
+
+
+class Stub(object):
+  """A stub with callable RPC method names for attributes.
+
+  Instances of this type are context managers and only afford RPC invocation
+  when used in context.
+
+  Instances of this type, when used in context, respond to attribute access
+  as follows: if the requested attribute is the name of a unary-unary RPC
+  method, the value of the attribute will be a UnaryUnarySyncAsync with which
+  to invoke the RPC method. If the requested attribute is the name of a
+  unary-stream RPC method, the value of the attribute will be a callable taking
+  a request object and a timeout parameter and returning a CancellableIterator
+  that yields the response values of the RPC. If the requested attribute is the
+  name of a stream-unary RPC method, the value of the attribute will be a
+  StreamUnarySyncAsync with which to invoke the RPC method. If the requested
+  attribute is the name of a stream-stream RPC method, the value of the
+  attribute will be a callable taking an iterator of request objects and a
+  timeout and returning a CancellableIterator that yields the response values
+  of the RPC.
+
+  In all cases indication of abortion is indicated by raising of
+  exceptions.RpcError, exceptions.CancellationError,
+  and exceptions.ExpirationError.
+  """
+  __metaclass__ = abc.ABCMeta
+
+
+class Server(activated.Activated):
+  """A GRPC Server."""
+  __metaclass__ = abc.ABCMeta
+
+  @abc.abstractmethod
+  def port(self):
+    """Reports the port on which the server is serving.
+
+    This method may only be called while the server is activated.
+
+    Returns:
+      The port on which the server is serving.
+    """
+    raise NotImplementedError()