Merge pull request #22032 from ZHmao/implement-server-interceptor-for-unary-unary-call

[Aio] Implement server interceptor for unary unary call

src/python/grpcio/grpc/_cython/_cygrpc/aio/server.pxd.pxi

@@ -61,3 +61,4 @@ cdef class AioServer:
     cdef CallbackWrapper _shutdown_callback_wrapper
     cdef object _crash_exception  # Exception
     cdef set _ongoing_rpc_tasks
+    cdef tuple _interceptors

src/python/grpcio/grpc/_cython/_cygrpc/aio/server.pyx.pxi

@@ -15,6 +15,7 @@
 
 import inspect
 import traceback
+import functools
 
 
 cdef int _EMPTY_FLAG = 0
@@ -214,15 +215,34 @@ cdef class _ServicerContext:
         self._rpc_state.disable_next_compression = True
 
 
-cdef _find_method_handler(str method, tuple metadata, list generic_handlers):
+async def _run_interceptor(object interceptors, object query_handler,
+                           object handler_call_details):
+    interceptor = next(interceptors, None)
+    if interceptor:
+        continuation = functools.partial(_run_interceptor, interceptors,
+                                         query_handler)
+        return await interceptor.intercept_service(continuation, handler_call_details)
+    else:
+        return query_handler(handler_call_details)
+
+
+async def _find_method_handler(str method, tuple metadata, list generic_handlers,
+                          tuple interceptors):
+    def query_handlers(handler_call_details):
+        for generic_handler in generic_handlers:
+            method_handler = generic_handler.service(handler_call_details)
+            if method_handler is not None:
+                return method_handler
+        return None
+
     cdef _HandlerCallDetails handler_call_details = _HandlerCallDetails(method,
                                                                         metadata)
-
-    for generic_handler in generic_handlers:
-        method_handler = generic_handler.service(handler_call_details)
-        if method_handler is not None:
-            return method_handler
-    return None
+    # interceptor
+    if interceptors:
+        return await _run_interceptor(iter(interceptors), query_handlers,
+                                      handler_call_details)
+    else:
+        return query_handlers(handler_call_details)
 
 
 async def _finish_handler_with_unary_response(RPCState rpc_state,
@@ -523,13 +543,15 @@ async def _schedule_rpc_coro(object rpc_coro,
     await _handle_cancellation_from_core(rpc_task, rpc_state, loop)
 
 
-async def _handle_rpc(list generic_handlers, RPCState rpc_state, object loop):
+async def _handle_rpc(list generic_handlers, tuple interceptors,
+                      RPCState rpc_state, object loop):
     cdef object method_handler
     # Finds the method handler (application logic)
-    method_handler = _find_method_handler(
+    method_handler = await _find_method_handler(
         rpc_state.method().decode(),
         rpc_state.invocation_metadata(),
         generic_handlers,
+        interceptors,
     )
     if method_handler is None:
         rpc_state.status_sent = True
@@ -612,8 +634,9 @@ cdef class AioServer:
             SERVER_SHUTDOWN_FAILURE_HANDLER)
         self._crash_exception = None
 
+        self._interceptors = ()
         if interceptors:
-            raise NotImplementedError()
+            self._interceptors = interceptors
         if maximum_concurrent_rpcs:
             raise NotImplementedError()
         if thread_pool:
@@ -669,6 +692,7 @@ cdef class AioServer:
             # the coroutine onto event loop inside of the cancellation
             # coroutine.
             rpc_coro = _handle_rpc(self._generic_handlers,
+                                   self._interceptors,
                                    rpc_state,
                                    self._loop)
 

src/python/grpcio/grpc/experimental/aio/__init__.py

@@ -30,7 +30,7 @@ from ._base_channel import (Channel, StreamStreamMultiCallable,
                             UnaryUnaryMultiCallable)
 from ._call import AioRpcError
 from ._interceptor import (ClientCallDetails, InterceptedUnaryUnaryCall,
-                           UnaryUnaryClientInterceptor)
+                           UnaryUnaryClientInterceptor, ServerInterceptor)
 from ._server import server
 from ._base_server import Server, ServicerContext
 from ._typing import ChannelArgumentType
@@ -55,6 +55,7 @@ __all__ = (
     'ClientCallDetails',
     'UnaryUnaryClientInterceptor',
     'InterceptedUnaryUnaryCall',
+    'ServerInterceptor',
     'insecure_channel',
     'server',
     'Server',

src/python/grpcio/grpc/experimental/aio/_interceptor.py

@@ -16,7 +16,7 @@ import asyncio
 import collections
 import functools
 from abc import ABCMeta, abstractmethod
-from typing import Callable, Optional, Iterator, Sequence, Union
+from typing import Callable, Optional, Iterator, Sequence, Union, Awaitable
 
 import grpc
 from grpc._cython import cygrpc
@@ -30,6 +30,34 @@ from ._typing import (RequestType, SerializingFunction, DeserializingFunction,
 _LOCAL_CANCELLATION_DETAILS = 'Locally cancelled by application!'
 
 
+class ServerInterceptor(metaclass=ABCMeta):
+    """Affords intercepting incoming RPCs on the service-side.
+
+    This is an EXPERIMENTAL API.
+    """
+
+    @abstractmethod
+    async def intercept_service(
+            self, continuation: Callable[[grpc.HandlerCallDetails], Awaitable[
+                grpc.RpcMethodHandler]],
+            handler_call_details: grpc.HandlerCallDetails
+    ) -> grpc.RpcMethodHandler:
+        """Intercepts incoming RPCs before handing them over to a handler.
+
+        Args:
+            continuation: A function that takes a HandlerCallDetails and
+                proceeds to invoke the next interceptor in the chain, if any,
+                or the RPC handler lookup logic, with the call details passed
+                as an argument, and returns an RpcMethodHandler instance if
+                the RPC is considered serviced, or None otherwise.
+            handler_call_details: A HandlerCallDetails describing the RPC.
+
+        Returns:
+            An RpcMethodHandler with which the RPC may be serviced if the
+            interceptor chooses to service this RPC, or None otherwise.
+        """
+
+
 class ClientCallDetails(
         collections.namedtuple(
             'ClientCallDetails',

src/python/grpcio/grpc/experimental/aio/_server.py

@@ -23,6 +23,7 @@ from grpc._cython import cygrpc
 
 from . import _base_server
 from ._typing import ChannelArgumentType
+from ._interceptor import ServerInterceptor
 
 
 def _augment_channel_arguments(base_options: ChannelArgumentType,
@@ -41,6 +42,15 @@ class Server(_base_server.Server):
                  maximum_concurrent_rpcs: Optional[int],
                  compression: Optional[grpc.Compression]):
         self._loop = asyncio.get_event_loop()
+        if interceptors:
+            invalid_interceptors = [
+                interceptor for interceptor in interceptors
+                if not isinstance(interceptor, ServerInterceptor)
+            ]
+            if invalid_interceptors:
+                raise ValueError(
+                    'Interceptor must be ServerInterceptor, the '
+                    f'following are invalid: {invalid_interceptors}')
         self._server = cygrpc.AioServer(
             self._loop, thread_pool, generic_handlers, interceptors,
             _augment_channel_arguments(options, compression),
@@ -152,7 +162,8 @@ class Server(_base_server.Server):
         The Cython AioServer doesn't hold a ref-count to this class. It should
         be safe to slightly extend the underlying Cython object's life span.
         """
-        self._loop.create_task(self._server.shutdown(None))
+        if hasattr(self, '_server'):
+            self._loop.create_task(self._server.shutdown(None))
 
 
 def server(migration_thread_pool: Optional[Executor] = None,

src/python/grpcio_tests/tests_aio/tests.json

@@ -12,15 +12,16 @@
   "unit.channel_argument_test.TestChannelArgument",
   "unit.channel_ready_test.TestChannelReady",
   "unit.channel_test.TestChannel",
+  "unit.client_interceptor_test.TestInterceptedUnaryUnaryCall",
+  "unit.client_interceptor_test.TestUnaryUnaryClientInterceptor",
   "unit.close_channel_test.TestCloseChannel",
   "unit.compression_test.TestCompression",
   "unit.connectivity_test.TestConnectivityState",
   "unit.done_callback_test.TestDoneCallback",
   "unit.init_test.TestInsecureChannel",
   "unit.init_test.TestSecureChannel",
-  "unit.interceptor_test.TestInterceptedUnaryUnaryCall",
-  "unit.interceptor_test.TestUnaryUnaryClientInterceptor",
   "unit.metadata_test.TestMetadata",
+  "unit.server_interceptor_test.TestServerInterceptor",
   "unit.server_test.TestServer",
   "unit.timeout_test.TestTimeout",
   "unit.wait_for_ready_test.TestWaitForReady"

src/python/grpcio_tests/tests_aio/unit/_test_server.py

@@ -14,7 +14,6 @@
 
 import asyncio
 import datetime
-import logging
 
 import grpc
 from grpc.experimental import aio
@@ -117,8 +116,12 @@ def _create_extra_generic_handler(servicer: _TestServiceServicer):
                                                 rpc_method_handlers)
 
 
-async def start_test_server(port=0, secure=False, server_credentials=None):
-    server = aio.server(options=(('grpc.so_reuseport', 0),))
+async def start_test_server(port=0,
+                            secure=False,
+                            server_credentials=None,
+                            interceptors=None):
+    server = aio.server(options=(('grpc.so_reuseport', 0),),
+                        interceptors=interceptors)
     servicer = _TestServiceServicer()
     test_pb2_grpc.add_TestServiceServicer_to_server(servicer, server)
 

src/python/grpcio_tests/tests_aio/unit/server_interceptor_test.py

@@ -0,0 +1,168 @@
+# Copyright 2020 The gRPC Authors
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+import logging
+import unittest
+from typing import Callable, Awaitable, Any
+
+import grpc
+
+from grpc.experimental import aio
+
+from tests_aio.unit._test_server import start_test_server
+from tests_aio.unit._test_base import AioTestBase
+from src.proto.grpc.testing import messages_pb2
+
+
+class _LoggingInterceptor(aio.ServerInterceptor):
+
+    def __init__(self, tag: str, record: list) -> None:
+        self.tag = tag
+        self.record = record
+
+    async def intercept_service(
+            self, continuation: Callable[[grpc.HandlerCallDetails], Awaitable[
+                grpc.RpcMethodHandler]],
+            handler_call_details: grpc.HandlerCallDetails
+    ) -> grpc.RpcMethodHandler:
+        self.record.append(self.tag + ':intercept_service')
+        return await continuation(handler_call_details)
+
+
+class _GenericInterceptor(aio.ServerInterceptor):
+
+    def __init__(self, fn: Callable[[
+            Callable[[grpc.HandlerCallDetails], Awaitable[grpc.
+                                                          RpcMethodHandler]],
+            grpc.HandlerCallDetails
+    ], Any]) -> None:
+        self._fn = fn
+
+    async def intercept_service(
+            self, continuation: Callable[[grpc.HandlerCallDetails], Awaitable[
+                grpc.RpcMethodHandler]],
+            handler_call_details: grpc.HandlerCallDetails
+    ) -> grpc.RpcMethodHandler:
+        return await self._fn(continuation, handler_call_details)
+
+
+def _filter_server_interceptor(condition: Callable,
+                               interceptor: aio.ServerInterceptor
+                              ) -> aio.ServerInterceptor:
+
+    async def intercept_service(
+            continuation: Callable[[grpc.HandlerCallDetails], Awaitable[
+                grpc.RpcMethodHandler]],
+            handler_call_details: grpc.HandlerCallDetails
+    ) -> grpc.RpcMethodHandler:
+        if condition(handler_call_details):
+            return await interceptor.intercept_service(continuation,
+                                                       handler_call_details)
+        return await continuation(handler_call_details)
+
+    return _GenericInterceptor(intercept_service)
+
+
+class TestServerInterceptor(AioTestBase):
+
+    async def test_invalid_interceptor(self):
+
+        class InvalidInterceptor:
+            """Just an invalid Interceptor"""
+
+        with self.assertRaises(ValueError):
+            server_target, _ = await start_test_server(
+                interceptors=(InvalidInterceptor(),))
+
+    async def test_executed_right_order(self):
+        record = []
+        server_target, _ = await start_test_server(interceptors=(
+            _LoggingInterceptor('log1', record),
+            _LoggingInterceptor('log2', record),
+        ))
+
+        async with aio.insecure_channel(server_target) as channel:
+            multicallable = channel.unary_unary(
+                '/grpc.testing.TestService/UnaryCall',
+                request_serializer=messages_pb2.SimpleRequest.SerializeToString,
+                response_deserializer=messages_pb2.SimpleResponse.FromString)
+            call = multicallable(messages_pb2.SimpleRequest())
+            response = await call
+
+            # Check that all interceptors were executed, and were executed
+            # in the right order.
+            self.assertSequenceEqual([
+                'log1:intercept_service',
+                'log2:intercept_service',
+            ], record)
+            self.assertIsInstance(response, messages_pb2.SimpleResponse)
+
+    async def test_response_ok(self):
+        record = []
+        server_target, _ = await start_test_server(
+            interceptors=(_LoggingInterceptor('log1', record),))
+
+        async with aio.insecure_channel(server_target) as channel:
+            multicallable = channel.unary_unary(
+                '/grpc.testing.TestService/UnaryCall',
+                request_serializer=messages_pb2.SimpleRequest.SerializeToString,
+                response_deserializer=messages_pb2.SimpleResponse.FromString)
+            call = multicallable(messages_pb2.SimpleRequest())
+            response = await call
+            code = await call.code()
+
+            self.assertSequenceEqual(['log1:intercept_service'], record)
+            self.assertIsInstance(response, messages_pb2.SimpleResponse)
+            self.assertEqual(code, grpc.StatusCode.OK)
+
+    async def test_apply_different_interceptors_by_metadata(self):
+        record = []
+        conditional_interceptor = _filter_server_interceptor(
+            lambda x: ('secret', '42') in x.invocation_metadata,
+            _LoggingInterceptor('log3', record))
+        server_target, _ = await start_test_server(interceptors=(
+            _LoggingInterceptor('log1', record),
+            conditional_interceptor,
+            _LoggingInterceptor('log2', record),
+        ))
+
+        async with aio.insecure_channel(server_target) as channel:
+            multicallable = channel.unary_unary(
+                '/grpc.testing.TestService/UnaryCall',
+                request_serializer=messages_pb2.SimpleRequest.SerializeToString,
+                response_deserializer=messages_pb2.SimpleResponse.FromString)
+
+            metadata = (('key', 'value'),)
+            call = multicallable(messages_pb2.SimpleRequest(),
+                                 metadata=metadata)
+            await call
+            self.assertSequenceEqual([
+                'log1:intercept_service',
+                'log2:intercept_service',
+            ], record)
+
+            record.clear()
+            metadata = (('key', 'value'), ('secret', '42'))
+            call = multicallable(messages_pb2.SimpleRequest(),
+                                 metadata=metadata)
+            await call
+            self.assertSequenceEqual([
+                'log1:intercept_service',
+                'log3:intercept_service',
+                'log2:intercept_service',
+            ], record)
+
+
+if __name__ == '__main__':
+    logging.basicConfig()
+    unittest.main(verbosity=2)