[Aio] Unary unary client call barebones implementation

Implement the minimal stuff for making a unary call with the new
experimental gRPC Python implementation for Asyncio, called Aio.

What has been added:

- Minimal iomgr code for performing the required network and timer
calls.
- Minimal Cython code implementing the channel, call and the callback
context.
- Minimal Python code that mimics the synchronous implementation but
designed to be asynchronous.

Testing considerations:

Tests have to be executed using the `GRPC_ENABLE_FORK_SUPPORT=0`
environment variable for skipping the fork handles installed by
the core library. This is due to the usage of a syncrhonous server
used as a fixture executed in another process.

Co-authored-by: Manuel Miranda <manuel.miranda@skyscanner.net>
Co-authored-by: Mariano Anaya <mariano.anaya@skyscanner.net>
Co-authored-by: Zhanghui Mao <zhanghui.mao@skyscanner.net>
Co-authored-by: Lidi Zheng <lidiz@google.com>

AUTHORS

@@ -1,3 +1,4 @@
 Dropbox, Inc.
 Google Inc.
+Skyscanner Ltd.
 WeWork Companies Inc.

setup.py

@@ -265,6 +265,7 @@ if 'darwin' in sys.platform and PY3:
         r'macosx-10.7-\1',
         util.get_platform())
 
+
 def cython_extensions_and_necessity():
   cython_module_files = [os.path.join(PYTHON_STEM,
                                name.replace('.', '/') + '.pyx')
@@ -295,6 +296,8 @@ def cython_extensions_and_necessity():
   need_cython = BUILD_WITH_CYTHON
   if not BUILD_WITH_CYTHON:
     need_cython = need_cython or not commands.check_and_update_cythonization(extensions)
+  # TODO: the strategy for conditional compiling and exposing the aio Cython
+  # dependencies will be revisited by https://github.com/grpc/grpc/issues/19728
   return commands.try_cythonize(extensions, linetracing=ENABLE_CYTHON_TRACING, mandatory=BUILD_WITH_CYTHON), need_cython
 
 CYTHON_EXTENSION_MODULES, need_cython = cython_extensions_and_necessity()

src/python/grpcio/grpc/_cython/BUILD.bazel

@@ -8,6 +8,20 @@ pyx_library(
         "__init__.py",
         "_cygrpc/_hooks.pxd.pxi",
         "_cygrpc/_hooks.pyx.pxi",
+        "_cygrpc/aio/call.pxd.pxi",
+        "_cygrpc/aio/call.pyx.pxi",
+        "_cygrpc/aio/callbackcontext.pxd.pxi",
+        "_cygrpc/aio/channel.pxd.pxi",
+        "_cygrpc/aio/channel.pyx.pxi",
+        "_cygrpc/aio/grpc_aio.pxd.pxi",
+        "_cygrpc/aio/grpc_aio.pyx.pxi",
+        "_cygrpc/aio/iomgr/iomgr.pyx.pxi",
+        "_cygrpc/aio/iomgr/resolver.pxd.pxi",
+        "_cygrpc/aio/iomgr/resolver.pyx.pxi",
+        "_cygrpc/aio/iomgr/socket.pxd.pxi",
+        "_cygrpc/aio/iomgr/socket.pyx.pxi",
+        "_cygrpc/aio/iomgr/timer.pxd.pxi",
+        "_cygrpc/aio/iomgr/timer.pyx.pxi",
         "_cygrpc/arguments.pxd.pxi",
         "_cygrpc/arguments.pyx.pxi",
         "_cygrpc/call.pxd.pxi",
@@ -27,6 +41,8 @@ pyx_library(
         "_cygrpc/grpc_gevent.pxd.pxi",
         "_cygrpc/grpc_gevent.pyx.pxi",
         "_cygrpc/grpc_string.pyx.pxi",
+        "_cygrpc/iomgr.pxd.pxi",
+        "_cygrpc/iomgr.pyx.pxi",
         "_cygrpc/metadata.pxd.pxi",
         "_cygrpc/metadata.pyx.pxi",
         "_cygrpc/operation.pxd.pxi",

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

@@ -0,0 +1,27 @@
+# Copyright 2019 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.
+
+
+cdef class _AioCall:
+    cdef:
+        AioChannel _channel
+        CallbackContext _watcher_call
+        grpc_completion_queue * _cq
+        grpc_experimental_completion_queue_functor _functor
+        object _waiter_call
+
+    @staticmethod
+    cdef void functor_run(grpc_experimental_completion_queue_functor* functor, int succeed)
+    @staticmethod
+    cdef void watcher_call_functor_run(grpc_experimental_completion_queue_functor* functor, int succeed)

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

@@ -0,0 +1,149 @@
+# Copyright 2019 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.
+
+cimport cpython
+
+_EMPTY_FLAGS = 0
+_EMPTY_METADATA = ()
+_OP_ARRAY_LENGTH = 6
+
+
+cdef class _AioCall:
+
+
+    def __cinit__(self, AioChannel channel):
+        self._channel = channel
+        self._functor.functor_run = _AioCall.functor_run
+
+        self._cq = grpc_completion_queue_create_for_callback(
+            <grpc_experimental_completion_queue_functor *> &self._functor,
+            NULL
+        )
+
+        self._watcher_call.functor.functor_run = _AioCall.watcher_call_functor_run
+        self._watcher_call.waiter = <cpython.PyObject *> self
+        self._waiter_call = None
+
+    def __dealloc__(self):
+        grpc_completion_queue_shutdown(self._cq)
+        grpc_completion_queue_destroy(self._cq)
+
+    def __repr__(self):
+        class_name = self.__class__.__name__
+        id_ = id(self)
+        return f"<{class_name} {id_}>"
+
+    @staticmethod
+    cdef void functor_run(grpc_experimental_completion_queue_functor* functor, int succeed):
+        pass
+
+    @staticmethod
+    cdef void watcher_call_functor_run(grpc_experimental_completion_queue_functor* functor, int succeed):
+        call = <_AioCall>(<CallbackContext *>functor).waiter
+
+        assert call._waiter_call
+
+        if succeed == 0:
+            call._waiter_call.set_exception(Exception("Some error ocurred"))
+        else:
+            call._waiter_call.set_result(None)
+
+    async def unary_unary(self, method, request):
+        cdef grpc_call * call
+        cdef grpc_slice method_slice
+        cdef grpc_op * ops
+
+        cdef Operation initial_metadata_operation
+        cdef Operation send_message_operation
+        cdef Operation send_close_from_client_operation
+        cdef Operation receive_initial_metadata_operation
+        cdef Operation receive_message_operation
+        cdef Operation receive_status_on_client_operation
+
+        cdef grpc_call_error call_status
+
+
+        method_slice = grpc_slice_from_copied_buffer(
+            <const char *> method,
+            <size_t> len(method)
+        )
+
+        call = grpc_channel_create_call(
+            self._channel.channel,
+            NULL,
+            0,
+            self._cq,
+            method_slice,
+            NULL,
+            _timespec_from_time(None),
+            NULL
+        )
+
+        grpc_slice_unref(method_slice)
+
+        ops = <grpc_op *>gpr_malloc(sizeof(grpc_op) * _OP_ARRAY_LENGTH)
+
+        initial_metadata_operation = SendInitialMetadataOperation(_EMPTY_METADATA, GRPC_INITIAL_METADATA_USED_MASK)
+        initial_metadata_operation.c()
+        ops[0] = <grpc_op> initial_metadata_operation.c_op
+
+        send_message_operation = SendMessageOperation(request, _EMPTY_FLAGS)
+        send_message_operation.c()
+        ops[1] = <grpc_op> send_message_operation.c_op
+
+        send_close_from_client_operation = SendCloseFromClientOperation(_EMPTY_FLAGS)
+        send_close_from_client_operation.c()
+        ops[2] = <grpc_op> send_close_from_client_operation.c_op
+
+        receive_initial_metadata_operation = ReceiveInitialMetadataOperation(_EMPTY_FLAGS)
+        receive_initial_metadata_operation.c()
+        ops[3] = <grpc_op> receive_initial_metadata_operation.c_op
+
+        receive_message_operation = ReceiveMessageOperation(_EMPTY_FLAGS)
+        receive_message_operation.c()
+        ops[4] = <grpc_op> receive_message_operation.c_op
+
+        receive_status_on_client_operation = ReceiveStatusOnClientOperation(_EMPTY_FLAGS)
+        receive_status_on_client_operation.c()
+        ops[5] = <grpc_op> receive_status_on_client_operation.c_op
+
+        self._waiter_call = asyncio.get_event_loop().create_future()
+
+        call_status = grpc_call_start_batch(
+            call,
+            ops,
+            _OP_ARRAY_LENGTH,
+            &self._watcher_call.functor,
+            NULL
+        )
+
+        try:
+            if call_status != GRPC_CALL_OK:
+                self._waiter_call = None
+                raise Exception("Error with grpc_call_start_batch {}".format(call_status))
+
+            await self._waiter_call
+
+        finally:
+            initial_metadata_operation.un_c()
+            send_message_operation.un_c()
+            send_close_from_client_operation.un_c()
+            receive_initial_metadata_operation.un_c()
+            receive_message_operation.un_c()
+            receive_status_on_client_operation.un_c()
+
+            grpc_call_unref(call)
+            gpr_free(ops)
+
+        return receive_message_operation.message()

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

@@ -0,0 +1,20 @@
+# Copyright 2019 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.
+
+cimport cpython
+
+cdef struct CallbackContext:
+    grpc_experimental_completion_queue_functor functor
+    cpython.PyObject *waiter
+

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

@@ -0,0 +1,18 @@
+# Copyright 2019 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.
+
+cdef class AioChannel:
+    cdef:
+        grpc_channel * channel
+        bytes _target

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

@@ -0,0 +1,30 @@
+# Copyright 2019 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.
+
+cdef class AioChannel:
+    def __cinit__(self, bytes target):
+        self.channel = grpc_insecure_channel_create(<char *>target, NULL, NULL)
+        self._target = target
+
+    def __repr__(self):
+        class_name = self.__class__.__name__ 
+        id_ = id(self)
+        return f"<{class_name} {id_}>"
+
+    def close(self):
+        grpc_channel_destroy(self.channel)
+
+    async def unary_unary(self, method, request):
+        call = _AioCall(self)
+        return await call.unary_unary(method, request)

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

@@ -0,0 +1,25 @@
+# Copyright 2019 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.
+# distutils: language=c++
+
+cdef extern from "src/core/lib/iomgr/timer_manager.h":
+  void grpc_timer_manager_set_threading(bint enabled);
+
+cdef extern from "src/core/lib/iomgr/iomgr_internal.h":
+  void grpc_set_default_iomgr_platform();
+
+cdef extern from "src/core/lib/iomgr/executor.h" namespace "grpc_core":
+    cdef cppclass Executor:
+        @staticmethod
+        void SetThreadingAll(bint enable);

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

@@ -0,0 +1,37 @@
+# Copyright 2019 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.
+
+
+cdef bint _grpc_aio_initialized = 0
+
+
+def init_grpc_aio():
+    global _grpc_aio_initialized
+
+    if _grpc_aio_initialized:
+        return
+
+    install_asyncio_iomgr()
+    grpc_init()
+
+    # Timers are triggered by the Asyncio loop. We disable
+    # the background thread that is being used by the native
+    # gRPC iomgr.
+    grpc_timer_manager_set_threading(0)
+
+    # gRPC callbaks are executed within the same thread used by the Asyncio
+    # event loop, as it is being done by the other Asyncio callbacks.
+    Executor.SetThreadingAll(0)
+
+    _grpc_aio_initialized = 1

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

@@ -0,0 +1,185 @@
+# Copyright 2019 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.
+
+
+from cpython cimport Py_INCREF, Py_DECREF
+
+from libc cimport string
+
+cdef grpc_socket_vtable asyncio_socket_vtable
+cdef grpc_custom_resolver_vtable asyncio_resolver_vtable
+cdef grpc_custom_timer_vtable asyncio_timer_vtable
+cdef grpc_custom_poller_vtable asyncio_pollset_vtable
+
+
+cdef grpc_error* asyncio_socket_init(
+        grpc_custom_socket* grpc_socket,
+        int domain) with gil:
+    socket = _AsyncioSocket.create(grpc_socket)
+    Py_INCREF(socket)
+    grpc_socket.impl = <void*>socket
+    return <grpc_error*>0
+
+
+cdef void asyncio_socket_destroy(grpc_custom_socket* grpc_socket) with gil:
+    Py_DECREF(<_AsyncioSocket>grpc_socket.impl)
+
+
+cdef void asyncio_socket_connect(
+        grpc_custom_socket* grpc_socket,
+        const grpc_sockaddr* addr,
+        size_t addr_len,
+        grpc_custom_connect_callback connect_cb) with gil:
+
+    host, port = sockaddr_to_tuple(addr, addr_len)
+    socket = <_AsyncioSocket>grpc_socket.impl
+    socket.connect(host, port, connect_cb)
+
+
+cdef void asyncio_socket_close(
+        grpc_custom_socket* grpc_socket,
+        grpc_custom_close_callback close_cb) with gil:
+    socket = (<_AsyncioSocket>grpc_socket.impl)
+    socket.close()
+    close_cb(grpc_socket)
+
+
+cdef void asyncio_socket_shutdown(grpc_custom_socket* grpc_socket) with gil:
+    socket = (<_AsyncioSocket>grpc_socket.impl)
+    socket.close()
+
+
+cdef void asyncio_socket_write(
+        grpc_custom_socket* grpc_socket,
+        grpc_slice_buffer* slice_buffer,
+        grpc_custom_write_callback write_cb) with gil:
+    socket = (<_AsyncioSocket>grpc_socket.impl)
+    socket.write(slice_buffer, write_cb)
+
+
+cdef void asyncio_socket_read(
+        grpc_custom_socket* grpc_socket,
+        char* buffer_,
+        size_t length,
+        grpc_custom_read_callback read_cb) with gil:
+    socket = (<_AsyncioSocket>grpc_socket.impl)
+    socket.read(buffer_, length, read_cb)
+
+
+cdef grpc_error* asyncio_socket_getpeername(
+        grpc_custom_socket* grpc_socket,
+        const grpc_sockaddr* addr,
+        int* length) with gil:
+    raise NotImplemented()
+
+
+cdef grpc_error* asyncio_socket_getsockname(
+        grpc_custom_socket* grpc_socket,
+        const grpc_sockaddr* addr,
+        int* length) with gil:
+    raise NotImplemented()
+
+
+cdef grpc_error* asyncio_socket_listen(grpc_custom_socket* grpc_socket) with gil:
+    raise NotImplemented()
+
+
+cdef grpc_error* asyncio_socket_bind(
+        grpc_custom_socket* grpc_socket,
+        const grpc_sockaddr* addr,
+        size_t len, int flags) with gil:
+    raise NotImplemented()
+
+
+cdef void asyncio_socket_accept(
+        grpc_custom_socket* grpc_socket,
+        grpc_custom_socket* grpc_socket_client,
+        grpc_custom_accept_callback accept_cb) with gil:
+    raise NotImplemented()
+
+
+cdef grpc_error* asyncio_resolve(
+        char* host,
+        char* port,
+        grpc_resolved_addresses** res) with gil:
+    raise NotImplemented()
+
+
+cdef void asyncio_resolve_async(
+        grpc_custom_resolver* grpc_resolver,
+        char* host,
+        char* port) with gil:
+    resolver = _AsyncioResolver.create(grpc_resolver)
+    resolver.resolve(host, port)
+
+
+cdef void asyncio_timer_start(grpc_custom_timer* grpc_timer) with gil:
+    timer = _AsyncioTimer.create(grpc_timer, grpc_timer.timeout_ms / 1000.0)
+    Py_INCREF(timer)
+    grpc_timer.timer = <void*>timer
+
+
+cdef void asyncio_timer_stop(grpc_custom_timer* grpc_timer) with gil:
+    timer = <_AsyncioTimer>grpc_timer.timer
+    timer.stop()
+    Py_DECREF(timer)
+
+
+cdef void asyncio_init_loop() with gil:
+    pass
+
+
+cdef void asyncio_destroy_loop() with gil:
+    pass
+
+
+cdef void asyncio_kick_loop() with gil:
+    pass
+
+
+cdef void asyncio_run_loop(size_t timeout_ms) with gil:
+    pass
+
+
+def install_asyncio_iomgr():
+    asyncio_resolver_vtable.resolve = asyncio_resolve
+    asyncio_resolver_vtable.resolve_async = asyncio_resolve_async
+
+    asyncio_socket_vtable.init = asyncio_socket_init
+    asyncio_socket_vtable.connect = asyncio_socket_connect
+    asyncio_socket_vtable.destroy = asyncio_socket_destroy
+    asyncio_socket_vtable.shutdown = asyncio_socket_shutdown
+    asyncio_socket_vtable.close = asyncio_socket_close
+    asyncio_socket_vtable.write = asyncio_socket_write
+    asyncio_socket_vtable.read = asyncio_socket_read
+    asyncio_socket_vtable.getpeername = asyncio_socket_getpeername
+    asyncio_socket_vtable.getsockname = asyncio_socket_getsockname
+    asyncio_socket_vtable.bind = asyncio_socket_bind
+    asyncio_socket_vtable.listen = asyncio_socket_listen
+    asyncio_socket_vtable.accept = asyncio_socket_accept
+
+    asyncio_timer_vtable.start = asyncio_timer_start
+    asyncio_timer_vtable.stop = asyncio_timer_stop
+
+    asyncio_pollset_vtable.init = asyncio_init_loop
+    asyncio_pollset_vtable.poll = asyncio_run_loop
+    asyncio_pollset_vtable.kick = asyncio_kick_loop
+    asyncio_pollset_vtable.shutdown = asyncio_destroy_loop
+
+    grpc_custom_iomgr_init(
+        &asyncio_socket_vtable,
+        &asyncio_resolver_vtable,
+        &asyncio_timer_vtable,
+        &asyncio_pollset_vtable
+    )

src/python/grpcio/grpc/_cython/_cygrpc/aio/iomgr/resolver.pxd.pxi

@@ -0,0 +1,23 @@
+# Copyright 2019 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.
+
+cdef class _AsyncioResolver:
+    cdef:
+        grpc_custom_resolver* _grpc_resolver
+        object _task_resolve
+
+    @staticmethod
+    cdef _AsyncioResolver create(grpc_custom_resolver* grpc_resolver)
+
+    cdef void resolve(self, char* host, char* port)

src/python/grpcio/grpc/_cython/_cygrpc/aio/iomgr/resolver.pyx.pxi

@@ -0,0 +1,61 @@
+# Copyright 2019 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.
+
+
+cdef class _AsyncioResolver:
+    def __cinit__(self):
+        self._grpc_resolver = NULL
+        self._task_resolve = None
+
+    @staticmethod
+    cdef _AsyncioResolver create(grpc_custom_resolver* grpc_resolver):
+        resolver = _AsyncioResolver()
+        resolver._grpc_resolver = grpc_resolver
+        return resolver
+
+    def __repr__(self):
+        class_name = self.__class__.__name__ 
+        id_ = id(self)
+        return f"<{class_name} {id_}>"
+
+    def _resolve_cb(self, future):
+        error = False
+        try:
+            res = future.result()
+        except Exception as e:
+            error = True
+        finally:
+            self._task_resolve = None
+
+        if not error:
+            grpc_custom_resolve_callback(
+                <grpc_custom_resolver*>self._grpc_resolver,
+                tuples_to_resolvaddr(res),
+                <grpc_error*>0
+            )
+        else:
+            grpc_custom_resolve_callback(
+                <grpc_custom_resolver*>self._grpc_resolver,
+                NULL,
+                grpc_socket_error("getaddrinfo {}".format(str(e)).encode())
+            )
+
+    cdef void resolve(self, char* host, char* port):
+        assert not self._task_resolve
+
+        loop = asyncio.get_event_loop()
+        self._task_resolve = asyncio.ensure_future(
+            loop.getaddrinfo(host, port)
+        )
+        self._task_resolve.add_done_callback(self._resolve_cb)

src/python/grpcio/grpc/_cython/_cygrpc/aio/iomgr/socket.pxd.pxi

@@ -0,0 +1,34 @@
+# Copyright 2019 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.
+
+
+cdef class _AsyncioSocket:
+    cdef:
+        grpc_custom_socket * _grpc_socket
+        grpc_custom_connect_callback _grpc_connect_cb
+        grpc_custom_read_callback _grpc_read_cb
+        object _reader
+        object _writer
+        object _task_read
+        object _task_connect
+        char * _read_buffer
+
+    @staticmethod
+    cdef _AsyncioSocket create(grpc_custom_socket * grpc_socket)
+
+    cdef void connect(self, object host, object port, grpc_custom_connect_callback grpc_connect_cb)
+    cdef void write(self, grpc_slice_buffer * g_slice_buffer, grpc_custom_write_callback grpc_write_cb)
+    cdef void read(self, char * buffer_, size_t length, grpc_custom_read_callback grpc_read_cb)
+    cdef bint is_connected(self)
+    cdef void close(self)

src/python/grpcio/grpc/_cython/_cygrpc/aio/iomgr/socket.pyx.pxi

@@ -0,0 +1,134 @@
+# Copyright 2019 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 socket
+
+from libc cimport string
+
+cdef class _AsyncioSocket:
+    def __cinit__(self):
+        self._grpc_socket = NULL
+        self._grpc_connect_cb = NULL
+        self._grpc_read_cb = NULL
+        self._reader = None
+        self._writer = None
+        self._task_connect = None
+        self._task_read = None
+        self._read_buffer = NULL
+
+    @staticmethod
+    cdef _AsyncioSocket create(grpc_custom_socket * grpc_socket):
+        socket = _AsyncioSocket()
+        socket._grpc_socket = grpc_socket
+        return socket
+
+    def __repr__(self):
+        class_name = self.__class__.__name__ 
+        id_ = id(self)
+        connected = self.is_connected()
+        return f"<{class_name} {id_} connected={connected}>"
+
+    def _connect_cb(self, future):
+        error = False
+        try:
+            self._reader, self._writer = future.result()
+        except Exception as e:
+            error = True
+        finally:
+            self._task_connect = None
+
+        if not error:
+            # gRPC default posix implementation disables nagle
+            # algorithm.
+            sock = self._writer.transport.get_extra_info('socket')
+            sock.setsockopt(socket.IPPROTO_TCP, socket.TCP_NODELAY, True)
+
+            self._grpc_connect_cb(
+                <grpc_custom_socket*>self._grpc_socket,
+                <grpc_error*>0
+            )
+        else:
+            self._grpc_connect_cb(
+                <grpc_custom_socket*>self._grpc_socket,
+                grpc_socket_error("connect {}".format(str(e)).encode())
+            )
+
+    def _read_cb(self, future):
+        error = False
+        try:
+            buffer_ = future.result()
+        except Exception as e:
+            error = True
+            error_msg = str(e)
+        finally:
+            self._task_read = None
+
+        if not error:
+            string.memcpy(
+                <void*>self._read_buffer,
+                <char*>buffer_,
+                len(buffer_)
+            )
+            self._grpc_read_cb(
+                <grpc_custom_socket*>self._grpc_socket,
+                len(buffer_),
+                <grpc_error*>0
+            )
+        else:
+            self._grpc_read_cb(
+                <grpc_custom_socket*>self._grpc_socket,
+                -1,
+                grpc_socket_error("read {}".format(error_msg).encode())
+            )
+
+    cdef void connect(self, object host, object port, grpc_custom_connect_callback grpc_connect_cb):
+        assert not self._task_connect
+
+        self._task_connect = asyncio.ensure_future(
+            asyncio.open_connection(host, port)
+        )
+        self._grpc_connect_cb = grpc_connect_cb
+        self._task_connect.add_done_callback(self._connect_cb)
+
+    cdef void read(self, char * buffer_, size_t length, grpc_custom_read_callback grpc_read_cb):
+        assert not self._task_read
+
+        self._task_read = asyncio.ensure_future(
+            self._reader.read(n=length)
+        )
+        self._grpc_read_cb = grpc_read_cb
+        self._task_read.add_done_callback(self._read_cb)
+        self._read_buffer = buffer_
+ 
+    cdef void write(self, grpc_slice_buffer * g_slice_buffer, grpc_custom_write_callback grpc_write_cb):
+        cdef char* start
+        buffer_ = bytearray()
+        for i in range(g_slice_buffer.count):
+            start = grpc_slice_buffer_start(g_slice_buffer, i)
+            length = grpc_slice_buffer_length(g_slice_buffer, i)
+            buffer_.extend(<bytes>start[:length])
+
+        self._writer.write(buffer_)
+
+        grpc_write_cb(
+            <grpc_custom_socket*>self._grpc_socket,
+            <grpc_error*>0
+        )
+
+    cdef bint is_connected(self):
+        return self._reader and not self._reader._transport.is_closing()
+
+    cdef void close(self):
+        if self.is_connected():
+            self._writer.close()

src/python/grpcio/grpc/_cython/_cygrpc/aio/iomgr/timer.pxd.pxi

@@ -0,0 +1,25 @@
+# Copyright 2019 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.
+
+cdef class _AsyncioTimer:
+    cdef:
+        grpc_custom_timer * _grpc_timer
+        object _deadline
+        object _timer_handler
+        int _active
+
+    @staticmethod
+    cdef _AsyncioTimer create(grpc_custom_timer * grpc_timer, deadline)
+
+    cdef stop(self)

src/python/grpcio/grpc/_cython/_cygrpc/aio/iomgr/timer.pyx.pxi

@@ -0,0 +1,45 @@
+# Copyright 2019 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.
+
+
+cdef class _AsyncioTimer:
+    def __cinit__(self):
+        self._grpc_timer = NULL
+        self._timer_handler = None
+        self._active = 0
+
+    @staticmethod
+    cdef _AsyncioTimer create(grpc_custom_timer * grpc_timer, deadline):
+        timer = _AsyncioTimer()
+        timer._grpc_timer = grpc_timer
+        timer._deadline = deadline
+        timer._timer_handler = asyncio.get_event_loop().call_later(deadline, timer._on_deadline)
+        timer._active = 1
+        return timer
+
+    def _on_deadline(self):
+        self._active = 0
+        grpc_custom_timer_callback(self._grpc_timer, <grpc_error*>0)
+
+    def __repr__(self):
+        class_name = self.__class__.__name__ 
+        id_ = id(self)
+        return f"<{class_name} {id_} deadline={self._deadline} active={self._active}>"
+
+    cdef stop(self):
+        if self._active == 0:
+            return
+
+        self._timer_handler.cancel()
+        self._active = 0

src/python/grpcio/grpc/_cython/_cygrpc/grpc.pxi

@@ -41,6 +41,11 @@ cdef extern from "grpc/byte_buffer_reader.h":
     pass
 
 
+cdef extern from "grpc/impl/codegen/grpc_types.h":
+    ctypedef struct grpc_experimental_completion_queue_functor:
+        void (*functor_run)(grpc_experimental_completion_queue_functor*, int);
+
+
 cdef extern from "grpc/grpc.h":
 
   ctypedef struct grpc_slice:
@@ -325,6 +330,7 @@ cdef extern from "grpc/grpc.h":
   ctypedef struct grpc_op:
     grpc_op_type type "op"
     uint32_t flags
+    void * reserved
     grpc_op_data data
 
   void grpc_init() nogil
@@ -350,6 +356,10 @@ cdef extern from "grpc/grpc.h":
   void grpc_completion_queue_shutdown(grpc_completion_queue *cq) nogil
   void grpc_completion_queue_destroy(grpc_completion_queue *cq) nogil
 
+  grpc_completion_queue *grpc_completion_queue_create_for_callback(
+    grpc_experimental_completion_queue_functor* shutdown_callback,
+    void *reserved) nogil
+
   grpc_call_error grpc_call_start_batch(
       grpc_call *call, const grpc_op *ops, size_t nops, void *tag,
       void *reserved) nogil

src/python/grpcio/grpc/_cython/_cygrpc/grpc_gevent.pxd.pxi

@@ -13,115 +13,6 @@
 # limitations under the License.
 # distutils: language=c++
 
-cdef extern from "grpc/impl/codegen/slice.h":
-  struct grpc_slice_buffer:
-    int count
-
-cdef extern from "src/core/lib/iomgr/error.h":
-  struct grpc_error:
-    pass
-
-cdef extern from "src/core/lib/iomgr/gevent_util.h":
-  grpc_error* grpc_socket_error(char* error) 
-  char* grpc_slice_buffer_start(grpc_slice_buffer* buffer, int i)
-  int grpc_slice_buffer_length(grpc_slice_buffer* buffer, int i)
-
-cdef extern from "src/core/lib/iomgr/sockaddr.h":
-  ctypedef struct grpc_sockaddr:
-    pass
-
-cdef extern from "src/core/lib/iomgr/resolve_address.h":
-  ctypedef struct grpc_resolved_addresses:
-    size_t naddrs
-    grpc_resolved_address* addrs
-
-  ctypedef struct grpc_resolved_address:
-    char[128] addr
-    size_t len
-
-cdef extern from "src/core/lib/iomgr/resolve_address_custom.h":
-  struct grpc_custom_resolver:
-    pass
-
-  struct grpc_custom_resolver_vtable:
-    grpc_error* (*resolve)(char* host, char* port, grpc_resolved_addresses** res);
-    void (*resolve_async)(grpc_custom_resolver* resolver, char* host, char* port);
-
-  void grpc_custom_resolve_callback(grpc_custom_resolver* resolver,
-                                    grpc_resolved_addresses* result,
-                                    grpc_error* error);
-
-cdef extern from "src/core/lib/iomgr/tcp_custom.h":
-  struct grpc_custom_socket:
-    void* impl
-    # We don't care about the rest of the fields
-  ctypedef void (*grpc_custom_connect_callback)(grpc_custom_socket* socket,
-                                             grpc_error* error)
-  ctypedef void (*grpc_custom_write_callback)(grpc_custom_socket* socket,
-                                           grpc_error* error)
-  ctypedef void (*grpc_custom_read_callback)(grpc_custom_socket* socket,
-                                          size_t nread, grpc_error* error)
-  ctypedef void (*grpc_custom_accept_callback)(grpc_custom_socket* socket,
-                                            grpc_custom_socket* client,
-                                            grpc_error* error)
-  ctypedef void (*grpc_custom_close_callback)(grpc_custom_socket* socket)
-
-  struct grpc_socket_vtable:
-      grpc_error* (*init)(grpc_custom_socket* socket, int domain);
-      void (*connect)(grpc_custom_socket* socket, const grpc_sockaddr* addr,
-                      size_t len, grpc_custom_connect_callback cb);
-      void (*destroy)(grpc_custom_socket* socket);
-      void (*shutdown)(grpc_custom_socket* socket);
-      void (*close)(grpc_custom_socket* socket, grpc_custom_close_callback cb);
-      void (*write)(grpc_custom_socket* socket, grpc_slice_buffer* slices,
-                    grpc_custom_write_callback cb);
-      void (*read)(grpc_custom_socket* socket, char* buffer, size_t length,
-                   grpc_custom_read_callback cb);
-      grpc_error* (*getpeername)(grpc_custom_socket* socket,
-                                 const grpc_sockaddr* addr, int* len);
-      grpc_error* (*getsockname)(grpc_custom_socket* socket,
-                             const grpc_sockaddr* addr, int* len);
-      grpc_error* (*bind)(grpc_custom_socket* socket, const grpc_sockaddr* addr,
-                          size_t len, int flags);
-      grpc_error* (*listen)(grpc_custom_socket* socket);
-      void (*accept)(grpc_custom_socket* socket, grpc_custom_socket* client,
-                     grpc_custom_accept_callback cb);
-
-cdef extern from "src/core/lib/iomgr/timer_custom.h":
-  struct grpc_custom_timer:
-    void* timer
-    int timeout_ms
-     # We don't care about the rest of the fields
-
-  struct grpc_custom_timer_vtable:
-    void (*start)(grpc_custom_timer* t);
-    void (*stop)(grpc_custom_timer* t);
-
-  void grpc_custom_timer_callback(grpc_custom_timer* t, grpc_error* error);
-
-cdef extern from "src/core/lib/iomgr/pollset_custom.h":
-  struct grpc_custom_poller_vtable:
-    void (*init)()
-    void (*poll)(size_t timeout_ms)
-    void (*kick)()
-    void (*shutdown)()
-
-cdef extern from "src/core/lib/iomgr/iomgr_custom.h":
-  void grpc_custom_iomgr_init(grpc_socket_vtable* socket,
-                            grpc_custom_resolver_vtable* resolver,
-                            grpc_custom_timer_vtable* timer,
-                            grpc_custom_poller_vtable* poller);
-
-cdef extern from "src/core/lib/iomgr/sockaddr_utils.h":
-  int grpc_sockaddr_get_port(const grpc_resolved_address *addr);
-  int grpc_sockaddr_to_string(char **out, const grpc_resolved_address *addr,
-                              int normalize);
-  void grpc_string_to_sockaddr(grpc_resolved_address *out, char* addr, int port);
-  int grpc_sockaddr_set_port(const grpc_resolved_address *resolved_addr,
-                             int port)
-  const char* grpc_sockaddr_get_uri_scheme(const grpc_resolved_address* resolved_addr)
-
-
 cdef class TimerWrapper:
 
   cdef grpc_custom_timer *c_timer

src/python/grpcio/grpc/_cython/_cygrpc/grpc_gevent.pyx.pxi

@@ -15,7 +15,6 @@
 
 cimport cpython
 from libc cimport string
-from libc.stdlib cimport malloc, free
 import errno
 gevent_g = None
 gevent_socket = None
@@ -24,51 +23,6 @@ gevent_event = None
 g_event = None
 g_pool = None
 
-cdef grpc_error* grpc_error_none():
-  return <grpc_error*>0
-
-cdef grpc_error* socket_error(str syscall, str err):
-  error_str = "{} failed: {}".format(syscall, err)
-  error_bytes = str_to_bytes(error_str)
-  return grpc_socket_error(error_bytes)
-
-cdef resolved_addr_to_tuple(grpc_resolved_address* address):
-  cdef char* res_str
-  port = grpc_sockaddr_get_port(address)
-  str_len = grpc_sockaddr_to_string(&res_str, address, 0) 
-  byte_str = _decode(<bytes>res_str[:str_len])
-  if byte_str.endswith(':' + str(port)):
-    byte_str = byte_str[:(0 - len(str(port)) - 1)]
-  byte_str = byte_str.lstrip('[')
-  byte_str = byte_str.rstrip(']')
-  byte_str = '{}'.format(byte_str)
-  return byte_str, port
-
-cdef sockaddr_to_tuple(const grpc_sockaddr* address, size_t length):
-  cdef grpc_resolved_address c_addr
-  string.memcpy(<void*>c_addr.addr, <void*> address, length)
-  c_addr.len = length
-  return resolved_addr_to_tuple(&c_addr)
-
-cdef sockaddr_is_ipv4(const grpc_sockaddr* address, size_t length):
-  cdef grpc_resolved_address c_addr
-  string.memcpy(<void*>c_addr.addr, <void*> address, length)
-  c_addr.len = length
-  return grpc_sockaddr_get_uri_scheme(&c_addr) == b'ipv4'
-
-cdef grpc_resolved_addresses* tuples_to_resolvaddr(tups):
-  cdef grpc_resolved_addresses* addresses
-  tups_set = set((tup[4][0], tup[4][1]) for tup in tups)
-  addresses = <grpc_resolved_addresses*> malloc(sizeof(grpc_resolved_addresses))
-  addresses.naddrs = len(tups_set)
-  addresses.addrs = <grpc_resolved_address*> malloc(sizeof(grpc_resolved_address) * len(tups_set))
-  i = 0
-  for tup in set(tups_set):
-    hostname = str_to_bytes(tup[0])
-    grpc_string_to_sockaddr(&addresses.addrs[i], hostname, tup[1])
-    i += 1
-  return addresses
-
 def _spawn_greenlet(*args):
   greenlet = g_pool.spawn(*args)
 

src/python/grpcio/grpc/_cython/_cygrpc/iomgr.pxd.pxi

@@ -0,0 +1,124 @@
+# Copyright 2019 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.
+# distutils: language=c++
+
+cdef extern from "grpc/impl/codegen/slice.h":
+  struct grpc_slice_buffer:
+    int count
+
+cdef extern from "src/core/lib/iomgr/error.h":
+  struct grpc_error:
+    pass
+
+# TODO(https://github.com/grpc/grpc/issues/20135) Change the filename
+# for something more meaningful.
+cdef extern from "src/core/lib/iomgr/gevent_util.h":
+  grpc_error* grpc_socket_error(char* error) 
+  char* grpc_slice_buffer_start(grpc_slice_buffer* buffer, int i)
+  int grpc_slice_buffer_length(grpc_slice_buffer* buffer, int i)
+
+cdef extern from "src/core/lib/iomgr/sockaddr.h":
+  ctypedef struct grpc_sockaddr:
+    pass
+
+cdef extern from "src/core/lib/iomgr/resolve_address.h":
+  ctypedef struct grpc_resolved_addresses:
+    size_t naddrs
+    grpc_resolved_address* addrs
+
+  ctypedef struct grpc_resolved_address:
+    char[128] addr
+    size_t len
+
+cdef extern from "src/core/lib/iomgr/resolve_address_custom.h":
+  struct grpc_custom_resolver:
+    pass
+
+  struct grpc_custom_resolver_vtable:
+    grpc_error* (*resolve)(char* host, char* port, grpc_resolved_addresses** res);
+    void (*resolve_async)(grpc_custom_resolver* resolver, char* host, char* port);
+
+  void grpc_custom_resolve_callback(grpc_custom_resolver* resolver,
+                                    grpc_resolved_addresses* result,
+                                    grpc_error* error);
+
+cdef extern from "src/core/lib/iomgr/tcp_custom.h":
+  struct grpc_custom_socket:
+    void* impl
+    # We don't care about the rest of the fields
+  ctypedef void (*grpc_custom_connect_callback)(grpc_custom_socket* socket,
+                                             grpc_error* error)
+  ctypedef void (*grpc_custom_write_callback)(grpc_custom_socket* socket,
+                                           grpc_error* error)
+  ctypedef void (*grpc_custom_read_callback)(grpc_custom_socket* socket,
+                                          size_t nread, grpc_error* error)
+  ctypedef void (*grpc_custom_accept_callback)(grpc_custom_socket* socket,
+                                            grpc_custom_socket* client,
+                                            grpc_error* error)
+  ctypedef void (*grpc_custom_close_callback)(grpc_custom_socket* socket)
+
+  struct grpc_socket_vtable:
+      grpc_error* (*init)(grpc_custom_socket* socket, int domain);
+      void (*connect)(grpc_custom_socket* socket, const grpc_sockaddr* addr,
+                      size_t len, grpc_custom_connect_callback cb);
+      void (*destroy)(grpc_custom_socket* socket);
+      void (*shutdown)(grpc_custom_socket* socket);
+      void (*close)(grpc_custom_socket* socket, grpc_custom_close_callback cb);
+      void (*write)(grpc_custom_socket* socket, grpc_slice_buffer* slices,
+                    grpc_custom_write_callback cb);
+      void (*read)(grpc_custom_socket* socket, char* buffer, size_t length,
+                   grpc_custom_read_callback cb);
+      grpc_error* (*getpeername)(grpc_custom_socket* socket,
+                                 const grpc_sockaddr* addr, int* len);
+      grpc_error* (*getsockname)(grpc_custom_socket* socket,
+                             const grpc_sockaddr* addr, int* len);
+      grpc_error* (*bind)(grpc_custom_socket* socket, const grpc_sockaddr* addr,
+                          size_t len, int flags);
+      grpc_error* (*listen)(grpc_custom_socket* socket);
+      void (*accept)(grpc_custom_socket* socket, grpc_custom_socket* client,
+                     grpc_custom_accept_callback cb);
+
+cdef extern from "src/core/lib/iomgr/timer_custom.h":
+  struct grpc_custom_timer:
+    void* timer
+    int timeout_ms
+     # We don't care about the rest of the fields
+
+  struct grpc_custom_timer_vtable:
+    void (*start)(grpc_custom_timer* t);
+    void (*stop)(grpc_custom_timer* t);
+
+  void grpc_custom_timer_callback(grpc_custom_timer* t, grpc_error* error);
+
+cdef extern from "src/core/lib/iomgr/pollset_custom.h":
+  struct grpc_custom_poller_vtable:
+    void (*init)()
+    void (*poll)(size_t timeout_ms)
+    void (*kick)()
+    void (*shutdown)()
+
+cdef extern from "src/core/lib/iomgr/iomgr_custom.h":
+  void grpc_custom_iomgr_init(grpc_socket_vtable* socket,
+                            grpc_custom_resolver_vtable* resolver,
+                            grpc_custom_timer_vtable* timer,
+                            grpc_custom_poller_vtable* poller);
+
+cdef extern from "src/core/lib/iomgr/sockaddr_utils.h":
+  int grpc_sockaddr_get_port(const grpc_resolved_address *addr);
+  int grpc_sockaddr_to_string(char **out, const grpc_resolved_address *addr,
+                              int normalize);
+  void grpc_string_to_sockaddr(grpc_resolved_address *out, char* addr, int port);
+  int grpc_sockaddr_set_port(const grpc_resolved_address *resolved_addr,
+                             int port)
+  const char* grpc_sockaddr_get_uri_scheme(const grpc_resolved_address* resolved_addr)

src/python/grpcio/grpc/_cython/_cygrpc/iomgr.pyx.pxi

@@ -0,0 +1,62 @@
+# Copyright 2019 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.
+# distutils: language=c++
+
+from libc cimport string
+from libc.stdlib cimport malloc
+
+cdef grpc_error* grpc_error_none():
+  return <grpc_error*>0
+
+cdef grpc_error* socket_error(str syscall, str err):
+  error_str = "{} failed: {}".format(syscall, err)
+  error_bytes = str_to_bytes(error_str)
+  return grpc_socket_error(error_bytes)
+
+cdef resolved_addr_to_tuple(grpc_resolved_address* address):
+  cdef char* res_str
+  port = grpc_sockaddr_get_port(address)
+  str_len = grpc_sockaddr_to_string(&res_str, address, 0) 
+  byte_str = _decode(<bytes>res_str[:str_len])
+  if byte_str.endswith(':' + str(port)):
+    byte_str = byte_str[:(0 - len(str(port)) - 1)]
+  byte_str = byte_str.lstrip('[')
+  byte_str = byte_str.rstrip(']')
+  byte_str = '{}'.format(byte_str)
+  return byte_str, port
+
+cdef sockaddr_to_tuple(const grpc_sockaddr* address, size_t length):
+  cdef grpc_resolved_address c_addr
+  string.memcpy(<void*>c_addr.addr, <void*> address, length)
+  c_addr.len = length
+  return resolved_addr_to_tuple(&c_addr)
+
+cdef sockaddr_is_ipv4(const grpc_sockaddr* address, size_t length):
+  cdef grpc_resolved_address c_addr
+  string.memcpy(<void*>c_addr.addr, <void*> address, length)
+  c_addr.len = length
+  return grpc_sockaddr_get_uri_scheme(&c_addr) == b'ipv4'
+
+cdef grpc_resolved_addresses* tuples_to_resolvaddr(tups):
+  cdef grpc_resolved_addresses* addresses
+  tups_set = set((tup[4][0], tup[4][1]) for tup in tups)
+  addresses = <grpc_resolved_addresses*> malloc(sizeof(grpc_resolved_addresses))
+  addresses.naddrs = len(tups_set)
+  addresses.addrs = <grpc_resolved_address*> malloc(sizeof(grpc_resolved_address) * len(tups_set))
+  i = 0
+  for tup in set(tups_set):
+    hostname = str_to_bytes(tup[0])
+    grpc_string_to_sockaddr(&addresses.addrs[i], hostname, tup[1])
+    i += 1
+  return addresses

src/python/grpcio/grpc/_cython/cygrpc.pxd

@@ -32,7 +32,18 @@ include "_cygrpc/time.pxd.pxi"
 include "_cygrpc/vtable.pxd.pxi"
 include "_cygrpc/_hooks.pxd.pxi"
 
+include "_cygrpc/iomgr.pxd.pxi"
+
 include "_cygrpc/grpc_gevent.pxd.pxi"
 
 IF UNAME_SYSNAME != "Windows":
     include "_cygrpc/fork_posix.pxd.pxi"
+
+# Following pxi files are part of the Aio module
+include "_cygrpc/aio/iomgr/socket.pxd.pxi"
+include "_cygrpc/aio/iomgr/timer.pxd.pxi"
+include "_cygrpc/aio/iomgr/resolver.pxd.pxi"
+include "_cygrpc/aio/grpc_aio.pxd.pxi"
+include "_cygrpc/aio/callbackcontext.pxd.pxi"
+include "_cygrpc/aio/call.pxd.pxi"
+include "_cygrpc/aio/channel.pxd.pxi"

src/python/grpcio/grpc/_cython/cygrpc.pyx

@@ -17,6 +17,13 @@ cimport cpython
 
 import os.path
 import sys
+try:
+    import asyncio
+except ImportError:
+    # TODO(https://github.com/grpc/grpc/issues/19728) Improve how Aio Cython is
+    # distributed without breaking none compatible Python versions. For now, if
+    # Asyncio package is not available we just skip it.
+    pass
 
 # TODO(atash): figure out why the coverage tool gets confused about the Cython
 # coverage plugin when the following files don't have a '.pxi' suffix.
@@ -39,6 +46,8 @@ include "_cygrpc/time.pyx.pxi"
 include "_cygrpc/vtable.pyx.pxi"
 include "_cygrpc/_hooks.pyx.pxi"
 
+include "_cygrpc/iomgr.pyx.pxi"
+
 include "_cygrpc/grpc_gevent.pyx.pxi"
 
 IF UNAME_SYSNAME == "Windows":
@@ -46,6 +55,16 @@ IF UNAME_SYSNAME == "Windows":
 ELSE:
     include "_cygrpc/fork_posix.pyx.pxi"
 
+# Following pxi files are part of the Aio module
+include "_cygrpc/aio/iomgr/iomgr.pyx.pxi"
+include "_cygrpc/aio/iomgr/socket.pyx.pxi"
+include "_cygrpc/aio/iomgr/timer.pyx.pxi"
+include "_cygrpc/aio/iomgr/resolver.pyx.pxi"
+include "_cygrpc/aio/grpc_aio.pyx.pxi"
+include "_cygrpc/aio/call.pyx.pxi"
+include "_cygrpc/aio/channel.pyx.pxi"
+
+
 #
 # initialize gRPC
 #

src/python/grpcio/grpc/experimental/BUILD.bazel

@@ -1,9 +1,21 @@
 package(default_visibility = ["//visibility:public"])
 
+py_library(
+    name = "aio",
+    srcs = [
+        "aio/__init__.py",
+        "aio/_channel.py",
+    ],
+    deps = [
+        "//src/python/grpcio/grpc/_cython:cygrpc",
+    ],
+)
+
 py_library(
     name = "experimental",
     srcs = ["__init__.py",],
     deps = [
+        ":aio",
         ":gevent",
         ":session_cache",
     ],

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

@@ -0,0 +1,123 @@
+# Copyright 2019 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.
+"""gRPC's Asynchronous Python API."""
+
+import abc
+import six
+
+from grpc._cython.cygrpc import init_grpc_aio
+
+
+class Channel(six.with_metaclass(abc.ABCMeta)):
+    """Asynchronous Channel implementation."""
+
+    @abc.abstractmethod
+    def unary_unary(self,
+                    method,
+                    request_serializer=None,
+                    response_deserializer=None):
+        """Creates a UnaryUnaryMultiCallable for a unary-unary method.
+
+        Args:
+          method: The name of the RPC method.
+          request_serializer: Optional behaviour for serializing the request
+            message. Request goes unserialized in case None is passed.
+          response_deserializer: Optional behaviour for deserializing the
+            response message. Response goes undeserialized in case None
+            is passed.
+
+        Returns:
+          A UnaryUnaryMultiCallable value for the named unary-unary method.
+        """
+        raise NotImplementedError()
+
+    @abc.abstractmethod
+    async def close(self):
+        """Closes this Channel and releases all resources held by it.
+
+        Closing the Channel will proactively terminate all RPCs active with the
+        Channel and it is not valid to invoke new RPCs with the Channel.
+
+        This method is idempotent.
+        """
+        raise NotImplementedError()
+
+    @abc.abstractmethod
+    async def __aenter__(self):
+        """Starts an asynchronous context manager.
+
+        Returns:
+          Channel the channel that was instantiated.
+        """
+        raise NotImplementedError()
+
+    @abc.abstractmethod
+    async def __aexit__(self, exc_type, exc_val, exc_tb):
+        """Finishes the asynchronous context manager by closing gracefully the channel."""
+        raise NotImplementedError()
+
+
+class UnaryUnaryMultiCallable(six.with_metaclass(abc.ABCMeta)):
+    """Affords invoking a unary-unary RPC from client-side in an asynchronous way."""
+
+    @abc.abstractmethod
+    async def __call__(self,
+                       request,
+                       timeout=None,
+                       metadata=None,
+                       credentials=None,
+                       wait_for_ready=None,
+                       compression=None):
+        """Asynchronously invokes the underlying RPC.
+
+        Args:
+          request: The request value for the RPC.
+          timeout: An optional duration of time in seconds to allow
+            for the RPC.
+          metadata: Optional :term:`metadata` to be transmitted to the
+            service-side of the RPC.
+          credentials: An optional CallCredentials for the RPC. Only valid for
+            secure Channel.
+          wait_for_ready: This is an EXPERIMENTAL argument. An optional
+            flag to enable wait for ready mechanism
+          compression: An element of grpc.compression, e.g.
+            grpc.compression.Gzip. This is an EXPERIMENTAL option.
+
+        Returns:
+          The response value for the RPC.
+
+        Raises:
+          RpcError: Indicating that the RPC terminated with non-OK status. The
+            raised RpcError will also be a Call for the RPC affording the RPC's
+            metadata, status code, and details.
+        """
+        raise NotImplementedError()
+
+
+def insecure_channel(target, options=None, compression=None):
+    """Creates an insecure asynchronous Channel to a server.
+
+    Args:
+      target: The server address
+      options: An optional list of key-value pairs (channel args
+        in gRPC Core runtime) to configure the channel.
+      compression: An optional value indicating the compression method to be
+        used over the lifetime of the channel. This is an EXPERIMENTAL option.
+
+    Returns:
+      A Channel.
+    """
+    from grpc.experimental.aio import _channel  # pylint: disable=cyclic-import
+    return _channel.Channel(target, ()
+                            if options is None else options, None, compression)

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

@@ -0,0 +1,105 @@
+# Copyright 2019 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.
+"""Invocation-side implementation of gRPC Asyncio Python."""
+
+from grpc import _common
+from grpc._cython import cygrpc
+from grpc.experimental import aio
+
+
+class UnaryUnaryMultiCallable(aio.UnaryUnaryMultiCallable):
+
+    def __init__(self, channel, method, request_serializer,
+                 response_deserializer):
+        self._channel = channel
+        self._method = method
+        self._request_serializer = request_serializer
+        self._response_deserializer = response_deserializer
+
+    async def __call__(self,
+                       request,
+                       timeout=None,
+                       metadata=None,
+                       credentials=None,
+                       wait_for_ready=None,
+                       compression=None):
+
+        if timeout:
+            raise NotImplementedError("TODO: timeout not implemented yet")
+
+        if metadata:
+            raise NotImplementedError("TODO: metadata not implemented yet")
+
+        if credentials:
+            raise NotImplementedError("TODO: credentials not implemented yet")
+
+        if wait_for_ready:
+            raise NotImplementedError(
+                "TODO: wait_for_ready not implemented yet")
+
+        if compression:
+            raise NotImplementedError("TODO: compression not implemented yet")
+
+        response = await self._channel.unary_unary(
+            self._method, _common.serialize(request, self._request_serializer))
+
+        return _common.deserialize(response, self._response_deserializer)
+
+
+class Channel(aio.Channel):
+    """A cygrpc.AioChannel-backed implementation of grpc.experimental.aio.Channel."""
+
+    def __init__(self, target, options, credentials, compression):
+        """Constructor.
+
+        Args:
+          target: The target to which to connect.
+          options: Configuration options for the channel.
+          credentials: A cygrpc.ChannelCredentials or None.
+          compression: An optional value indicating the compression method to be
+            used over the lifetime of the channel.
+        """
+
+        if options:
+            raise NotImplementedError("TODO: options not implemented yet")
+
+        if credentials:
+            raise NotImplementedError("TODO: credentials not implemented yet")
+
+        if compression:
+            raise NotImplementedError("TODO: compression not implemented yet")
+
+        self._channel = cygrpc.AioChannel(_common.encode(target))
+
+    def unary_unary(self,
+                    method,
+                    request_serializer=None,
+                    response_deserializer=None):
+
+        return UnaryUnaryMultiCallable(self._channel, _common.encode(method),
+                                       request_serializer,
+                                       response_deserializer)
+
+    async def _close(self):
+        # TODO: Send cancellation status
+        self._channel.close()
+
+    async def __aenter__(self):
+        return self
+
+    async def __aexit__(self, exc_type, exc_val, exc_tb):
+        await self._close()
+
+    async def close(self):
+        await self._close()

src/python/grpcio_tests/commands.py

@@ -107,6 +107,35 @@ class TestLite(setuptools.Command):
         self.distribution.fetch_build_eggs(self.distribution.tests_require)
 
 
+class TestAio(setuptools.Command):
+    """Command to run aio tests without fetching or building anything."""
+
+    description = 'run aio tests without fetching or building anything.'
+    user_options = []
+
+    def initialize_options(self):
+        pass
+
+    def finalize_options(self):
+        pass
+
+    def run(self):
+        self._add_eggs_to_path()
+
+        import tests
+        loader = tests.Loader()
+        loader.loadTestsFromNames(['tests_aio'])
+        runner = tests.Runner()
+        result = runner.run(loader.suite)
+        if not result.wasSuccessful():
+            sys.exit('Test failure')
+
+    def _add_eggs_to_path(self):
+        """Fetch install and test requirements"""
+        self.distribution.fetch_build_eggs(self.distribution.install_requires)
+        self.distribution.fetch_build_eggs(self.distribution.tests_require)
+
+
 class TestGevent(setuptools.Command):
     """Command to run tests w/gevent."""
 

src/python/grpcio_tests/setup.py

@@ -58,6 +58,7 @@ COMMAND_CLASS = {
     'run_interop': commands.RunInterop,
     'test_lite': commands.TestLite,
     'test_gevent': commands.TestGevent,
+    'test_aio': commands.TestAio,
 }
 
 PACKAGE_DATA = {

src/python/grpcio_tests/tests/_sanity/_sanity_test.py

@@ -25,17 +25,20 @@ class SanityTest(unittest.TestCase):
 
     maxDiff = 32768
 
+    TEST_PKG_MODULE_NAME = 'tests'
+    TEST_PKG_PATH = 'tests'
+
     def testTestsJsonUpToDate(self):
         """Autodiscovers all test suites and checks that tests.json is up to date"""
         loader = tests.Loader()
-        loader.loadTestsFromNames(['tests'])
+        loader.loadTestsFromNames([self.TEST_PKG_MODULE_NAME])
         test_suite_names = sorted({
             test_case_class.id().rsplit('.', 1)[0]
             for test_case_class in tests._loader.iterate_suite_cases(
                 loader.suite)
         })
 
-        tests_json_string = pkgutil.get_data('tests', 'tests.json')
+        tests_json_string = pkgutil.get_data(self.TEST_PKG_PATH, 'tests.json')
         tests_json = json.loads(tests_json_string.decode()
                                 if six.PY3 else tests_json_string)
 

src/python/grpcio_tests/tests_aio/__init__.py

@@ -0,0 +1,21 @@
+# Copyright 2019 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.
+
+from __future__ import absolute_import
+
+from tests import _loader
+from tests import _runner
+
+Loader = _loader.Loader
+Runner = _runner.Runner

src/python/grpcio_tests/tests_aio/_sanity/__init__.py

@@ -0,0 +1,13 @@
+# Copyright 2019 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.

src/python/grpcio_tests/tests_aio/_sanity/_sanity_test.py

@@ -0,0 +1,27 @@
+# Copyright 2019 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 unittest
+
+from tests._sanity import _sanity_test
+
+
+class AioSanityTest(_sanity_test.SanityTest):
+
+    TEST_PKG_MODULE_NAME = 'tests_aio'
+    TEST_PKG_PATH = 'tests_aio'
+
+
+if __name__ == '__main__':
+    unittest.main(verbosity=2)

src/python/grpcio_tests/tests_aio/tests.json

@@ -0,0 +1,5 @@
+[
+  "_sanity._sanity_test.AioSanityTest",
+  "unit.channel_test.TestChannel",
+  "unit.init_test.TestInsecureChannel"
+]

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

@@ -0,0 +1,13 @@
+# Copyright 2019 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.

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

@@ -0,0 +1,58 @@
+# Copyright 2019 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 grpc.experimental import aio
+from tests_aio.unit import test_base
+from src.proto.grpc.testing import messages_pb2
+
+
+class TestChannel(test_base.AioTestBase):
+
+    def test_async_context(self):
+
+        async def coro():
+            async with aio.insecure_channel(self.server_target) as channel:
+                hi = channel.unary_unary(
+                    '/grpc.testing.TestService/UnaryCall',
+                    request_serializer=messages_pb2.SimpleRequest.
+                    SerializeToString,
+                    response_deserializer=messages_pb2.SimpleResponse.FromString
+                )
+                await hi(messages_pb2.SimpleRequest())
+
+        self.loop.run_until_complete(coro())
+
+    def test_unary_unary(self):
+
+        async def coro():
+            channel = aio.insecure_channel(self.server_target)
+            hi = channel.unary_unary(
+                '/grpc.testing.TestService/UnaryCall',
+                request_serializer=messages_pb2.SimpleRequest.SerializeToString,
+                response_deserializer=messages_pb2.SimpleResponse.FromString)
+            response = await hi(messages_pb2.SimpleRequest())
+
+            self.assertEqual(type(response), messages_pb2.SimpleResponse)
+
+            await channel.close()
+
+        self.loop.run_until_complete(coro())
+
+
+if __name__ == '__main__':
+    logging.basicConfig()
+    unittest.main(verbosity=2)

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

@@ -0,0 +1,35 @@
+# Copyright 2019 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 grpc.experimental import aio
+from tests_aio.unit import test_base
+
+
+class TestInsecureChannel(test_base.AioTestBase):
+
+    def test_insecure_channel(self):
+
+        async def coro():
+            channel = aio.insecure_channel(self.server_target)
+            self.assertIsInstance(channel, aio.Channel)
+
+        self.loop.run_until_complete(coro())
+
+
+if __name__ == '__main__':
+    logging.basicConfig()
+    unittest.main(verbosity=2)

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

@@ -0,0 +1,50 @@
+# Copyright 2019 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 argparse
+
+from concurrent import futures
+from time import sleep
+
+import grpc
+from src.proto.grpc.testing import messages_pb2
+from src.proto.grpc.testing import test_pb2_grpc
+
+
+# TODO (https://github.com/grpc/grpc/issues/19762)
+# Change for an asynchronous server version once it's implemented.
+class TestServiceServicer(test_pb2_grpc.TestServiceServicer):
+
+    def UnaryCall(self, request, context):
+        return messages_pb2.SimpleResponse()
+
+
+if __name__ == "__main__":
+    parser = argparse.ArgumentParser(description='Synchronous gRPC server.')
+    parser.add_argument(
+        '--host_and_port',
+        required=True,
+        type=str,
+        nargs=1,
+        help='the host and port to listen.')
+    args = parser.parse_args()
+
+    server = grpc.server(
+        futures.ThreadPoolExecutor(max_workers=1),
+        options=(('grpc.so_reuseport', 1),))
+    test_pb2_grpc.add_TestServiceServicer_to_server(TestServiceServicer(),
+                                                    server)
+    server.add_insecure_port(args.host_and_port[0])
+    server.start()
+    server.wait_for_termination()

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

@@ -0,0 +1,101 @@
+# Copyright 2019 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 os
+import sys
+import subprocess
+
+import asyncio
+import unittest
+import socket
+
+from grpc.experimental import aio
+from tests_aio.unit import sync_server
+
+
+def _get_free_loopback_tcp_port():
+    if socket.has_ipv6:
+        tcp_socket = socket.socket(socket.AF_INET6)
+        host = "::1"
+        host_target = "[::1]"
+    else:
+        tcp_socket = socket.socket(socket.AF_INET)
+        host = "127.0.0.1"
+        host_target = host
+    tcp_socket.setsockopt(socket.SOL_SOCKET, socket.SO_REUSEPORT, 1)
+    tcp_socket.bind((host, 0))
+    address_tuple = tcp_socket.getsockname()
+    return tcp_socket, "%s:%s" % (host_target, address_tuple[1])
+
+
+class _Server:
+    """_Server is an wrapper for a sync-server subprocess.
+
+    The synchronous server is executed in another process which initializes
+    implicitly the grpc using the synchronous configuration. Both worlds
+    can not coexist within the same process.
+    """
+
+    def __init__(self, host_and_port):  # pylint: disable=W0621
+        self._host_and_port = host_and_port
+        self._handle = None
+
+    def start(self):
+        assert self._handle is None
+
+        try:
+            from google3.pyglib import resources
+            executable = resources.GetResourceFilename(
+                "google3/third_party/py/grpc/sync_server")
+            args = [executable, '--host_and_port', self._host_and_port]
+        except ImportError:
+            executable = sys.executable
+            directory, _ = os.path.split(os.path.abspath(__file__))
+            filename = directory + '/sync_server.py'
+            args = [
+                executable, filename, '--host_and_port', self._host_and_port
+            ]
+
+        self._handle = subprocess.Popen(args)
+
+    def terminate(self):
+        if not self._handle:
+            return
+
+        self._handle.terminate()
+        self._handle.wait()
+        self._handle = None
+
+
+class AioTestBase(unittest.TestCase):
+
+    def setUp(self):
+        self._socket, self._target = _get_free_loopback_tcp_port()
+        self._server = _Server(self._target)
+        self._server.start()
+        self._loop = asyncio.new_event_loop()
+        asyncio.set_event_loop(self._loop)
+        aio.init_grpc_aio()
+
+    def tearDown(self):
+        self._server.terminate()
+        self._socket.close()
+
+    @property
+    def loop(self):
+        return self._loop
+
+    @property
+    def server_target(self):
+        return self._target

tools/run_tests/run_tests.py

@@ -703,6 +703,10 @@ class PythonConfig(
 
 class PythonLanguage(object):
 
+    _DEFAULT_COMMAND = 'test_lite'
+    _TEST_SPECS_FILE = 'src/python/grpcio_tests/tests/tests.json'
+    _TEST_FOLDER = 'test'
+
     def configure(self, config, args):
         self.config = config
         self.args = args
@@ -710,8 +714,7 @@ class PythonLanguage(object):
 
     def test_specs(self):
         # load list of known test suites
-        with open(
+        with open(self._TEST_SPECS_FILE) as tests_json_file:
-                'src/python/grpcio_tests/tests/tests.json') as tests_json_file:
             tests_json = json.load(tests_json_file)
         environment = dict(_FORCE_ENVIRON_FOR_WRAPPERS)
         return [
@@ -721,7 +724,8 @@ class PythonLanguage(object):
                 environ=dict(
                     list(environment.items()) + [(
                         'GRPC_PYTHON_TESTRUNNER_FILTER', str(suite_name))]),
-                shortname='%s.test.%s' % (config.name, suite_name),
+                shortname='%s.%s.%s' % (config.name, self._TEST_FOLDER,
+                                        suite_name),
             ) for suite_name in tests_json for config in self.pythons
         ]
 
@@ -789,7 +793,7 @@ class PythonLanguage(object):
             venv_relative_python = ['bin/python']
             toolchain = ['unix']
 
-        test_command = 'test_lite'
+        test_command = self._DEFAULT_COMMAND
         if args.iomgr_platform == 'gevent':
             test_command = 'test_gevent'
         runner = [
@@ -882,6 +886,31 @@ class PythonLanguage(object):
         return 'python'
 
 
+class PythonAioLanguage(PythonLanguage):
+
+    _DEFAULT_COMMAND = 'test_aio'
+    _TEST_SPECS_FILE = 'src/python/grpcio_tests/tests_aio/tests.json'
+    _TEST_FOLDER = 'test_aio'
+
+    def configure(self, config, args):
+        self.config = config
+        self.args = args
+        self.pythons = self._get_pythons(self.args)
+
+    def _get_pythons(self, args):
+        """Get python runtimes to test with, based on current platform, architecture, compiler etc."""
+
+        if args.compiler not in ('python3.6', 'python3.7', 'python3.8'):
+            raise Exception('Compiler %s not supported.' % args.compiler)
+        if args.iomgr_platform not in ('native'):
+            raise Exception(
+                'Iomgr platform %s not supported.' % args.iomgr_platform)
+        return super()._get_pythons(args)
+
+    def __str__(self):
+        return 'python_aio'
+
+
 class RubyLanguage(object):
 
     def configure(self, config, args):
@@ -1269,6 +1298,7 @@ _LANGUAGES = {
     'php': PhpLanguage(),
     'php7': Php7Language(),
     'python': PythonLanguage(),
+    'python-aio': PythonAioLanguage(),
     'ruby': RubyLanguage(),
     'csharp': CSharpLanguage(),
     'objc': ObjCLanguage(),