# Copyright 2021 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.
"""The graceful shutdown example for the asyncio Greeter server."""

import asyncio
import logging

import grpc
import helloworld_pb2
import helloworld_pb2_grpc

# Coroutines to be invoked when the event loop is shutting down.
_cleanup_coroutines = []


class Greeter(helloworld_pb2_grpc.GreeterServicer):

    async def SayHello(
            self, request: helloworld_pb2.HelloRequest,
            context: grpc.aio.ServicerContext) -> helloworld_pb2.HelloReply:
        logging.info('Received request, sleeping for 4 seconds...')
        await asyncio.sleep(4)
        logging.info('Sleep completed, responding')
        return helloworld_pb2.HelloReply(message='Hello, %s!' % request.name)


async def serve() -> None:
    server = grpc.aio.server()
    helloworld_pb2_grpc.add_GreeterServicer_to_server(Greeter(), server)
    listen_addr = '[::]:50051'
    server.add_insecure_port(listen_addr)
    logging.info("Starting server on %s", listen_addr)
    await server.start()

    async def server_graceful_shutdown():
        logging.info("Starting graceful shutdown...")
        # Shuts down the server with 0 seconds of grace period. During the
        # grace period, the server won't accept new connections and allow
        # existing RPCs to continue within the grace period.
        await server.stop(5)

    _cleanup_coroutines.append(server_graceful_shutdown())
    await server.wait_for_termination()


if __name__ == '__main__':
    logging.basicConfig(level=logging.INFO)
    loop = asyncio.get_event_loop()
    try:
        loop.run_until_complete(serve())
    finally:
        loop.run_until_complete(*_cleanup_coroutines)
        loop.close()
