grpc/examples/python/cancellation/client.py

# Copyright the 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.
"""An example of cancelling requests in gRPC."""

from __future__ import absolute_import
from __future__ import division
from __future__ import print_function

from concurrent import futures
import datetime
import logging
import time

import grpc

from examples.python.cancellation import hash_name_pb2
from examples.python.cancellation import hash_name_pb2_grpc

_LOGGER = logging.getLogger(__name__)

# Interface:
#   Cancel after we have n matches or we have an exact match.


# Test whether cancelling cancels a long-running unary RPC (I doubt it).
# Start the server with a single thread.
# Start a request and cancel it soon after.
# Start another request. If it succesfully cancelled, this will block forever.
# Add a bunch of logging so we know what's happening.

def main():
    # TODO(rbellevi): Fix the connaissance of target.
    with grpc.insecure_channel('localhost:50051') as channel:
        stub = hash_name_pb2_grpc.HashFinderStub(channel)
        while True:
            print("Sending request")
            future = stub.Find.future(hash_name_pb2.HashNameRequest(desired_name="doctor",
                                                                      maximum_hamming_distance=0))
            # TODO(rbellevi): Do not leave in a cancellation based on timeout.
            # That's best handled by, well.. timeout.
            try:
                result = future.result(timeout=2.0)
                print("Got response: \n{}".format(response))
            except grpc.FutureTimeoutError:
                print("Cancelling request")
                future.cancel()


if __name__ == "__main__":
    logging.basicConfig()
    main()