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# Copyright 2019 the gRPC authors.
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#
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# Licensed under the Apache License, Version 2.0 (the "License");
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# you may not use this file except in compliance with the License.
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# You may obtain a copy of the License at
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#
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# http://www.apache.org/licenses/LICENSE-2.0
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#
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# Unless required by applicable law or agreed to in writing, software
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# distributed under the License is distributed on an "AS IS" BASIS,
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# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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# See the License for the specific language governing permissions and
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# limitations under the License.
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"""An example of cancelling requests in gRPC."""
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from __future__ import absolute_import
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from __future__ import division
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from __future__ import print_function
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from concurrent import futures
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import argparse
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import logging
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import threading
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import grpc
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import search
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from examples.python.cancellation import hash_name_pb2
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from examples.python.cancellation import hash_name_pb2_grpc
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_LOGGER = logging.getLogger(__name__)
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_SERVER_HOST = 'localhost'
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_DESCRIPTION = "A server for finding hashes similar to names."
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class HashFinder(hash_name_pb2_grpc.HashFinderServicer):
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def __init__(self, maximum_hashes):
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super(HashFinder, self).__init__()
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self._maximum_hashes = maximum_hashes
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def Find(self, request, context):
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stop_event = threading.Event()
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def on_rpc_done():
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_LOGGER.debug("Attempting to regain servicer thread.")
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stop_event.set()
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context.add_callback(on_rpc_done)
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candidates = []
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try:
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candidates = list(
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search.search(request.desired_name,
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request.ideal_hamming_distance, stop_event,
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self._maximum_hashes))
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except search.ResourceLimitExceededError:
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_LOGGER.info("Cancelling RPC due to exhausted resources.")
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context.cancel()
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_LOGGER.debug("Servicer thread returning.")
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if not candidates:
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return hash_name_pb2.HashNameResponse()
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return candidates[-1]
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def FindRange(self, request, context):
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stop_event = threading.Event()
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def on_rpc_done():
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_LOGGER.debug("Attempting to regain servicer thread.")
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stop_event.set()
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context.add_callback(on_rpc_done)
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secret_generator = search.search(
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request.desired_name,
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request.ideal_hamming_distance,
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stop_event,
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self._maximum_hashes,
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interesting_hamming_distance=request.interesting_hamming_distance)
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try:
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for candidate in secret_generator:
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yield candidate
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except search.ResourceLimitExceededError:
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_LOGGER.info("Cancelling RPC due to exhausted resources.")
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context.cancel()
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_LOGGER.debug("Regained servicer thread.")
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def _running_server(port, maximum_hashes):
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# We use only a single servicer thread here to demonstrate that, if managed
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# carefully, cancelled RPCs can need not continue occupying servicers
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# threads.
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server = grpc.server(
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futures.ThreadPoolExecutor(max_workers=1), maximum_concurrent_rpcs=1)
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hash_name_pb2_grpc.add_HashFinderServicer_to_server(
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HashFinder(maximum_hashes), server)
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address = '{}:{}'.format(_SERVER_HOST, port)
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actual_port = server.add_insecure_port(address)
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server.start()
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print("Server listening at '{}'".format(address))
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return server
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def main():
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parser = argparse.ArgumentParser(description=_DESCRIPTION)
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parser.add_argument(
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'--port',
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type=int,
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default=50051,
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nargs='?',
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help='The port on which the server will listen.')
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parser.add_argument(
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'--maximum-hashes',
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type=int,
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default=1000000,
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nargs='?',
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help='The maximum number of hashes to search before cancelling.')
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args = parser.parse_args()
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server = _running_server(args.port, args.maximum_hashes)
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server.wait_for_termination()
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if __name__ == "__main__":
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logging.basicConfig()
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main()
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