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# 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.
"""An example of cancelling requests in gRPC."""
from __future__ import absolute_import
from __future__ import division
from __future__ import print_function
import argparse
from concurrent import futures
import logging
import threading
import grpc
import search
from examples.python.cancellation import hash_name_pb2
from examples.python.cancellation import hash_name_pb2_grpc
_LOGGER = logging.getLogger(__name__)
_SERVER_HOST = 'localhost'
_DESCRIPTION = "A server for finding hashes similar to names."
class HashFinder(hash_name_pb2_grpc.HashFinderServicer):
def __init__(self, maximum_hashes):
super(HashFinder, self).__init__()
self._maximum_hashes = maximum_hashes
def Find(self, request, context):
stop_event = threading.Event()
def on_rpc_done():
_LOGGER.debug("Attempting to regain servicer thread.")
stop_event.set()
context.add_callback(on_rpc_done)
candidates = []
try:
candidates = list(
search.search(request.desired_name,
request.ideal_hamming_distance, stop_event,
self._maximum_hashes))
except search.ResourceLimitExceededError:
_LOGGER.info("Cancelling RPC due to exhausted resources.")
context.cancel()
_LOGGER.debug("Servicer thread returning.")
if not candidates:
return hash_name_pb2.HashNameResponse()
return candidates[-1]
def FindRange(self, request, context):
stop_event = threading.Event()
def on_rpc_done():
_LOGGER.debug("Attempting to regain servicer thread.")
stop_event.set()
context.add_callback(on_rpc_done)
secret_generator = search.search(
request.desired_name,
request.ideal_hamming_distance,
stop_event,
self._maximum_hashes,
interesting_hamming_distance=request.interesting_hamming_distance)
try:
for candidate in secret_generator:
yield candidate
except search.ResourceLimitExceededError:
_LOGGER.info("Cancelling RPC due to exhausted resources.")
context.cancel()
_LOGGER.debug("Regained servicer thread.")
def _running_server(port, maximum_hashes):
# We use only a single servicer thread here to demonstrate that, if managed
# carefully, cancelled RPCs can need not continue occupying servicers
# threads.
server = grpc.server(futures.ThreadPoolExecutor(max_workers=1),
maximum_concurrent_rpcs=1)
hash_name_pb2_grpc.add_HashFinderServicer_to_server(
HashFinder(maximum_hashes), server)
address = '{}:{}'.format(_SERVER_HOST, port)
actual_port = server.add_insecure_port(address)
server.start()
print("Server listening at '{}'".format(address))
return server
def main():
parser = argparse.ArgumentParser(description=_DESCRIPTION)
parser.add_argument('--port',
type=int,
default=50051,
nargs='?',
help='The port on which the server will listen.')
parser.add_argument(
'--maximum-hashes',
type=int,
default=1000000,
nargs='?',
help='The maximum number of hashes to search before cancelling.')
args = parser.parse_args()
server = _running_server(args.port, args.maximum_hashes)
server.wait_for_termination()
if __name__ == "__main__":
logging.basicConfig()
main()
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