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# Copyright 2015 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.
"""Reference implementation for health checking in gRPC Python."""
import threading
import grpc
from grpc_health.v1 import health_pb2 as _health_pb2
from grpc_health.v1 import health_pb2_grpc as _health_pb2_grpc
SERVICE_NAME = _health_pb2.DESCRIPTOR.services_by_name['Health'].full_name
class _Watcher():
def __init__(self):
self._condition = threading.Condition()
self._responses = list()
self._open = True
def __iter__(self):
return self
def _next(self):
with self._condition:
while not self._responses and self._open:
self._condition.wait()
if self._responses:
return self._responses.pop(0)
else:
raise StopIteration()
def next(self):
return self._next()
def __next__(self):
return self._next()
def add(self, response):
with self._condition:
self._responses.append(response)
self._condition.notify()
def close(self):
with self._condition:
self._open = False
self._condition.notify()
class HealthServicer(_health_pb2_grpc.HealthServicer):
"""Servicer handling RPCs for service statuses."""
def __init__(self):
self._lock = threading.RLock()
self._server_status = {}
self._watchers = {}
def _on_close_callback(self, watcher, service):
def callback():
with self._lock:
self._watchers[service].remove(watcher)
watcher.close()
return callback
def Check(self, request, context):
with self._lock:
status = self._server_status.get(request.service)
if status is None:
context.set_code(grpc.StatusCode.NOT_FOUND)
return _health_pb2.HealthCheckResponse()
else:
return _health_pb2.HealthCheckResponse(status=status)
def Watch(self, request, context):
service = request.service
with self._lock:
status = self._server_status.get(service)
if status is None:
status = _health_pb2.HealthCheckResponse.SERVICE_UNKNOWN # pylint: disable=no-member
watcher = _Watcher()
watcher.add(_health_pb2.HealthCheckResponse(status=status))
if service not in self._watchers:
self._watchers[service] = set()
self._watchers[service].add(watcher)
context.add_callback(self._on_close_callback(watcher, service))
return watcher
def set(self, service, status):
"""Sets the status of a service.
Args:
service: string, the name of the service. NOTE, '' must be set.
status: HealthCheckResponse.status enum value indicating the status of
the service
"""
with self._lock:
self._server_status[service] = status
if service in self._watchers:
for watcher in self._watchers[service]:
watcher.add(_health_pb2.HealthCheckResponse(status=status))
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