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# Copyright 2020 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.
"""Reference implementation for health checking in gRPC Python."""
import asyncio
import collections
from typing import MutableMapping
import grpc
from grpc_health.v1 import health_pb2 as _health_pb2
from grpc_health.v1 import health_pb2_grpc as _health_pb2_grpc
class HealthServicer(_health_pb2_grpc.HealthServicer):
"""An AsyncIO implementation of health checking servicer."""
_server_status: MutableMapping[
str, '_health_pb2.HealthCheckResponse.ServingStatus']
_server_watchers: MutableMapping[str, asyncio.Condition]
_gracefully_shutting_down: bool
def __init__(self) -> None:
self._server_status = {"": _health_pb2.HealthCheckResponse.SERVING}
self._server_watchers = collections.defaultdict(asyncio.Condition)
self._gracefully_shutting_down = False
async def Check(self, request: _health_pb2.HealthCheckRequest,
context) -> None:
status = self._server_status.get(request.service)
if status is None:
await context.abort(grpc.StatusCode.NOT_FOUND)
else:
return _health_pb2.HealthCheckResponse(status=status)
async def Watch(self, request: _health_pb2.HealthCheckRequest,
context) -> None:
condition = self._server_watchers[request.service]
last_status = None
try:
async with condition:
while True:
status = self._server_status.get(
request.service,
_health_pb2.HealthCheckResponse.SERVICE_UNKNOWN)
# NOTE(lidiz) If the observed status is the same, it means
# there are missing intermediate statuses. It's considered
# acceptable since peer only interested in eventual status.
if status != last_status:
# Responds with current health state
await context.write(
_health_pb2.HealthCheckResponse(status=status))
# Records the last sent status
last_status = status
# Polling on health state changes
await condition.wait()
finally:
if request.service in self._server_watchers:
del self._server_watchers[request.service]
async def _set(
self, service: str,
status: _health_pb2.HealthCheckResponse.ServingStatus) -> None:
if service in self._server_watchers:
condition = self._server_watchers.get(service)
async with condition:
self._server_status[service] = status
condition.notify_all()
else:
self._server_status[service] = status
async def set(
self, service: str,
status: _health_pb2.HealthCheckResponse.ServingStatus) -> None:
"""Sets the status of a service.
Args:
service: string, the name of the service.
status: HealthCheckResponse.status enum value indicating the status of
the service
"""
if self._gracefully_shutting_down:
return
else:
await self._set(service, status)
async def enter_graceful_shutdown(self) -> None:
"""Permanently sets the status of all services to NOT_SERVING.
This should be invoked when the server is entering a graceful shutdown
period. After this method is invoked, future attempts to set the status
of a service will be ignored.
"""
if self._gracefully_shutting_down:
return
else:
self._gracefully_shutting_down = True
for service in self._server_status:
await self._set(service,
_health_pb2.HealthCheckResponse.NOT_SERVING)
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