Simplify the logic and improve readability

src/python/grpcio_health_checking/grpc_health/v1/_async.py

@@ -39,25 +39,25 @@ class AsyncHealthServicer(_health_pb2_grpc.HealthServicer):
             return _health_pb2.HealthCheckResponse(status=status)
 
     async def Watch(self, request: _health_pb2.HealthCheckRequest, context):
-        status = self._server_status.get(request.service)
-
-        if status is None:
-            status = _health_pb2.HealthCheckResponse.SERVICE_UNKNOWN
-
-        try:
         condition = self._server_watchers[request.service]
+        try:
             async with condition:
+                while True:
+                    status = self._server_status.get(request.service)
+
+                    if status:
                         # Responds with current health state
                         await context.write(
                             _health_pb2.HealthCheckResponse(status=status))
+                    else:
+                        # Responds with default value
+                        await context.write(
+                            _health_pb2.HealthCheckResponse(
+                                status=_health_pb2.HealthCheckResponse.
+                                SERVICE_UNKNOWN))
 
                     # Polling on health state changes
-                while True:
                     await condition.wait()
-
-                    status = self._server_status.get(request.service)
-                    await context.write(
-                        _health_pb2.HealthCheckResponse(status=status))
         finally:
             del self._server_watchers[request.service]
 

src/python/grpcio_tests/tests_aio/health_check/health_servicer_test.py

@@ -143,6 +143,8 @@ class HealthServicerTest(AioTestBase):
 
         await self._servicer.set('some-other-service',
                                  health_pb2.HealthCheckResponse.SERVING)
+        # The change of health status in other service should be isolated.
+        # Hence, no additional notification should be observed.
         with self.assertRaises(asyncio.TimeoutError):
             await asyncio.wait_for(queue.get(), test_constants.SHORT_TIMEOUT)
 
@@ -193,8 +195,8 @@ class HealthServicerTest(AioTestBase):
         await task
 
         # Wait for the serving coroutine to process client cancellation.
-        timeout = time.time() + test_constants.TIME_ALLOWANCE
-        while (time.time() < timeout and self._servicer._server_watchers):
+        timeout = time.monotonic() + test_constants.TIME_ALLOWANCE
+        while (time.monotonic() < timeout and self._servicer._server_watchers):
             await asyncio.sleep(1)
         self.assertFalse(self._servicer._server_watchers,
                          'There should not be any watcher left')