# 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."""Server-side implementation of gRPC Asyncio Python."""fromconcurrent.futuresimportExecutorfromtypingimportAny,Dict,Optional,Sequenceimportgrpcfromgrpcimport_commonfromgrpcimport_compressionfromgrpc._cythonimportcygrpcfrom.import_base_serverfrom._interceptorimportServerInterceptorfrom._typingimportChannelArgumentTypedef_augment_channel_arguments(base_options:ChannelArgumentType,compression:Optional[grpc.Compression]):compression_option=_compression.create_channel_option(compression)returntuple(base_options)+compression_optionclassServer(_base_server.Server):"""Serves RPCs."""def__init__(self,thread_pool:Optional[Executor],generic_handlers:Optional[Sequence[grpc.GenericRpcHandler]],interceptors:Optional[Sequence[Any]],options:ChannelArgumentType,maximum_concurrent_rpcs:Optional[int],compression:Optional[grpc.Compression],):self._loop=cygrpc.get_working_loop()ifinterceptors:invalid_interceptors=[interceptorforinterceptorininterceptorsifnotisinstance(interceptor,ServerInterceptor)]ifinvalid_interceptors:error_msg=("Interceptor must be ServerInterceptor,""the following are invalid:{invalid_interceptors}")raiseValueError(error_msg)self._server=cygrpc.AioServer(self._loop,thread_pool,generic_handlers,interceptors,_augment_channel_arguments(options,compression),maximum_concurrent_rpcs,)defadd_generic_rpc_handlers(self,generic_rpc_handlers:Sequence[grpc.GenericRpcHandler])->None:"""Registers GenericRpcHandlers with this Server.        This method is only safe to call before the server is started.        Args:          generic_rpc_handlers: A sequence of GenericRpcHandlers that will be          used to service RPCs.        """self._server.add_generic_rpc_handlers(generic_rpc_handlers)defadd_registered_method_handlers(self,service_name:str,method_handlers:Dict[str,grpc.RpcMethodHandler],)->None:# TODO(xuanwn): Implement this for AsyncIO.passdefadd_insecure_port(self,address:str)->int:"""Opens an insecure port for accepting RPCs.        This method may only be called before starting the server.        Args:          address: The address for which to open a port. If the port is 0,            or not specified in the address, then the gRPC runtime will choose a port.        Returns:          An integer port on which the server will accept RPC requests.        """return_common.validate_port_binding_result(address,self._server.add_insecure_port(_common.encode(address)))defadd_secure_port(self,address:str,server_credentials:grpc.ServerCredentials)->int:"""Opens a secure port for accepting RPCs.        This method may only be called before starting the server.        Args:          address: The address for which to open a port.            if the port is 0, or not specified in the address, then the gRPC            runtime will choose a port.          server_credentials: A ServerCredentials object.        Returns:          An integer port on which the server will accept RPC requests.        """return_common.validate_port_binding_result(address,self._server.add_secure_port(_common.encode(address),server_credentials),)asyncdefstart(self)->None:"""Starts this Server.        This method may only be called once. (i.e. it is not idempotent).        """awaitself._server.start()asyncdefstop(self,grace:Optional[float])->None:"""Stops this Server.        This method immediately stops the server from servicing new RPCs in        all cases.        If a grace period is specified, this method waits until all active        RPCs are finished or until the grace period is reached. RPCs that haven't        been terminated within the grace period are aborted.        If a grace period is not specified (by passing None for grace), all        existing RPCs are aborted immediately and this method blocks until        the last RPC handler terminates.        This method is idempotent and may be called at any time. Passing a        smaller grace value in a subsequent call will have the effect of        stopping the Server sooner (passing None will have the effect of        stopping the server immediately). Passing a larger grace value in a        subsequent call will not have the effect of stopping the server later        (i.e. the most restrictive grace value is used).        Args:          grace: A duration of time in seconds or None.        """awaitself._server.shutdown(grace)asyncdefwait_for_termination(self,timeout:Optional[float]=None)->bool:"""Block current coroutine until the server stops.        This is an EXPERIMENTAL API.        The wait will not consume computational resources during blocking, and        it will block until one of the two following conditions are met:        1) The server is stopped or terminated;        2) A timeout occurs if timeout is not `None`.        The timeout argument works in the same way as `threading.Event.wait()`.        https://docs.python.org/3/library/threading.html#threading.Event.wait        Args:          timeout: A floating point number specifying a timeout for the            operation in seconds.        Returns:          A bool indicates if the operation times out.        """returnawaitself._server.wait_for_termination(timeout)def__del__(self):"""Schedules a graceful shutdown in current event loop.        The Cython AioServer doesn't hold a ref-count to this class. It should        be safe to slightly extend the underlying Cython object's life span.        """ifhasattr(self,"_server"):ifself._server.is_running():cygrpc.schedule_coro_threadsafe(self._server.shutdown(None),self._loop,)
[docs]defserver(migration_thread_pool:Optional[Executor]=None,handlers:Optional[Sequence[grpc.GenericRpcHandler]]=None,interceptors:Optional[Sequence[Any]]=None,options:Optional[ChannelArgumentType]=None,maximum_concurrent_rpcs:Optional[int]=None,compression:Optional[grpc.Compression]=None,):"""Creates a Server with which RPCs can be serviced.    Args:      migration_thread_pool: A futures.ThreadPoolExecutor to be used by the        Server to execute non-AsyncIO RPC handlers for migration purpose.      handlers: An optional list of GenericRpcHandlers used for executing RPCs.        More handlers may be added by calling add_generic_rpc_handlers any time        before the server is started.      interceptors: An optional list of ServerInterceptor objects that observe        and optionally manipulate the incoming RPCs before handing them over to        handlers. The interceptors are given control in the order they are        specified. This is an EXPERIMENTAL API.      options: An optional list of key-value pairs (:term:`channel_arguments` in gRPC runtime)        to configure the channel.      maximum_concurrent_rpcs: The maximum number of concurrent RPCs this server        will service before returning RESOURCE_EXHAUSTED status, or None to        indicate no limit.      compression: An element of grpc.compression, e.g.        grpc.compression.Gzip. This compression algorithm will be used for the        lifetime of the server unless overridden by set_compression.    Returns:      A Server object.    """returnServer(migration_thread_pool,()ifhandlersisNoneelsehandlers,()ifinterceptorsisNoneelseinterceptors,()ifoptionsisNoneelseoptions,maximum_concurrent_rpcs,compression,)