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The C based gRPC (C++, Python, Ruby, Objective-C, PHP, C#)
https://grpc.io/
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103 lines
4.0 KiB
103 lines
4.0 KiB
/* |
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* |
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* Copyright 2015 gRPC authors. |
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* |
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* Licensed under the Apache License, Version 2.0 (the "License"); |
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* you may not use this file except in compliance with the License. |
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* You may obtain a copy of the License at |
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* |
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* http://www.apache.org/licenses/LICENSE-2.0 |
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* |
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* Unless required by applicable law or agreed to in writing, software |
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* distributed under the License is distributed on an "AS IS" BASIS, |
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. |
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* See the License for the specific language governing permissions and |
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* limitations under the License. |
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* |
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*/ |
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#ifndef GRPCPP_IMPL_CLIENT_UNARY_CALL_H |
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#define GRPCPP_IMPL_CLIENT_UNARY_CALL_H |
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#include <grpcpp/impl/call.h> |
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#include <grpcpp/impl/call_op_set.h> |
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#include <grpcpp/impl/channel_interface.h> |
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#include <grpcpp/impl/codegen/core_codegen_interface.h> |
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#include <grpcpp/support/config.h> |
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#include <grpcpp/support/status.h> |
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namespace grpc { |
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class ClientContext; |
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namespace internal { |
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class RpcMethod; |
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/// Wrapper that performs a blocking unary call. May optionally specify the base |
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/// class of the Request and Response so that the internal calls and structures |
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/// below this may be based on those base classes and thus achieve code reuse |
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/// across different RPCs (e.g., for protobuf, MessageLite would be a base |
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/// class). |
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template <class InputMessage, class OutputMessage, |
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class BaseInputMessage = InputMessage, |
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class BaseOutputMessage = OutputMessage> |
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Status BlockingUnaryCall(ChannelInterface* channel, const RpcMethod& method, |
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grpc::ClientContext* context, |
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const InputMessage& request, OutputMessage* result) { |
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static_assert(std::is_base_of<BaseInputMessage, InputMessage>::value, |
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"Invalid input message specification"); |
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static_assert(std::is_base_of<BaseOutputMessage, OutputMessage>::value, |
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"Invalid output message specification"); |
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return BlockingUnaryCallImpl<BaseInputMessage, BaseOutputMessage>( |
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channel, method, context, request, result) |
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.status(); |
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} |
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template <class InputMessage, class OutputMessage> |
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class BlockingUnaryCallImpl { |
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public: |
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BlockingUnaryCallImpl(ChannelInterface* channel, const RpcMethod& method, |
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grpc::ClientContext* context, |
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const InputMessage& request, OutputMessage* result) { |
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grpc::CompletionQueue cq(grpc_completion_queue_attributes{ |
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GRPC_CQ_CURRENT_VERSION, GRPC_CQ_PLUCK, GRPC_CQ_DEFAULT_POLLING, |
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nullptr}); // Pluckable completion queue |
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grpc::internal::Call call(channel->CreateCall(method, context, &cq)); |
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CallOpSet<CallOpSendInitialMetadata, CallOpSendMessage, |
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CallOpRecvInitialMetadata, CallOpRecvMessage<OutputMessage>, |
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CallOpClientSendClose, CallOpClientRecvStatus> |
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ops; |
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status_ = ops.SendMessagePtr(&request); |
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if (!status_.ok()) { |
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return; |
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} |
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ops.SendInitialMetadata(&context->send_initial_metadata_, |
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context->initial_metadata_flags()); |
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ops.RecvInitialMetadata(context); |
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ops.RecvMessage(result); |
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ops.AllowNoMessage(); |
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ops.ClientSendClose(); |
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ops.ClientRecvStatus(context, &status_); |
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call.PerformOps(&ops); |
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cq.Pluck(&ops); |
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// Some of the ops might fail. If the ops fail in the core layer, status |
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// would reflect the error. But, if the ops fail in the C++ layer, the |
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// status would still be the same as the one returned by gRPC Core. This can |
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// happen if deserialization of the message fails. |
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// TODO(yashykt): If deserialization fails, but the status received is OK, |
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// then it might be a good idea to change the status to something better |
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// than StatusCode::UNIMPLEMENTED to reflect this. |
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if (!ops.got_message && status_.ok()) { |
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status_ = Status(StatusCode::UNIMPLEMENTED, |
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"No message returned for unary request"); |
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} |
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} |
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Status status() { return status_; } |
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private: |
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Status status_; |
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}; |
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} // namespace internal |
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} // namespace grpc |
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#endif // GRPCPP_IMPL_CLIENT_UNARY_CALL_H
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