text: /*
   *
   * Copyright 2015, Google Inc.
   * All rights reserved.
   *
   * Redistribution and use in source and binary forms, with or without
   * modification, are permitted provided that the following conditions are
   * met:
   *
   *     * Redistributions of source code must retain the above copyright
   * notice, this list of conditions and the following disclaimer.
   *     * Redistributions in binary form must reproduce the above
   * copyright notice, this list of conditions and the following disclaimer
   * in the documentation and/or other materials provided with the
   * distribution.
   *     * Neither the name of Google Inc. nor the names of its
   * contributors may be used to endorse or promote products derived from
   * this software without specific prior written permission.
   *
   * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
   * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
   * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
   * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
   * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
   * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
   * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
   * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
   * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
   * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
   * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
   *
   */
  
  #ifndef GRPCXX_ASYNC_UNARY_CALL_H
  #define GRPCXX_ASYNC_UNARY_CALL_H
  
  #include <grpc++/channel_interface.h>
  #include <grpc++/client_context.h>
  #include <grpc++/completion_queue.h>
  #include <grpc++/server_context.h>
  #include <grpc++/impl/call.h>
  #include <grpc++/impl/service_type.h>
  #include <grpc++/status.h>
  #include <grpc/support/log.h>
  
  namespace grpc {
  template <class R>
  class ClientAsyncResponseReader GRPC_FINAL {
   public:
    ClientAsyncResponseReader(ChannelInterface* channel, CompletionQueue* cq,
                              const RpcMethod& method, ClientContext* context,
                              const grpc::protobuf::Message& request, void* tag)
        : context_(context), call_(channel->CreateCall(method, context, cq)) {
      init_buf_.Reset(tag);
      init_buf_.AddSendInitialMetadata(&context->send_initial_metadata_);
      init_buf_.AddSendMessage(request);
      init_buf_.AddClientSendClose();
      call_.PerformOps(&init_buf_);
    }
  
    void ReadInitialMetadata(void* tag) {
      GPR_ASSERT(!context_->initial_metadata_received_);
  
      meta_buf_.Reset(tag);
      meta_buf_.AddRecvInitialMetadata(context_);
      call_.PerformOps(&meta_buf_);
    }
  
    void Finish(R* msg, Status* status, void* tag) {
      finish_buf_.Reset(tag);
      if (!context_->initial_metadata_received_) {
        finish_buf_.AddRecvInitialMetadata(context_);
      }
      finish_buf_.AddRecvMessage(msg);
      finish_buf_.AddClientRecvStatus(context_, status);
      call_.PerformOps(&finish_buf_);
    }
  
   private:
    ClientContext* context_;
    Call call_;
    CallOpBuffer init_buf_;
    CallOpBuffer meta_buf_;
    CallOpBuffer finish_buf_;
  };
  
  template <class W>
  class ServerAsyncResponseWriter GRPC_FINAL
      : public ServerAsyncStreamingInterface {
   public:
    explicit ServerAsyncResponseWriter(ServerContext* ctx)
        : call_(nullptr, nullptr, nullptr), ctx_(ctx) {}
  
    void SendInitialMetadata(void* tag) GRPC_OVERRIDE {
      GPR_ASSERT(!ctx_->sent_initial_metadata_);
  
      meta_buf_.Reset(tag);
      meta_buf_.AddSendInitialMetadata(&ctx_->initial_metadata_);
      ctx_->sent_initial_metadata_ = true;
      call_.PerformOps(&meta_buf_);
    }
  
    void Finish(const W& msg, const Status& status, void* tag) {
      finish_buf_.Reset(tag);
      if (!ctx_->sent_initial_metadata_) {
        finish_buf_.AddSendInitialMetadata(&ctx_->initial_metadata_);
        ctx_->sent_initial_metadata_ = true;
      }
      // The response is dropped if the status is not OK.
      if (status.IsOk()) {
        finish_buf_.AddSendMessage(msg);
      }
      finish_buf_.AddServerSendStatus(&ctx_->trailing_metadata_, status);
      call_.PerformOps(&finish_buf_);
    }
  
    void FinishWithError(const Status& status, void* tag) {
      GPR_ASSERT(!status.IsOk());
      finish_buf_.Reset(tag);
      if (!ctx_->sent_initial_metadata_) {
        finish_buf_.AddSendInitialMetadata(&ctx_->initial_metadata_);
        ctx_->sent_initial_metadata_ = true;
      }
      finish_buf_.AddServerSendStatus(&ctx_->trailing_metadata_, status);
      call_.PerformOps(&finish_buf_);
    }
  
   private:
    void BindCall(Call* call) GRPC_OVERRIDE { call_ = *call; }
  
    Call call_;
    ServerContext* ctx_;
    CallOpBuffer meta_buf_;
    CallOpBuffer finish_buf_;
  };
  
  }  // namespace grpc
  
  #endif  // GRPCXX_ASYNC_UNARY_CALL_H
  