cpp/helloworld/greeter_async_server.cc

/*
 *
 * 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.
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 * 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
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 * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
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 */

#include <memory>
#include <iostream>
#include <string>
#include <thread>

#include <grpc/grpc.h>
#include <grpc/support/log.h>
#include <grpc++/completion_queue.h>
#include <grpc++/server.h>
#include <grpc++/server_builder.h>
#include <grpc++/server_context.h>
#include <grpc++/server_credentials.h>
#include "helloworld.grpc.pb.h"

using grpc::Server;
using grpc::ServerAsyncResponseWriter;
using grpc::ServerBuilder;
using grpc::ServerContext;
using grpc::ServerCompletionQueue;
using grpc::Status;
using helloworld::HelloRequest;
using helloworld::HelloReply;
using helloworld::Greeter;

class ServerImpl final {
 public:
  ~ServerImpl() {
    server_->Shutdown();
    cq_->Shutdown();
  }

  // There is no shutdown handling in this code.
  void Run() {
    std::string server_address("0.0.0.0:50051");

    ServerBuilder builder;
    builder.AddListeningPort(server_address, grpc::InsecureServerCredentials());
    builder.RegisterAsyncService(&service_);
    cq_ = builder.AddCompletionQueue();
    server_ = builder.BuildAndStart();
    std::cout << "Server listening on " << server_address << std::endl;

    HandleRpcs();
  }

 private:
  class CallData {
   public:
    CallData(Greeter::AsyncService* service, ServerCompletionQueue* cq)
        : service_(service), cq_(cq), responder_(&ctx_), status_(CREATE) {
      Proceed();
    }

    void Proceed() {
      if (status_ == CREATE) {
        service_->RequestSayHello(&ctx_, &request_, &responder_, cq_, cq_,
                                  this);
        status_ = PROCESS;
      } else if (status_ == PROCESS) {
        new CallData(service_, cq_);
        std::string prefix("Hello ");
        reply_.set_message(prefix + request_.name());
        responder_.Finish(reply_, Status::OK, this);
        status_ = FINISH;
      } else {
        delete this;
      }
    }

   private:
    Greeter::AsyncService* service_;
    ServerCompletionQueue* cq_;
    ServerContext ctx_;
    HelloRequest request_;
    HelloReply reply_;
    ServerAsyncResponseWriter<HelloReply> responder_;
    enum CallStatus { CREATE, PROCESS, FINISH };
    CallStatus status_;
  };

  // This can be run in multiple threads if needed.
  void HandleRpcs() {
    new CallData(&service_, cq_.get());
    void* tag;
    bool ok;
    while (true) {
      cq_->Next(&tag, &ok);
      GPR_ASSERT(ok);
      static_cast<CallData*>(tag)->Proceed();
    }
  }

  std::unique_ptr<ServerCompletionQueue> cq_;
  Greeter::AsyncService service_;
  std::unique_ptr<Server> server_;
};

int main(int argc, char** argv) {
  ServerImpl server;
  server.Run();

  return 0;
}