For grpc/grpc#19159

c++_async_stream_client.cc

/*
*
* Copyright 2016, 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.
*
*/

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

#include <grpc++/grpc++.h>

#include "helloworld.grpc.pb.h"

using grpc::Channel;
using grpc::ClientAsyncReaderWriter;
using grpc::ClientContext;
using grpc::CompletionQueue;
using grpc::Status;
using helloworld::HelloRequest;
using helloworld::HelloReply;
using helloworld::Greeter;

// NOTE: This is a complex example for an asynchronous, bidirectional streaming
// client. For a simpler example, start with the
// greeter_client/greeter_async_client first.
class AsyncBidiGreeterClient {
    enum class Type {
        READ = 1,
        WRITE = 2,
        CONNECT = 3,
        WRITES_DONE = 4,
        FINISH = 5
    };

public:
    explicit AsyncBidiGreeterClient(std::shared_ptr<Channel> channel)
        : stub_(Greeter::NewStub(channel)) {
        grpc_thread_.reset(
            new std::thread(std::bind(&AsyncBidiGreeterClient::GrpcThread, this)));
        stream_ = stub_->AsyncSayHelloEx(&context_, &cq_,
            reinterpret_cast<void*>(Type::CONNECT));
    }

    ~AsyncBidiGreeterClient() {
        std::cout << "Shutting down client...." << std::endl;
        grpc::Status status;
        cq_.Shutdown();
        grpc_thread_->join();
    }

    // Similar to the async hello example in greeter_async_client but does not
    // wait for the response. Instead queues up a tag in the completion queue
    // that is notified when the server responds back (or when the stream is
    // closed). Returns false when the stream is requested to be closed.
    bool AsyncSayHello(const std::string& user) {
        if (user == "quit") {
            stream_->WritesDone(reinterpret_cast<void*>(Type::WRITES_DONE));
            return true;
        }

        // Data we are sending to the server.
        request_.set_name(user);

        // This is important: You can have at most one write or at most one read
        // at any given time. The throttling is performed by gRPC completion
        // queue. If you queue more than one write/read, the stream will crash.
        // Because this stream is bidirectional, you *can* have a single read
        // and a single write request queued for the same stream. Writes and reads
        // are independent of each other in terms of ordering/delivery.
        //std::cout << " ** Sending request: " << user << std::endl;
        stream_->Write(request_, reinterpret_cast<void*>(Type::WRITE));
        return true;
    }

private:
    void AsyncHelloRequestNextMessage() {

        // The tag is the link between our thread (main thread) and the completion
        // queue thread. The tag allows the completion queue to fan off
        // notification handlers for the specified read/write requests as they
        // are being processed by gRPC.
        stream_->Read(&response_, reinterpret_cast<void*>(Type::READ));
    }

    // Runs a gRPC completion-queue processing thread. Checks for 'Next' tag
    // and processes them until there are no more (or when the completion queue
    // is shutdown).
    void GrpcThread() {
        while (true) {
            void* got_tag;
            bool ok = false;
            // Block until the next result is available in the completion queue "cq".
            // The return value of Next should always be checked. This return value
            // tells us whether there is any kind of event or the cq_ is shutting
            // down.
            if (!cq_.Next(&got_tag, &ok)) {
                std::cerr << "Client stream closed. Quitting" << std::endl;
                break;
            }

            // It's important to process all tags even if the ok is false. One might
            // want to deallocate memory that has be reinterpret_cast'ed to void*
            // when the tag got initialized. For our example, we cast an int to a
            // void*, so we don't have extra memory management to take care of.
            if (ok) {
                //std::cout << std::endl << "**** Processing completion queue tag " << got_tag << std::endl;
                switch (static_cast<Type>(reinterpret_cast<long>(got_tag))) {
                case Type::READ:
                    std::cout << "Read a new message:" << response_.message() << std::endl;
                    break;
                case Type::WRITE:
                    std::cout << "Sent message :" << request_.name() << std::endl;
                    AsyncHelloRequestNextMessage();
                    break;
                case Type::CONNECT:
                    std::cout << "Server connected." << std::endl;
                    break;
                case Type::WRITES_DONE:
                    std::cout << "writesdone sent,sleeping 5s" << std::endl;
                    stream_->Finish(&finish_status_, reinterpret_cast<void*>(Type::FINISH));
                    break;
                case Type::FINISH:
                    std::cout << "Client finish status:" << finish_status_.error_code() << ", msg:" << finish_status_.error_message() << std::endl;
                    //context_.TryCancel();
                    cq_.Shutdown();
                    break;
                default:
                    std::cerr << "Unexpected tag " << got_tag << std::endl;
                    assert(false);
                }
            }
        }
    }

    // Context for the client. It could be used to convey extra information to
    // the server and/or tweak certain RPC behaviors.
    ClientContext context_;

    // The producer-consumer queue we use to communicate asynchronously with the
    // gRPC runtime.
    CompletionQueue cq_;

    // Out of the passed in Channel comes the stub, stored here, our view of the
    // server's exposed services.
    std::unique_ptr<Greeter::Stub> stub_;

    // The bidirectional, asynchronous stream for sending/receiving messages.
    std::unique_ptr<ClientAsyncReaderWriter<HelloRequest, HelloReply>> stream_;

    // Allocated protobuf that holds the response. In real clients and servers,
    // the memory management would a bit more complex as the thread that fills
    // in the response should take care of concurrency as well as memory
    // management.
    HelloRequest request_;
    HelloReply response_;

    // Thread that notifies the gRPC completion queue tags.
    std::unique_ptr<std::thread> grpc_thread_;

    // Finish status when the client is done with the stream.
    grpc::Status finish_status_ = grpc::Status::OK;
};

int main(int argc, char** argv) {
    AsyncBidiGreeterClient greeter(grpc::CreateChannel(
        "localhost:50051", grpc::InsecureChannelCredentials()));

    std::string text;
    while (true) {
        //std::cout << "Enter text (type quit to end): ";
        std::cin >> text;

        // Async RPC call that sends a message and awaits a response.
        if (!greeter.AsyncSayHello(text)) {
            std::cout << "Quitting." << std::endl;
            break;
        }
    }
    return 0;
}

c++_async_stream_server.cc

/*
 *
 * Copyright 2015 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.
 *
 */

#include <memory>
#include <iostream>
#include <string>
#include <thread>
#include <vector>
#include <random>
#include <atomic>

#include <grpc++/grpc++.h>
#include <grpc/support/log.h>

#include "helloworld.grpc.pb.h"

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

int g_thread_num = 1;
int g_cq_num = 1;
int g_pool = 1;
int g_port = 50051;

std::atomic<void*>**    g_instance_pool = nullptr;


class CallDataBase {
public:

    CallDataBase(Greeter::AsyncService* service, ServerCompletionQueue* cq) : service_(service), cq_(cq){
    }

    virtual void Proceed(bool ok) = 0;

protected:

  // The means of communication with the gRPC runtime for an asynchronous
  // server.
  Greeter::AsyncService* service_;
  // The producer-consumer queue where for asynchronous server notifications.
  ServerCompletionQueue* cq_;

  // Context for the rpc, allowing to tweak aspects of it such as the use
  // of compression, authentication, as well as to send metadata back to the
  // client.
  ServerContext ctx_;

  // What we get from the client.
  HelloRequest request_;
  // What we send back to the client.
  HelloReply reply_;


};

class CallDataUnary : CallDataBase {
 public:
  // Take in the "service" instance (in this case representing an asynchronous
  // server) and the completion queue "cq" used for asynchronous communication
  // with the gRPC runtime.
  CallDataUnary(Greeter::AsyncService* service, ServerCompletionQueue* cq) : CallDataBase(service,cq),responder_(&ctx_), status_(CREATE) {
    // Invoke the serving logic right away.

    // As part of the initial CREATE state, we *request* that the system
    // start processing SayHello requests. In this request, "this" acts are
    // the tag uniquely identifying the request (so that different CallDataUnary
    // instances can serve different requests concurrently), in this case
    // the memory address of this CallDataUnary instance.

      service_->RequestSayHello(&ctx_, &request_, &responder_, cq_, cq_, (void*)this);
      status_ = PROCESS;
  }

  void Proceed(bool ok) {

     if (status_ == PROCESS) {
      // Spawn a new CallDataUnary instance to serve new clients while we process
      // the one for this CallDataUnary. The instance will deallocate itself as
      // part of its FINISH state.

      new CallDataUnary(service_, cq_);

      // The actual processing.
      std::string prefix("Hello ");
      reply_.set_message(prefix + request_.name());

      // And we are done! Let the gRPC runtime know we've finished, using the
      // memory address of this instance as the uniquely identifying tag for
      // the event.
      status_ = FINISH;
      responder_.Finish(reply_, Status::OK, (void*)this);
    } else {
      GPR_ASSERT(status_ == FINISH);
      // Once in the FINISH state, deallocate ourselves (CallDataUnary).
      delete this;
    }
  }

 private:

  // The means to get back to the client.
  ServerAsyncResponseWriter<HelloReply> responder_;

  // Let's implement a tiny state machine with the following states.
  enum CallStatus { CREATE, PROCESS, FINISH };
  CallStatus status_;  // The current serving state.
};


class CallDataBidi : CallDataBase {

 public:

  // Take in the "service" instance (in this case representing an asynchronous
  // server) and the completion queue "cq" used for asynchronous communication
  // with the gRPC runtime.
  CallDataBidi(Greeter::AsyncService* service, ServerCompletionQueue* cq) : CallDataBase(service,cq),rw_(&ctx_){
    // Invoke the serving logic right away.

    status_ = BidiStatus::CONNECT;

    ctx_.AsyncNotifyWhenDone((void*)this);
    service_->RequestSayHelloEx(&ctx_, &rw_, cq_, cq_, (void*)this);
  }

  void Proceed(bool ok) {

      std::unique_lock<std::mutex> _wlock(this->m_mutex);

    switch (status_) {
    case BidiStatus::READ:

        //Meaning client said it wants to end the stream either by a 'writedone' or 'finish' call.
        if (!ok) {
            std::cout << "thread:" << std::this_thread::get_id() << " tag:" << this << " CQ returned false." << std::endl;
            Status _st(StatusCode::OUT_OF_RANGE,"test error msg");
            rw_.Finish(_st,(void*)this);
            status_ = BidiStatus::DONE;
            std::cout << "thread:" << std::this_thread::get_id() << " tag:" << this << " after call Finish(), cancelled:" << this->ctx_.IsCancelled() << std::endl;
            break;
        }

        std::cout << "thread:" << std::this_thread::get_id() << " tag:" << this << " Read a new message:" << request_.name() << std::endl;

        reply_.set_message("arthur");
        rw_.Write(reply_, (void*)this);

        status_ = BidiStatus::WRITE;
        break;

    case BidiStatus::WRITE:
        std::cout << "thread:" << std::this_thread::get_id() << " tag:" << this << " Written a message:" << reply_.message() << std::endl;
        rw_.Read(&request_, (void*)this);
        status_ = BidiStatus::READ;
        break;

    case BidiStatus::CONNECT:
        std::cout << "thread:" << std::this_thread::get_id() << " tag:" << this << " connected:" << std::endl;
        new CallDataBidi(service_, cq_);
        rw_.Read(&request_, (void*)this);
        status_ = BidiStatus::READ;
        break;

    case BidiStatus::DONE:
        std::cout << "thread:" << std::this_thread::get_id() << " tag:" << this
                << " Server done, cancelled:" << this->ctx_.IsCancelled() << std::endl;
        status_ = BidiStatus::FINISH;
        break;

    case BidiStatus::FINISH:
        std::cout << "thread:" << std::this_thread::get_id() <<  "tag:" << this << " Server finish, cancelled:" << this->ctx_.IsCancelled() << std::endl;
        _wlock.unlock();
        delete this;
        break;

    default:
        std::cerr << "Unexpected tag " << int(status_) << std::endl;
        assert(false);
    }
  }

 private:

  // The means to get back to the client.
  ServerAsyncReaderWriter<HelloReply,HelloRequest>    rw_;

  // Let's implement a tiny state machine with the following states.
  enum class BidiStatus { READ = 1, WRITE = 2, CONNECT = 3, DONE = 4, FINISH = 5 };
  BidiStatus status_;

  std::mutex    m_mutex;
};


class ServerImpl final {
 public:
  ~ServerImpl() {
    server_->Shutdown();
    // Always shutdown the completion queue after the server.
    for (const auto& _cq : m_cq)
        _cq->Shutdown();
  }

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

    ServerBuilder builder;
    // Listen on the given address without any authentication mechanism.
    builder.AddListeningPort(server_address, grpc::InsecureServerCredentials());
    // Register "service_" as the instance through which we'll communicate with
    // clients. In this case it corresponds to an *asynchronous* service.
    builder.RegisterService(&service_);
    // Get hold of the completion queue used for the asynchronous communication
    // with the gRPC runtime.

    for (int i = 0; i < g_cq_num; ++i) {
        //cq_ = builder.AddCompletionQueue();
        m_cq.emplace_back(builder.AddCompletionQueue());
    }

    // Finally assemble the server.
    server_ = builder.BuildAndStart();
    std::cout << "Server listening on " << server_address << std::endl;

    // Proceed to the server's main loop.
    std::vector<std::thread*> _vec_threads;

    for (int i = 0; i < g_thread_num; ++i) {
        int _cq_idx = i % g_cq_num;
        for (int j = 0; j < g_pool; ++j) {
            new CallDataUnary(&service_, m_cq[_cq_idx].get());
            new CallDataBidi(&service_, m_cq[_cq_idx].get());
        }

        _vec_threads.emplace_back(new std::thread(&ServerImpl::HandleRpcs, this, _cq_idx));
    }

    std::cout << g_thread_num << " working aysnc threads spawned" << std::endl;

    for (const auto& _t : _vec_threads)
        _t->join();
  }

 private:
  // Class encompasing the state and logic needed to serve a request.

  // This can be run in multiple threads if needed.
  void HandleRpcs(int cq_idx) {
    // Spawn a new CallDataUnary instance to serve new clients.
    void* tag;  // uniquely identifies a request.
    bool ok;
    while (true) {
      // Block waiting to read the next event from the completion queue. The
      // event is uniquely identified by its tag, which in this case is the
      // memory address of a CallDataUnary instance.
      // The return value of Next should always be checked. This return value
      // tells us whether there is any kind of event or cq_ is shutting down.
      //GPR_ASSERT(cq_->Next(&tag, &ok));
      GPR_ASSERT(m_cq[cq_idx]->Next(&tag, &ok));

      CallDataBase* _p_ins = (CallDataBase*)tag;
      _p_ins->Proceed(ok);
    }
  }

  std::vector<std::unique_ptr<ServerCompletionQueue>>  m_cq;

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

const char* ParseCmdPara( char* argv,const char* para) {
    auto p_target = std::strstr(argv,para);
    if (p_target == nullptr) {
        printf("para error argv[%s] should be %s \n",argv,para);
        return nullptr;
    }
    p_target += std::strlen(para);
    return p_target;
}

int main(int argc, char** argv) {
  if (argc != 5) {
      std::cout << "Usage:./program --thread=xx --cq=xx --pool=xx --port=xx";
      return 0;
  }

  g_thread_num = std::atoi(ParseCmdPara(argv[1],"--thread="));
  g_cq_num = std::atoi(ParseCmdPara(argv[2],"--cq="));
  g_pool = std::atoi(ParseCmdPara(argv[3],"--pool="));
  g_port = std::atoi(ParseCmdPara(argv[4],"--port="));

  ServerImpl server;
  server.Run();

  return 0;
}

thanks bro，it helps me a lot.