rest_rpc/io_service_pool.h

#ifndef REST_RPC_IO_SERVICE_POOL_H_
#define REST_RPC_IO_SERVICE_POOL_H_

#include <boost/asio.hpp>
#include <vector>
#include <memory>
#include <boost/noncopyable.hpp>

namespace rest_rpc {
namespace rpc_service {
class io_service_pool : private boost::noncopyable {
 public:
  explicit io_service_pool(std::size_t pool_size) : next_io_service_(0) {
    if (pool_size == 0) throw std::runtime_error("io_service_pool size is 0");

    for (std::size_t i = 0; i < pool_size; ++i) {
      io_service_ptr io_service(new boost::asio::io_service);
      work_ptr work(new boost::asio::io_service::work(*io_service));
      io_services_.push_back(io_service);
      work_.push_back(work);
    }
  }

  void run() {
    std::vector<std::shared_ptr<std::thread>> threads;
    for (std::size_t i = 0; i < io_services_.size(); ++i) {
      threads.emplace_back(
          std::make_shared<std::thread>([](io_service_ptr svr) { svr->run(); }, io_services_[i]));
    }

    for (std::size_t i = 0; i < threads.size(); ++i) threads[i]->join();
  }

  void stop() {
    for (std::size_t i = 0; i < io_services_.size(); ++i) {
      io_services_[i]->stop();
    }
  }

  boost::asio::io_service& get_io_service() {
    boost::asio::io_service& io_service = *io_services_[next_io_service_];
    ++next_io_service_;
    if (next_io_service_ == io_services_.size()) next_io_service_ = 0;
    return io_service;
  }

 private:
  typedef std::shared_ptr<boost::asio::io_service> io_service_ptr;
  typedef std::shared_ptr<boost::asio::io_service::work> work_ptr;

  /// The pool of io_services.
  std::vector<io_service_ptr> io_services_;

  /// The work that keeps the io_services running.
  std::vector<work_ptr> work_;

  /// The next io_service to use for a connection.
  std::size_t next_io_service_;
};
}  // namespace rpc_service
}  // namespace rest_rpc

#endif  // REST_RPC_IO_SERVICE_POOL_H_