doc/html/boost_asio/example/cpp03/http/server2/io_context_pool.cpp
//
// io_context_pool.cpp
// ~~~~~~~~~~~~~~~~~~~
//
// Copyright (c) 2003-2023 Christopher M. Kohlhoff (chris at kohlhoff dot com)
//
// Distributed under the Boost Software License, Version 1.0. (See accompanying
// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
//
#include "server.hpp"
#include <stdexcept>
#include <boost/thread/thread.hpp>
#include <boost/bind/bind.hpp>
#include <boost/shared_ptr.hpp>
namespace http {
namespace server2 {
io_context_pool::io_context_pool(std::size_t pool_size)
: next_io_context_(0)
{
if (pool_size == 0)
throw std::runtime_error("io_context_pool size is 0");
// Give all the io_contexts work to do so that their run() functions will not
// exit until they are explicitly stopped.
for (std::size_t i = 0; i < pool_size; ++i)
{
io_context_ptr io_context(new boost::asio::io_context);
io_contexts_.push_back(io_context);
work_.push_back(boost::asio::make_work_guard(*io_context));
}
}
void io_context_pool::run()
{
// Create a pool of threads to run all of the io_contexts.
std::vector<boost::shared_ptr<boost::thread> > threads;
for (std::size_t i = 0; i < io_contexts_.size(); ++i)
{
boost::shared_ptr<boost::thread> thread(new boost::thread(
boost::bind(&boost::asio::io_context::run, io_contexts_[i])));
threads.push_back(thread);
}
// Wait for all threads in the pool to exit.
for (std::size_t i = 0; i < threads.size(); ++i)
threads[i]->join();
}
void io_context_pool::stop()
{
// Explicitly stop all io_contexts.
for (std::size_t i = 0; i < io_contexts_.size(); ++i)
io_contexts_[i]->stop();
}
boost::asio::io_context& io_context_pool::get_io_context()
{
// Use a round-robin scheme to choose the next io_context to use.
boost::asio::io_context& io_context = *io_contexts_[next_io_context_];
++next_io_context_;
if (next_io_context_ == io_contexts_.size())
next_io_context_ = 0;
return io_context;
}
} // namespace server2
} // namespace http