| // |
| // process_per_connection.cpp |
| // ~~~~~~~~~~~~~~~~~~~~~~~~~~ |
| // |
| // Copyright (c) 2003-2015 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 <boost/asio/io_service.hpp> |
| #include <boost/asio/ip/tcp.hpp> |
| #include <boost/asio/signal_set.hpp> |
| #include <boost/asio/write.hpp> |
| #include <boost/array.hpp> |
| #include <boost/bind.hpp> |
| #include <cstdlib> |
| #include <iostream> |
| #include <sys/types.h> |
| #include <sys/wait.h> |
| #include <unistd.h> |
| |
| using boost::asio::ip::tcp; |
| |
| class server |
| { |
| public: |
| server(boost::asio::io_service& io_service, unsigned short port) |
| : io_service_(io_service), |
| signal_(io_service, SIGCHLD), |
| acceptor_(io_service, tcp::endpoint(tcp::v4(), port)), |
| socket_(io_service) |
| { |
| start_signal_wait(); |
| start_accept(); |
| } |
| |
| private: |
| void start_signal_wait() |
| { |
| signal_.async_wait(boost::bind(&server::handle_signal_wait, this)); |
| } |
| |
| void handle_signal_wait() |
| { |
| // Only the parent process should check for this signal. We can determine |
| // whether we are in the parent by checking if the acceptor is still open. |
| if (acceptor_.is_open()) |
| { |
| // Reap completed child processes so that we don't end up with zombies. |
| int status = 0; |
| while (waitpid(-1, &status, WNOHANG) > 0) {} |
| |
| start_signal_wait(); |
| } |
| } |
| |
| void start_accept() |
| { |
| acceptor_.async_accept(socket_, |
| boost::bind(&server::handle_accept, this, _1)); |
| } |
| |
| void handle_accept(const boost::system::error_code& ec) |
| { |
| if (!ec) |
| { |
| // Inform the io_service that we are about to fork. The io_service cleans |
| // up any internal resources, such as threads, that may interfere with |
| // forking. |
| io_service_.notify_fork(boost::asio::io_service::fork_prepare); |
| |
| if (fork() == 0) |
| { |
| // Inform the io_service that the fork is finished and that this is the |
| // child process. The io_service uses this opportunity to create any |
| // internal file descriptors that must be private to the new process. |
| io_service_.notify_fork(boost::asio::io_service::fork_child); |
| |
| // The child won't be accepting new connections, so we can close the |
| // acceptor. It remains open in the parent. |
| acceptor_.close(); |
| |
| // The child process is not interested in processing the SIGCHLD signal. |
| signal_.cancel(); |
| |
| start_read(); |
| } |
| else |
| { |
| // Inform the io_service that the fork is finished (or failed) and that |
| // this is the parent process. The io_service uses this opportunity to |
| // recreate any internal resources that were cleaned up during |
| // preparation for the fork. |
| io_service_.notify_fork(boost::asio::io_service::fork_parent); |
| |
| socket_.close(); |
| start_accept(); |
| } |
| } |
| else |
| { |
| std::cerr << "Accept error: " << ec.message() << std::endl; |
| start_accept(); |
| } |
| } |
| |
| void start_read() |
| { |
| socket_.async_read_some(boost::asio::buffer(data_), |
| boost::bind(&server::handle_read, this, _1, _2)); |
| } |
| |
| void handle_read(const boost::system::error_code& ec, std::size_t length) |
| { |
| if (!ec) |
| start_write(length); |
| } |
| |
| void start_write(std::size_t length) |
| { |
| boost::asio::async_write(socket_, boost::asio::buffer(data_, length), |
| boost::bind(&server::handle_write, this, _1)); |
| } |
| |
| void handle_write(const boost::system::error_code& ec) |
| { |
| if (!ec) |
| start_read(); |
| } |
| |
| boost::asio::io_service& io_service_; |
| boost::asio::signal_set signal_; |
| tcp::acceptor acceptor_; |
| tcp::socket socket_; |
| boost::array<char, 1024> data_; |
| }; |
| |
| int main(int argc, char* argv[]) |
| { |
| try |
| { |
| if (argc != 2) |
| { |
| std::cerr << "Usage: process_per_connection <port>\n"; |
| return 1; |
| } |
| |
| boost::asio::io_service io_service; |
| |
| using namespace std; // For atoi. |
| server s(io_service, atoi(argv[1])); |
| |
| io_service.run(); |
| } |
| catch (std::exception& e) |
| { |
| std::cerr << "Exception: " << e.what() << std::endl; |
| } |
| } |