diff options
Diffstat (limited to '3rdparty/asio/src/examples/cpp03/fork/process_per_connection.cpp')
-rw-r--r-- | 3rdparty/asio/src/examples/cpp03/fork/process_per_connection.cpp | 160 |
1 files changed, 160 insertions, 0 deletions
diff --git a/3rdparty/asio/src/examples/cpp03/fork/process_per_connection.cpp b/3rdparty/asio/src/examples/cpp03/fork/process_per_connection.cpp new file mode 100644 index 00000000000..483147e9552 --- /dev/null +++ b/3rdparty/asio/src/examples/cpp03/fork/process_per_connection.cpp @@ -0,0 +1,160 @@ +// +// process_per_connection.cpp +// ~~~~~~~~~~~~~~~~~~~~~~~~~~ +// +// Copyright (c) 2003-2016 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 <asio/io_context.hpp> +#include <asio/ip/tcp.hpp> +#include <asio/signal_set.hpp> +#include <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 asio::ip::tcp; + +class server +{ +public: + server(asio::io_context& io_context, unsigned short port) + : io_context_(io_context), + signal_(io_context, SIGCHLD), + acceptor_(io_context, tcp::endpoint(tcp::v4(), port)), + socket_(io_context) + { + 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 asio::error_code& ec) + { + if (!ec) + { + // Inform the io_context that we are about to fork. The io_context cleans + // up any internal resources, such as threads, that may interfere with + // forking. + io_context_.notify_fork(asio::io_context::fork_prepare); + + if (fork() == 0) + { + // Inform the io_context that the fork is finished and that this is the + // child process. The io_context uses this opportunity to create any + // internal file descriptors that must be private to the new process. + io_context_.notify_fork(asio::io_context::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_context that the fork is finished (or failed) and that + // this is the parent process. The io_context uses this opportunity to + // recreate any internal resources that were cleaned up during + // preparation for the fork. + io_context_.notify_fork(asio::io_context::fork_parent); + + socket_.close(); + start_accept(); + } + } + else + { + std::cerr << "Accept error: " << ec.message() << std::endl; + start_accept(); + } + } + + void start_read() + { + socket_.async_read_some(asio::buffer(data_), + boost::bind(&server::handle_read, this, _1, _2)); + } + + void handle_read(const asio::error_code& ec, std::size_t length) + { + if (!ec) + start_write(length); + } + + void start_write(std::size_t length) + { + asio::async_write(socket_, asio::buffer(data_, length), + boost::bind(&server::handle_write, this, _1)); + } + + void handle_write(const asio::error_code& ec) + { + if (!ec) + start_read(); + } + + asio::io_context& io_context_; + 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; + } + + asio::io_context io_context; + + using namespace std; // For atoi. + server s(io_context, atoi(argv[1])); + + io_context.run(); + } + catch (std::exception& e) + { + std::cerr << "Exception: " << e.what() << std::endl; + } +} |