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This is an example of using Boost's Asynchronous I/O Library as a simple web server application. The codes are courtesy of Alex Ott. The implementations are at test-mcmt.cpp while the headers are defined at common.h. A more indepth explanation is given in the Alex Ott's website.
test-mcmt.cpp
/** * @file test-mcmt.cpp * @author Alex Ott <alexott@gmail.com> * * @brief Impelements many threads - many connections strategy of connections handling. * All input/output is async. Server use several io_service objects to scale to work on * multiprocessor/multicore systems * * */#include "common.h"#include <deque>typedef std::deque<io_service_ptr> ios_deque; /** * Connection class, implementing async input/output * */class connection : public boost::enable_shared_from_this<connection> { public: typedef boost::shared_ptr<connection> pointer; /** * Create new connection * * @param io_service io_service in which this connection will work * * @return pointer to newly allocated object */ static pointer create(ba::io_service& io_service) { return pointer(new connection(io_service)); } /** * Return socket, associated with this connection. This socket used in accept operation * * * @return reference to socket */ ba::ip::tcp::socket& socket() { return socket_; } /** * Start input/output chain with reading of headers from browser * */ void start() { // start reading of headers from browser boost::asio::async_read_until(socket_, buf, boost::regex("\r\n\r\n"), boost::bind(&connection::handle_read, shared_from_this(), ba::placeholders::error, ba::placeholders::bytes_transferred)); } private: /** * Initialize connection * * @param io_service * * @return */ connection(ba::io_service& io_service) : socket_(io_service) { } /** * Called when data written to browser * * @param error object, containing information about errors * @param bytes_transferred number of transferred bytes */ void handle_write(const boost::system::error_code& error, size_t bytes_transferred) { } /** * Called when data readed from browser * * @param error object, containing information about errors * @param bytes_transferred number of transferred bytes */ void handle_read(const boost::system::error_code& error, size_t bytes_transferred) { ba::async_write(socket_, ba::buffer(message_), boost::bind(&connection::handle_write, shared_from_this(), ba::placeholders::error, ba::placeholders::bytes_transferred)); } ba::ip::tcp::socket socket_; /**< socket, associated with browser */ boost::asio::streambuf buf; /**< buffer for request data */ static std::string message_; /**< data, that we'll return to browser */ }; std::string connection::message_="HTTP/1.0 200 OK\r\nContent-Type: text/html\r\n\r\n" "<html><head><title>test</title>" "</head><body><h1>Test</h1><p>This is a test!</p></body></html>"; /** * Server class * */class server { public: /** * Initialize all needed data * * @param io_service reference to io_service * @param port port to listen on, by default - 10001 */ server(const ios_deque& io_services, int port=10001) : io_services_(io_services), acceptor_(*io_services.front(), ba::ip::tcp::endpoint(ba::ip::tcp::v4(), port)) { start_accept(); } private: /** * start connection accepting in async mode * */ void start_accept() { // select next io_service object io_services_.push_back(io_services_.front()); io_services_.pop_front(); // create new connection connection::pointer new_connection = connection::create(*io_services_.front()); // start acceptor in async mode acceptor_.async_accept(new_connection->socket(), boost::bind(&server::handle_accept, this, new_connection, ba::placeholders::error)); } /** * Run when new connection is accepted * * @param new_connection accepted connection * @param error reference to error object */ void handle_accept(connection::pointer new_connection, const boost::system::error_code& error) { if (!error) { new_connection->start(); start_accept(); } } ios_deque io_services_; /**< deque of pointers to io_services */ ba::ip::tcp::acceptor acceptor_; /**< object, that accepts new connections */ }; /** * Main routine * * @param argc number of arguments * @param argv pointers to arguments * * @return error code */int main(int argc, char** argv) { try { int thread_num=10; // read number of threads with io_services from command line, if provided if(argc > 1) thread_num=boost::lexical_cast<int>(argv[1]); ios_deque io_services; std::deque<ba::io_service::work> io_service_work; boost::thread_group thr_grp; // create threads for each io_service for (int i = 0; i < thread_num; ++i) { io_service_ptr ios(new ba::io_service); io_services.push_back(ios); io_service_work.push_back(ba::io_service::work(*ios)); // run io_service in their own thread thr_grp.create_thread(boost::bind(&ba::io_service::run, ios)); } // create server server server(io_services); // wait until all thread will finished thr_grp.join_all(); } catch (std::exception& e) { std::cerr << e.what() << std::endl; } return 0; }
common.h
/** * @file common.h * @author Alex Ott <alexott@gmail.com> * * @brief Declarations and includes, common for all boost::asio based programs * * */#ifndef _COMMON_H #define _COMMON_H 1 #include <boost/asio.hpp>#include <boost/shared_ptr.hpp>#include <boost/enable_shared_from_this.hpp>#include <boost/algorithm/string.hpp>#include <boost/lexical_cast.hpp>#include <boost/regex.hpp>#include <boost/bind.hpp>#include <boost/thread/thread.hpp>#include <iostream>#include <string>namespace ba=boost::asio; namespace bs=boost::system; typedef boost::shared_ptr<ba::ip::tcp::socket> socket_ptr; typedef boost::shared_ptr<ba::io_service> io_service_ptr; #endif /* _COMMON_H */
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