boost::asio::io_service和io_service::work和boost::thread_group配合使用

boost::asio::io_service和io_service::work和boost::thread_group配合使用

//注释中的Page是指：Boost程序库完全开发指南(第三版)#include <iostream>//Page542: 在头文件<boost/asio.hpp>前定义此宏，它就会向标准流cerr输出运行日志。//#define BOOST_ASIO_ENABLE_HANDLER_TRACKING#include <boost/asio.hpp>#include <boost/thread.hpp>  long boost_thread_id_to_long(boost::thread::id id){    std::stringstream ss; ss << id;    return strtol(std::string(ss.str()).c_str(), (char**)NULL, 16);}#include <boost/date_time/posix_time/posix_time.hpp>std::string local_time_to_simple_string(){    boost::posix_time::ptime ptm = boost::posix_time::microsec_clock::local_time();    return boost::posix_time::to_simple_string(ptm);}#include <boost/format.hpp>std::string completion_handler_fun(float f, std::string str){    str = (boost::format("%|s|, thread_id=%|ld|, f=%|.3f|, str=%|s|")        % local_time_to_simple_string()        % boost_thread_id_to_long(boost::this_thread::get_id())        % f % str.c_str()).str();    std::cout << str << std::endl;    return str;}int main1(){    boost::asio::io_service io;    io.post(boost::bind(completion_handler_fun, 3.141592653f, "111"));    io.post(boost::bind(completion_handler_fun, 3.141592653f, "222"));    std::cout << "sleep some seconds before run" << std::endl;    boost::this_thread::sleep_for(boost::chrono::seconds(3));    io.run();    std::cout << "sleep some seconds after  run" << std::endl;    boost::this_thread::sleep_for(boost::chrono::seconds(3));    return 0;    //在这个程序中，主线程提供了io_service::run的上下文。也可以创建一个线程，然后在这个线程里执行run函数。    //当run开始后，就执行所有的handler，如果io_service里面没有可执行的handler了，就退出run函数了。}int main2(){    boost::asio::io_service io;    //请阅读Page540的io_service::work的描述。    //io_service::work会让io_service::run始终有事可做，所以不会退出run函数。    boost::asio::io_service::work wk(io);    io.post(boost::bind(completion_handler_fun, 3.141592653f, "111"));    io.post(boost::bind(completion_handler_fun, 3.141592653f, "222"));    std::cout << "sleep some seconds before run" << std::endl;    boost::this_thread::sleep_for(boost::chrono::seconds(3));    io.run();    //有io_service::work的存在，所以，即时没有可执行的handler了，也不会退出run函数。    std::cout << "io_service::run is end and will exit." << std::endl;    return 0;}int main3(){    boost::asio::io_service io;    //事先在io_service里面放了100个要执行的handler。    for (int i = 0; i < 100; ++i)    {        std::stringstream ss; ss << i;        io.post(boost::bind(completion_handler_fun, 3.141592653f, std::string(ss.str())));    }    boost::thread_group th_gp;    //线程组创建3个线程，同时处理这100个handler。    for (int i = 0; i < 3; ++i)    {        boost::thread* th_ptr = th_gp.create_thread(boost::bind(&boost::asio::io_service::run, boost::ref(io)));        std::cout << "thread_group, thread_id=" << boost_thread_id_to_long(th_ptr->get_id()) << std::endl;    }    //这3个线程可能同时往屏幕上输出，所以屏幕可能会乱。    //执行完handler后，run函数退出，线程退出，thread_group的join_all会执行完毕。    th_gp.join_all();    std::cout << "will exit" << std::endl;    boost::this_thread::sleep_for(boost::chrono::seconds(3));    return 0;}int main(){    boost::asio::io_service io;    //io_service::work阻止了io_service的run函数退出，所以thread_group的join_all函数会一直阻塞在那里。    boost::asio::io_service::work wk(io);    boost::thread_group th_gp;    for (int i = 0; i < 3; ++i)    {        boost::system::error_code error;        boost::thread* th_ptr = th_gp.create_thread(boost::bind(&boost::asio::io_service::run, boost::ref(io), error));        std::cout << "thread_group, thread_id=" << boost_thread_id_to_long(th_ptr->get_id()) << std::endl;    }    io.post(boost::bind(completion_handler_fun, 3.141592653f, "xxx"));    th_gp.join_all();    std::cout << "will exit" << std::endl;    boost::this_thread::sleep_for(boost::chrono::seconds(3));    return 0;}

完。