【Boost】boost库asio详解2——strand与io_service区别
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【Boost】boost库asio详解2——strand与io_service区别
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[cpp]?view plain?copy ?print? namespace?? {?? ????//?strand提供串行執行,?能夠保證線程安全,?同時被post或dispatch的方法,?不會被并發的執行.??? ????//?io_service不能保證線程安全?? ????boost::asio::io_service?m_service;?? ????boost::asio::strand?m_strand(m_service);?? ????boost::mutex?m_mutex;?? ?? ????void?print(int?id)?? ????{?? ????????//?boost::mutex::scoped_lock?lock(m_mutex);?? ????????static?int?count?=?0;?? ????????PRINT_DEBUG("id:?"?<<?boost::lexical_cast<std::string>(id));?? ????????PRINT_DEBUG("count:?"?<<?boost::lexical_cast<std::string>(++count));?? ????}?? ?????? ????void?ioRun1()?? ????{?? ????????while(true)?? ????????{?? ????????????m_service.run();?? ????????}?? ????}?? ?? ????void?ioRun2()?? ????{?? ????????while(true)?? ????????{?? ????????????m_service.run();?? ????????}?? ????}?? ?? ????void?strand_print1()?? ????{?? ????????//?PRINT_DEBUG("Enter?print1");?? ????????m_strand.dispatch(boost::bind(print,?1));?? ????????//?PRINT_DEBUG("Exit?print1");?? ????}?? ?? ????void?strand_print2()?? ????{?? ????????//?PRINT_DEBUG("Enter?print2");?? ????????m_strand.post(boost::bind(print,?2));?? ????????//?PRINT_DEBUG("Exit?print2");?? ????}?? ?? ????void?strand_print3()?? ????{?? ????????//?PRINT_DEBUG("Enter?print3");???????????????? ????????m_strand.post(boost::bind(print,?3));?? ????????//?PRINT_DEBUG("Exit?print3");?? ????}?? ?? ????void?strand_print4()?? ????{?? ????????//?PRINT_DEBUG("Enter?print4");?? ????????m_strand.post(boost::bind(print,?4));?? ????????//?PRINT_DEBUG("Exit?print4");?? ????}?? ?? ????//?將上面的m_strand換成m_service后，?? ????void?service_print1()?? ????{?? ????????//?PRINT_DEBUG("Enter?print1");?? ????????m_service.dispatch(boost::bind(print,?1));?? ????????//?PRINT_DEBUG("Exit?print1");?? ????}?? ?? ????void?service_print2()?? ????{?? ????????//?PRINT_DEBUG("Enter?print2");?? ????????m_service.post(boost::bind(print,?2));?? ????????//?PRINT_DEBUG("Exit?print2");?? ????}?? ?? ????void?service_print3()?? ????{?? ????????//?PRINT_DEBUG("Enter?print3");???????????????? ????????m_service.post(boost::bind(print,?3));?? ????????//?PRINT_DEBUG("Exit?print3");?? ????}?? ?? ????void?service_print4()?? ????{?? ????????//?PRINT_DEBUG("Enter?print4");?? ????????m_service.post(boost::bind(print,?4));?? ????????//?PRINT_DEBUG("Exit?print4");?? ????}?? }?? ?? void?test_strand()?? {?? ????boost::thread?ios1(ioRun1);?? ????boost::thread?ios2(ioRun2);?? ?????? ????boost::thread?t1(strand_print1);?? ????boost::thread?t2(strand_print2);?? ????boost::thread?t3(strand_print3);?? ????boost::thread?t4(strand_print4);?? ?? ????t1.join();?? ????t2.join();?? ????t3.join();?? ????t4.join();?? ?? ????m_server.run();?? }?? ?? void?test_service()?? {?? ????boost::thread?ios1(ioRun1);?? ????boost::thread?ios2(ioRun2);?? ?? ????boost::thread?t1(service_print1);?? ????boost::thread?t2(service_print2);?? ????boost::thread?t3(service_print3);?? ????boost::thread?t4(service_print4);?? ?????? ????t1.join();?? ????t2.join();?? ????t3.join();?? ????t4.join();?? ?????? ????m_service.run();?? }??
test_strand的執行結果:
[cpp]?view plain?copy ?print? 2013-01-05?17:25:34?626?[8228]?DEBUG?-?id:?4?? 2013-01-05?17:25:34?631?[8228]?DEBUG?-?count:?1?? 2013-01-05?17:25:34?634?[5692]?DEBUG?-?id:?1?? 2013-01-05?17:25:34?637?[5692]?DEBUG?-?count:?2?? 2013-01-05?17:25:34?640?[5692]?DEBUG?-?id:?2?? 2013-01-05?17:25:34?642?[5692]?DEBUG?-?count:?3?? 2013-01-05?17:25:34?646?[5692]?DEBUG?-?id:?3?? 2013-01-05?17:25:34?649?[5692]?DEBUG?-?count:?4??
test_ioserivice的執行結果:
[cpp]?view plain?copy ?print? 2013-01-05?17:26:28?071?[3236]?DEBUG?-?id:?1?? 2013-01-05?17:26:28?071?[5768]?DEBUG?-?id:?2?? 2013-01-05?17:26:28?071?[5108]?DEBUG?-?id:?3?? 2013-01-05?17:26:28?076?[3236]?DEBUG?-?count:?1?? 2013-01-05?17:26:28?079?[5768]?DEBUG?-?count:?2?? 2013-01-05?17:26:28?083?[5108]?DEBUG?-?count:?3?? 2013-01-05?17:26:28?087?[3236]?DEBUG?-?id:?4?? 2013-01-05?17:26:28?099?[3236]?DEBUG?-?count:?4??
從結果可以看到, 在test_strand中print中兩個打印函數成對執行, 在test_ioservice兩個打印函數就沒有線程安全可言了.
如果要保證test_ioservice同步, 就要加上mutex, 在代碼中被注釋的那句.?
注意從日志的線程號中可知: 真正執行print()是主線程, ios1, ios2, 而t1, t2, t3, t4線程只是往ioservice的隊列中加入任務.
[cpp]?view plain?copy ?print?
[cpp]?view plain?copy ?print?
如果要保證test_ioservice同步, 就要加上mutex, 在代碼中被注釋的那句.?
注意從日志的線程號中可知: 真正執行print()是主線程, ios1, ios2, 而t1, t2, t3, t4線程只是往ioservice的隊列中加入任務.
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