C++ 线程池

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简单的线程池实现

下面这段代码摘自CppCMS thread_pool.cpp 。
CppCMS是一个C++ 的Web开发框架，用于可发展的网站，性能极高。推荐给大家使用。
/////////////////////////////////////////////////////////////////////////////////                                                                             //  Copyright (C) 2008-2012  Artyom Beilis (Tonkikh) <artyomtnk@yahoo.com>     //                                                                             //  See accompanying file COPYING.TXT file for licensing details./////////////////////////////////////////////////////////////////////////////////#define CPPCMS_SOURCE#include <cppcms/thread_pool.h>#include <booster/backtrace.h>#include <booster/log.h>#include <ostream>#include <list>#include <vector>#include <cppcms/config.h>#ifdef CPPCMS_USE_EXTERNAL_BOOST#   include <boost/bind.hpp>#else // Internal Boost#   include <cppcms_boost/bind.hpp>    namespace boost = cppcms_boost;#endif#include <booster/shared_ptr.h>#include <booster/thread.h>#if defined(CPPCMS_POSIX)#include <signal.h>#endif namespace cppcms {namespace impl {    class thread_pool : public booster::noncopyable {    public:        bool cancel(int id) {            booster::unique_lock<booster::mutex> lock(mutex_);            queue_type::iterator p;            for(p=queue_.begin();p!=queue_.end();++p) {                if(p->first==id) {                    queue_.erase(p);                    return true;                }            }            return false;        }        int post(booster::function<void()> const &job)        {            booster::unique_lock<booster::mutex> lock(mutex_);            int id=job_id_++;            queue_.push_back(std::make_pair(id,job));            cond_.notify_one();            return id;        }        thread_pool(int threads) :            shut_down_(false),            job_id_(0)        {            workers_.resize(threads);            #if defined(CPPCMS_POSIX)            sigset_t set,old;            sigfillset(&set);            pthread_sigmask(SIG_BLOCK,&set,&old);            #endif            for(int i=0;i<threads;i++) {                workers_[i].reset(new booster::thread(boost::bind(&thread_pool::worker,this)));            }            #if defined(CPPCMS_POSIX)            pthread_sigmask(SIG_SETMASK,&old,0);            #endif        }        void stop()        {            {                booster::unique_lock<booster::mutex> lock(mutex_);                shut_down_=true;                cond_.notify_all();            }            for(unsigned i=0;i<workers_.size();i++) {                booster::shared_ptr<booster::thread> thread=workers_[i];                workers_[i].reset();                if(thread)                    thread->join();            }        }        ~thread_pool()        {            try {                stop();            }            catch(...)            {            }        }    private:        void worker()        {            for(;;) {                booster::function<void()> job;                {                    booster::unique_lock<booster::mutex> lock(mutex_);                    if(shut_down_)                        return;                    if(!queue_.empty()) {                        queue_.front().second.swap(job);                        queue_.pop_front();                    }                    else {                        cond_.wait(lock);                    }                }                if(job) {                    try {                        job();                    }                    catch(std::exception const &e) {                        BOOSTER_ERROR("cppcms") << "Catched exception in thread pool" << e.what() <<'\n'                                    << booster::trace(e);                    }                    catch(...) {                        BOOSTER_ERROR("cppcms") << "Catched unknown exception in thread pool";                    }                }            }           }        booster::mutex mutex_;        booster::condition_variable cond_;        bool shut_down_;            int job_id_;        typedef std::list<std::pair<int,booster::function<void()> > > queue_type;        queue_type queue_;        std::vector<booster::shared_ptr<booster::thread> > workers_;    };}thread_pool::thread_pool(int n) :    impl_(new impl::thread_pool(n)){}int thread_pool::post(booster::function<void()>  const &job){    return impl_->post(job);}void thread_pool::stop(){    impl_->stop();}bool thread_pool::cancel(int id){    return impl_->cancel(id);}thread_pool::~thread_pool(){}} // cppcms
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