- 1.包装线程对象
class task : public std::tr1::enable_shared_from_this<task>
{
public:
task():exit_(false){}
task( const task & ) = delete;
~task(){}
task & operator =( const task &) = delete;
void start();
void stop()
{
exit_ = true;
sync_.notify_one();
}
void set_job( const std::function<void()> & job, const std::string & file, int line)
{//提交任务
{
std::unique_lock<std::mutex> lock(mutex_);
job_ = job;
file_ = file;
line_ = line;
}
sync_.notify_one();//通知主线程有任务要运行....
}
void print_job(){
LOG(INFO)<<"sumbit from:"<<file_<<":"<<line_;
}
private:
bool exit_;
std::mutex mutex_;
std::condition_variable sync_;
std::function< void()> job_; //线程运行的任务，线程随意时刻，最多仅仅能运行一个任务。
std::thread::id id_;
std::string file_;
int line_;
};void task::start()
{
auto job_proxy = [this] (){
id_ = std::this_thread::get_id();
while( !exit_ )
{
std::unique_lock<std::mutex> lock(mutex_);
if( job_ )
{//有任务了，须要运行任务了
try
{
job_(); //运行任务的代码
}catch( std::exception & e)
{
}catch(...)
{
}
job_ = std::function<void()>(); //释放任务绑定的资源，主要为闭包捕获的资源，特别是shared_ptr对象.
tasks->job_completed( shared_from_this() ); //任务运行完毕，通知线程池
}else{
//没有任务的时候，等待其它线程提交任务。。
sync_.wait(lock);
}
}
};
std::thread t(job_proxy); //创建并启动与task管理的线程
t.detach(); //分离模式，thread对象销毁了。可是其创建的线程还活着。。。
}
- 2.线程池管理对象
class task_pool
{
public:
task_pool(unsigned int pool_size = 128):max_size_(pool_size),stop_all_(true)
{
}
~task_pool()
{
}
void job_completed( const std::tr1::shared_ptr<task> & t)//回收task对象
{
std::lock_guard<std::mutex> lock(mutex_);
bool need_to_notify = idle_tasks_.empty() && (!wait_for_running_jobs_.empty());
busying_tasks_.erase(t);
idle_tasks_.push_back(t);
LOG(INFO)<<"after job_completed, current idle tasks size:"<< idle_tasks_.size()
<<" busying tasks size:"<<busying_tasks_.size()
<<" wait for running jobs size:"<<wait_for_running_jobs_.size();
if( !busying_tasks_.empty() ){
(*busying_tasks_.begin())->print_job();
}
if( need_to_notify )//任务太多了。之前空暇线程使用完了。有任务在等待运行，须要通知
{
sync_.notify_one();
}
};
//提交任务
void submit_job( const std::function<void()> & job, const std::string file, int line)
{
if( stop_all_ )
{
return;
}
std::lock_guard<std::mutex> lock(mutex_);
bool need_notify = wait_for_running_jobs_.empty();
wait_for_running_jobs_.push(std::make_tuple(job,file,line));
if( need_notify )//等待运行的任务为空时。须要通知，其它情况不须要通知.
{
sync_.notify_one();
}
}
void execute_job()
{
while(true)
{
std::unique_lock<std::mutex> lock(mutex_);
while(!stop_all_ && wait_for_running_jobs_.empty() )
{
//等待其它线程提交任务
sync_.wait(lock);
}
if( stop_all_ )
{
return;
}
while(!stop_all_ && idle_tasks_.empty())
{
//有任务要运行，可是没有空暇线程，等待其它任务运行完毕。
sync_.wait(lock);
}
if( stop_all_ )
{
return;
}
//有任务。也有空暇线程了
auto t = get_task();
auto job =wait_for_running_jobs_.front();
wait_for_running_jobs_.pop();
//分发任务到task 线程.
t->set_job(std::get<0>(job), std::get<1>(job), std::get<2>(job));
}
}
void stop_all()
{
std::lock_guard<std::mutex> lock(mutex_);
stop_all_ = true;
for( auto t : idle_tasks_ )
{
t->stop();
}
idle_tasks_.clear();
for( auto t : busying_tasks_ )
{
t->stop();
}
while(!wait_for_running_jobs_.empty()){
wait_for_running_jobs_.pop();
}
sync_.notify_one();
}
void start()
{// 初始化启动线程池主线程
try
{
std::thread t( [this]{ execute_job();});
t.detach();
stop_all_ = false;
allocate_tasks();
}catch( std::exception & e )
{
LOG(FATAL) << "start tasks pool ... error"<<e.what();
}
}
protected:
std::tr1::shared_ptr<task> get_task()
{
//获取task对象
if( ! idle_tasks_.empty() )
{
auto t = *idle_tasks_.begin();
idle_tasks_.pop_front(); //从空暇队列移除
busying_tasks_.insert(t); //增加忙队列
return t;
}
return std::tr1::shared_ptr<task>();
}
void allocate_tasks() //初始化线程池
{
for( int i = 0 ; i < max_size_; i ++ )
{
std::tr1::shared_ptr<task> t( new task());
try{
t->start();
idle_tasks_.push_back(t);
}catch( std::exception & e)
{ //超过进程最大线程数限制时，会跑出异常。
。。
break;
}
}
}
private :
unsigned int max_size_;
std::list < std::tr1::shared_ptr<task> > idle_tasks_; //空暇任务队列
std::set < std::tr1::shared_ptr<task> > busying_tasks_;//正在运行任务的队列
std::queue< std::tuple< std::function<void()> , std::string, int > > wait_for_running_jobs_; //等待运行的任务
std::mutex mutex_;
std::condition_variable sync_;
bool stop_all_;
};
- usage
static task_pool * tasks = nullptr;
static std::once_flag init_flag;
static std::once_flag finit_flag;
void run_job(const std::function<void()> & job , const std::string & file, int line )
{
if( tasks != nullptr)
tasks->submit_job(job, file,line);
}
void task_pool_init( unsigned max_task_size)
{
std::call_once(init_flag,[max_task_size]{
tasks = new task_pool(max_task_size);
tasks->start();
});
}
void task_pool_finit()
{
std::call_once(finit_flag,[]{ tasks->stop_all();});
}