boost::thread

1、boost::thread类就代表一个可执行的线程。缺省构造函数创建一个代表当前执行线程的实例。

#include <boost/thread/thread.hpp>
#include <iostream>
#include <thread>         // std::thread, std::thread::id, std::this_thread::get_id  
#include <chrono>         // std::chrono::seconds 
void hello()
{
    std::cout << "Hello world, I'm a thread!" << std::endl;
    std::this_thread::sleep_for(std::chrono::seconds(5));
}
 
 int main(int argc, char* argv[])
{
     boost::thread thrd(&hello);
     thrd.join();
     return 0;
}

 

2、在类内部创建线程

class HelloWorld
{
public:
  static void hello()
  {
     std::cout <<"Hello world, I''m a thread!"<< std::endl;
  }

  static void start()
  {
     boost::thread thrd( hello );
     thrd.join();
  }
}; 

int main(int argc, char* argv[])
{
    HelloWorld::start();
    return 0;
}

 

3、绑定函数对象

 #include <boost/thread/thread.hpp>
 #include <boost/thread/mutex.hpp>
 #include <boost/bind.hpp>
 #include <iostream>
 boost::mutex io_mutex;
 void count(int id)
 {
     for (int i = 0; i < 10; ++i)
     {
         boost::mutex::scoped_lock
         lock(io_mutex);
         std::cout << id << ": " <<
         i << std::endl;
     }
 }
 
 int main(int argc, char* argv[])
 {
      boost::thread thrd1(boost::bind(&count, 1));
     boost::thread thrd2(boost::bind(&count, 2));
     thrd1.join();
     thrd2.join();
     return 0;
 }

 

 

4、如果要求start()和hello()方法不能是静态方法则采用下面的方法创建线程：

 class HelloWorld
 {
     public:
     void hello()
     {
         std::cout <<
         "Hello world, I''m a thread!"
         << std::endl;
     }
     void start()
     {
         boost::function0<void> f =  boost::bind(&HelloWorld::hello,this);
         boost::thread thrd( f );
         thrd.join();
     }
 }; 
 int main(int argc, char* argv[])
 {
     HelloWorld hello;
     hello.start();
     return 0;
 }

 

5、用类内部函数在类外部创建线程

 class HelloWorld
 {
     public:
     void hello(const std::string& str)
     {
         std::cout < }
     }; 
   
 int main(int argc, char* argv[])
 { 
     HelloWorld obj;
     boost::thread thrd( boost::bind(&HelloWorld::hello,&obj,"Hello world, I''m a thread!" ) ) ;
     thrd.join();
     return 0;
 }

 

6、每个线程都处理属于自己的数据实例，尽管它们都是使用同一个boost::thread_specific_ptr。

#include <boost/thread/thread.hpp>
#include <boost/thread/mutex.hpp>
#include <boost/thread/tss.hpp>
#include <iostream>

boost::mutex io_mutex;
boost::thread_specific_ptr<int> ptr;
     
struct count
{
  count(int id) : id(id) { }
  void operator()()
  {
        if(ptr.get() == 0)
           ptr.reset(new int(0));
        for (int i = 0; i < 10; ++i)
        {
           (*ptr)++;
           boost::mutex::scoped_lock lock(io_mutex);
           std::cout << id << ": " << *ptr << std::endl;
        }
   }
   int id;
};
    
int main(int argc, char* argv[])
{
    boost::thread thrd1(count(1));
    boost::thread thrd2(count(2));
    thrd1.join();
    thrd2.join();
    return 0;
}

 

7、boost::call_once的例子。其中定义了一个静态的全局整数，初始值为0；还有一个由BOOST_ONCE_INIT初始化的静态boost::once_flag实例。

只被执行了一次。

#include <boost/thread/thread.hpp>
#include <boost/thread/once.hpp>
#include <iostream>
 
int i = 0;
boost::once_flag flag = BOOST_ONCE_INIT;
 
void init()
{
   ++i;
}

void thread()
{
   boost::call_once(&init, flag);
}

int main(int argc, char* argv[])
{
   boost::thread thrd1(&thread);
   boost::thread thrd2(&thread);
   thrd1.join();
   thrd2.join();
   std::cout << i << std::endl;
   return 0;
}