<Boost> boost::thread 多线程的使用

boost::thread参考帮助文档：http://www.boost.org/doc/libs/1_57_0/doc/html/thread.html

1. Windows的多线程

参考博文：http://blog.youkuaiyun.com/morewindows/article/details/7421759

#include <process.h>

CRITICAL_SECTION g_cs;
void WinThread(LPVOID lP)
{
	EnterCriticalSection(&g_cs);		// 使用临界区保证互斥运行：另外还有事件Event, 信号量Semaphone， 互斥锁Mutex等
	string *pstr = (string*)lP;
	cout << "My WinThread: " << *pstr << endl << flush;

	// do somthing
	delete pstr;
	LeaveCriticalSection(&g_cs);
}

unsigned int WINAPI WinThread2(void * lP)	// 需要定义为__stdcall
{
	EnterCriticalSection(&g_cs);
	string *pstr = (string*)lP;
	cout << "My Winthread2: " << *pstr << endl;

	delete pstr;
	LeaveCriticalSection(&g_cs);

	_endthreadex(0);
	return 0;
}

void TestWinThread()
{
	InitializeCriticalSection(&g_cs);
	HANDLE hThread = CreateThread(NULL, 0, 
		(LPTHREAD_START_ROUTINE)WinThread,	// 线程函数
		new string("CreateThread"),			// 函数参数: 需要新开辟内存，或静态、全局变量
		0, NULL);
	
	WaitForSingleObject(hThread, INFINITE);	// 无限期等待线程执行结束
	CloseHandle(hThread);

	uintptr_t pTh = _beginthreadex(NULL, 0, WinThread2, new string("_beginthreadex"), 0, NULL);
	WaitForSingleObject((HANDLE)pTh, 1000); // 等待线程执行完毕，超时时间1秒钟
	cout << "_beginthreadex executed; " << endl;
}

运行结果：

2. boost::thread

boost::thread 的出现解决了函数参数需要静态、全局变量或者开辟新内存的问题。

博文参考：http://blog.youkuaiyun.com/iamnieo/article/details/2908621

看官方帮助文档：

struct callable
{
    void operator()();
};

boost::thread copies_are_safe()
{
    callable x;
    return boost::thread(x);
} // x is destroyed, but the newly-created thread has a copy, so this is OK

boost::thread oops()
{
    callable x;
    return boost::thread(boost::ref(x));
} // x is destroyed, but the newly-created thread still has a reference
  // this leads to undefined behaviour

我们可以：

struct MyCallable
{
	MyCallable(int i) { m_iNo = i;}

	void operator()()
	{
		for (int i = 0; i < 10; i++)
		{
			cout << "[" << m_iNo << "]报数" << i  << endl;
		}
	}

	int m_iNo;
};

void TestThread()
{
	boost::thread t(MyCallable(0));	
	t.join();		// 主线程阻塞至t线程完成
	return;
}

运行结果：

采用函数的形式，这里我们加入多线程互斥锁进行同步，是线程之间不相互影响。

boost::mutex io_mutex;
void BoostThreadFunc(int i)
{
	boost::mutex::scoped_lock sl(io_mutex);	 // sl构造函数，调用io_mutex.lock()
	MyCallable mc(i);
	mc();

	// sl析构函数， 调用io_mutext.unlock()
}

void TestThread()
{

	boost::thread t1(BoostThreadFunc, 1);
	boost::thread t2(BoostThreadFunc, 2);
#if 1
        t1.join();
        t2.join();
#else
	boost::thread::native_handle_type handles[2];
	handles[0] = t1.native_handle();
	handles[1] = t2.native_handle();

	WaitForMultipleObjects(2, handles, TRUE, INFINITE);		// 等待t1,t2线程都执行结束

	t1.detach();
	t2.detach();
#endif
}

运行结果：

如果不加锁的话，执行的结果的不可预见的。

也支持多个参数：

class MyThreadPara
{
public:
	MyThreadPara(string str) : m_strInfo(str) { }
	
	void Print() {
		cout << m_strInfo << endl;
	}
private:
	string m_strInfo;
};

void BoostThreadClassParaFunc(int i, MyThreadPara para1, MyThreadPara para2) // 最多9个
{
	boost::mutex::scoped_lock sl(io_mutex);	 // sl构造函数，调用io_mutex.lock()
	cout << "[" << i << "]" << endl;
	para1.Print();
	para2.Print();
	// sl析构函数， 调用io_mutext.unlock()
}

void TestThread()
{
	boost::thread t3(BoostThreadClassParaFunc, 3, MyThreadPara(string("FirstClassPara")), MyThreadPara(string("SecondClassPara")));
	t3.join();
}

执行结果：