Linux平台用C++实现事件对象，同步线程

前文在Win32平台上用C++实现了事件对象Event，对线程进行同步，以达到期望目的。这次在Linux平台上实现与之类似的事件对象。与其相关的一组API包括：pthread_mutex_init，pthread_cond_init，pthread_mutex_lock，pthread_cond_wait，pthread_mutex_unlock，pthread_cond_broadcast，pthread_cond_timedwait，pthread_cond_destroy，pthread_mutex_destroy。这些API的说明可以在这里找到：http://www.9linux.com/。下边，是封装的事件对象类，以及测试代码。使用VS2005编辑，在虚拟机 Fedora 13中编译，测试通过。

MyEvent.h

#ifndef My_Event_Header
#define My_Event_Header

#include <iostream>
#include <pthread.h>
#include <errno.h>

using namespace std;

//---------------------------------------------------------------

class CEventImpl
{
protected:

    /*
     动态方式初始化互斥锁,初始化状态变量m_cond
    `bAutoReset  true   人工重置
                 false  自动重置
    */
    CEventImpl(bool manualReset);

    /*
     注销互斥锁,注销状态变量m_cond
    */
    ~CEventImpl();

    /*
     将当前事件对象设置为有信号状态
     若自动重置，则等待该事件对象的所有线程只有一个可被调度
     若人工重置，则等待该事件对象的所有线程变为可被调度
    */
    void SetImpl();

    /*
     以当前事件对象，阻塞线程，将其永远挂起
     直到事件对象被设置为有信号状态
    */
    bool WaitImpl();

    /*
     以当前事件对象，阻塞线程，将其挂起指定时间间隔
     之后线程自动恢复可调度
    */
    bool WaitImpl(long milliseconds);

    /*
     将当前事件对象设置为无信号状态
    */
    void ResetImpl();

private:
    bool            m_manual;
    volatile bool   m_state;
    pthread_mutex_t m_mutex;
    pthread_cond_t  m_cond;
};

inline void CEventImpl::SetImpl()
{
    if (pthread_mutex_lock(&m_mutex))
        cout<<"cannot signal event (lock)"<<endl;

    //设置状态变量为true，对应有信号
    m_state = true;

    //cout<<"CEventImpl::SetImpl m_state = "<<m_state<<endl;

    //重新激活所有在等待m_cond变量的线程
    if (pthread_cond_broadcast(&m_cond))
    {
        pthread_mutex_unlock(&m_mutex);
        cout<<"cannot signal event"<<endl;
    }
    pthread_mutex_unlock(&m_mutex);
}

inline void CEventImpl::ResetImpl()
{
    if (pthread_mutex_lock(&m_mutex))
        cout<<"cannot reset event"<<endl;

    //设置状态变量为false，对应无信号
    m_state = false;

    //cout<<"CEventImpl::ResetImpl m_state = "<<m_state<<endl;

    pthread_mutex_unlock(&m_mutex);
}

//---------------------------------------------------------------

class CMyEvent: private CEventImpl
{
public:
    CMyEvent(bool bManualReset = true);
    ~CMyEvent();

    void Set();
    bool Wait();
    bool Wait(long milliseconds);
    bool TryWait(long milliseconds);
    void Reset();

private:
    CMyEvent(const CMyEvent&);
    CMyEvent& operator = (const CMyEvent&);
};


inline void CMyEvent::Set()
{
    SetImpl();
}

inline bool CMyEvent::Wait()
{
    return WaitImpl();
}

inline bool CMyEvent::Wait(long milliseconds)
{
    if (!WaitImpl(milliseconds))
    {
        cout<<"time out"<<endl;
        return false;
    }
    else
    {
        return true;
    }
}

inline bool CMyEvent::TryWait(long milliseconds)
{
    return WaitImpl(milliseconds);
}

inline void CMyEvent::Reset()
{
    ResetImpl();
}

#endif

MyEvent.cpp

#include "MyEvent.h"
#include <sys/time.h>

CEventImpl::CEventImpl(bool manualReset): m_manual(manualReset), m_state(false)
{
    if (pthread_mutex_init(&m_mutex, NULL))
        cout<<"cannot create event (mutex)"<<endl;
    if (pthread_cond_init(&m_cond, NULL))
        cout<<"cannot create event (condition)"<<endl;
}

CEventImpl::~CEventImpl()
{
    pthread_cond_destroy(&m_cond);
    pthread_mutex_destroy(&m_mutex);
}

bool CEventImpl::WaitImpl()
{
    if (pthread_mutex_lock(&m_mutex))
    {
        cout<<"wait for event failed (lock)"<<endl;
        return false;
    }
    while (!m_state)
    {
        //cout<<"CEventImpl::WaitImpl while m_state = "<<m_state<<endl;

        //对互斥体进行原子的解锁工作,然后等待状态信号
        if (pthread_cond_wait(&m_cond, &m_mutex))
        {
            pthread_mutex_unlock(&m_mutex);
            cout<<"wait for event failed"<<endl;
            return false;
        }
    }
    if (m_manual)
        m_state = false;
    pthread_mutex_unlock(&m_mutex);

    //cout<<"CEventImpl::WaitImpl end m_state = "<<m_state<<endl;

    return true;
}

bool CEventImpl::WaitImpl(long milliseconds)
{
    int rc = 0;
    struct timespec abstime;
    struct timeval tv;
    gettimeofday(&tv, NULL);
    abstime.tv_sec  = tv.tv_sec + milliseconds / 1000;
    abstime.tv_nsec = tv.tv_usec*1000 + (milliseconds % 1000)*1000000;
    if (abstime.tv_nsec >= 1000000000)
    {
        abstime.tv_nsec -= 1000000000;
        abstime.tv_sec++;
    }

    if (pthread_mutex_lock(&m_mutex) != 0)
    {
        cout<<"wait for event failed (lock)"<<endl;
        return false;
    }
    while (!m_state)
    {
        //自动释放互斥体并且等待m_cond状态,并且限制了最大的等待时间
        if ((rc = pthread_cond_timedwait(&m_cond, &m_mutex, &abstime)))
        {
            if (rc == ETIMEDOUT) break;
            pthread_mutex_unlock(&m_mutex);
            cout<<"cannot wait for event"<<endl;
            return false;
        }
    }
    if (rc == 0 && m_manual)
        m_state = false;
    pthread_mutex_unlock(&m_mutex);
    return rc == 0;
}

CMyEvent::CMyEvent(bool bManualReset): CEventImpl(bManualReset)
{
}

CMyEvent::~CMyEvent()
{
}

    下边是测试代码

// pthread_event.cpp : 定义控制台应用程序的入口点。
//

#include <unistd.h>
#include "MyEvent.h"

#define PRINT_TIMES 10

//创建一个人工自动重置事件对象
CMyEvent g_myEvent;
int g_iNum = 0;


//线程函数1
void * ThreadProc1(void *pParam)
{
    for (int i = 0; i < PRINT_TIMES; i++)
    {
        g_iNum++;
        cout<<"ThreadProc1 do print, Num = "<<g_iNum<<endl;

        //设置事件为有信号状态
        g_myEvent.Set();

        sleep(1);
    }

    return (void *)0;
}

//线程函数2
void * ThreadProc2(void *pParam)
{
    bool bRet = false;
    while ( 1 )
    {
        if ( g_iNum >= PRINT_TIMES )
        {
            break;
        }

        //以当前事件对象阻塞本线程，将其挂起
        bRet = g_myEvent.Wait();
        if ( bRet )
        {
            cout<<"ThreadProc2 do print, Num = "<<g_iNum<<endl;

            //设置事件为无信号状态
            g_myEvent.Reset();
        }
        else
        {
            cout<<"ThreadProc2 system exception"<<endl;
        }
    }

    return (void *)0;
}


int main(int argc, char* argv[])
{
    pthread_t thread1,thread2;
    pthread_attr_t attr1,attr2;


    //创建两个工作线程
    pthread_attr_init(&attr1);
    pthread_attr_setdetachstate(&attr1,PTHREAD_CREATE_JOINABLE);
    if (pthread_create(&thread1,&attr1, ThreadProc1,NULL) == -1)
    {
        cout<<"Thread 1: create failed"<<endl;
    }
    pthread_attr_init(&attr2);
    pthread_attr_setdetachstate(&attr2,PTHREAD_CREATE_JOINABLE);
    if (pthread_create(&thread2,&attr2, ThreadProc2,NULL) == -1)
    {
        cout<<"Thread 2: create failed"<<endl;
    }

    //等待线程结束
    void *result;
    pthread_join(thread1,&result);
    pthread_join(thread2,&result);

    //关闭线程，释放资源
    pthread_attr_destroy(&attr1);
    pthread_attr_destroy(&attr2);

    int iWait;
    cin>>iWait;

    return 0;
}

    编译，运行。可以看到，与Win32平台上的测试结果相同，好神奇！

from:http://blog.csdn.net/chexlong/article/details/7080537