Linux/POSIX等效于Win32的CreateEvent,SetEvent,WaitForSingleObject

Question

我写了一个小类来同步Linux(实际上是Android)和Windows的线程.

这是我的界面的Win32实现:

    class SyncObjectWin32 : public SyncObject
    {
    private:

        const HANDLE m_hEvent;

    public:

        SyncObjectWin32()
          : m_hEvent( ::CreateEvent( NULL, FALSE, FALSE ) )
        {
            if( NULL == m_hEvent )
                throw core::Exception( "sys::SyncObjectWin32::SyncObjectWin32() - Failed to create event." );
        }

        ~SyncObjectWin32()
        {
            ::CloseHandle( m_hEvent );
        }

        void WaitForSignal()
        {
            ::WaitForSingleObject( m_hEvent );
        }

        void Signal()
        {
            ::SetEvent( m_hEvent );
        }
    };

问题是我不确定什么是POSIX等价物.到目前为止,基于这个问题,我已经编写了以下课程,但由于答案不完整,我不确定如何完成课程:

    class SyncObjectPosix
    {
    private:

        pthread_mutex_t m_oMutex;

    public:

        SyncObjectPosix()
        {
            pthread_mutex_lock( m_oMutex );                 // lock mutex
            bool & signalled = find_signal( condition );  // find predicate
            signalled = true;                          // set predicate
            pthread_mutex_unlock( m_oMutex );               // unlock mutex
            pthread_cond_signal( condition );            // signal condition variable
        }

        ~SyncObjectPosix()
        {

        }

        void WaitForSignal()
        {
            pthread_mutex_lock(mutex);                         // lock mutex
            bool & signalled = find_signal( condition );          // find predicate
            while (!signalled)
            {
              pthread_cond_timedwait(condition, m_oMutex, timeout);
            }
            signalled = false;                                 // reset predicate
            pthread_mutex_unlock( m_oMutex );                       // unlock mutex
        }

        void Signal()
        {

        }
    };

Answer 1

检查一下eventfd.CreateEvent如果你只需要一个消费者和一个生产者,它似乎几乎相当于.

CreateEvent - > eventfd

CloseHandle - > close

SetEvent - > write

WaitForSingleObject - > read

WaitForMultipleObjects- > select和read相应的fd

更多阅读 http://www.sourcexr.com/articles/2013/10/26/lightweight-inter-process-signaling-with-eventfd

Answer 2

所描述的POSIX等价物是POSIX条件变量.请注意,条件变量必须始终与POSIX互斥锁配对使用,但很多情况下,多个条件变量使用相同的互斥锁,因此如果您不打算将互斥锁专用于条件变量,则不应将其置于班级.在Win32和POSIX API之间的意义映射应该是:

CreateEvent - > pthread_cond_init

CloseHandle - > pthread_cond_destroy

WaitForSingleObject- > pthread_cond_wait或pthread_cond_timedwait

SetEvent- > pthread_cond_signal或pthread_cond_broadcast

幸运的是,有很多关于此的文档,但我推荐基本的编程POSIX线程.

Answer 3

您的代码的 pthreads 等效项是：

class SyncObjectPosix
{
private:

    bool signalled;
    pthread_mutex_t mutex;
    pthread_cond_t cond;

public:

    SyncObjectPosix()
    {
        signalled = false;
        pthread_mutex_init(&mutex, NULL);
        pthread_cond_init(&cond, NULL);
    }

    ~SyncObjectPosix()
    {
        pthread_mutex_destroy(&mutex);
        pthread_cond_destroy(&cond);
    }

    void WaitForSignal()
    {
        pthread_mutex_lock(&mutex);
        while (!signalled)
        {
            pthread_cond_wait(&cond, &mutex);
        }
        signalled = false;
        pthread_mutex_unlock(&mutex);
    }

    void Signal()
    {
        pthread_mutex_lock(&mutex);
        signalled = true;
        pthread_mutex_unlock(&mutex);
        pthread_cond_signal(&cond);
    }
};