[Threads-devel] about timed_mutex

From: rick68 (rick68_at_[hidden])
Date: 2007-06-29 08:23:11

I try timed_mutex whit linux, but it not work.

in mutex.cpp:

============================================
void timed_mutex::do_lock()
{
    int res = 0;
    res = pthread_mutex_lock(&m_mutex);
    assert(res == 0);

    while (m_locked)
    {
        res = pthread_cond_wait(&m_condition, &m_mutex);
        assert(res == 0);
    }

    assert(!m_locked);
    m_locked = true;

    res = pthread_mutex_unlock(&m_mutex);
    assert(res == 0);
}

bool timed_mutex::do_timedlock(const xtime& xt)
{
    int res = 0;
    res = pthread_mutex_lock(&m_mutex);
    assert(res == 0);

    timespec ts;
    to_timespec(xt, ts);

    while (m_locked)
    {
        res = pthread_cond_timedwait(&m_condition, &m_mutex, &ts);
        assert(res == 0 || res == ETIMEDOUT);

        if (res == ETIMEDOUT)
            break;
    }

    bool ret = false;
    if (!m_locked)
    {
        m_locked = true;
        ret = true;
    }

    res = pthread_mutex_unlock(&m_mutex);
    assert(res == 0);
    return ret;
}

void timed_mutex::do_lock(cv_state&)
{
    int res = 0;
    while (m_locked)
    {
        res = pthread_cond_wait(&m_condition, &m_mutex);
        assert(res == 0);
    }

    assert(!m_locked);
    m_locked = true;

    res = pthread_mutex_unlock(&m_mutex);
    assert(res == 0);
}
============================================

All while-loop never running, because of
boost::timed_mutex::scoped_timed_lock will check m_locked is false.

So, I change while-loop to do-while-loop:

============================================
void timed_mutex::do_lock()
{
    int res = 0;
    res = pthread_mutex_lock(&m_mutex);
    assert(res == 0);

    do
    {
        res = pthread_cond_wait(&m_condition, &m_mutex);
        assert(res == 0);
    } while (res);

    assert(!m_locked);
    m_locked = true;

    res = pthread_mutex_unlock(&m_mutex);
    assert(res == 0);
}

bool timed_mutex::do_timedlock(const xtime& xt)
{
    int res = 0;
    res = pthread_mutex_lock(&m_mutex);
    assert(res == 0);

    timespec ts;
    to_timespec(xt, ts);

    do
     {
         res = pthread_cond_timedwait(&m_condition, &m_mutex, &ts);
         assert(res == 0 || res == ETIMEDOUT);

         if (res == ETIMEDOUT)
             break;
     } while(true);

    bool ret = false;
    if (!m_locked)
    {
        m_locked = true;
        ret = true;
    }

    res = pthread_mutex_unlock(&m_mutex);
    assert(res == 0);
    return ret;
}

void timed_mutex::do_lock(cv_state&)
{
    int res = 0;

    do
    {
        res = pthread_cond_wait(&m_condition, &m_mutex);
        assert(res == 0);
    } while (res);

    assert(!m_locked);
    m_locked = true;

    res = pthread_mutex_unlock(&m_mutex);
    assert(res == 0);
}
============================================

It's work very well~ :)

Rick.