I have a class, Queue, that I tried to make thread safe. It has these three member variables:

    std::queue<T>   m_queue;
    pthread_mutex_t m_mutex;
    pthread_cond_t  m_condition;

and a push and pop implemented as:

    template<class T> void Queue<T>::push(T value)
    {
        pthread_mutex_lock( &m_mutex );
        m_queue.push(value);
        if( !m_queue.empty() )
        {
            pthread_cond_signal( &m_condition );
        }
        pthread_mutex_unlock( &m_mutex );
    }

    template<class T> bool Queue<T>::pop(T& value, bool block)
    {
        bool rtn = false;
        pthread_mutex_lock( &m_mutex );
        if( block )
        {
            while( m_queue.empty() )
            {
                pthread_cond_wait( &m_condition, &m_mutex );
            }
        }
        if( !m_queue.empty() )
        {
            value = m_queue.front();
            m_queue.pop();  
            rtn = true;
        }
        pthread_mutex_unlock( &m_mutex );
        return rtn;
    }

Unfortunately there are occasional issues that may be the fault of this code. That is, there are two threads and sometimes thread 1 never comes out of push() and at other times thread 2 never comes out of pop() (the block parameter is true) though the queue isn't empty.

I understand there are other implementations available, but I'd like to try to fix this code, if needed. Anyone see any issues?

The constructor has the appropriate initializations:

    Queue()
    {
        pthread_mutex_init( &mMutex, NULL );
        pthread_cond_init( &mCondition, NULL );
    }

and the destructor, the corresponding 'destroy' calls.