c++ - boost 获取锁失败

Question

我正在开发一个实时音乐应用程序。作为新手使用 boost 库。我使用 protected SyncronizedQueue 实现了生产者/消费者关系，实际上我实现了 https://www.quantnet.com/cplusplus-multithreading-boost/ 的 18.11 和 18.12 部分。 .解析 midi 输入时出现以下异常:

terminate called after throwing an instance of 'boost::exception_detail::clone_impl
<boost::exception_detail::error_info_injector<boost::lock_error> >'
what():  boost::lock_error

producer中解析输入的代码:

RtMidiIn *midiin = new RtMidiIn();
std::vector<unsigned char> message;
int nBytes, i;
double stamp;
m_queue=queue;        

// Check available ports.
unsigned int nPorts = midiin->getPortCount();
if ( nPorts == 0 ) {
    std::cout << "No ports available!\n";
    goto cleanup;
}

midiin->openPort( 1 );

// Don't ignore sysex, timing, or active sensing messages.
midiin->ignoreTypes( false, false, false );

// Install an interrupt handler function.
done = false;
(void) signal(SIGINT, finish);

// Periodically check input queue.
std::cout << "Reading MIDI from port ... quit with Ctrl-C.\n";
while ( !done ) {
  stamp = midiin->getMessage( &message );
  nBytes = message.size();
  if(nBytes>0){
    if((message.size()!=1)&&((int)message.at(0)!=137)){
            for ( i=0; i<nBytes; i++ )
            std::cout << "Byte " << i << " = " << (int)message[i] << ", ";
            if ( nBytes > 0 )
            std::cout << "stamp = " << stamp << std::endl;
            m_queue->Enqueue("asd");
    }
}
}

它在第一次遇到时就崩溃了:

m_queue->Enqueue("asd");

尝试执行时:

boost::unique_lock<boost::mutex> lock(m_mutex);

感谢任何帮助!

编辑1:

这是 SynchronizedQueue 对象。调用 Enqueue() 时抛出异常。

template <typename T>
class SynchronizedQueue
{
private:
    std::queue<T> m_queue;                      // Use STL queue to store data
    mutable boost::mutex m_mutex;                       // The mutex to synchronise on
    boost::condition_variable m_cond;       // The condition to wait for

public:

    // Add data to the queue and notify others
    void Enqueue(const T& data)
    {
        // Acquire lock on the queue
            boost::unique_lock<boost::mutex> lock(m_mutex);
        // Add the data to the queue
        m_queue.push(data);
            // Notify others that data is ready
        m_cond.notify_one();
        } // Lock is automatically released here

    // Get data from the queue. Wait for data if not available
    T Dequeue()
    {

        // Acquire lock on the queue
        boost::unique_lock<boost::mutex> lock(m_mutex);
        //lock();
        // When there is no data, wait till someone fills it.
        // Lock is automatically released in the wait and obtained 
        // again after the wait
        while (m_queue.size()==0) m_cond.wait(lock);

        // Retrieve the data from the queue
        T result=m_queue.front(); m_queue.pop();
        return result;
    } // Lock is automatically released here
};

Answer 1

大多数时候，当我遇到这样的问题时，是因为被锁定的互斥量已经被破坏或尚未构建。您确定，当解析器线程开始解析时，您传递给解析器的队列已经构建好了吗？或者可能是，包含队列作为局部变量的循环的退出停止了？也许您可以进行快速测试并向队列中添加一个 d'tor 并在那里设置一个断点。

问候托尔斯滕