[Qt-interest] Feeding a QThread from a QList

[Mike Blackwell]

I'm working on a class based on QThread that controls a piece of
hardware which I need to send commands to. The commands are queued in
a QList inside the class. The class run method waits for new commands
to appear in the list and executes them, emitting a signal with the
result. The class looks something like this:

class ComandRunner : public QThread
{
    Q_OBJECT
public:
    void run(void);

public slot:
    int addCommand(Command *cmd);

signals:
    void commandComplete(int id);

private:
    QList<Command *> m_commands;
    QMutex m_cmdAccess;
    QSemaphore m_cmdCount;
};

int CommandRunner::addCommand(Command *cmd)
{
    m_cmdAccess.lock();
    m_commands.append(cmd);
    m_cmdCount.release(1);
    m_cmdAccess.unlock();

    return cmd->m_ID;
}

void CommandRunner::run(void)
{
    while (1) {
        // Wait for a command to become available
        m_cmdCount.acquire(1);
        // Grab the fist command in the queue
        m_cmdAccess.lock();
        Command *cmd = m_commands.takeFirst();
        m_cmdAccess.unlock();
        // Execute command...
    }
}

A couple of questions about this. First, is the right (or a good)
approach? Using both a mutex and a semaphore seems slightly redundant.
Plus, the semaphore is basically mirroring the QList item count. Is
there a canonical way of maintaining a list of events for a thread to
execute? Second, I never call exec() from the run method. Will this
prevent me from using queued signals and slots to to communicate with
other threads? Is there a way to make this work in this framework?

Thanks for any advice!

Mike Blackwell