Method start_loop

smallthinker/tools/server/server.cpp:1656–1699

* Main loop consists of these steps: * - Wait until a new task arrives * - Process the task (i.e. maybe copy data into slot) * - Check if multitask is finished * - Update all slots */

     * - Update all slots
     */
    void start_loop() {
        running = true;

        while (true) {
            QUE_DBG("%s", "processing new tasks\n");

            while (true) {
                std::unique_lock<std::mutex> lock(mutex_tasks);
                if (!running) {
                    QUE_DBG("%s", "terminate\n");
                    return;
                }
                if (queue_tasks.empty()) {
                    lock.unlock();
                    break;
                }
                server_task task = std::move(queue_tasks.front());
                queue_tasks.pop_front();
                lock.unlock();

                QUE_DBG("processing task, id = %d\n", task.id);
                callback_new_task(std::move(task));
            }

            // all tasks in the current loop is processed, slots data is now ready
            QUE_DBG("%s", "update slots\n");

            callback_update_slots();

            QUE_DBG("%s", "waiting for new tasks\n");
            {
                std::unique_lock<std::mutex> lock(mutex_tasks);
                if (!running) {
                    QUE_DBG("%s", "terminate\n");
                    return;
                }
                if (queue_tasks.empty()) {
                    condition_tasks.wait(lock, [&]{
                        return (!queue_tasks.empty() || !running);
                    });
                }
            }
        }
    }

private:
    void cleanup_pending_task(int id_target) {