Method dequeue

src/threaded_queue.hh:121–136

Get the first element from the queue. Blocks until one is available.

  // Get the first element from the queue. Blocks until one is available.
  T dequeue(int keep_only_latest = 0) {
    std::unique_lock<std::mutex> lock(mutex_);
    waiter_->cv.wait(lock, [&]() { return !priority_.empty() || !queue_.empty(); });

    auto execute = [&](std::deque<T> *q) {
      if (keep_only_latest > 0 && q->size() > keep_only_latest)
        q->erase(q->begin(), q->end() - keep_only_latest);
      auto val = std::move(q->front());
      q->pop_front();
      --total_count_;
      return val;
    };
    if (!priority_.empty())
      return execute(&priority_);
    return execute(&queue_);
  }

  // Get the first element from the queue without blocking. Returns a null
  // value if the queue is empty.