title: Celery: standard method for querying pending tasks?
body: <p>Is there any standard/backend-independent method for querying pending tasks based on certain fields?</p>
  
  <p>For example, I have a task which needs to run once after the “last user interaction”, and I'd like to implement it something like:</p>
  
  <pre><code>def user_changed_content():
      task = find_task(name="handle_content_change")
      if task is None:
          task = queue_task("handle_content_change")
      task.set_eta(datetime.now() + timedelta(minutes=5))
      task.save()
  </code></pre>
  
  <p>Or is it simpler to hook directly into the storage backend?</p>