| # Copyright 2017 The Chromium Authors. All rights reserved. |
| # Use of this source code is governed by a BSD-style license that can be |
| # found in the LICENSE file. |
| |
| from google.appengine.api import taskqueue |
| |
| from gae_libs import pipelines |
| |
| |
| class DelayPipeline(pipelines.AsynchronousPipeline): |
| """Delays pipeline execution by n seconds. |
| |
| Usage: |
| delay = yield DelayPipeline(<n seconds>) |
| with pipeline.After(delay): |
| DoSomethingAfterDelay() |
| """ |
| input_type = int |
| output_type = int |
| |
| def RunImpl(self, seconds): |
| task = self.get_callback_task( |
| countdown=seconds, name='delay-' + self.pipeline_id) |
| try: |
| task.add(self.queue_name) |
| except (taskqueue.TombstonedTaskError, |
| taskqueue.TaskAlreadyExistsError): # pragma: no cover |
| pass |
| |
| def CallbackImpl(self, seconds, _): |
| return None, seconds |
