/**
* Executes a background task.
*
* <p>The task payload is either type Deferrable or Key; in the latter case, retrieve (then
* delete) the Deferrable instance from the datastore.
*/
@Override
public void doPost(HttpServletRequest req, HttpServletResponse res)
throws ServletException, IOException {
try {
Object payload = deserialize(req);
if (payload instanceof Key) {
// get Deferrable from datastore
Blob taskBlob = (Blob) getDatastoreService().get((Key) payload).getProperty(TASK_PROPERTY);
deleteEntity((Key) payload);
if (taskBlob != null) {
payload = deserialize(taskBlob.getBytes());
}
}
if (payload instanceof Deferrable) {
((Deferrable) payload).doTask();
} else if (payload != null) {
log.severe("invalid payload type: " + payload.getClass().getName());
// don't retry task
}
} catch (EntityNotFoundException e) {
log.severe(e.toString()); // don't retry task
} catch (PermanentTaskFailure e) {
log.severe(e.toString()); // don't retry task
}
}
