/**
* Subscribe the feed of publisher. To prevent cycles, a task can only subscribe to its ancestor.
* Feed is a generic form of execution-time feedback (type, value) pair from one task to another
* task. Examples include dynamic partitions (which are only available at execution time). The
* MoveTask may pass the list of dynamic partitions to the StatsTask since after the MoveTask the
* list of dynamic partitions are lost (MoveTask moves them to the table's destination directory
* which is mixed with old partitions).
*
* @param publisher this feed provider.
*/
public void subscribeFeed(Task<? extends Serializable> publisher) {
if (publisher != this && publisher.ancestorOrSelf(this)) {
if (publisher.getFeedSubscribers() == null) {
publisher.setFeedSubscribers(new LinkedList<Task<? extends Serializable>>());
}
publisher.getFeedSubscribers().add(this);
}
}
