Class IteratingNestedCallback

java.lang.Object
org.eclipse.jetty.util.IteratingCallback
org.eclipse.jetty.util.IteratingNestedCallback
All Implemented Interfaces:
Callback, Invocable
Direct Known Subclasses:
ContentCopier

public abstract class IteratingNestedCallback extends IteratingCallback
Iterating Nested Callback.

This specialized callback is used when breaking up an asynchronous task into smaller asynchronous tasks. A typical pattern is that a successful callback is used to schedule the next sub task, but if that task completes quickly and uses the calling thread to callback the success notification, this can result in a growing stack depth.

To avoid this issue, this callback uses an AtomicBoolean to note if the success callback has been called during the processing of a sub task, and if so then the processing iterates rather than recurses.

This callback is passed to the asynchronous handling of each sub task and a call the IteratingCallback.succeeded() on this call back represents completion of the subtask. Only once all the subtasks are completed is the Callback.succeeded() method called on the Callback instance passed the the IteratingNestedCallback(Callback) constructor.