org.eclipse.jetty.util.IteratingNestedCallback Maven / Gradle / Ivy
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// Copyright (c) 1995-2022 Mort Bay Consulting Pty Ltd and others.
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// are made available under the terms of the Eclipse Public License v1.0
// and Apache License v2.0 which accompanies this distribution.
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// http://www.eclipse.org/legal/epl-v10.html
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// The Apache License v2.0 is available at
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package org.eclipse.jetty.util;
/**
* 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 {@link #succeeded()} on this call back represents
* completion of the subtask. Only once all the subtasks are completed is
* the {@link Callback#succeeded()} method called on the {@link Callback} instance
* passed the the {@link #IteratingNestedCallback(Callback)} constructor.
*/
public abstract class IteratingNestedCallback extends IteratingCallback
{
final Callback _callback;
public IteratingNestedCallback(Callback callback)
{
_callback = callback;
}
@Override
public InvocationType getInvocationType()
{
return _callback.getInvocationType();
}
@Override
protected void onCompleteSuccess()
{
_callback.succeeded();
}
@Override
protected void onCompleteFailure(Throwable x)
{
_callback.failed(x);
}
@Override
public String toString()
{
return String.format("%s@%x", getClass().getSimpleName(), hashCode());
}
}