Package org.eclipse.jetty.util

Class CountingCallback

java.lang.Object
org.eclipse.jetty.util.Callback.Completing
org.eclipse.jetty.util.Callback.Nested
org.eclipse.jetty.util.CountingCallback
All Implemented Interfaces:
Callback, Invocable
public class CountingCallback extends Callback.Nested

A callback wrapper that succeeds the wrapped callback when the count is reached, or on first failure.

This callback is particularly useful when an async operation is split into multiple parts, for example when an original byte buffer that needs to be written, along with a callback, is split into multiple byte buffers, since it allows the original callback to be wrapped and notified only when the last part has been processed.

Example:

 public void process(EndPoint endPoint, ByteBuffer buffer, Callback callback)
 {
     ByteBuffer[] buffers = split(buffer);
     CountCallback countCallback = new CountCallback(callback, buffers.length);
     endPoint.write(countCallback, buffers);
 }