/*
* Licensed to Elasticsearch under one or more contributor
* license agreements. See the NOTICE file distributed with
* this work for additional information regarding copyright
* ownership. Elasticsearch licenses this file to you under
* the Apache License, Version 2.0 (the "License"); you may
* not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing,
* software distributed under the License is distributed on an
* "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
* KIND, either express or implied. See the License for the
* specific language governing permissions and limitations
* under the License.
*/
package org.elasticsearch.action;
import java.util.concurrent.atomic.AtomicBoolean;
/**
* A listener that ensures that only one of onResponse or onFailure is called. And the method
* the is called is only called once. Subclasses should implement notification logic with
* innerOnResponse and innerOnFailure.
*/
public abstract class NotifyOnceListener<Response> implements ActionListener<Response> {
private final AtomicBoolean hasBeenCalled = new AtomicBoolean(false);
protected abstract void innerOnResponse(Response response);
protected abstract void innerOnFailure(Exception e);
@Override
public final void onResponse(Response response) {
if (hasBeenCalled.compareAndSet(false, true)) {
innerOnResponse(response);
}
}
@Override
public final void onFailure(Exception e) {
if (hasBeenCalled.compareAndSet(false, true)) {
innerOnFailure(e);
}
}
}