org.killbill.billing.osgi.KillbillEventObservable Maven / Gradle / Ivy
/*
* Copyright 2010-2014 Ning, Inc.
* Copyright 2014-2020 Groupon, Inc
* Copyright 2020-2020 Equinix, Inc
* Copyright 2014-2020 The Billing Project, LLC
*
* The Billing Project 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.killbill.billing.osgi;
import java.lang.reflect.Field;
import java.util.Observable;
import java.util.Observer;
import java.util.Vector;
public class KillbillEventObservable extends Observable {
//
// Override notifyObservers from Observable to prevent from having to
// call setChanged and then notifyObservers, which are not atomic
// and can lead to losing events.
//
@Override
public void notifyObservers(final Object arg) {
final Vector obsCopy = getDeclaredField("obs");
final Object[] arrLocal = obsCopy.toArray();
for (int i = arrLocal.length - 1; i >= 0; i--) {
((Observer) arrLocal[i]).update(this, arg);
}
}
public void setChangedAndNotifyObservers(final Object event) {
setChanged();
notifyObservers(event);
}
//
// Ugly hack to access private field 'obs'
//
@SuppressWarnings("unchecked")
private T getDeclaredField(final String fieldName) {
try {
final Field f = Observable.class.getDeclaredField(fieldName);
f.setAccessible(true);
return (T) f.get(this);
} catch (final NoSuchFieldException e) {
throw new RuntimeException("Failed to retrieve private field from Observable class " + fieldName, e);
} catch (final IllegalAccessException e) {
throw new RuntimeException("Failed to retrieve private field from Observable class " + fieldName, e);
}
}
}