org.apache.tomcat.util.modeler.BaseNotificationBroadcaster Maven / Gradle / Ivy
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* Licensed to the Apache Software Foundation (ASF) under one or more
* contributor license agreements. See the NOTICE file distributed with
* this work for additional information regarding copyright ownership.
* The ASF 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.apache.tomcat.util.modeler;
import java.util.ArrayList;
import javax.management.ListenerNotFoundException;
import javax.management.MBeanNotificationInfo;
import javax.management.Notification;
import javax.management.NotificationBroadcaster;
import javax.management.NotificationFilter;
import javax.management.NotificationListener;
/**
* Implementation of NotificationBroadcaster for attribute
* change notifications. This class is used by BaseModelMBean to
* handle notifications of attribute change events to interested listeners.
*
*
* @author Craig R. McClanahan
* @author Costin Manolache
*/
public class BaseNotificationBroadcaster implements NotificationBroadcaster {
// ----------------------------------------------------------- Constructors
// ----------------------------------------------------- Instance Variables
/**
* The set of registered BaseNotificationBroadcasterEntry
* entries.
*/
protected ArrayList entries =
new ArrayList<>();
// --------------------------------------------------------- Public Methods
/**
* Add a notification event listener to this MBean.
*
* @param listener Listener that will receive event notifications
* @param filter Filter object used to filter event notifications
* actually delivered, or null for no filtering
* @param handback Handback object to be sent along with event
* notifications
*
* @exception IllegalArgumentException if the listener parameter is null
*/
@Override
public void addNotificationListener(NotificationListener listener,
NotificationFilter filter,
Object handback)
throws IllegalArgumentException {
synchronized (entries) {
// Optimization to coalesce attribute name filters
if (filter instanceof BaseAttributeFilter) {
BaseAttributeFilter newFilter = (BaseAttributeFilter) filter;
for (BaseNotificationBroadcasterEntry item : entries) {
if ((item.listener == listener) &&
(item.filter != null) &&
(item.filter instanceof BaseAttributeFilter) &&
(item.handback == handback)) {
BaseAttributeFilter oldFilter =
(BaseAttributeFilter) item.filter;
String newNames[] = newFilter.getNames();
String oldNames[] = oldFilter.getNames();
if (newNames.length == 0) {
oldFilter.clear();
} else {
if (oldNames.length != 0) {
for (String newName : newNames) {
oldFilter.addAttribute(newName);
}
}
}
return;
}
}
}
// General purpose addition of a new entry
entries.add(new BaseNotificationBroadcasterEntry
(listener, filter, handback));
}
}
/**
* Return an MBeanNotificationInfo object describing the
* notifications sent by this MBean.
*/
@Override
public MBeanNotificationInfo[] getNotificationInfo() {
return new MBeanNotificationInfo[0];
}
/**
* Remove a notification event listener from this MBean.
*
* @param listener The listener to be removed (any and all registrations
* for this listener will be eliminated)
*
* @exception ListenerNotFoundException if this listener is not
* registered in the MBean
*/
@Override
public void removeNotificationListener(NotificationListener listener)
throws ListenerNotFoundException {
synchronized (entries) {
entries.removeIf(item -> item.listener == listener);
}
}
/**
* Send the specified notification to all interested listeners.
*
* @param notification The notification to be sent
*/
public void sendNotification(Notification notification) {
synchronized (entries) {
for (BaseNotificationBroadcasterEntry item : entries) {
if ((item.filter != null) &&
(!item.filter.isNotificationEnabled(notification))) {
continue;
}
item.listener.handleNotification(notification, item.handback);
}
}
}
}
/**
* Utility class representing a particular registered listener entry.
*/
class BaseNotificationBroadcasterEntry {
public BaseNotificationBroadcasterEntry(NotificationListener listener,
NotificationFilter filter,
Object handback) {
this.listener = listener;
this.filter = filter;
this.handback = handback;
}
public NotificationFilter filter = null;
public Object handback = null;
public NotificationListener listener = null;
}