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* ORACLE PROPRIETARY/CONFIDENTIAL. Use is subject to license terms.
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package javax.management;
import java.util.
Collections;
import java.util.
List;
import java.util.
Objects;
import java.util.concurrent.
CopyOnWriteArrayList;
import java.util.concurrent.
Executor;
import com.sun.jmx.remote.util.
ClassLogger;
/**
* <p>Provides an implementation of {@link
* javax.management.NotificationEmitter NotificationEmitter}
* interface. This can be used as the super class of an MBean that
* sends notifications.</p>
*
* <p>By default, the notification dispatch model is synchronous.
* That is, when a thread calls sendNotification, the
* <code>NotificationListener.handleNotification</code> method of each listener
* is called within that thread. You can override this default
* by overriding <code>handleNotification</code> in a subclass, or by passing an
* Executor to the constructor.</p>
*
* <p>If the method call of a filter or listener throws an {@link Exception},
* then that exception does not prevent other listeners from being invoked. However,
* if the method call of a filter or of {@code Executor.execute} or of
* {@code handleNotification} (when no {@code Excecutor} is specified) throws an
* {@link Error}, then that {@code Error} is propagated to the caller of
* {@link #sendNotification sendNotification}.</p>
*
* <p>Remote listeners added using the JMX Remote API (see JMXConnector) are not
* usually called synchronously. That is, when sendNotification returns, it is
* not guaranteed that any remote listeners have yet received the notification.</p>
*
* @since 1.5
*/
public class
NotificationBroadcasterSupport implements
NotificationEmitter {
/**
* Constructs a NotificationBroadcasterSupport where each listener is invoked by the
* thread sending the notification. This constructor is equivalent to
* {@link NotificationBroadcasterSupport#NotificationBroadcasterSupport(Executor,
* MBeanNotificationInfo[] info) NotificationBroadcasterSupport(null, null)}.
*/
public
NotificationBroadcasterSupport() {
this(null, (
MBeanNotificationInfo[]) null);
}
/**
* Constructs a NotificationBroadcasterSupport where each listener is invoked using
* the given {@link java.util.concurrent.Executor}. When {@link #sendNotification
* sendNotification} is called, a listener is selected if it was added with a null
* {@link NotificationFilter}, or if {@link NotificationFilter#isNotificationEnabled
* isNotificationEnabled} returns true for the notification being sent. The call to
* <code>NotificationFilter.isNotificationEnabled</code> takes place in the thread
* that called <code>sendNotification</code>. Then, for each selected listener,
* {@link Executor#execute executor.execute} is called with a command
* that calls the <code>handleNotification</code> method.
* This constructor is equivalent to
* {@link NotificationBroadcasterSupport#NotificationBroadcasterSupport(Executor,
* MBeanNotificationInfo[] info) NotificationBroadcasterSupport(executor, null)}.
* @param executor an executor used by the method <code>sendNotification</code> to
* send each notification. If it is null, the thread calling <code>sendNotification</code>
* will invoke the <code>handleNotification</code> method itself.
* @since 1.6
*/
public
NotificationBroadcasterSupport(
Executor executor) {
this(
executor, (
MBeanNotificationInfo[]) null);
}
/**
* <p>Constructs a NotificationBroadcasterSupport with information
* about the notifications that may be sent. Each listener is
* invoked by the thread sending the notification. This
* constructor is equivalent to {@link
* NotificationBroadcasterSupport#NotificationBroadcasterSupport(Executor,
* MBeanNotificationInfo[] info)
* NotificationBroadcasterSupport(null, info)}.</p>
*
* <p>If the <code>info</code> array is not empty, then it is
* cloned by the constructor as if by {@code info.clone()}, and
* each call to {@link #getNotificationInfo()} returns a new
* clone.</p>
*
* @param info an array indicating, for each notification this
* MBean may send, the name of the Java class of the notification
* and the notification type. Can be null, which is equivalent to
* an empty array.
*
* @since 1.6
*/
public
NotificationBroadcasterSupport(
MBeanNotificationInfo...
info) {
this(null,
info);
}
/**
* <p>Constructs a NotificationBroadcasterSupport with information about the notifications that may be sent,
* and where each listener is invoked using the given {@link java.util.concurrent.Executor}.</p>
*
* <p>When {@link #sendNotification sendNotification} is called, a
* listener is selected if it was added with a null {@link
* NotificationFilter}, or if {@link
* NotificationFilter#isNotificationEnabled isNotificationEnabled}
* returns true for the notification being sent. The call to
* <code>NotificationFilter.isNotificationEnabled</code> takes
* place in the thread that called
* <code>sendNotification</code>. Then, for each selected
* listener, {@link Executor#execute executor.execute} is called
* with a command that calls the <code>handleNotification</code>
* method.</p>
*
* <p>If the <code>info</code> array is not empty, then it is
* cloned by the constructor as if by {@code info.clone()}, and
* each call to {@link #getNotificationInfo()} returns a new
* clone.</p>
*
* @param executor an executor used by the method
* <code>sendNotification</code> to send each notification. If it
* is null, the thread calling <code>sendNotification</code> will
* invoke the <code>handleNotification</code> method itself.
*
* @param info an array indicating, for each notification this
* MBean may send, the name of the Java class of the notification
* and the notification type. Can be null, which is equivalent to
* an empty array.
*
* @since 1.6
*/
public
NotificationBroadcasterSupport(
Executor executor,
MBeanNotificationInfo...
info) {
this.
executor = (
executor != null) ?
executor :
defaultExecutor;
notifInfo =
info == null ?
NO_NOTIFICATION_INFO :
info.
clone();
}
/**
* Adds a listener.
*
* @param listener The listener to receive notifications.
* @param filter The filter object. If filter is null, no
* filtering will be performed before handling notifications.
* @param handback An opaque object to be sent back to the
* listener when a notification is emitted. This object cannot be
* used by the Notification broadcaster object. It should be
* resent unchanged with the notification to the listener.
*
* @exception IllegalArgumentException thrown if the listener is null.
*
* @see #removeNotificationListener
*/
public void
addNotificationListener(
NotificationListener listener,
NotificationFilter filter,
Object handback) {
if (
listener == null) {
throw new
IllegalArgumentException ("Listener can't be null") ;
}
listenerList.
add(new
ListenerInfo(
listener,
filter,
handback));
}
public void
removeNotificationListener(
NotificationListener listener)
throws
ListenerNotFoundException {
ListenerInfo wildcard = new
WildcardListenerInfo(
listener);
boolean
removed =
listenerList.
removeAll(
Collections.
singleton(
wildcard));
if (!
removed)
throw new
ListenerNotFoundException("Listener not registered");
}
public void
removeNotificationListener(
NotificationListener listener,
NotificationFilter filter,
Object handback)
throws
ListenerNotFoundException {
ListenerInfo li = new
ListenerInfo(
listener,
filter,
handback);
boolean
removed =
listenerList.
remove(
li);
if (!
removed) {
throw new
ListenerNotFoundException("Listener not registered " +
"(with this filter and " +
"handback)");
// or perhaps not registered at all
}
}
public
MBeanNotificationInfo[]
getNotificationInfo() {
if (
notifInfo.length == 0)
return
notifInfo;
else
return
notifInfo.
clone();
}
/**
* Sends a notification.
*
* If an {@code Executor} was specified in the constructor, it will be given one
* task per selected listener to deliver the notification to that listener.
*
* @param notification The notification to send.
*/
public void
sendNotification(
Notification notification) {
if (
notification == null) {
return;
}
boolean
enabled;
for (
ListenerInfo li :
listenerList) {
try {
enabled =
li.
filter == null ||
li.
filter.
isNotificationEnabled(
notification);
} catch (
Exception e) {
if (
logger.
debugOn()) {
logger.
debug("sendNotification",
e);
}
continue;
}
if (
enabled) {
executor.
execute(new
SendNotifJob(
notification,
li));
}
}
}
/**
* <p>This method is called by {@link #sendNotification
* sendNotification} for each listener in order to send the
* notification to that listener. It can be overridden in
* subclasses to change the behavior of notification delivery,
* for instance to deliver the notification in a separate
* thread.</p>
*
* <p>The default implementation of this method is equivalent to
* <pre>
* listener.handleNotification(notif, handback);
* </pre>
*
* @param listener the listener to which the notification is being
* delivered.
* @param notif the notification being delivered to the listener.
* @param handback the handback object that was supplied when the
* listener was added.
*
*/
protected void
handleNotification(
NotificationListener listener,
Notification notif,
Object handback) {
listener.
handleNotification(
notif,
handback);
}
// private stuff
private static class
ListenerInfo {
NotificationListener listener;
NotificationFilter filter;
Object handback;
ListenerInfo(
NotificationListener listener,
NotificationFilter filter,
Object handback) {
this.
listener =
listener;
this.
filter =
filter;
this.
handback =
handback;
}
@
Override
public boolean
equals(
Object o) {
if (!(
o instanceof
ListenerInfo))
return false;
ListenerInfo li = (
ListenerInfo)
o;
if (
li instanceof
WildcardListenerInfo)
return (
li.
listener ==
listener);
else
return (
li.
listener ==
listener &&
li.
filter ==
filter
&&
li.
handback ==
handback);
}
@
Override
public int
hashCode() {
return
Objects.
hashCode(
listener);
}
}
private static class
WildcardListenerInfo extends
ListenerInfo {
WildcardListenerInfo(
NotificationListener listener) {
super(
listener, null, null);
}
@
Override
public boolean
equals(
Object o) {
assert (!(
o instanceof
WildcardListenerInfo));
return
o.
equals(this);
}
@
Override
public int
hashCode() {
return super.hashCode();
}
}
private
List<
ListenerInfo>
listenerList =
new
CopyOnWriteArrayList<
ListenerInfo>();
// since 1.6
private final
Executor executor;
private final
MBeanNotificationInfo[]
notifInfo;
private final static
Executor defaultExecutor = new
Executor() {
// DirectExecutor using caller thread
public void
execute(
Runnable r) {
r.
run();
}
};
private static final
MBeanNotificationInfo[]
NO_NOTIFICATION_INFO =
new
MBeanNotificationInfo[0];
private class
SendNotifJob implements
Runnable {
public
SendNotifJob(
Notification notif,
ListenerInfo listenerInfo) {
this.
notif =
notif;
this.
listenerInfo =
listenerInfo;
}
public void
run() {
try {
handleNotification(
listenerInfo.
listener,
notif,
listenerInfo.
handback);
} catch (
Exception e) {
if (
logger.
debugOn()) {
logger.
debug("SendNotifJob-run",
e);
}
}
}
private final
Notification notif;
private final
ListenerInfo listenerInfo;
}
private static final
ClassLogger logger =
new
ClassLogger("javax.management", "NotificationBroadcasterSupport");
}