This adds the NotificationBroadcasterSupport class. Changelog:
2007-01-21 Andrew John Hughes <[EMAIL PROTECTED]>
* javax/management/NotificationBroadcasterSupport.java:
New file.
--
Andrew :-)
Escape the Java Trap with GNU Classpath!
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Index: javax/management/NotificationBroadcasterSupport.java
===================================================================
RCS file: javax/management/NotificationBroadcasterSupport.java
diff -N javax/management/NotificationBroadcasterSupport.java
--- /dev/null 1 Jan 1970 00:00:00 -0000
+++ javax/management/NotificationBroadcasterSupport.java 21 Jan 2007
02:45:38 -0000
@@ -0,0 +1,390 @@
+/* NotificationBroadcasterSupport.java -- Supporting implementation.
+ Copyright (C) 2007 Free Software Foundation, Inc.
+
+This file is part of GNU Classpath.
+
+GNU Classpath is free software; you can redistribute it and/or modify
+it under the terms of the GNU General Public License as published by
+the Free Software Foundation; either version 2, or (at your option)
+any later version.
+
+GNU Classpath is distributed in the hope that it will be useful, but
+WITHOUT ANY WARRANTY; without even the implied warranty of
+MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
+General Public License for more details.
+
+You should have received a copy of the GNU General Public License
+along with GNU Classpath; see the file COPYING. If not, write to the
+Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
+02110-1301 USA.
+
+Linking this library statically or dynamically with other modules is
+making a combined work based on this library. Thus, the terms and
+conditions of the GNU General Public License cover the whole
+combination.
+
+As a special exception, the copyright holders of this library give you
+permission to link this library with independent modules to produce an
+executable, regardless of the license terms of these independent
+modules, and to copy and distribute the resulting executable under
+terms of your choice, provided that you also meet, for each linked
+independent module, the terms and conditions of the license of that
+module. An independent module is a module which is not derived from
+or based on this library. If you modify this library, you may extend
+this exception to your version of the library, but you are not
+obligated to do so. If you do not wish to do so, delete this
+exception statement from your version. */
+
+package javax.management;
+
+import gnu.classpath.ListenerData;
+
+import java.util.ArrayList;
+import java.util.Iterator;
+import java.util.List;
+
+import java.util.concurrent.Executor;
+
+/**
+ * <p>
+ * Provides an implementation of the [EMAIL PROTECTED] NotificationEmitter}
+ * interface, which beans may utilise by extension. By default,
+ * a synchronous dispatch system is provided, whereby the
+ * [EMAIL PROTECTED] #handleNotification(NotificationListener, Notification,
+ * Object)} is called once per listener by
+ * [EMAIL PROTECTED] #sendNotification(Notification)} before returning.
+ * Thus, unless the listener is remote, it will have received
+ * the notification before the method returns.
+ * This may be changed by overriding the <code>handleNotification</code>
+ * method, or by providing an [EMAIL PROTECTED] java.util.concurrent.Executor}
to
+ * use. With the latter, the dispatch of a notification to a particular
+ * listener will form one task performed by the executor.
+ * </p>
+ * <p>
+ * Any exceptions thrown by the dispatch process will be caught, allowing
+ * other listeners to still receive the notification. However, any
+ * [EMAIL PROTECTED] Error}s that are thrown will be propogated to the caller
of
+ * [EMAIL PROTECTED] #sendNotification(Notification)}.
+ * </p>
+ *
+ * @author Andrew John Hughes ([EMAIL PROTECTED])
+ * @since 1.5
+ */
+public class NotificationBroadcasterSupport
+ implements NotificationEmitter
+{
+
+ /**
+ * The executor for dispatch, or
+ * <code>null</code> if this thread should
+ * handle dispatch itself.
+ */
+ private Executor executor;
+
+ /**
+ * An array containing information on each
+ * notification, or <code>null</code> if an
+ * empty array should be returned by
+ * [EMAIL PROTECTED] #getNotificationInfo()}.
+ */
+ private MBeanNotificationInfo[] info;
+
+ /**
+ * The list of listeners registered with
+ * this broadcaster.
+ */
+ private final List<ListenerData> listeners =
+ new ArrayList<ListenerData>();
+
+ /**
+ * Constructs a [EMAIL PROTECTED] NotificationBroadcasterSupport} using
+ * the default synchronous dispatch model, where a single
+ * thread sends the notification to all listeners. This
+ * is equivalent to calling
+ * <code>NotificationBroadcasterSupport(null, null)</code>.
+ */
+ public NotificationBroadcasterSupport()
+ {
+ this(null, null);
+ }
+
+ /**
+ * Constructs a [EMAIL PROTECTED] NotificationBroadcasterSupport} where
+ * the specified (@link java.util.concurrent.Executor} is used
+ * to perform each invocation of the
+ * [EMAIL PROTECTED] #handleNotification(NotificationListener, Notification,
+ * Object)} method. Filtering is performed beforehand, by this
+ * thread; only calls which have successfully passed through the
+ * filter are sent to the executor. This is equivalent to calling
+ * <code>NotificationBroadcasterSupport(executor, null)</code>.
+ *
+ * @param executor the executor to use for each call to
+ * <code>handleNotification()</code>.
+ * @since 1.6
+ */
+ public NotificationBroadcasterSupport(Executor executor)
+ {
+ this(executor, null);
+ }
+
+ /**
+ * Constructs a [EMAIL PROTECTED] NotificationBroadcasterSupport} using
+ * the default synchronous dispatch model, where a single
+ * thread sends the notification to all listeners. The specified
+ * [EMAIL PROTECTED] MBeanNotificationInfo} array is used to provide
+ * information about the notifications on calls to
+ * [EMAIL PROTECTED] #getNotificationInfo()}, where a clone will be
+ * returned if the array is non-empty. This is equivalent to
+ * calling <code>NotificationBroadcasterSupport(null, info)</code>.
+ *
+ * @param info an array of [EMAIL PROTECTED] MBeanNotificationInfo} objects
+ * describing the notifications delivered by this
+ * broadcaster. This may be <code>null</code>, which
+ * is taken as being equivalent to an empty array.
+ */
+ public NotificationBroadcasterSupport(MBeanNotificationInfo... info)
+ {
+ this(null, info);
+ }
+
+ /**
+ * Constructs a [EMAIL PROTECTED] NotificationBroadcasterSupport} where
+ * the specified (@link java.util.concurrent.Executor} is used
+ * to perform each invocation of the
+ * [EMAIL PROTECTED] #handleNotification(NotificationListener, Notification,
+ * Object)} method. Filtering is performed beforehand, by this
+ * thread; only calls which have successfully passed through the
+ * filter are sent to the executor. The specified
+ * [EMAIL PROTECTED] MBeanNotificationInfo} array is used to provide
+ * information about the notifications on calls to
+ * [EMAIL PROTECTED] #getNotificationInfo()}, where a clone will be
+ * returned if the array is non-empty.
+ *
+ * @param executor the executor to use for each call to
+ * <code>handleNotification()</code>.
+ * @param info an array of [EMAIL PROTECTED] MBeanNotificationInfo} objects
+ * describing the notifications delivered by this
+ * broadcaster. This may be <code>null</code>, which
+ * is taken as being equivalent to an empty array.
+ * @since 1.6
+ */
+ public NotificationBroadcasterSupport(Executor executor,
+ MBeanNotificationInfo... info)
+ {
+ this.executor = executor;
+ this.info = info;
+ }
+
+ /**
+ * Registers the specified listener as a new recipient of
+ * notifications from this bean. If non-null, the filter
+ * argument will be used to select which notifications are
+ * delivered. The supplied object will also be passed to
+ * the recipient with each notification. This should not
+ * be modified by the broadcaster, but instead should be
+ * passed unmodified to the listener.
+ *
+ * @param listener the new listener, who will receive
+ * notifications from this broadcasting bean.
+ * @param filter a filter to determine which notifications are
+ * delivered to the listener, or <code>null</code>
+ * if no filtering is required.
+ * @param passback an object to be passed to the listener with
+ * each notification.
+ * @throws IllegalArgumentException if <code>listener</code> is
+ * <code>null</code>.
+ * @see #removeNotificationListener(NotificationListener)
+ */
+ public void addNotificationListener(NotificationListener listener,
+ NotificationFilter filter,
+ Object passback)
+ throws IllegalArgumentException
+ {
+ if (listener == null)
+ throw new IllegalArgumentException("Null listener added to bean.");
+ listeners.add(new ListenerData(listener, filter, passback));
+ }
+
+ /**
+ * Returns an array describing the notifications this
+ * bean may send to its registered listeners. Ideally, this
+ * array should be complete, but in some cases, this may
+ * not be possible. However, be aware that some listeners
+ * may expect this to be so.
+ *
+ * @return the array of possible notifications.
+ */
+ public MBeanNotificationInfo[] getNotificationInfo()
+ {
+ if (info == null || info.length == 0)
+ return new MBeanNotificationInfo[0];
+ return info.clone();
+ }
+
+ /**
+ * This method is called on a per-listener basis, either
+ * from this thread or the supplied executor, and may be
+ * overridden by subclasses which wish to change how
+ * notifications are delivered. The default
+ * implementation simply calls
+ * <code>listener.handleNotification(notif, passback)</code>.
+ *
+ * @param listener the listener to send the notification to.
+ * @param notif the notification to dispatch.
+ * @param passback the passback object of the listener.
+ */
+ protected void handleNotification(NotificationListener listener,
+ Notification notif,
+ Object passback)
+ {
+ listener.handleNotification(notif, passback);
+ }
+
+ /**
+ * Removes the specified listener from the list of recipients
+ * of notifications from this bean. This includes all combinations
+ * of filters and passback objects registered for this listener.
+ * For more specific removal of listeners, see the subinterface
+ * [EMAIL PROTECTED] NotificationEmitter}.
+ *
+ * @param listener the listener to remove.
+ * @throws ListenerNotFoundException if the specified listener
+ * is not registered with this bean.
+ * @see #addNotificationListener(NotificationListener, NotificationFilter,
+ * java.lang.Object)
+ */
+ public void removeNotificationListener(NotificationListener listener)
+ throws ListenerNotFoundException
+ {
+ Iterator<ListenerData> it = listeners.iterator();
+ boolean foundOne = false;
+ while (it.hasNext())
+ {
+ if (it.next().getListener() == listener)
+ {
+ it.remove();
+ foundOne = true;
+ }
+ }
+ if (!foundOne)
+ throw new ListenerNotFoundException("The specified listener, " +
listener +
+ "is not registered with this bean.");
+ }
+
+ /**
+ * Removes the specified listener from the list of recipients
+ * of notifications from this bean. Only the first instance with
+ * the supplied filter and passback object is removed.
+ * <code>null</code> is used as a valid value for these parameters,
+ * rather than as a way to remove all registration instances for
+ * the specified listener; for this behaviour instead, see the details
+ * of the same method in [EMAIL PROTECTED] NotificationBroadcaster}.
+ *
+ * @param listener the listener to remove.
+ * @param filter the filter of the listener to remove.
+ * @param passback the passback object of the listener to remove.
+ * @throws ListenerNotFoundException if the specified listener
+ * is not registered with this bean.
+ * @see #addNotificationListener(NotificationListener, NotificationFilter,
+ * java.lang.Object)
+ */
+ public void removeNotificationListener(NotificationListener listener,
+ NotificationFilter filter,
+ Object passback)
+ throws ListenerNotFoundException
+ {
+ if (!(listeners.remove(new ListenerData(listener, filter, passback))))
+ {
+ throw new ListenerNotFoundException("The specified listener, " +
listener +
+ " with filter " + filter +
+ "and passback " + passback +
+ ", is not registered with this
bean.");
+ }
+ }
+
+ /**
+ * <p>
+ * Performs delivery of the notification. If an executor
+ * was specified on construction, this will be used to call
+ * [EMAIL PROTECTED] #handleNotification(NotificationListener, Notification,
+ * Object)}. If the executor is <code>null</code>, however,
+ * this thread calls the method itself in order to perform a
+ * synchronous dispatch of the notification to all eligible
+ * listeners.
+ * </p>
+ * <p>
+ * Prior to either process taking place, the listeners are filtered.
+ * Notifications are only delivered if the filter is either
+ * <code>null</code> or returns true from the
+ * [EMAIL PROTECTED] NotificationFilter#isNotificationEnabled(Notification)}
+ * method.
+ * </p>
+ *
+ * @param notif the notification to send.
+ */
+ public void sendNotification(Notification notif)
+ {
+ for (ListenerData ldata : listeners)
+ {
+ NotificationFilter filter = ldata.getFilter();
+ if (filter == null || filter.isNotificationEnabled(notif))
+ {
+ if (executor == null)
+ try
+ {
+ handleNotification(ldata.getListener(), notif,
+ ldata.getPassback());
+ }
+ catch (Exception e) { /* Ignore */ }
+ else
+ executor.execute(new DispatchTask(ldata, notif));
+ }
+ }
+ }
+
+ /**
+ * The dispatch task to be performed by an executor.
+ */
+ private final class DispatchTask
+ implements Runnable
+ {
+
+ /**
+ * The data on the listener being called.
+ */
+ private ListenerData ldata;
+
+ /**
+ * The notification to send.
+ */
+ private Notification notif;
+
+ /**
+ * Construct a new [EMAIL PROTECTED] DispatchTask}.
+ *
+ * @param ldata the listener data.
+ * @param notif the notification to send.
+ */
+ public DispatchTask(ListenerData ldata,
+ Notification notif)
+ {
+ this.ldata = ldata;
+ this.notif = notif;
+ }
+
+ /**
+ * Dispatch the notification.
+ */
+ public void run()
+ {
+ try
+ {
+ handleNotification(ldata.getListener(), notif,
+ ldata.getPassback());
+ }
+ catch (Exception e) { /* Ignore */ }
+ }
+ }
+
+}
+
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