org.scijava.event.DefaultEventBus Maven / Gradle / Ivy
Go to download
Show more of this group Show more artifacts with this name
Show all versions of scijava-common Show documentation
Show all versions of scijava-common Show documentation
SciJava Common is a shared library for SciJava software. It provides a plugin framework, with an extensible mechanism for service discovery, backed by its own annotation processor, so that plugins can be loaded dynamically. It is used by downstream projects in the SciJava ecosystem, such as ImageJ and SCIFIO.
/*
* #%L
* SciJava Common shared library for SciJava software.
* %%
* Copyright (C) 2009 - 2017 Board of Regents of the University of
* Wisconsin-Madison, Broad Institute of MIT and Harvard, and Max Planck
* Institute of Molecular Cell Biology and Genetics.
* %%
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions are met:
*
* 1. Redistributions of source code must retain the above copyright notice,
* this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright notice,
* this list of conditions and the following disclaimer in the documentation
* and/or other materials provided with the distribution.
*
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
* AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
* ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDERS OR CONTRIBUTORS BE
* LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
* CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
* SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
* INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
* CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
* ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
* POSSIBILITY OF SUCH DAMAGE.
* #L%
*/
package org.scijava.event;
import java.lang.reflect.InvocationTargetException;
import java.lang.reflect.Type;
import java.util.Arrays;
import java.util.List;
import org.bushe.swing.event.CleanupEvent;
import org.bushe.swing.event.ThreadSafeEventService;
import org.scijava.log.LogService;
import org.scijava.service.Service;
import org.scijava.thread.ThreadService;
/**
* An {@link org.bushe.swing.event.EventService} implementation for SciJava.
*
* It is called "DefaultEventBus" rather than "DefaultEventService" to avoid a
* name clash with {@link DefaultEventService}, which is not an
* {@link org.bushe.swing.event.EventService} but rather a SciJava
* {@link Service} implementation.
*
*
* @author Curtis Rueden
*/
public class DefaultEventBus extends ThreadSafeEventService {
private final ThreadService threadService;
private final LogService log;
public DefaultEventBus(final ThreadService threadService,
final LogService log)
{
super(200L, false, null, null, null);
this.threadService = threadService;
this.log = log;
}
// -- DefaultEventBus methods --
public void publishNow(final Object event) {
if (event == null) {
throw new IllegalArgumentException("Cannot publish null event.");
}
publishNow(event, null, null, getSubscribers(event.getClass()),
getVetoSubscribers(event.getClass()), null);
}
public void publishNow(final Type genericType, final Object event) {
if (genericType == null) {
throw new IllegalArgumentException("genericType must not be null.");
}
if (event == null) {
throw new IllegalArgumentException("Cannot publish null event.");
}
publishNow(event, null, null, getSubscribers(genericType), null, null);
}
public void publishNow(final String topicName, final Object eventObj) {
publishNow(null, topicName, eventObj, getSubscribers(topicName),
getVetoEventListeners(topicName), null);
}
public void publishLater(final Object event) {
if (event == null) {
throw new IllegalArgumentException("Cannot publish null event.");
}
publishLater(event, null, null, getSubscribers(event.getClass()),
getVetoSubscribers(event.getClass()), null);
}
public void publishLater(final Type genericType, final Object event) {
if (genericType == null) {
throw new IllegalArgumentException("genericType must not be null.");
}
if (event == null) {
throw new IllegalArgumentException("Cannot publish null event.");
}
publishLater(event, null, null, getSubscribers(genericType), null, null);
}
public void publishLater(final String topicName, final Object eventObj) {
publishLater(null, topicName, eventObj, getSubscribers(topicName),
getVetoEventListeners(topicName), null);
}
// -- org.bushe.swing.event.EventService methods --
@Override
public void publish(final Object event) {
// HACK: Work around a deadlock problem caused by ThreadSafeEventService:
// 1) The ThreadSafeEventService superclass has a special cleanup thread
// that takes care of cleaning up stale references. Every time it runs, it
// publishes some CleanupEvents using publish(Object) to announce that this
// is occurring. Normally, such publication delegates to
// publishNow, which calls ThreadService#invoke, which calls
// EventQueue.invokeAndWait, which queues the publication for execution on
// the EDT and then blocks until publication is complete.
// 2) When the ThreadSafeEventService publishes the CleanupEvents, it does
// so inside a synchronized block that locks on a "listenerLock" object.
// 3) Unfortunately, since the CleanupEvent publication is merely *queued*,
// any other pending operations on the EDT happen first. If one such
// operation meanwhile calls e.g.
// ThreadSafeEventService#getSubscribers(Class), it will deadlock because
// those getter methods are also synchronized on the listenerLock object.
// Hence, our hack workaround is to instead use publishLater for the
// CleanupEvents, since no one really cares about them anyway. ;-)
if (event instanceof CleanupEvent) {
publishLater(event);
return;
}
publishNow(event);
}
@Override
public void publish(final Type genericType, final Object event) {
publishNow(genericType, event);
}
@Override
public void publish(final String topicName, final Object eventObj) {
publishNow(topicName, eventObj);
}
// -- Internal methods --
@Override
protected void publish(final Object event, final String topic,
final Object eventObj,
@SuppressWarnings("rawtypes") final List subscribers,
@SuppressWarnings("rawtypes") final List vetoSubscribers,
final StackTraceElement[] callingStack)
{
publishNow(event, topic, eventObj, subscribers, vetoSubscribers,
callingStack);
}
// -- Helper methods --
private void publishNow(final Object event, final String topic,
final Object eventObj,
@SuppressWarnings("rawtypes") final List subscribers,
@SuppressWarnings("rawtypes") final List vetoSubscribers,
final StackTraceElement[] callingStack)
{
if (subscribers == null || subscribers.isEmpty()) return;
try {
threadService.invoke(new Runnable() {
@Override
public void run() {
log.debug("publish(" + event + "," + topic + "," + eventObj +
"), called from non-EDT Thread:" + Arrays.toString(callingStack));
DefaultEventBus.super.publish(event, topic, eventObj, subscribers,
vetoSubscribers, callingStack);
}
});
}
catch (final InterruptedException exc) {
log.error(exc);
}
catch (final InvocationTargetException exc) {
log.error(exc);
}
}
private void publishLater(final Object event, final String topic,
final Object eventObj,
@SuppressWarnings("rawtypes") final List subscribers,
@SuppressWarnings("rawtypes") final List vetoSubscribers,
final StackTraceElement[] callingStack)
{
if (subscribers == null || subscribers.isEmpty()) return;
threadService.run(new Runnable() {
@Override
public void run() {
log.debug("publish(" + event + "," + topic + "," + eventObj +
"), called from non-EDT Thread:" + Arrays.toString(callingStack));
DefaultEventBus.super.publish(event, topic, eventObj, subscribers,
vetoSubscribers, callingStack);
}
});
}
}