/*
* Autopsy Forensic Browser
*
* Copyright 2011-2015 Basis Technology Corp.
* Contact: carrier <at> sleuthkit <dot> org
*
* Licensed 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.sleuthkit.autopsy.events;
import java.beans.PropertyChangeListener;
import java.util.Map;
import java.util.Set;
import java.util.concurrent.ConcurrentHashMap;
import java.util.logging.Level;
import org.sleuthkit.autopsy.coreutils.Logger;
/**
* Provides thread-safe support for publishing events to registered subscribers
* on this Autopsy node. Subscribers are constrained to be
* PropertyChangeListeners to integrate with the legacy use of JavaBeans
* PropertyChangeEvents and PropertyChangeListeners as an application event
* system.
*/
final class LocalEventPublisher {
private static final Logger logger = Logger.getLogger(LocalEventPublisher.class.getName());
private final Map<String, Set<PropertyChangeListener>> subscribersByEvent;
/**
* Constructs an object for publishing events to registered subscribers on
* this Autopsy node.
*/
LocalEventPublisher() {
subscribersByEvent = new ConcurrentHashMap<>();
}
/**
* Adds an event subscriber to this publisher.
*
* @param eventNames The events the subscriber is interested in.
* @param subscriber The subscriber to add.
*/
void addSubscriber(Set<String> eventNames, PropertyChangeListener subscriber) {
for (String eventName : eventNames) {
addSubscriber(eventName, subscriber);
}
}
/**
* Adds an event subscriber to this publisher.
*
* @param eventName The event the subscriber is interested in.
* @param subscriber The subscriber to add.
*/
void addSubscriber(String eventName, PropertyChangeListener subscriber) {
subscribersByEvent.putIfAbsent(eventName, ConcurrentHashMap.<PropertyChangeListener>newKeySet());
Set<PropertyChangeListener> subscribers = subscribersByEvent.get(eventName);
subscribers.add(subscriber);
}
/**
* Removes an event subscriber from this publisher.
*
* @param eventNames The events the subscriber is no longer interested in.
* @param subscriber The subscriber to remove.
*/
void removeSubscriber(Set<String> eventNames, PropertyChangeListener subscriber) {
for (String eventName : eventNames) {
removeSubscriber(eventName, subscriber);
}
}
/**
* Removes an event subscriber from this publisher.
*
* @param eventNames The event the subscriber is no longer interested in.
* @param subscriber The subscriber to remove.
*/
void removeSubscriber(String eventName, PropertyChangeListener subscriber) {
Set<PropertyChangeListener> subscribers = subscribersByEvent.getOrDefault(eventName, null);
if (null != subscribers) {
subscribers.remove(subscriber);
}
}
/**
* Publishes an event to all registered subscribers, even if a subscriber
* throws an exception.
*
* @param event The event to be published.
*/
void publish(AutopsyEvent event) {
Set<PropertyChangeListener> subscribers = subscribersByEvent.getOrDefault(event.getPropertyName(), null);
if (null != subscribers) {
for (PropertyChangeListener subscriber : subscribers) {
try {
subscriber.propertyChange(event);
} catch (Exception ex) {
logger.log(Level.SEVERE, "Exception thrown by subscriber", ex); //NON-NLS
}
}
}
}
}