EventManger.java
- /**
- *
- * Copyright 2015 Florian Schmaus
- *
- * 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.jivesoftware.smack.util;
- import java.util.Map;
- import java.util.concurrent.ConcurrentHashMap;
- /**
- * The event manager class is used to perform actions and wait for an event, which is usually caused by the action (or maybe never occurs).
- * <p>
- * Events are distinguished by an unique event key. They can produce an event result, which can simply be null.
- * </p>
- * <p>
- * The action is able to throw an exception.
- * </p>
- *
- * @param <K> the event key.
- * @param <R> the event result.
- * @param <E> the exception which could be thrown by the action.
- */
- public class EventManger<K, R, E extends Exception> {
- private final Map<K, Reference<R>> events = new ConcurrentHashMap<>();
- /**
- * Perform an action and wait for an event.
- * <p>
- * The event is signaled with {@link #signalEvent(Object, Object)}.
- * </p>
- *
- * @param eventKey the event key, must not be null.
- * @param timeout the timeout to wait for the event in milliseconds.
- * @param action the action to perform prior waiting for the event, must not be null.
- * @return the event value, may be null.
- * @throws InterruptedException if interrupted while waiting for the event.
- * @throws E depending on the concrete use case.
- */
- public R performActionAndWaitForEvent(K eventKey, long timeout, Callback<E> action) throws InterruptedException, E {
- final Reference<R> reference = new Reference<>();
- events.put(eventKey, reference);
- try {
- synchronized (reference) {
- action.action();
- reference.wait(timeout);
- }
- return reference.eventResult;
- }
- finally {
- events.remove(eventKey);
- }
- }
- /**
- * Signal an event and the event result.
- * <p>
- * This method will return <code>false</code> if the event was not created with
- * {@link #performActionAndWaitForEvent(Object, long, Callback)}.
- * </p>
- *
- * @param eventKey the event key, must not be null.
- * @param eventResult the event result, may be null.
- * @return true if the event was found and signaled, false otherwise.
- */
- public boolean signalEvent(K eventKey, R eventResult) {
- final Reference<R> reference = events.get(eventKey);
- if (reference == null) {
- return false;
- }
- reference.eventResult = eventResult;
- synchronized (reference) {
- reference.notifyAll();
- }
- return true;
- }
- private static class Reference<V> {
- volatile V eventResult;
- }
- public interface Callback<E extends Exception> {
- void action() throws E;
- }
- }