sshj/src/main/java/net/schmizz/concurrent/Event.java

/*
 * Copyright 2010 Shikhar Bhushan
 *
 * 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 net.schmizz.concurrent;

import java.util.concurrent.TimeUnit;
import java.util.concurrent.locks.ReentrantLock;

/*
 * Syntactic sugar around Future
 */

/**
 * A kind of {@link Future} that caters to boolean values.
 * <p/>
 * An event can be set, cleared, or awaited, similar to Python's {@code threading.event}. The key difference is that a
 * waiter may be delivered an exception of parameterized type {@code T}. Furthermore, an event {@link #isSet()} when it
 * is not {@code null} i.e. it can be either {@code true} or {@code false} when set.
 *
 * @see Future
 */
public class Event<T extends Throwable>
        extends Future<Boolean, T> {

    /**
     * Creates this event with given {@code name} and exception {@code chainer}. Allocates a new {@link
     * java.util.concurrent.locks.Lock Lock} object for this event.
     *
     * @param name    name of this event
     * @param chainer {@link ExceptionChainer} that will be used for chaining exceptions
     */
    public Event(String name, ExceptionChainer<T> chainer) {
        super(name, chainer);
    }

    /**
     * Creates this event with given {@code name}, exception {@code chainer}, and associated {@code lock}.
     *
     * @param name    name of this event
     * @param chainer {@link ExceptionChainer} that will be used for chaining exceptions
     * @param lock    lock to use
     */
    public Event(String name, ExceptionChainer<T> chainer, ReentrantLock lock) {
        super(name, chainer, lock);
    }

    /** Sets this event to be {@code true}. Short for {@code set(true)}. */
    public void set() {
        super.set(true);
    }

    /**
     * Await this event to have a definite {@code true} or {@code false} value.
     *
     * @throws T if another thread meanwhile informs this event of an error
     */
    public void await()
            throws T {
        super.get();
    }

    /**
     * Await this event to have a definite {@code true} or {@code false} value, for {@code timeout} duration.
     *
     * @param timeout timeout
     * @param unit    the time unit for the timeout
     *
     * @throws T if another thread meanwhile informs this event of an error, or timeout expires
     */
    public void await(long timeout, TimeUnit unit)
            throws T {
        super.get(timeout, unit);
    }

}