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/*
* The MIT License (MIT)
*
* Copyright (c) 2007-2024 Daniel Alievsky, AlgART Laboratory (http://algart.net)
*
* Permission is hereby granted, free of charge, to any person obtaining a copy
* of this software and associated documentation files (the "Software"), to deal
* in the Software without restriction, including without limitation the rights
* to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
* copies of the Software, and to permit persons to whom the Software is
* furnished to do so, subject to the following conditions:
*
* The above copyright notice and this permission notice shall be included in all
* copies or substantial portions of the Software.
*
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
* AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
* LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
* OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
* SOFTWARE.
*/
package net.algart.contexts;
import java.util.Objects;
/**
* The class allowing to execute some action, interruptible via standard Java technique,
* in terms of some {@link InterruptionContext}.
* This is a bridge between {@link InterruptionContext} and standard interruption technique
* based on thread.interrupt() and Thread.interrupted() calls.
*
* To use this class, please override its {@link #run()} method and call {@link #doInterruptibly()}.
*
* @param the type of the result data returned by this action.
*
* @author Daniel Alievsky
*/
public abstract class InterruptibleAction {
private final InterruptionContext context;
/**
* Creates an instance of this class with the given interruption context.
*
* @param context an interruption context that will be used for interruption of the action.
* @throws NullPointerException if the argument is {@code null}.
*/
protected InterruptibleAction(InterruptionContext context) {
Objects.requireNonNull(context, "Null context argument");
this.context = context;
}
/**
* Executes {@link #run()} method and returns its result.
*
* If the interruption context requests an interruption
* (i.e. an {@link InterruptionContext.Event interruption event} occurs),
* the current thread, executing {@link #run()} method, is interrupted
* by its interrupt() method.
* As a result, the {@link #run()} method should stop and
* throw the standard InterruptedException.
* This method catches it and translates into {@link InterruptionException} with the corresponding cause;
* this {@link InterruptionException} is thrown.
*
*
So, this method can be interrupted by both ways: by the standard
* thread.interrupt() call and by interruption mechanism
* provided by the {@link InterruptionContext}.
*
* @return the result of {@link #run()} method.
* @throws InterruptionException if the {@link #run()} method throws InterruptedException.
*/
public T doInterruptibly() throws InterruptionException {
final Thread currentThread = Thread.currentThread();
InterruptionContext.Listener listener = new InterruptionContext.Listener() {
public void interruptionRequested(InterruptionContext.Event event) {
currentThread.interrupt();
}
};
context.addInterruptionListener(listener);
try {
return run();
} catch (InterruptedException ex) {
throw new InterruptionException(ex);
} finally {
context.removeInterruptionListener(listener);
}
}
/**
* This method performs some action or throws InterruptedException
* in a case when the current thread is interrupted via thread.interrupt() call.
*
* @return the computed result.
* @throws InterruptedException if the current thread is interrupted via thread.interrupt() call.
*/
public abstract T run() throws InterruptedException;
}