/*******************************************************************************
* Copyright (c) 2016 Bruno Medeiros and other Contributors.
* All rights reserved. This program and the accompanying materials
* are made available under the terms of the Eclipse Public License v1.0
* which accompanies this distribution, and is available at
* http://www.eclipse.org/legal/epl-v10.html
*
* Contributors:
* Bruno Medeiros - initial API and implementation
*******************************************************************************/
package melnorme.utilbox.concurrency;
import static melnorme.utilbox.core.Assert.AssertNamespace.assertTrue;
import java.util.concurrent.ExecutionException;
import java.util.concurrent.Future;
import java.util.concurrent.TimeUnit;
import java.util.concurrent.TimeoutException;
import melnorme.utilbox.core.fntypes.Result;
/**
* Variant of {@link Future} with a safer and more precise API, with regards to exception throwing:
*
* - Does not throw {@link ExecutionException}. If you want an Exception as a possible result, use {@link Result}.
* - If cancellation occurs, this throws a checked exception instead of an unchecked exception.
*
* @param <RESULT> The result type returned by the result methods.
* @param <EXCEPTION> The exception thrown by the result methods.
* It should not be {@link InterruptedException} or {@link OperationCancellation} !
*
* @see Future2
*
*/
public interface BasicFuture<RESULT> extends AsyncSupplier<RESULT> {
/** @return true if execution of this future has terminated already. */
boolean isTerminated();
/** @return true if execution of this future has terminated with a cancellation. */
boolean isCancelled();
/** @return true if terminated with a result, without being cancelled. */
default boolean isCompletedSuccessfully() {
return isTerminated() && !isCancelled();
}
/* ----------------- ----------------- */
void awaitTermination() throws InterruptedException;
void awaitTermination(long timeout, TimeUnit unit) throws InterruptedException, TimeoutException;
/**
* It is only legal to call this method if the future has terminated already.
* @return the result or throw OperationCancellation if cancelled.
*/
default RESULT getResult_forTerminated() throws OperationCancellation {
assertTrue(isTerminated());
if(isCancelled()) {
throw new OperationCancellation();
}
return getResult_forSuccessfulyCompleted();
}
/**
* It is only legal to call this method if the future has completed successfully.
* ({@link #isCompletedSuccessfully()} == true)
* @return the result or throw OperationCancellation if cancelled.
*/
RESULT getResult_forSuccessfulyCompleted();
/* ----------------- ----------------- */
@Override
default RESULT awaitResult()
throws OperationCancellation, InterruptedException {
awaitTermination();
return getResult_forTerminated();
}
@Override
default RESULT awaitResult(long timeout, TimeUnit unit)
throws OperationCancellation, InterruptedException, TimeoutException {
awaitTermination(timeout, unit);
return getResult_forTerminated();
}
}