/*
 * Copyright (C) 2010, Google Inc.
 * and other copyright owners as documented in the project's IP log.
 *
 * This program and the accompanying materials are made available
 * under the terms of the Eclipse Distribution License v1.0 which
 * accompanies this distribution, is reproduced below, and is
 * available at http://www.eclipse.org/org/documents/edl-v10.php
 *
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or
 * without modification, are permitted provided that the following
 * conditions are met:
 *
 * - Redistributions of source code must retain the above copyright
 *   notice, this list of conditions and the following disclaimer.
 *
 * - Redistributions in binary form must reproduce the above
 *   copyright notice, this list of conditions and the following
 *   disclaimer in the documentation and/or other materials provided
 *   with the distribution.
 *
 * - Neither the name of the Eclipse Foundation, Inc. nor the
 *   names of its contributors may be used to endorse or promote
 *   products derived from this software without specific prior
 *   written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND
 * CONTRIBUTORS "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES,
 * INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR
 * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
 * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
 * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
 * CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
 * STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF
 * ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 */

package org.eclipse.jgit.lib;

/**
 * Asynchronous operation handle.
 *
 * Callers that start an asynchronous operation are supplied with a handle that
 * may be used to attempt cancellation of the operation if the caller does not
 * wish to continue.
 */
public interface AsyncOperation {
	/**
	 * Cancels the running task.
	 *
	 * Attempts to cancel execution of this task. This attempt will fail if the
	 * task has already completed, already been cancelled, or could not be
	 * cancelled for some other reason. If successful, and this task has not
	 * started when cancel is called, this task should never run. If the task
	 * has already started, then the mayInterruptIfRunning parameter determines
	 * whether the thread executing this task should be interrupted in an
	 * attempt to stop the task.
	 *
	 * @param mayInterruptIfRunning
	 *            true if the thread executing this task should be interrupted;
	 *            otherwise, in-progress tasks are allowed to complete
	 * @return false if the task could not be cancelled, typically because it
	 *         has already completed normally; true otherwise
	 */
	boolean cancel(boolean mayInterruptIfRunning);

	/**
	 * Release resources used by the operation, including cancellation.
	 */
	void release();
}