/*

 * Copyright 2007-2009 Sun Microsystems, Inc.  All Rights Reserved.

 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.

 *

 * This code is free software; you can redistribute it and/or modify it

 * under the terms of the GNU General Public License version 2 only, as

 * published by the Free Software Foundation.  Sun designates this

 * particular file as subject to the "Classpath" exception as provided

 * by Sun in the LICENSE file that accompanied this code.

 *

 * This code is distributed in the hope that it will be useful, but WITHOUT

 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or

 * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License

 * version 2 for more details (a copy is included in the LICENSE file that

 * accompanied this code).

 *

 * You should have received a copy of the GNU General Public License version

 * 2 along with this work; if not, write to the Free Software Foundation,

 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.

 *

 * Please contact Sun Microsystems, Inc., 4150 Network Circle, Santa Clara,

 * CA 95054 USA or visit www.sun.com if you need additional information or

 * have any questions.

 */

package java.nio.channels;

/**

 * A handler for consuming the result of an asynchronous I/O operation.

 *

 * <p> The asynchronous channels defined in this package allow a completion

 * handler to be specified to consume the result of an asynchronous operation.

 * The {@link #completed completed} method is invoked when the I/O operation

 * completes successfully. The {@link #failed failed} method is invoked if the

 * I/O operations fails. The {@link #cancelled cancelled} method is invoked when

 * the I/O operation is cancelled by invoking the {@link

 * java.util.concurrent.Future#cancel cancel} method. The implementations of

 * these methods should complete in a timely manner so as to avoid keeping the

 * invoking thread from dispatching to other completion handlers.

 *

 * @param   <V>     The result type of the I/O operation

 * @param   <A>     The type of the object attached to the I/O operation

 *

 * @since 1.7

 */

public interface CompletionHandler<V,A> {

    /**

     * Invoked when an operation has completed.

     *

     * @param   result

     *          The result of the I/O operation.

     * @param   attachment

     *          The object attached to the I/O operation when it was initiated.

     */

    void completed(V result, A attachment);

    /**

     * Invoked when an operation fails.

     *

     * @param   exc

     *          The exception to indicate why the I/O operation failed

     * @param   attachment

     *          The object attached to the I/O operation when it was initiated.

     */

    void failed(Throwable exc, A attachment);

    /**

     * Invoked when an operation is cancelled by invoking the {@link

     * java.util.concurrent.Future#cancel cancel} method.

     *

     * @param   attachment

     *          The object attached to the I/O operation when it was initiated.

     */

    void cancelled(A attachment);

}