001/**
002 * Copyright (c) 2008-2009 Apple Inc. All rights reserved.
003 * Copyright (C) 2009-2010, Progress Software Corporation and/or its
004 * subsidiaries or affiliates.  All rights reserved.
005
006 * Licensed under the Apache License, Version 2.0 (the "License");
007 * you may not use this file except in compliance with the License.
008 * You may obtain a copy of the License at
009 *
010 *     http://www.apache.org/licenses/LICENSE-2.0
011 *
012 * Unless required by applicable law or agreed to in writing, software
013 * distributed under the License is distributed on an "AS IS" BASIS,
014 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
015 * See the License for the specific language governing permissions and
016 * limitations under the License.
017 */
018package org.fusesource.hawtdispatch;
019
020/**
021 * <p>
022 * Implemented by dispatch objects which use a reference counted life cycle.
023 * </p><p>
024 * Dispatch objects start with a retained count of one.  Retaining the object increments the retain counter,
025 * releasing, decrements the counter.  When the counter reaches zero, the object should
026 * not longer be accessed as it will release any resources it needs to perform normal
027 * processing.
028 * </p>
029 *
030 * @author <a href="http://hiramchirino.com">Hiram Chirino</a>
031 */
032public interface Retained {
033
034    /**
035     * <p>
036     * Increment the reference count of this object.
037     * </p>
038     *
039     * Calls to {@link #retain()} must be balanced with calls to
040     * {@link #release()}.
041     */
042    public void retain();
043
044    /**
045     * <p>
046     * Decrement the reference count of this object.
047     * </p><p>
048     * An object is asynchronously disposed once all references are
049     * released. Using a disposed object will cause undefined errors.
050     * The system does not guarantee that a given client is the last or
051     * only reference to a given object.
052     * </p>
053     */
054    public void release();
055
056    /**
057     * @return the retained counter
058     */
059    public int retained();
060
061
062    /**
063     * <p>
064     * Adds a disposer runnable that is executed once the object is disposed.
065     * </p><p>
066     * A dispatch object's disposer runnable will be invoked on the object's target queue
067     * once the object's retain counter reaches zero. This disposer may be
068     * used by the application to release any resources associated with the object.
069     * </p>
070     *
071     * @param disposer
072     */
073//    public void setDisposer(Runnable disposer);
074
075}