| gvSIG desktop 1

/* gvSIG. Geographic Information System of the Valencian Government

 *

 * Copyright (C) 2007-2008 Infrastructures and Transports Department

 * of the Valencian Government (CIT)

 * 

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

 * modify it under the terms of the GNU General Public License

 * as published by the Free Software Foundation; either version 2

 * of the License, or (at your option) any later version.

 * 

 * This program 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 for more details.

 * 

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

 * along with this program; if not, write to the Free Software

 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, 

 * MA  02110-1301, USA.

 * 

 */

/*

 * AUTHORS (In addition to CIT):

 * 2009 {}  {{Task}}

 */

package org.gvsig.tools.dispose.impl;

import java.lang.ref.Reference;

import java.lang.ref.ReferenceQueue;

import java.lang.ref.WeakReference;

import java.util.Iterator;

import java.util.LinkedHashSet;

import java.util.Set;

import org.gvsig.tools.dispose.Disposable;

import org.gvsig.tools.dispose.DisposableManager;

import org.gvsig.tools.exception.BaseException;

/**

 * Default implementation for the {@link DisposableManager}.

 * 

 * @author 2009- <a href="cordinyana@gvsig.org">C?sar Ordi?ana</a> - gvSIG team

 */

public class WeakReferencingDisposableManager implements DisposableManager {

        private static final int MAX_QUEUE_ITERATIONS = 10;

        private Set boundDisposables;

        private ReferenceQueue referenceQueue;

        private final int maxQueueIterations;

        public WeakReferencingDisposableManager() {

                this(MAX_QUEUE_ITERATIONS);

        }

        public WeakReferencingDisposableManager(int maxQueueIterations) {

                this.maxQueueIterations = maxQueueIterations;

                boundDisposables = new LinkedHashSet();

                referenceQueue = new ReferenceQueue();

        }

        public boolean bind(Disposable disposable) {

                Iterator iterator = boundDisposables.iterator();

                while (iterator.hasNext()) {

                        Reference ref = (Reference) iterator.next();

                        if (!ref.isEnqueued()) {

                                Disposable boundDisposable = (Disposable) ref.get();

                                // Check for object identity

                                if (boundDisposable == disposable) {

                                        return false;

                                }

                        } else {

                                iterator.remove();

                        }

                }

                boolean result =

                                boundDisposables.add(new WeakReference(disposable,

                                                referenceQueue));

                disposeQueuedReferences();

                return result;

        }

        public boolean release(Disposable disposable) {

                boolean result = false;

                Iterator iterator = boundDisposables.iterator();

                while (iterator.hasNext()) {

                        Reference ref = (Reference) iterator.next();

                        if (!ref.isEnqueued()) {

                                Disposable boundDisposable = (Disposable) ref.get();

                                // Check for object identity

                                if (boundDisposable == disposable) {

                                        iterator.remove();

                                        boundDisposable.dispose();

                                        ref.clear();

                                        result = true;

                                        break;

                                }

                        } else {

                                iterator.remove();

                        }

                }

                releaseQueuedReferences();

                disposeQueuedReferences();

                return result;

        }

        public void releaseAll() throws BaseException {

                Iterator iterator = boundDisposables.iterator();

                boundDisposables = new LinkedHashSet();

                while (iterator.hasNext()) {

                        Reference ref = (Reference) iterator.next();

                        if (!ref.isEnqueued()) {

                                Disposable disposable = (Disposable) ref.get();

                                disposable.dispose();

                                ref.clear();

                        }

                        iterator.remove();

                }

                disposeQueuedReferences();

        }

        public int getBoundDisposableCount() {

                releaseQueuedReferences();

                disposeQueuedReferences();

                return boundDisposables.size();

        }

        public Set getBoundDisposables() {

                Set boundDispoToReturn = new LinkedHashSet(boundDisposables.size());

                Iterator iterator = boundDisposables.iterator();

                while (iterator.hasNext()) {

                        Reference ref = (Reference) iterator.next();

                        if (!ref.isEnqueued()) {

                                boundDispoToReturn.add(ref.get());

                        } else {

                                iterator.remove();

                        }

                }

                disposeQueuedReferences();

                return boundDispoToReturn;

        }

        private void releaseQueuedReferences() {

                Iterator iterator = boundDisposables.iterator();

                while (iterator.hasNext()) {

                        Reference ref = (Reference) iterator.next();

                        if (ref.isEnqueued()) {

                                iterator.remove();

                        }

                }

        }

        private void disposeQueuedReferences() {

                for (int i = 0; i < maxQueueIterations; i++) {

                        Reference ref = referenceQueue.poll();

                        if (ref == null) {

                                return;

                        }

                        Disposable disposable = (Disposable) ref.get();

                        if (disposable != null) {

                                disposable.dispose();

                        }

                }

        }

}