Application: gvSIG desktop

/**

 * gvSIG. Desktop Geographic Information System.

 *

 * Copyright (C) 2007-2013 gvSIG Association.

 *

 * 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 3

 * 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.

 *

 * For any additional information, do not hesitate to contact us

 * at info AT gvsig.com, or visit our website www.gvsig.com.

 */

package org.gvsig.fmap.dal.resource.spi;

import java.lang.ref.WeakReference;

import java.util.ArrayList;

import java.util.Iterator;

import java.util.List;

import org.gvsig.fmap.dal.exception.CopyParametersException;

import org.gvsig.fmap.dal.exception.InitializeException;

import org.gvsig.fmap.dal.resource.Resource;

import org.gvsig.fmap.dal.resource.ResourceAction;

import org.gvsig.fmap.dal.resource.ResourceNotification;

import org.gvsig.fmap.dal.resource.ResourceParameters;

import org.gvsig.fmap.dal.resource.exception.AccessResourceException;

import org.gvsig.fmap.dal.resource.exception.PrepareResourceException;

import org.gvsig.fmap.dal.resource.exception.ResourceException;

import org.gvsig.fmap.dal.resource.exception.ResourceExecuteException;

import org.gvsig.fmap.dal.resource.exception.ResourceNotifyChangesException;

import org.gvsig.fmap.dal.resource.exception.ResourceNotifyCloseException;

import org.gvsig.fmap.dal.resource.exception.ResourceNotifyDisposeException;

import org.gvsig.fmap.dal.resource.exception.ResourceNotifyOpenException;

import org.gvsig.fmap.dal.resource.impl.DefaultResourceNotification;

import org.gvsig.tools.observer.Observer;

import org.gvsig.tools.observer.WeakReferencingObservable;

import org.gvsig.tools.observer.impl.BaseWeakReferencingObservable;

import org.gvsig.tools.observer.impl.DelegateWeakReferencingObservable;

/**

 * <p>

 * Base implementation for Resource

 * </p>

 * 

 * <p>

 * This implementation not define the {@link Resource#begin()} and

 * {@link Resource#end()}

 * </p>

 * 

 * @author jmvivo

 * 

 */

public abstract class AbstractResource implements ResourceProvider,

                WeakReferencingObservable {

        private DelegateWeakReferencingObservable delegateObservable;

        private List consumers;

        private long lastTimeOpen;

        private long lastTimeUsed;

        private ResourceParameters parameters;

        private ResourceParameters preparedParameters;

        private Object data;

        private int openCount;

        /**

         * Number of times an execute is being simultaneously performed with this

         * resource.

         */

        private int executeCount = 0;

        protected final Object lock;

        protected AbstractResource(ResourceParameters parameters)

                        throws InitializeException {

                consumers = new ArrayList();

                lastTimeOpen = System.currentTimeMillis();

                lastTimeUsed = lastTimeOpen;

                openCount = 0;

                preparedParameters = null;

                delegateObservable = new DelegateWeakReferencingObservable(this);

                lock = new Object();

                try {

                        this.parameters = (ResourceParameters) parameters.getCopy();

                } catch (CopyParametersException e) {

                        throw new InitializeException(e);

                }

        }

        protected final void updateLastTimeUsed() {

                lastTimeUsed = System.currentTimeMillis();

        }

        protected final void updateLastTimeOpen() {

                lastTimeOpen = System.currentTimeMillis();

                lastTimeUsed = lastTimeOpen;

        }

        public final long getLastTimeOpen() {

                return lastTimeOpen;

        }

        public final long getLastTimeUsed() {

                return lastTimeUsed;

        }

        public final ResourceParameters getParameters() {

                if (preparedParameters != null) {

                        return preparedParameters;

                }

                return this.parameters;

        }

        public void prepare(ResourceParameters params)

                        throws PrepareResourceException {

                ResourceNotification notification =

                                new DefaultResourceNotification(this,

                                                ResourceNotification.PREPARE, params);

                this.delegateObservable.notifyObservers(notification);

        }

        public void prepare() throws PrepareResourceException {

                if (preparedParameters == null) {

                        try {

                                ResourceParameters params =

                                                (ResourceParameters) parameters.getCopy();

                                prepare(params);

                                preparedParameters = params;

                        } catch (CopyParametersException e) {

                                throw new PrepareResourceException(this, e);

                        }

                }

        }

        public void notifyOpen() throws ResourceNotifyOpenException {

                this.notifyObserver(ResourceNotification.OPEN);

                updateLastTimeOpen();

                openCount++;

        }

        public void notifyClose() throws ResourceNotifyCloseException {

                if (openCount <= 0) {

                        throw new IllegalStateException();

                }

                this.notifyObserver(ResourceNotification.CLOSE);

                openCount--;

        }

        public void notifyChanges() throws ResourceNotifyChangesException {

                this.notifyObserver(ResourceNotification.CHANGED);

                Iterator it = consumers.iterator();

                while (it.hasNext()) {

                        ResourceConsumer consumer =

                                        (ResourceConsumer) ((WeakReference) it.next()).get();

                        if (consumer != null) {

                                consumer.resourceChanged(this);

                        } else {

                                it.remove();

                        }

                }

        }

        public boolean isOpen() {

                return this.openCount > 0;

        }

        public int openCount() {

                return this.openCount;

        }

        public void addObserver(Observer o) {

                this.delegateObservable.addObserver(o);

        }

        public void deleteObserver(Observer o) {

                this.delegateObservable.deleteObserver(o);

        }

        public void deleteObservers() {

                this.delegateObservable.deleteObservers();

        }

        public final void addObservers(BaseWeakReferencingObservable observers) {

                this.delegateObservable.addObservers(observers);

        }

        public final void addConsumer(ResourceConsumer consumer) {

                this.updateConsumersList();

                consumers.add(new WeakReference(consumer));

        }

        public final void removeConsumer(ResourceConsumer consumer) {

                ResourceConsumer cur;

                Iterator it = consumers.iterator();

                while (it.hasNext()) {

                        cur = (ResourceConsumer) ((WeakReference) it.next()).get();

                        if (cur == null || (cur == consumer)) {

                                it.remove();

                        }

                }

        }

        public int getConsumersCount() {

                this.updateConsumersList();

                return consumers.size();

        }

        private synchronized void updateConsumersList() {

                Iterator it = consumers.iterator();

                WeakReference ref;

                while (it.hasNext()) {

                        ref = (WeakReference) it.next();

                        if (ref.get() == null) {

                                it.remove();

                        }

                }

        }

        public void closeRequest() throws ResourceException {

                if (inUse()) {

                        return;

                }

                if (consumers != null) {

                        for (int i = 0; i < consumers.size(); i++) {

                        }

                }

                if (consumers != null) {

                        Iterator it = consumers.iterator();

                        while (it.hasNext()) {

                                ResourceConsumer consumer =

                                                (ResourceConsumer) ((WeakReference) it.next()).get();

                                if (consumer != null) {

                                        consumer.closeResourceRequested(this);

                                } else {

                                        it.remove();

                                }

                        }

                }

        }

        public void setData(Object data) {

                this.data = data;

        }

        public Object getData() {

                return this.data;

        }

        protected void notifyObserver(String type) {

                if (delegateObservable != null) {

                        this.delegateObservable.notifyObservers(new DefaultResourceNotification(

                                        this, type));

                }

        }

        public void notifyDispose() throws ResourceNotifyDisposeException {

                this.notifyObserver(ResourceNotification.DISPOSE);

                if (consumers != null) {

                        consumers.clear();

                }

                lastTimeOpen = 0l;

                lastTimeUsed = 0l;

                data = null;

                if (delegateObservable != null) {

                        delegateObservable.deleteObservers();

                }

        }

        public final boolean inUse() {

                return executeCount > 0;

        }

        public Object execute(ResourceAction action)

                        throws ResourceExecuteException {

                Object value = null;

                synchronized (lock) {

                        executeBegins();

                        try {

                                value = performExecution(action);

                        } catch (Exception e) {

                                throw new ResourceExecuteException(this, e);

                        } finally {

                                executeEnds();

                        }

                }

                return value;

        }

        protected Object performExecution(ResourceAction action) throws Exception {

                return action.run();

        }

        protected final void executeBegins() {

                executeCount++;

        }

        protected final void executeEnds() {

                updateLastTimeUsed();

                executeCount--;

        }

        /**

         * Returns the name of the {@link Resource}.

         * 

         * @throws AccessResourceException

         *             if there is an error while accessing the resource

         */

        public abstract String getName() throws AccessResourceException;

        /**

         * Returns the real resource represented by this object.

         * 

         * @throws AccessResourceException

         *             if there is an error while accessing the resource

         */

        public abstract Object get() throws AccessResourceException;

}