Application: gvSIG desktop » Library: org.gvsig.tools

/**

 * gvSIG. Desktop Geographic Information System.

 *

 * Copyright (C) 2007-2021 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.tools.util;

import java.io.Closeable;

import java.io.IOException;

import org.gvsig.tools.dispose.Disposable;

import org.gvsig.tools.dispose.DisposeUtils;

import org.slf4j.Logger;

import org.slf4j.LoggerFactory;

/**

 *

 * @author gvSIG Team

 * @param <T>

 */

public class CachedValue<T> {

    public static final Logger LOGGER = LoggerFactory.getLogger(CachedValue.class);

  private T value = null;

  private long lastAccess = 0;

  private long expireTimeInMillis;

  private java.util.concurrent.Callable<T> reload;

  public CachedValue() {

    this(3000, null);

  }

  public CachedValue(long expireTimeInMillis) {

    this(expireTimeInMillis, null);

  }

  public CachedValue(java.util.concurrent.Callable<T> reload) {

      this(3000, reload);

  }

  public CachedValue(long expireTimeInMillis, java.util.concurrent.Callable<T> reload) {

    this.expireTimeInMillis = expireTimeInMillis;

    this.reload = reload;

  }

  protected void reload() {

    if( this.reload!=null ) {

        try {

            this.value = this.reload.call();

        } catch (Exception ex) {

            // FIXME: calling Callable.call exception ??

        }

    }

  }

  protected final T getValue() {

    return this.value;

  }

  protected void setValue(T value) {

    this.value = value;

  }

  public final boolean isExpired() {

    long now = System.currentTimeMillis();

    return (now - lastAccess) > expireTimeInMillis;

  }

  public final void set(T value) {

    this.value = value;

    lastAccess = System.currentTimeMillis();

  }

  public final void setExpireTime(long expireTimeInMillis) {

    this.expireTimeInMillis = expireTimeInMillis;

  }

  public final long getExpireTime() {

    return expireTimeInMillis;

  }

  public final void resetAccess() {

    this.lastAccess = System.currentTimeMillis();

  }

  public final void expired() {

//      LOGGER.info("Force expired "+this.getClass().getSimpleName()+" ***"+this.toString()+"***");

    this.lastAccess = 0;

  }

  public final T get() {

    if (isExpired()) {

      if( value instanceof Disposable ) {

        DisposeUtils.disposeQuietly((Disposable) value);

      } else if( value instanceof Closeable ) {

        try {

          ((Closeable)value).close();

        } catch (IOException ex) {

          // Ignore

        }

      }

      value = null;

      reload();

    }

    lastAccess = System.currentTimeMillis();

    return value;

  }

}