TilePage.java

/**
 * This program is free software: you can redistribute it and/or modify
 * it under the terms of the GNU Lesser 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 Lesser General Public License
 *  along with this program.  If not, see <http://www.gnu.org/licenses/>.
 * 
 * @author Gabriel Roldan (OpenGeo) 2010
 *  
 */
package org.geowebcache.diskquota.storage;

/**
 * A rectangular group of tiles in a specific TileSet zoom level. The size of the group is
 * calculated by the TilePageCalculator, at the time of writing the calculation uses a logarithmic
 * relation to the number of tiles in the zoom level. 
 * <p> 
 * The tile page is the atomic information handled by the disk quota subsystem, informations about
 * frequency and freshness of use is handled at this level, as such this is the minimum amount of
 * tiles the disk quota subsystem evicts when the 
 * 
 * @author Andrea Aime - GeoSolutions
 *
 */
public class TilePage {

    private long id;

    private String tileSetId;

    private String key;

    private byte pageZ;

    private int pageY;

    private int pageX;

    private int creationTimeMinutes;

    public TilePage() {
    }
    
    public TilePage(String tileSetId, int pageX, int pageY, int zoomLevel, int creationTimeMinutes) {
        this.tileSetId = tileSetId;
        this.pageX = pageX;
        this.pageY = pageY;
        this.pageZ = (byte) zoomLevel;
        this.creationTimeMinutes = creationTimeMinutes;
        StringBuilder sb = new StringBuilder(128);
        computeId(tileSetId, pageX, pageY, zoomLevel, sb);
        this.key = sb.toString();
    }

    public TilePage(String tileSetId, int pageX, int pageY, int zoomLevel) {
        this(tileSetId, pageX, pageY, zoomLevel, SystemUtils.get().currentTimeMinutes());
    }

    public static void computeId(String tileSetId, int pageX, int pageY, int pageZ,
            StringBuilder target) {

        target.append(tileSetId).append('@').append(pageX).append(',').append(pageY).append(',')
                .append(pageZ).toString();
    }

    public long getId() {
        return id;
    }

    public String getKey() {
        return key;
    }

    @Override
    public boolean equals(Object o) {
        if (!(o instanceof TilePage)) {
            return false;
        }
        TilePage t = (TilePage) o;
        return key.equals(t.key);
    }

    @Override
    public int hashCode() {
        return 17 * key.hashCode();
    }

    public String getTileSetId() {
        return tileSetId;
    }

    public byte getZoomLevel() {
        return pageZ;
    }

    public int getPageY() {
        return pageY;
    }

    public int getPageX() {
        return pageX;
    }

    public int getCreationTimeMinutes() {
        return creationTimeMinutes;
    }

    public String toString() {
        return new StringBuilder(getClass().getSimpleName()).append('[').append(key).append(']')
                .toString();
    }

}