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makumba » org » makumba » commons » NamedResources.java
///////////////////////////////
//  Makumba, Makumba tag library
//  Copyright (C) 2000-2003  http://www.makumba.org
//
//  This library 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 2.1 of the License, or (at your option) any later version.
//
//  This library 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
//  Lesser General Public License for more details.
//
//  You should have received a copy of the GNU Lesser General Public
//  License along with this library; if not, write to the Free Software
//  Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
//
//  -------------
//  $Id: NamedResources.java 1688 2007-09-25 12:54:46Z manuel_gay $
//  $Name$
/////////////////////////////////////

package org.makumba.commons;

import java.util.ArrayList;
import java.util.HashMap;
import java.util.Iterator;
import java.util.List;
import java.util.Map;
import java.util.Vector;


/**
 * An instance of this class holds a cache of resources. If a resource is requested but is not present, it is produced
 * using the associated NamedResourceFactory, in a thread-safe way
 * 
 * @author Cristian Bogdan
 * @version $Id: NamedResources.java 1688 2007-09-25 12:54:46Z manuel_gay $
 * @see org.makumba.commons.NamedResourceFactory
 */
public class NamedResources implements java.io.Serializable {

    private static final long serialVersionUID = 1L;

    static boolean soft_static_caches;
    static {
        String soft = null;
        try {
            soft = System.getProperty("makumba.soft-static-caches");
        } catch (SecurityException se) {
        } // for applets
        if (soft != null)
            soft = soft.trim();
        soft_static_caches = "true".equals(soft);
    }

    NamedResourceFactory f;

    String name;

    Map values = new HashMap();

    int hits, misses;

    static List staticCaches = new ArrayList();

    static Vector allCaches = new Vector();

    /**
     * Cleans-up all the static and soft caches
     */
    static public void cleanup() {
        for (int i = 0; i < staticCaches.size(); i++)
            ((NamedResources) staticCaches.get(i)).close();
        staticCaches.clear();
        for (int i = 0; i < allCaches.size(); i++)
            ((java.lang.ref.WeakReference) allCaches.elementAt(i)).clear();
        allCaches.clear();

    }

    /**
     * Creates a static cache
     * @param name the name of the cache
     * @param fact the {@link NamdedResourceFactory} used to create the cache
     * @param soft <code>true</code> if this should be a soft cache
     * @return The identifier of this cache
     */
    public synchronized static int makeStaticCache(String name, NamedResourceFactory fact, boolean soft) {
        staticCaches.add(soft ? new SoftNamedResources(name, fact) : new NamedResources(name, fact));
        return staticCaches.size() - 1;
    }

    /**
     * Creates a static cache
     * @param name the name of the cache
     * @param fact the NamdedResourceFactory used to create the cache
     * @return The identifier of this cache
     */
    public synchronized static int makeStaticCache(String name, NamedResourceFactory fact) {
        return makeStaticCache(name, fact, soft_static_caches);
    }

    /**
     * Gets the static cache identified by n
     * @param n the index of the cached object in the cache
     * @return The cache of resources
     */
    public static NamedResources getStaticCache(int n) {
        return (NamedResources) staticCaches.get(n);
    }

    /**
     * Cleans the given cache. Use this for developping purposes.
     * @param n the index of the cache to be cleaned
     */
    public static void cleanStaticCache(int n) {
        ((NamedResources) staticCaches.get(n)).values = new HashMap();
    }

    /**
     * Wraps information about the cache into a Map
     * @return A Map having as keys the names of the caches and as value an array of int containing the size, hits and misses of each cache
     */
    public static Map getCacheInfo() {
        Map m = new HashMap();
        for (int i = 0; i < allCaches.size(); i++) {
            NamedResources nr = (NamedResources) ((java.lang.ref.WeakReference) allCaches.elementAt(i)).get();
            if (nr == null)
                continue;
            int[] n = (int[]) m.get(nr.getName());
            if (n == null) {
                m.put(nr.getName(), n = new int[3]);
            }
            n[0] += nr.size();
            n[1] += nr.hits;
            n[2] += nr.misses;
        }
        return m;
    }

    /** 
     * Initializes using the given factory
     * @param name the name of the NamedResources object to initalise
     * @param f the {@link NamedResourceFactory} used to construct the NamedResource
     */
    public NamedResources(String name, NamedResourceFactory f) {
        this.name = name;
        this.f = f;
        allCaches.addElement(new java.lang.ref.WeakReference(this));
    }

    /**
     * Checks if a resource is known
     * @param name the name of the resource to be checked
     * @return <code>true</code> if the resource is known, <code>false</code> otherwise
     */
    public boolean knowResource(Object name) {
        try {
            return values.get(f.getHashObject(name)) != null;
        } catch (Throwable t) {
            throw new RuntimeWrappedException(t);
        }
    }

    /**
     * Whatever supplementary stuff the factory wants to keep
     * @return An object with the supplementary things the factory may need
     */
    public Object getSupplementary() {
        return f.supplementary;
    }

    /** 
     * Gets a specific resource. If it doesn't exist, calls the NamedResourceFactory to produce it
     * @param name the name of the resource to get
     * @return The resource
     */
    public Object getResource(Object name) {
        NameValue nv = null;

        synchronized (this) {
            Object hash = null;
            try {
                hash = f.getHashObject(name);
            } catch (Throwable t) {
                throw new RuntimeWrappedException(t);
            }
            nv = getNameValue(name, hash);
        }
        return nv.getResource();
    }

    protected NameValue getNameValue(Object name, Object hash) {
        NameValue nv = (NameValue) values.get(hash);
        if (nv == null) {
            misses++;
            values.put(hash, nv = new NameValue(name, hash, f));
        } else
            hits++;
        return nv;
    }

    public int size() {
        return values.size();
    }

    public String getName() {
        return name;
    }

    /** 
     * Closes each contained object by calling its close() method, if any
     */
    public void close() {
        for (Iterator i = values.keySet().iterator(); i.hasNext();) {
            Object nvo = values.get(i.next());
            if (nvo instanceof java.lang.ref.Reference) {
                nvo = ((java.lang.ref.Reference) nvo).get();
                if (nvo == null)
                    continue;
            }

            if (!(((NameValue) nvo).returner instanceof NameValue))
                continue;

            Object o = ((NameValue) nvo).getResource();

            java.lang.reflect.Method m = null;
            if (o == null)
                continue;
            try {
                m = o.getClass().getMethod("close", ((java.lang.Class[]) null));
            } catch (NoSuchMethodException e) {
                // we assume homogenous caches
                return;
            }
            try {
                m.invoke(o, ((java.lang.Object[]) null));
            } catch (Throwable t) {
                t.printStackTrace();
            }
        }
        values.clear();
    }
}
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