hudson.remoting.ExportedClassLoaderTable Maven / Gradle / Ivy

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Contains the bootstrap code to bridge separate JVMs into a single semi-shared space. Reusable outside Hudson.

There is a newer version: 3.0.3

/*******************************************************************************
 *
 * Copyright (c) 2004-2009 Oracle Corporation.
 *
 * All rights reserved. This program and the accompanying materials
 * are made available under the terms of the Eclipse Public License v1.0
 * which accompanies this distribution, and is available at
 * http://www.eclipse.org/legal/epl-v10.html
 *
 * Contributors: 
*
*    Kohsuke Kawaguchi
 *     
 *
 *******************************************************************************/ 

package hudson.remoting;

import java.lang.ref.WeakReference;
import java.util.HashMap;
import java.util.Map;
import java.util.WeakHashMap;

/**
 * Manages unique ID for classloaders.
 *
 * @author Kohsuke Kawaguchi
 */
final class ExportedClassLoaderTable {
    private final Map> table = new HashMap>();
    private final WeakHashMap reverse = new WeakHashMap();

    // id==0 is reserved for bootstrap classloader
    private int iota = 1;


    public synchronized int intern(ClassLoader cl) {
        if(cl==null)    return 0;   // bootstrap classloader

        Integer id = reverse.get(cl);
        if(id==null) {
            id = iota++;
            table.put(id,new WeakReference(cl));
            reverse.put(cl,id);
        }

        return id;
    }

    public synchronized ClassLoader get(int id) {
        WeakReference ref = table.get(id);
        if(ref==null)   return null;
        return ref.get();
    }
}