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Contains the core Hudson code and view files to render HTML.
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/*******************************************************************************
 *
 * 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.model;

/**
 * Represents things that {@link Queue.Executable} uses while running.
 *
 * 
 * This is used in {@link Queue} to support basic mutual exclusion/locks. If two
 * {@link Queue.Task}s require the same {@link Resource}, they will not
 * be run at the same time.
 *
 * 

 * Resources are compared by using their {@link #displayName names}, and
 * need not have the "same object" semantics. 
 *
 * @since 1.121
 */
public final class Resource {
    /**
     * Human-readable name of this resource.
     * Used for rendering HTML.
     */
    //TODO: review and check whether we can do it private
    public final String displayName;

    /**
     * Parent resource.
     *
     * 

     * A child resource is considered a part of the parent resource,
     * so acquiring the parent resource always imply acquiring all
     * the child resources.
     */
    //TODO: review and check whether we can do it private
    public final Resource parent;

    /**
     * Maximum number of concurrent write.
     */
    //TODO: review and check whether we can do it private
    public final int numConcurrentWrite;

    public Resource(Resource parent, String displayName) {
        this(parent,displayName,1);
    }

    /**
     * @since 1.155
     */
    public Resource(Resource parent, String displayName, int numConcurrentWrite) {
        if(numConcurrentWrite<1)
            throw new IllegalArgumentException();
        
        this.parent = parent;
        this.displayName = displayName;
        this.numConcurrentWrite = numConcurrentWrite;
    }

    public Resource(String displayName) {
        this(null,displayName);
    }

    public String getDisplayName() {
        return displayName;
    }

    public Resource getParent() {
        return parent;
    }

    public int getNumConcurrentWrite() {
        return numConcurrentWrite;
    }

    /**
     * Checks the resource collision.
     *
     * @param count
     *      If we are testing W/W conflict, total # of write counts.
     *      For R/W conflict test, this value should be set to {@link Integer#MAX_VALUE}.
     */
    public boolean isCollidingWith(Resource that, int count) {
        assert that!=null;
        for(Resource r=that; r!=null; r=r.parent)
            if(this.equals(r) && r.numConcurrentWrite