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/*
 * The contents of this file are subject to the terms 
 * of the Common Development and Distribution License 
 * (the "License").  You may not use this file except 
 * in compliance with the License.
 * 
 * You can obtain a copy of the license at 
 * glassfish/bootstrap/legal/CDDLv1.0.txt or 
 * https://glassfish.dev.java.net/public/CDDLv1.0.html. 
 * See the License for the specific language governing 
 * permissions and limitations under the License.
 * 
 * When distributing Covered Code, include this CDDL 
 * HEADER in each file and include the License file at 
 * glassfish/bootstrap/legal/CDDLv1.0.txt.  If applicable, 
 * add the following below this CDDL HEADER, with the 
 * fields enclosed by brackets "[]" replaced with your 
 * own identifying information: Portions Copyright [yyyy] 
 * [name of copyright owner]
 */
// Copyright (c) 1998, 2007, Oracle. All rights reserved.  
package oracle.toplink.essentials.internal.helper;

import java.util.*;

/**
 * INTERNAL:
 * 
 * Purpose: Be used for deadlock avoidance through allowing detection and resolution.
 *
 * 

 * Responsibilities:
 * 

 *  Keep track of all deferred locks of each thread.
 * 
 Keep track of all active locks of each thread..
 * 
 Maintain the depth of the each thread.
 * 
 */
public class DeferredLockManager {
    protected Vector deferredLocks;
    protected Vector activeLocks;
    protected int threadDepth;
    protected boolean isThreadComplete;
    
    public static boolean SHOULD_USE_DEFERRED_LOCKS = true;

    /**
     * DeferredLockManager constructor comment.
     */
    public DeferredLockManager() {
        super();
        this.deferredLocks = new Vector(1);
        this.activeLocks = new Vector(1);
        this.threadDepth = 0;
        this.isThreadComplete = false;
    }

    /**
     * add a concurrency manager as active locks to the DLM
     */
    public void addActiveLock(Object manager) {
        getActiveLocks().addElement(manager);
    }

    /**
     * add a concurrency manager as deferred locks to the DLM
     */
    public void addDeferredLock(Object manager) {
        getDeferredLocks().addElement(manager);
    }

    /**
     * decrement the depth of the thread
     */
    public void decrementDepth() {
        threadDepth--;
    }

    /**
     * Return a set of the active locks from the DLM
     */
    public Vector getActiveLocks() {
        return activeLocks;
    }

    /**
     * Return a set of the deferred locks
     */
    public Vector getDeferredLocks() {
        return deferredLocks;
    }

    /**
     * Return the depth of the thread associated with the DLM, being used to release the lock
     */
    public int getThreadDepth() {
        return threadDepth;
    }

    /**
     * Return if there are any deferred locks.
     */
    public boolean hasDeferredLock() {
        return !getDeferredLocks().isEmpty();
    }

    /**
     * increment the depth of the thread
     */
    public void incrementDepth() {
        threadDepth++;
    }

    /**
     * Return if the thread is complete
     */
    public boolean isThreadComplete() {
        return isThreadComplete;
    }

    /**
     * Release the active lock on the DLM
     */
    public void releaseActiveLocksOnThread() {
        Vector activeLocks = getActiveLocks();
        if (!activeLocks.isEmpty()) {
            for (Enumeration activeLocksEnum = activeLocks.elements();
                     activeLocksEnum.hasMoreElements();) {
                ConcurrencyManager manager = (ConcurrencyManager)activeLocksEnum.nextElement();
                manager.release();
            }
        }
        setIsThreadComplete(true);
    }

    /**
     * set a set of the active locks to the DLM
     */
    public void setActiveLocks(Vector activeLocks) {
        this.activeLocks = activeLocks;
    }

    /**
     * set a set of the deferred locks to the DLM
     */
    public void setDeferredLocks(Vector deferredLocks) {
        this.deferredLocks = deferredLocks;
    }

    /**
     * set if the thread is complete in the given DLM
     */
    public void setIsThreadComplete(boolean isThreadComplete) {
        this.isThreadComplete = isThreadComplete;
    }
}