ThreadActionData.java

/*
 * JBoss, Home of Professional Open Source
 * Copyright 2006, Red Hat Middleware LLC, and individual contributors 
 * as indicated by the @author tags. 
 * See the copyright.txt in the distribution for a
 * full listing of individual contributors. 
 * This copyrighted material is made available to anyone wishing to use,
 * modify, copy, or redistribute it subject to the terms and conditions
 * of the GNU Lesser General Public License, v. 2.1.
 * This program is distributed in the hope that it will be useful, but WITHOUT A 
 * 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,
 * v.2.1 along with this distribution; if not, write to the Free Software
 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, 
 * MA  02110-1301, USA.
 * 
 * (C) 2005-2006,
 * @author JBoss Inc.
 */
/*
 * Copyright (C) 1998, 1999, 2000, 2001,
 *
 * Arjuna Solutions Limited,
 * Newcastle upon Tyne,
 * Tyne and Wear,
 * UK.
 *
 * $Id: ThreadActionData.java 2342 2006-03-30 13:06:17Z  $
 */

package org.jboss.narayana.blacktie.jatmibroker.core.tx;

import java.util.EmptyStackException;
import java.util.NoSuchElementException;
import java.util.Stack;


/**
 * This class maintains a mapping between a thread and its notion of the current transaction. Essentially this is a stack of
 * transactions.
 * 
 * @author Mark Little (mark@arjuna.com)
 * @version $Id: ThreadActionData.java 2342 2006-03-30 13:06:17Z $
 * @since JTS 1.0.
 */

public class ThreadActionData {

    public static TransactionImpl currentAction() {
        // XXX NOT USED ThreadActionData.setup();
        Stack txs = (Stack) _threadList.get();

        if (txs != null) {
            try {
                return (TransactionImpl) txs.peek();
            } catch (EmptyStackException e) {
            }
        }

        return null;
    }

    public static void pushAction(TransactionImpl a) {
        pushAction(a, true);
    }

    /**
     * By setting the register flag accordingly, information about the thread may not be propagated to the action, i.e., only
     * the thread's notion of current changes.
     */

    public static void pushAction(TransactionImpl a, boolean register) {
        Thread t = Thread.currentThread();
        Stack txs = (Stack) _threadList.get();

        if (txs == null) {
            txs = new Stack();
            txs.push(a);

            _threadList.set(txs);
        } else
            txs.push(a);

        if (register)
            a.addChildThread(t);
    }

    /**
     * Put back the entire hierarchy, removing whatever is already there.
     */

    public static void restoreActions(TransactionImpl act) {
        purgeActions();

        if (act != null) {
            /*
             * First get the hierarchy from the bottom up.
             */

            java.util.Stack s = new java.util.Stack();
            TransactionImpl nextLevel = act.parent();

            s.push(act);

            while (nextLevel != null) {
                s.push(nextLevel);

                nextLevel = nextLevel.parent();
            }

            /*
             * Now push the hierarchy onto the thread stack.
             */

            try {
                while (!s.empty()) {
                    pushAction((TransactionImpl) s.pop());
                }
            } catch (Exception ex) {
            }
        }
    }

    public static TransactionImpl popAction() throws EmptyStackException {
        return popAction(ThreadUtil.getThreadId(), true);
    }

    public static TransactionImpl popAction(boolean unregister) throws EmptyStackException {
        return popAction(ThreadUtil.getThreadId(), unregister);
    }

    public static TransactionImpl popAction(String threadId) throws EmptyStackException {
        return popAction(threadId, true);
    }

    /**
     * By setting the unregister flag accordingly, information about the thread is not removed from the action.
     */

    public static TransactionImpl popAction(String threadId, boolean unregister) throws EmptyStackException {
        Stack txs = (Stack) _threadList.get();

        if (txs != null) {
            TransactionImpl a = (TransactionImpl) txs.pop();

            if ((a != null) && (unregister)) {
                a.removeChildThread(threadId);
            }

            if (txs.size() == 0) {
                _threadList.set(null);
            }

            return a;
        }

        return null;
    }

    public static void purgeAction(TransactionImpl act) throws NoSuchElementException {
        ThreadActionData.purgeAction(act, Thread.currentThread(), true);
    }

    public static void purgeAction(TransactionImpl act, Thread t) throws NoSuchElementException {
        ThreadActionData.purgeAction(act, t, true);
    }

    public static void purgeAction(TransactionImpl act, Thread t, boolean unregister) throws NoSuchElementException {
        if ((act != null) && (unregister)) {
            act.removeChildThread(ThreadUtil.getThreadId(t));
        }

        Stack txs = (Stack) _threadList.get();

        if (txs != null) {
            txs.removeElement(act);

            if (txs.size() == 0) {
                _threadList.set(null);
            }
        }
    }

    public static void purgeActions() {
        purgeActions(Thread.currentThread(), true);
    }

    public static void purgeActions(Thread t) {
        purgeActions(t, true);
    }

    public static void purgeActions(Thread t, boolean unregister) {
        Stack txs = (Stack) _threadList.get();

        _threadList.set(null);

        if (txs != null) {
            if (unregister) {
                while (!txs.empty()) {
                    TransactionImpl act = (TransactionImpl) txs.pop();

                    if (act != null) {
                        act.removeChildThread(ThreadUtil.getThreadId(t));
                    }
                }
            }
        }
    }

    /**
     * Add a per thread setup object to the global list. This should only happen before the transaction service really begins,
     * or you risk having some threads see one view of the list that is different to other threads.
     * 
     * @param s the setup to add.
     */
    /*
     * XXX NOT USED public static void addSetup (ThreadSetup s) { synchronized (_threadSetups) { _threadSetups.add(s); } }
     */
    /**
     * Remove a per thread setup object to the global list. This should only happen after the transaction service really ends,
     * or you risk having some threads see one view of the list that is different to other threads.
     * 
     */
    /*
     * XXX NOT USED public static boolean removeSetup (ThreadSetup s) { synchronized (_threadSetups) { return
     * _threadSetups.remove(s); } }
     * 
     * private static void setup () { for (int i = 0; i < _threadSetups.size(); i++) { ThreadSetup s = (ThreadSetup)
     * _threadSetups.get(i);
     * 
     * if (s != null) s.setup(); } }
     * 
     * private static ArrayList _threadSetups = new ArrayList();
     */
    private static ThreadLocal _threadList = new ThreadLocal();

}