Quadcap Embeddable Database

com/quadcap/sql/lock/Transaction.java

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package com.quadcap.sql.lock;

/* Copyright 1999 - 2003 Quadcap Software.  All rights reserved.
 *
 * This software is distributed under the Quadcap Free Software License.
 * This software may be used or modified for any purpose, personal or
 * commercial.  Open Source redistributions are permitted.  Commercial
 * redistribution of larger works derived from, or works which bundle
 * this software requires a "Commercial Redistribution License"; see
 * http://www.quadcap.com/purchase.
 *
 * Redistributions qualify as "Open Source" under  one of the following terms:
 *   
 *    Redistributions are made at no charge beyond the reasonable cost of
 *    materials and delivery.
 *
 *    Redistributions are accompanied by a copy of the Source Code or by an
 *    irrevocable offer to provide a copy of the Source Code for up to three
 *    years at the cost of materials and delivery.  Such redistributions
 *    must allow further use, modification, and redistribution of the Source
 *    Code under substantially the same terms as this license.
 *
 * Redistributions of source code must retain the copyright notices as they
 * appear in each source code file, these license terms, and the
 * disclaimer/limitation of liability set forth as paragraph 6 below.
 *
 * Redistributions in binary form must reproduce this Copyright Notice,
 * these license terms, and the disclaimer/limitation of liability set
 * forth as paragraph 6 below, in the documentation and/or other materials
 * provided with the distribution.
 *
 * The Software is provided on an "AS IS" basis.  No warranty is
 * provided that the Software is free of defects, or fit for a
 * particular purpose.  
 *
 * Limitation of Liability. Quadcap Software shall not be liable
 * for any damages suffered by the Licensee or any third party resulting
 * from use of the Software.
 */

import java.util.ArrayList;
import java.util.HashMap;
import java.util.Iterator;

import java.util.Enumeration;

import javax.concurrent.Mutex;
import javax.concurrent.Sync;

import com.quadcap.util.Debug;
import com.quadcap.util.Util;

/**
 * Locks are acquired on behalf of transactions.
 *
 * @author Stan Bailes
 */
public class Transaction extends PooledObject {
    long                        transactionId;

    Object                      osync           = new Object();
    Sync                        sync            = null;
    volatile HeldLock           wait            = null;
    TransactionObserver         observer        = null;

    /**
     * No-arg constructor
     */
    public Transaction() {}

    final public PooledObject create() { return new Transaction(); }

    /**
     * Initialze this new transaction
     */
    final void init(long transactionId) {
        this.transactionId = transactionId;
        this.wait = null;
    }

    public final Sync getSync() throws InterruptedException {
        synchronized (osync) {
            if (sync == null) {
                sync.acquire();
            }
            return sync;
        }
    }

    public final void setWait(HeldLock wait) {
        if (this.wait != null && wait != null) {
            throw new RuntimeException("Transaction already waiting for " +
                                       this.wait +
                                       ", new wait = " + wait);
        }
        this.wait = wait;
    }

    public final void clearWait() {
        this.wait = null;
    }

    public final HeldLock getWait() { return wait; }
    public final Lock getWaitLock() {
        return wait == null ? null : wait.lock;
    }
    public final int getWaitMode() {
        return wait == null ? LockMode.NL : wait.getWaitMode();
    }
    public final long getTransactionId() {
        //#ifdef DEBUG
        assertLive();
        //#endif
        return transactionId;
    }

    //#ifdef DEBUG
    public String toString() {
        StringBuffer sb = new StringBuffer("T:");
        sb.append(String.valueOf((int)(transactionId & 0xffffffffL)));
        if (wait != null) {
            sb.append(" WAIT: ");
            sb.append(wait.lock.toString());
            sb.append(" mode ");
            sb.append(LockMode.toString(getWaitMode()));
            sb.append(" T:");
            sb.append(wait.getTransaction().transactionId);
        }
        return sb.toString();
    }

    public String dump() {
        StringBuffer sb = new StringBuffer(toString());
        if (wait != null) {
            sb.append(" waitLock: ");
            sb.append(wait);
        }
        return sb.toString();
    }
    //#endif

    public void setObserver(TransactionObserver obj) { observer = obj; }
    public TransactionObserver getObserver() { return observer; }
}