Glassfish example source code file (SessionLock.java)

This example Glassfish source code file (SessionLock.java) is included in the DevDaily.com "Java Source Code Warehouse" project. The intent of this project is to help you "Learn Java by Example" ^TM.

Java - Glassfish tags/keywords

background_lock, foreground_lock, foreground_lock, sessionlock, sessionlock, string, string, stringbuilder, stringbuilder

The Glassfish SessionLock.java source code

/*
 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS HEADER.
 *
 * Copyright (c) 1997-2010 Oracle and/or its affiliates. All rights reserved.
 *
 * The contents of this file are subject to the terms of either the GNU
 * General Public License Version 2 only ("GPL") or the Common Development
 * and Distribution License("CDDL") (collectively, the "License").  You
 * may not use this file except in compliance with the License.  You can
 * obtain a copy of the License at
 * https://glassfish.dev.java.net/public/CDDL+GPL_1_1.html
 * or packager/legal/LICENSE.txt.  See the License for the specific
 * language governing permissions and limitations under the License.
 *
 * When distributing the software, include this License Header Notice in each
 * file and include the License file at packager/legal/LICENSE.txt.
 *
 * GPL Classpath Exception:
 * Oracle designates this particular file as subject to the "Classpath"
 * exception as provided by Oracle in the GPL Version 2 section of the License
 * file that accompanied this code.
 *
 * Modifications:
 * If applicable, add the following below the License Header, with the fields
 * enclosed by brackets [] replaced by your own identifying information:
 * "Portions Copyright [year] [name of copyright owner]"
 *
 * Contributor(s):
 * If you wish your version of this file to be governed by only the CDDL or
 * only the GPL Version 2, indicate your decision by adding "[Contributor]
 * elects to include this software in this distribution under the [CDDL or GPL
 * Version 2] license."  If you don't indicate a single choice of license, a
 * recipient has the option to distribute your version of this file under
 * either the CDDL, the GPL Version 2 or to extend the choice of license to
 * its licensees as provided above.  However, if you add GPL Version 2 code
 * and therefore, elected the GPL Version 2 license, then the option applies
 * only if the new code is made subject to such option by the copyright
 * holder.
 *
 *
 * This file incorporates work covered by the following copyright and
 * permission notice:
 *
 * Copyright 2004 The Apache Software Foundation
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package org.apache.catalina.session;


public class SessionLock {
    
    private static final String BACKGROUND_LOCK = "background_lock";
    private static final String FOREGROUND_LOCK = "foreground_lock";
    
    /** Creates a new instance of SessionLock */
    public SessionLock() {
    }

    /**
     * get the lock type
     *
     */     
    public String getLockType() {
        return _lockType;
    }

    /**
     * set the lock type - lockType must be BACKGROUND_LOCK or FOREGROUND_LOCK
     *
     * @param lockType the type of the lock
     */    
    public void setLockType(String lockType) {
        _lockType = lockType;
        // If resetting lock then also reset the _hasNonHttpLockOccurred
        if (lockType == null) {
            _hasNonHttpLockOccurred = false;
        }
    }
    
    /**
     * get the foregroundRefCount
     *
     */     
    public int getForegroundRefCount() {
        return _foregroundRefCount;
    }
    
    /**
     * set the foregroundRefCount
     *
     * @param foregroundRefCount
     */    
    public void setForegroundRefCount(int foregroundRefCount) {
        _foregroundRefCount = foregroundRefCount;
    }
    
    /**
     * increment the foregroundRefCount
     *
     */      
    public void incrementForegroundRefCount() {
        _foregroundRefCount++;
    }
    
    /**
     * decrement the foregroundRefCount
     *
     */    
    public void decrementForegroundRefCount() {
        _foregroundRefCount--;
    }    
    
    /**
     * return whether lock is background locked
     *
     */    
    public boolean isBackgroundLocked() {
        if(_lockType == null) {
            return false;
        }
        return (_lockType.equals(BACKGROUND_LOCK));
    }
    
    /**
     * return whether lock is foreground locked
     *
     */     
    public boolean isForegroundLocked() {
        if(_lockType == null) {
            return false;
        }
        return (_lockType.equals(FOREGROUND_LOCK));
    }
    
    /**
     * return whether lock is locked (either foreground or background)
     *
     */       
    public boolean isLocked() {
        return (_lockType != null);
    }
   
    /**
     * @return true if lock has been locked by non-http request, false otherwise
     */       
    public boolean hasNonHttpLockOccurred() {    
        return _hasNonHttpLockOccurred;
    }

    /**
     * unlock the lock
     * if background locked the lock will become fully unlocked
     * if foreground locked the lock will become fully unlocked
     * if foregroundRefCount was 1; otherwise it will
     * decrement the foregroundRefCount and the lock will remain foreground locked
     *
     */    
    public void unlock() {
        if(!isLocked())
            return;
        if(isBackgroundLocked()) {
            this.setLockType(null);
            this.setForegroundRefCount(0);
            return;
        }
        if(isForegroundLocked()) {
            decrementForegroundRefCount();
            if(_foregroundRefCount == 0) {
                this.setLockType(null);
            }
        }                        
    } 
    
    /**
     * unlock the lock for the foreground locked case
     * the lock will be unlocked
     * if foregroundRefCount was 1; otherwise it will
     * decrement the foregroundRefCount and the lock will remain foreground locked
     *
     */    
    public void unlockForeground() {
        //unlock if the lock is foreground locked
        //else do nothing        
        if(!isLocked())
            return;
        if(isForegroundLocked()) {
            decrementForegroundRefCount();
            if(_foregroundRefCount == 0) {
                this.setLockType(null);
            }
        }                        
    }  
    
    /**
     * unlock the lock
     * this is a force unlock; foregroundRefCount is ignored
     *
     */      
    public void unlockForegroundCompletely() {
        //unlock completely if the lock is foreground locked
        //else do nothing        
        if(!isLocked())
            return;
        if(isForegroundLocked()) {
            this.setForegroundRefCount(0);
            this.setLockType(null);
        }                        
    }      
    
    /**
     * unlock the lock for the background locked case
     * the lock will be unlocked
     *
     */     
    public void unlockBackground() {
        //unlock if the lock is background locked
        //else do nothing
        if(!isLocked())
            return;
        if(isBackgroundLocked()) {
            this.setLockType(null);
            this.setForegroundRefCount(0);
            return;
        }                        
    }     
    
    /**
     * if possible, the lock will be foreground locked
     * if it was already foreground locked; it will
     * remain so and the foregroundRefCount will be incremented
     *
     * if the lock is already background locked the method
     * will return false and the lock remains background locked 
     * (i.e. lock failed) otherwise it will return true (lock succeeded)
     */     
    public synchronized boolean lockForeground() {
        return lockForeground(true);
    }

    public synchronized boolean lockForeground(boolean isHttp) {
        if (!isHttp) {
            _hasNonHttpLockOccurred = true;
        }
        if (isBackgroundLocked()) {
            return false;
        }
        if (isForegroundLocked()) {
            incrementForegroundRefCount();
        } else {
            setForegroundRefCount(1);
        }
        setLockType(FOREGROUND_LOCK);

        return true;
    }
    
    /**
     * if possible, the lock will be background locked
     *
     * if the lock is already foreground locked the method
     * will return false and the lock remains foreground locked 
     * (i.e. lock failed) otherwise it will return true (lock succeeded)
     */      
    public synchronized boolean lockBackground() {
        if (isForegroundLocked()) {
            return false;
        } 
        setLockType(BACKGROUND_LOCK);
        setForegroundRefCount(0);

        return true;
    }
    
    /**
     * returns String representation of the state of the lock
     */     
    public String toString() {
        StringBuilder sb = new StringBuilder(50);
        sb.append("_lockType= " + _lockType);
        sb.append("\n" + "foregroundRefCount= " + _foregroundRefCount);
        return sb.toString();
    }
    
    private String _lockType = null;
    private int _foregroundRefCount = 0;
    private boolean _hasNonHttpLockOccurred = false;    
}