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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;
}
/**
* 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);
}
/**
* 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() {
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() {
StringBuffer sb = new StringBuffer(50);
sb.append("_lockType= " + _lockType);
sb.append("\n" + "foregroundRefCount= " + _foregroundRefCount);
return sb.toString();
}
private String _lockType = null;
private int _foregroundRefCount = 0;
}
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