File	Doc	Category	Size	Date	Package
SingleRemoveSynchronizedAddLock.java	API Doc	Apache Tomcat 6.0.14	7797	Fri Jul 20 04:20:36 BST 2007	org.apache.catalina.tribes.transport.bio.util

SingleRemoveSynchronizedAddLock

• java.lang.Object

Fields Summary
private long	addWaitTimeout Time in milliseconds after which threads waiting for an add lock are woken up. This is used as a safety measure in case thread notification via the unlock methods has a bug.
private long	removeWaitTimeout Time in milliseconds after which threads waiting for a remove lock are woken up. This is used as a safety measure in case thread notification via the unlock methods has a bug.
private Thread	remover The current remove thread. It is set to the remove thread polling for entries. It is reset to null when the remove thread releases the lock and proceeds processing the removed entries.
private boolean	addLocked A flag indicating, if an add thread owns the lock.
private boolean	removeLocked A flag indicating, if the remove thread owns the lock.
private boolean	removeEnabled A flag indicating, if the remove thread is allowed to wait for the lock. The flag is set to false, when aborting.
private boolean	dataAvailable A flag indicating, if the remover needs polling. It indicates, if the locked object has data available to be removed.

Constructors Summary
public SingleRemoveSynchronizedAddLock()
public SingleRemoveSynchronizedAddLock(boolean dataAvailable) this.dataAvailable=dataAvailable;

Methods Summary
public synchronized void	abortRemove() Abort any polling remover thread removeEnabled=false; if ( remover != null ) { remover.interrupt(); }
public synchronized long	getAddWaitTimeout() return Value of addWaitTimeout return addWaitTimeout;
public synchronized long	getRemoveWaitTimeout() return Value of removeWaitTimeout return removeWaitTimeout;
public synchronized boolean	isAddLocked() Check if an add thread owns the lock. return True iff an add thread owns the lock. return addLocked;
public synchronized boolean	isDataAvailable() Check if the locked object has data available i.e. the remover can stop poling and get the lock. return True iff the lock Object has data available. return dataAvailable;
public synchronized boolean	isRemoveLocked() Check if the remove thread owns the lock. return True iff the remove thread owns the lock. return removeLocked;
public synchronized boolean	isRemovePolling() Check if the remove thread is polling. return True iff the remove thread is polling. if ( remover != null ) { return true; } return false;
public synchronized void	lockAdd() Acquires the lock by an add thread and sets the add flag. If any add thread or the remove thread already acquired the lock this add thread will block until the lock is released. if ( addLocked || removeLocked ) { do { try { wait(addWaitTimeout); } catch ( InterruptedException e ) { Thread.currentThread().interrupted(); } } while ( addLocked || removeLocked ); } addLocked=true;
public synchronized boolean	lockRemove() Acquires the lock by the remove thread and sets the remove flag. If any add thread already acquired the lock or the queue is empty, the remove thread will block until the lock is released and the queue is not empty. removeLocked=false; removeEnabled=true; if ( ( addLocked || ! dataAvailable ) && removeEnabled ) { remover=Thread.currentThread(); do { try { wait(removeWaitTimeout); } catch ( InterruptedException e ) { Thread.currentThread().interrupted(); } } while ( ( addLocked || ! dataAvailable ) && removeEnabled ); remover=null; } if ( removeEnabled ) { removeLocked=true; } return removeLocked;
public synchronized void	setAddWaitTimeout(long timeout) Set value of addWaitTimeout addWaitTimeout = timeout;
public synchronized void	setRemoveWaitTimeout(long timeout) Set value of removeWaitTimeout removeWaitTimeout = timeout;
public synchronized void	unlockAdd(boolean dataAvailable) Releases the lock by an add thread and reset the remove flag. If the reader thread is polling, notify it. addLocked=false; this.dataAvailable=dataAvailable; if ( ( remover != null ) && ( dataAvailable || ! removeEnabled ) ) { remover.interrupt(); } else { notifyAll(); }
public synchronized void	unlockRemove() Releases the lock by the remove thread and reset the add flag. Notify all waiting add threads, that the lock has been released by the remove thread. removeLocked=false; dataAvailable=false; notifyAll();