org.apache.tapestry5.ioc.internal.util

Class LockSupport

java.lang.Object

org.apache.tapestry5.ioc.internal.util.LockSupport

Direct Known Subclasses:

AbstractResource, AlertStorage, ApplicationMessageCatalogObjectProvider, AssetSourceImpl, CachingObjectCreator, InternalComponentResourcesImpl, NamedSet, OneShotLock, TypeCoercerImpl

public abstract class LockSupport
extends Object

Base class for classes that need to manage a ReadWriteLock.

Constructor Summary

Constructors

Modifier	Constructor and Description
protected	LockSupport()

Method Summary

Modifier and Type	Method and Description
protected void	acquireReadLock() Locks the shared read lock.
protected void	downgradeWriteLockToReadLock() Takes the read lock then releases the write lock.
protected void	releaseReadLock() Releases the shared read lock.
protected void	releaseWriteLock() Releases the exclusive read lock.
protected void	takeWriteLock() Takes the exclusive write lock.
protected void	upgradeReadLockToWriteLock() Releases the read lock, then takes the write lock.

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Constructor Detail

LockSupport

protected LockSupport()

Method Detail

acquireReadLock

protected final void acquireReadLock()

Locks the shared read lock. Any number of threads may lock the read lock at the same time.

takeWriteLock

protected final void takeWriteLock()

Takes the exclusive write lock. Once started, no other thread lock the read or write lock. When this method returns, this thread will have locked the write lock and no other thread will have either the read or write lock. Note that this thread must first drop the read lock (if it has it) before attempting to take the write lock, or this method will block forever.

releaseReadLock

protected final void releaseReadLock()

Releases the shared read lock.

releaseWriteLock

protected final void releaseWriteLock()

Releases the exclusive read lock.

upgradeReadLockToWriteLock

protected final void upgradeReadLockToWriteLock()

Releases the read lock, then takes the write lock. There's a short window where the thread will have neither lock: during that window, some other thread may have a chance to take the write lock. In code, you'll often see a second check inside the code that has the write lock to see if the update to perform is still necessary.

downgradeWriteLockToReadLock

protected final void downgradeWriteLockToReadLock()

Takes the read lock then releases the write lock.