Class LockSupport

  extended by org.apache.tapestry5.ioc.internal.util.LockSupport
Direct Known Subclasses:
AbstractResource, AlertStorage, ApplicationMessageCatalogObjectProvider, CachingObjectCreator, InternalComponentResourcesImpl, NamedSet, OneShotLock, TypeCoercerImpl

public abstract class LockSupport
extends Object

Base class for classes that need to manage a ReadWriteLock.

Constructor Summary
protected LockSupport()
Method Summary
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


protected LockSupport()
Method Detail


protected final void acquireReadLock()
Locks the shared read lock. Any number of threads may lock the read lock at the same time.


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.


protected final void releaseReadLock()
Releases the shared read lock.


protected final void releaseWriteLock()
Releases the exclusive read lock.


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.


protected final void downgradeWriteLockToReadLock()
Takes the read lock then releases the write lock.

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