info.magnolia.cms.filters
Class SafeDestroyMgnlFilterWrapper.Switcher

java.lang.Object
  info.magnolia.cms.filters.SafeDestroyMgnlFilterWrapper.Switcher

Enclosing class:

SafeDestroyMgnlFilterWrapper

public static class SafeDestroyMgnlFilterWrapper.Switcher
extends Object

Construct for keeping a reference to a SafeDestroyMgnlFilterWrapper and change it with the guarantee that the returned previous reference will not get more read locks. It's then safe to destroy the returned reference.

Version:

$Id$

Constructor Summary

SafeDestroyMgnlFilterWrapper.Switcher()

Method Summary

SafeDestroyMgnlFilterWrapper	getFilter() This method is provided for introspection only.
SafeDestroyMgnlFilterWrapper	getFilterAndAcquireReadLock() Returns the current filter with a read lock held for the current thread.
SafeDestroyMgnlFilterWrapper	replaceFilter(SafeDestroyMgnlFilterWrapper newFilter) Replaces the current filter with a new one and returns the previous filter.

Methods inherited from class java.lang.Object

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

Constructor Detail

SafeDestroyMgnlFilterWrapper.Switcher

public SafeDestroyMgnlFilterWrapper.Switcher()

Method Detail

replaceFilter

public SafeDestroyMgnlFilterWrapper replaceFilter(SafeDestroyMgnlFilterWrapper newFilter)

Replaces the current filter with a new one and returns the previous filter. The returned filter is possibly still in use by currently executing requests but it will not be used by any more requests after this method returns.

Notes about the returned filter:

• No methods other than destroy() should be called on the returned filter
• The destroy() method will wait for all requests to complete before it is destroyed
• Calling the destroy() method from a request that has entered the filter WILL RESULT IN DEAD LOCK.

getFilterAndAcquireReadLock

public SafeDestroyMgnlFilterWrapper getFilterAndAcquireReadLock()

Returns the current filter with a read lock held for the current thread. After use the thread must relinquish the lock by calling releaseReadLock(). If no filter has been set this method returns null and no lock is taken.

getFilter

public SafeDestroyMgnlFilterWrapper getFilter()

This method is provided for introspection only. It is inherently UNSAFE as using this method and then acquiring the read lock on the returned filter breaks the guarantee that a replaced reference wont get more read locks.