com.gemstone.gemfire.internal.shared

Class FinalizeObject

java.lang.Object

java.lang.ref.Reference<T>

java.lang.ref.WeakReference<java.lang.Object>

com.gemstone.gemfire.internal.shared.FinalizeObject

All Implemented Interfaces:

com.gemstone.gnu.trove.TLinkable, java.io.Serializable

public abstract class FinalizeObject
extends java.lang.ref.WeakReference<java.lang.Object>
implements com.gemstone.gnu.trove.TLinkable

Base class to be used by classes that need to implement some actions in finalize. This will eventually be used by all server/client classes that need finalizers (instead of the expensive finalize methods) so is in the shared location now part of GemFire.

Note that there is a significant performance impact on GC when using Object.finalize() vs the approach below, so former should be removed from all code and never used in product code. It also leads to significant delays in GC itself leading to memory buildups.

Also note that this uses a WeakReference rather than a PhantomReference. The reason is that PhantomReference is not cleared when it is enqueued (at least in Java 7/8) so the referent remains alive till it is explicitly cleared by the queue poller. This unnecessarily increases the lifetime of the referent and can cause trouble if there is a rapid increase of such objects. Using a WeakReference avoids this where the referent will be cleared as before it is enqueued and will otherwise behave similar to a PhantomReference assuming the referent is not overriding the finalize method too.

See Also:

Serialized Form

Nested Class Summary

Nested Classes

Modifier and Type	Class and Description
static interface	FinalizeObject.BatchFinalize Interface that finalizers (extensions of FinalizeObject) can implement to indicate batching of finalization where possible e.g.
static class	FinalizeObject.State Simple wrapper class to share state across the base object and FinalizeObject.

Constructor Summary

Constructors

Modifier	Constructor and Description
protected	FinalizeObject(java.lang.Object referent, boolean server)

Method Summary

Modifier and Type	Method and Description
void	clear()
void	clearAll()
static void	clearFinalizationQueues()
protected abstract void	clearThis()
protected abstract boolean	doFinalize() The finalizer method for the object for post GC cleanup.
static FinalizeHolder	getClientHolder()
abstract FinalizeHolder	getHolder()
com.gemstone.gnu.trove.TLinkable	getNext()
com.gemstone.gnu.trove.TLinkable	getPrevious()
static FinalizeHolder	getServerHolder()
void	setNext(com.gemstone.gnu.trove.TLinkable linkable)
void	setPrevious(com.gemstone.gnu.trove.TLinkable linkable)

Methods inherited from class java.lang.ref.Reference

enqueue, get, isEnqueued

Methods inherited from class java.lang.Object

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

Constructor Detail

FinalizeObject

protected FinalizeObject(java.lang.Object referent,
                         boolean server)

Method Detail

getServerHolder

public static FinalizeHolder getServerHolder()

getClientHolder

public static FinalizeHolder getClientHolder()

clearFinalizationQueues

public static void clearFinalizationQueues()

clear

public final void clear()

Overrides:

clear in class java.lang.ref.Reference<java.lang.Object>

clearAll

public final void clearAll()

getNext

public final com.gemstone.gnu.trove.TLinkable getNext()

Specified by:

getNext in interface com.gemstone.gnu.trove.TLinkable

getPrevious

public final com.gemstone.gnu.trove.TLinkable getPrevious()

Specified by:

getPrevious in interface com.gemstone.gnu.trove.TLinkable

setNext

public final void setNext(com.gemstone.gnu.trove.TLinkable linkable)

Specified by:

setNext in interface com.gemstone.gnu.trove.TLinkable

setPrevious

public final void setPrevious(com.gemstone.gnu.trove.TLinkable linkable)

Specified by:

setPrevious in interface com.gemstone.gnu.trove.TLinkable

getHolder

public abstract FinalizeHolder getHolder()

clearThis

protected abstract void clearThis()

doFinalize

protected abstract boolean doFinalize()
                               throws java.lang.Exception

The finalizer method for the object for post GC cleanup. Return false to abort finalization just yet and place in a pending queue to be retried later.

Throws:

java.lang.Exception