Package org.aksw.commons.util.ref

Class RefImpl<T>

java.lang.Object

org.aksw.commons.util.ref.RefImpl<T>

Type Parameters:

T -

All Implemented Interfaces:

AutoCloseable, Ref<T>

public class RefImpl<T>
extends Object
implements Ref<T>

Implementation of a Ref TODO Avoid needless synchronization; a ConcurrentHashMap may help; ref.equals could do only reference comparison

Author:

raven

Field Summary

Fields

Modifier and Type	Field	Description
protected StackTraceElement[]	acquisitionStackTrace
protected int	activeChildRefs
protected Map<Ref<T>,Object>	childRefs
protected StackTraceElement[]	closeStackTrace
protected StackTraceElement[]	closeTriggerStackTrace
protected Object	comment
protected boolean	isClosed
protected RefImpl<T>	parent
protected AutoCloseable	releaseAction	The release action is run once immediately when the isAlive() state changes to false.
protected Object	synchronizer	Object on which to synchronize on before any change of state of this reference.
protected boolean	traceAcquisitions
protected T	value

Constructor Summary

Constructors

Constructor	Description
RefImpl(RefImpl<T> parent, T value, Object synchronizer, AutoCloseable releaseAction, Object comment)

Method Summary

Modifier and Type	Method	Description
Ref<T>	acquire(Object comment)	Acquire a new reference with a given comment object Acquiration fails if isAlive() returns false
protected void	checkRelease()
void	close()
static <T> Ref<T>	create(T value, Object synchronizer, AutoCloseable releaseAction)
static <T> Ref<T>	create(T value, Object synchronizer, AutoCloseable releaseAction, Object comment)
static <T> Ref<T>	create2(T value, Object synchronizer, java.util.function.Consumer<? super T> closer)	Create method where the close action is created from a provided lambda that accepts the value
static <T> Ref<T>	createClosed()
protected void	finalize()	TODO Switch to Java 9 Cleaner once we upgrade
static <T extends AutoCloseable> Ref<T>	fromCloseable(T value, Object synchronizer)
T	get()	Get the referent only iff this ref instance has not yet been closed.
StackTraceElement[]	getAcquisitionStackTrace()	Optional operation.
StackTraceElement[]	getCloseStackTrace()
StackTraceElement[]	getCloseTriggerStackTrace()
Object	getComment()
Ref<T>	getRootRef()	Get the root reference
Object	getSynchronizer()	Return the object on which reference acquisition, release and the close action are synchronized on.
boolean	isAlive()	A reference may itself be closed, but references to it may keep it alive
boolean	isClosed()	Check whether this reference is closed
protected void	release(Object childRef)
String	toString()

Methods inherited from class java.lang.Object

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

Methods inherited from interface org.aksw.commons.util.ref.Ref

acquire, acquireMapped

Field Detail

traceAcquisitions

protected boolean traceAcquisitions

value

protected T value

releaseAction

protected AutoCloseable releaseAction

The release action is run once immediately when the isAlive() state changes to false. The release action cannot 'revive' a reference as the reference is already 'dead'. The release action differs depending on how a reference was created: On the root reference, the releaseAction releases the wrapped resource On a child reference, the releaseAction releases itself (the child) from the parent one.

synchronizer

protected Object synchronizer

Object on which to synchronize on before any change of state of this reference. This allows for e.g. synchronizing on a Map<K, Reference<V>, such that closing a reference removes the map entry before it can be accessed and conversely, synchronizing on the map prevents the reference from becoming released. TODO Point to the ClaimingLoadingCache implementation

comment

protected Object comment

parent

protected RefImpl<T> parent

isClosed

protected volatile boolean isClosed

acquisitionStackTrace

protected StackTraceElement[] acquisitionStackTrace

closeStackTrace

protected StackTraceElement[] closeStackTrace

closeTriggerStackTrace

protected StackTraceElement[] closeTriggerStackTrace

childRefs

protected Map<Ref<T>,Object> childRefs

activeChildRefs

protected volatile int activeChildRefs

Constructor Detail

RefImpl

public RefImpl(RefImpl<T> parent,
               T value,
               Object synchronizer,
               AutoCloseable releaseAction,
               Object comment)

Method Detail

finalize

protected void finalize()
                 throws Throwable

TODO Switch to Java 9 Cleaner once we upgrade

Overrides:

finalize in class Object

Throws:

Throwable

getComment

public Object getComment()

getSynchronizer

public Object getSynchronizer()

Description copied from interface: Ref

Return the object on which reference acquisition, release and the close action are synchronized on.

Specified by:

getSynchronizer in interface Ref<T>

get

public T get()

Description copied from interface: Ref

Get the referent only iff this ref instance has not yet been closed. This method fails for closed alive refs. A closed reference is alive if it has unclosed child references. For most use cases the referent should be accessed using this method.

Specified by:

get in interface Ref<T>

Returns:

The referent

acquire

public Ref<T> acquire(Object comment)

Description copied from interface: Ref

Acquire a new reference with a given comment object Acquiration fails if isAlive() returns false

Specified by:

acquire in interface Ref<T>

Returns:

release

protected void release(Object childRef)

isAlive

public boolean isAlive()

Description copied from interface: Ref

A reference may itself be closed, but references to it may keep it alive

Specified by:

isAlive in interface Ref<T>

Returns:

true iff either this reference is not closed or there exists any acquired reference.

close

public void close()

Specified by:

close in interface AutoCloseable

Specified by:

close in interface Ref<T>

checkRelease

protected void checkRelease()

fromCloseable

public static <T extends AutoCloseable> Ref<T> fromCloseable(T value,
                                                             Object synchronizer)

create2

public static <T> Ref<T> create2(T value,
                                 Object synchronizer,
                                 java.util.function.Consumer<? super T> closer)

Create method where the close action is created from a provided lambda that accepts the value

create

public static <T> Ref<T> create(T value,
                                Object synchronizer,
                                AutoCloseable releaseAction)

create

public static <T> Ref<T> create(T value,
                                Object synchronizer,
                                AutoCloseable releaseAction,
                                Object comment)

createClosed

public static <T> Ref<T> createClosed()

isClosed

public boolean isClosed()

Description copied from interface: Ref

Check whether this reference is closed

Specified by:

isClosed in interface Ref<T>

getRootRef

public Ref<T> getRootRef()

Description copied from interface: Ref

Get the root reference

Specified by:

getRootRef in interface Ref<T>

getAcquisitionStackTrace

public StackTraceElement[] getAcquisitionStackTrace()

Description copied from interface: Ref

Optional operation. References may expose where they were acquired

Specified by:

getAcquisitionStackTrace in interface Ref<T>

Returns:

getCloseStackTrace

public StackTraceElement[] getCloseStackTrace()

Specified by:

getCloseStackTrace in interface Ref<T>

getCloseTriggerStackTrace

public StackTraceElement[] getCloseTriggerStackTrace()

Specified by:

getCloseTriggerStackTrace in interface Ref<T>

toString

public String toString()

Overrides:

toString in class Object