uka.util
Class WeakIDMap

java.lang.Object
  uka.util.IDConstants
      uka.util.IDMap
          uka.util.WeakIDMap

All Implemented Interfaces:

Printable, java.io.Serializable

Direct Known Subclasses:

PartitionedObjectSpace

public class WeakIDMap

extends IDMap

This class provides the same functionality as IDMap, but uses weak references. Adding an object to this container does not prevent it from being garbage collected. An identifier stays used until it is removed explicitly, even if the corresponding object was garbage collected.

Author:

Bernhard Haumacher

See Also:

Serialized Form

Nested Class Summary

(package private) static class

WeakIDMap.Ref Weakly refer to an object, and remember its hash code beyond its death.

Field Summary

private java.lang.ref.ReferenceQueue

queue

Fields inherited from class uka.util.IDMap

idToObject, INVALID_INDEX, space

Fields inherited from class uka.util.IDConstants

FIRST_NEW_ID, FIRST_VALID_ID, INVALID_ID, UNUSED_ID

Constructor Summary

WeakIDMap()

WeakIDMap(IDSpace space)

Method Summary

protected java.lang.Object	get(int id)
protected int	getIDForRef(WeakIDMap.Ref ref) Find the identifier for a given reference.
protected int	getIndexForID(int id)
Iterator	getObjects() Specialized implementation for @T@IDMap.getObjects() that prevents returning null values for already garbage collected objects.
Iterator	getObjects(IntIterator ids)
private void	initTransient()
int	pollID() Polls an internal ReferenceQueue for the next weakly reacheable object and returns the identifier that was associated with it.
protected void	restoreBeforeReadObject()
protected void	set(int id, java.lang.Object obj) Access to the underlying IDMap.idToObject array is encapsulated through the set(int, java.lang.Object) and get(int) methods.
int	waitForID() Wait until an object that is referenced from this map becomes weakly reacheable and return its identifier.
int	waitForID(long timeout) Wait at most timeout milliseconds until an object that is referenced from this map becomes weakly reacheable and return its identifier.

Methods inherited from class uka.util.IDMap

appendTo, clear, dump, findID, getHash, getID, getIndexForHash, getObject, getSize, getUsedIDs, isUsed, rawFindID, remove, resetObject, setObject

Methods inherited from class uka.util.IDConstants

isNew, isValid, normalizeID, toggleNew

Methods inherited from class java.lang.Object

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

Field Detail

queue

private transient java.lang.ref.ReferenceQueue queue

Constructor Detail

WeakIDMap

public WeakIDMap()

WeakIDMap

public WeakIDMap(IDSpace space)

Method Detail

initTransient

private void initTransient()

set

protected void set(int id,
                   java.lang.Object obj)

Description copied from class: IDMap

Access to the underlying IDMap.idToObject array is encapsulated through the IDMap.set(int, java.lang.Object) and IDMap.get(int) methods. Subclasses may use this hooks to add functionality whenever an object is stored or retrieved.

Overrides:

set in class IDMap

get

protected java.lang.Object get(int id)

Overrides:

get in class IDMap

See Also:

IDMap.set(int, java.lang.Object)

getIndexForID

protected int getIndexForID(int id)

Overrides:

getIndexForID in class IDMap

getObjects

public Iterator getObjects()

Specialized implementation for @T@IDMap.getObjects() that prevents returning null values for already garbage collected objects.

Overrides:

getObjects in class IDMap

getObjects

public Iterator getObjects(IntIterator ids)

Returns:

all objects that are identified by identifiers from the passed iterator. If an object for a given identifier has already been garbage collected, do not include a null value in the output sequence.

pollID

public int pollID()

Polls an internal ReferenceQueue for the next weakly reacheable object and returns the identifier that was associated with it. If there is no more weakly reacheable object, the method returns IDConstants.INVALID_ID.

waitForID

public int waitForID()
              throws java.lang.InterruptedException

Wait until an object that is referenced from this map becomes weakly reacheable and return its identifier.

Throws:

java.lang.InterruptedException

See Also:

pollID(), ReferenceQueue.remove()

waitForID

public int waitForID(long timeout)
              throws java.lang.InterruptedException

Wait at most timeout milliseconds until an object that is referenced from this map becomes weakly reacheable and return its identifier. If no object becomes unreferenced within timeout, IDConstants.INVALID_ID is returned.

Throws:

java.lang.InterruptedException

See Also:

pollID(), ReferenceQueue.remove(long)

getIDForRef

protected int getIDForRef(WeakIDMap.Ref ref)

Find the identifier for a given reference. No identifier is found, if the reference was already removed from this map. If that's the case, IDConstants.INVALID_ID is returned.

See Also:

IDMap.rawFindID(java.lang.Object, int)

restoreBeforeReadObject

protected void restoreBeforeReadObject()
                                throws java.lang.ClassNotFoundException,
                                       java.io.IOException

Overrides:

restoreBeforeReadObject in class IDMap

Throws:

java.lang.ClassNotFoundException

java.io.IOException