org.apache.druid.segment

Class ReferenceCountingCloseableObject<BaseObject extends Closeable>

java.lang.Object

org.apache.druid.segment.ReferenceCountingCloseableObject<BaseObject>

All Implemented Interfaces:

Closeable, AutoCloseable

Direct Known Subclasses:

ReferenceCountingIndexedTable, ReferenceCountingSegment

public abstract class ReferenceCountingCloseableObject<BaseObject extends Closeable>
extends Object
implements Closeable

ReferenceCountingCloseableObject implements something like automatic reference count-based resource management, backed by a Phaser. ReferenceCountingCloseableObject allows consumers to call close() before some other "users", which called increment() or incrementReferenceAndDecrementOnceCloseable(), but have not called decrement() yet or the closer for incrementReferenceAndDecrementOnceCloseable(), and the wrapped object won't be actually closed until that all references are released.

Field Summary

Fields

Modifier and Type	Field and Description
protected BaseObject	baseObject
protected Phaser	referents

Constructor Summary

Constructors

Constructor and Description
ReferenceCountingCloseableObject(BaseObject object)

Method Summary

Modifier and Type	Method and Description
void	close()
void	decrement() Decrement the reference count by one.
Closeable	decrementOnceCloseable() Returns a Closeable which action is to call decrement() only once.
int	getNumReferences()
boolean	increment() Increment the reference count by one.
Optional<Closeable>	incrementReferenceAndDecrementOnceCloseable() Returns an Optional of a Closeable from decrementOnceCloseable(), if it is able to successfully increment(), else nothing indicating that the reference could not be acquired.
boolean	isClosed()

Methods inherited from class java.lang.Object

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

Field Detail

referents

protected final Phaser referents

baseObject

protected final BaseObject extends Closeable baseObject

Constructor Detail

ReferenceCountingCloseableObject

public ReferenceCountingCloseableObject(BaseObject object)

Method Detail

getNumReferences

public int getNumReferences()

isClosed

public boolean isClosed()

increment

public boolean increment()

Increment the reference count by one.

decrement

public void decrement()

Decrement the reference count by one.

incrementReferenceAndDecrementOnceCloseable

public Optional<Closeable> incrementReferenceAndDecrementOnceCloseable()

Returns an Optional of a Closeable from decrementOnceCloseable(), if it is able to successfully increment(), else nothing indicating that the reference could not be acquired.

decrementOnceCloseable

public Closeable decrementOnceCloseable()

Returns a Closeable which action is to call decrement() only once. If close() is called on the returned Closeable object for the second time, it won't call decrement() again.

close

public void close()

Specified by:

close in interface Closeable

Specified by:

close in interface AutoCloseable