Package org.apache.hadoop.util.functional

Class LazyAutoCloseableReference<T extends AutoCloseable>

java.lang.Object

org.apache.hadoop.util.functional.LazyAtomicReference<T>

org.apache.hadoop.util.functional.LazyAutoCloseableReference<T>

Type Parameters:

T - type of reference.

All Implemented Interfaces:

AutoCloseable, Supplier<T>, CallableRaisingIOE<T>

public class LazyAutoCloseableReference<T extends AutoCloseable>
extends LazyAtomicReference<T>
implements AutoCloseable

A subclass of LazyAtomicReference which holds an AutoCloseable reference and calls close() when it itself is closed.

Constructor Summary

Constructors

Constructor	Description
LazyAutoCloseableReference(CallableRaisingIOE<? extends T> constructor)	Constructor for this instance.

Method Summary

Modifier and Type	Method	Description
void	close()	Close the reference value if it is non-null.
T	eval()	Get the value, constructing it if needed.
boolean	isClosed()	Is the reference closed?
static <T extends AutoCloseable> LazyAutoCloseableReference<T>	lazyAutoCloseablefromSupplier(Supplier<T> supplier)	Create from a supplier.

Methods inherited from class org.apache.hadoop.util.functional.LazyAtomicReference

apply, get, getConstructor, getReference, isSet, lazyAtomicReferenceFromSupplier, toString

Methods inherited from class java.lang.Object

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

Methods inherited from interface org.apache.hadoop.util.functional.CallableRaisingIOE

unchecked

Constructor Details

LazyAutoCloseableReference

public LazyAutoCloseableReference(CallableRaisingIOE<? extends T> constructor)

Constructor for this instance.

Parameters:

constructor - method to invoke to actually construct the inner object.

Method Details

eval

public T eval()
       throws IOException

Get the value, constructing it if needed.

Overrides:

eval in class LazyAtomicReference<T extends AutoCloseable>

Returns:

the value

Throws:

IllegalStateException - if the reference is closed.

IOException - on any evaluation failure

isClosed

public boolean isClosed()

Is the reference closed?

Returns:

true if the reference is closed.

close

public void close()
           throws Exception

Close the reference value if it is non-null. Sets the reference to null afterwards, even on a failure.

Specified by:

close in interface AutoCloseable

Throws:

Exception - failure to close.

lazyAutoCloseablefromSupplier

public static <T extends AutoCloseable>
LazyAutoCloseableReference<T> lazyAutoCloseablefromSupplier(Supplier<T> supplier)

Create from a supplier. This is not a constructor to avoid ambiguity when a lambda-expression is passed in.

Type Parameters:

T - type of reference

Parameters:

supplier - supplier implementation.

Returns:

a lazy reference.