Package wt.impact

Class WTChunkedIterator<T extends Persistable>

java.lang.Object

wt.impact.WTChunkedIterator<T>

All Implemented Interfaces:

AutoCloseable, Iterator<T>

public class WTChunkedIterator<T extends Persistable>
extends Object
implements Iterator<T>, AutoCloseable

WTCollection iterator that inflates and deflates object references in chunks. This iterator keeps memory usage low when iterating over large, deflated collections.

This iterator can only be used in the method server.

It is recommended that this iterator be used as resource in a try-with-resources block to ensure that inflated references are deflated if iteration terminates.

Examples:

 WTCollection objects;
     :
 // objects collection is created and populated with deflated references
     :
 try (WTChunkedIterator partIter = new WTChunkedIterator(objects, 1000, WTPart.class)) {
     while ( partIter.hasNext() ) {
         WTPart part = partIter.next();
             :
     }
 }
 // All references in the collection that were originally deflated will be 
 // automatically deflated when the try-with-resources block exits.
 // All references in the collection that were originally inflated will remain so.
     :
 

If a try-with-resources block is not used then close() should be called when the iterator is no longer needed:

 WTCollection objects;
     :
 // objects collection is populated with deflated references
     :
 WTChunkedIterator partIter = new WTChunkedIterator(objects, 1000, WTPart.class);
 while ( partIter.hasNext() ) {
    WTPart part = partIter.next();
             :
 }
 partIter.close(); // Deflate references.
     :
 

Supported API: true

Extendable: false

Constructor Summary

Constructors

Constructor	Description
WTChunkedIterator(WTCollection collection, int chunkSize)	Construct a new WTChunkedIterator for all Persistable classes.
WTChunkedIterator(WTCollection collection, int chunkSize, Class<T> filter)	Construct a new WTChunkedIterator for a filter class and all sub-classes.
WTChunkedIterator(WTCollection collection, int chunkSize, Class<T> filter, boolean includeSubclasses)	Construct a new WTChunkedIterator for a filter class.

Method Summary

Modifier and Type	Method	Description
void	close()	Deflate references and clear chunk collections.
boolean	hasNext()	Supported API: true
T	next()	Returns the next Persistable object in the collection.

Methods inherited from class java.lang.Object

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

Methods inherited from interface java.util.Iterator

forEachRemaining

Constructor Details

WTChunkedIterator

public WTChunkedIterator(WTCollection collection,
 int chunkSize)

Construct a new WTChunkedIterator for all Persistable classes. Inflates objects in chunks to keep memory usage low.

This iterator can only be used in the method server.

Supported API: true

Parameters:

collection - Collection of deflated object references.

chunkSize - Number of references that are inflated in a chunk.

WTChunkedIterator

public WTChunkedIterator(WTCollection collection,
 int chunkSize,
 Class<T> filter)

Construct a new WTChunkedIterator for a filter class and all sub-classes. Inflates objects in chunks to keep memory usage low.

This iterator can only be used in the method server.

Supported API: true

Parameters:

collection - Collection of deflated object references.

chunkSize - Number of references that are inflated in a chunk.

filter - Object class filter.

WTChunkedIterator

public WTChunkedIterator(WTCollection collection,
 int chunkSize,
 Class<T> filter,
 boolean includeSubclasses)

Construct a new WTChunkedIterator for a filter class. Inflates objects in chunks to keep memory usage low.

This iterator can only be used in the method server.

Supported API: true

Parameters:

collection - Collection of deflated object references.

chunkSize - Number of references that are inflated in a chunk.

filter - Object class filter.

includeSubclasses - True to iterated over the filter objects and all of its sub-classes, or false to iterated over only the filter objects.

Method Details

close

public void close()

Deflate references and clear chunk collections. Called automatically if iterator is a resource in a try-with-resources block.

Supported API: true

Specified by:

close in interface AutoCloseable

hasNext

public boolean hasNext()

Supported API: true

Specified by:

hasNext in interface Iterator<T extends Persistable>

Throws:

WTRuntimeException

next

public T next()

Returns the next Persistable object in the collection. Objects will be inflated and deflated in chunks within next() calls.

Supported API: true

Specified by:

next in interface Iterator<T extends Persistable>

Throws:

NoSuchElementException