org.apache.nifi.util

Class RingBuffer<T>

java.lang.Object

org.apache.nifi.util.RingBuffer<T>

public class RingBuffer<T>
extends Object

Thread-safe implementation of a RingBuffer

Nested Class Summary

Nested Classes

Modifier and Type	Class and Description
static interface	RingBuffer.Filter<S>
static interface	RingBuffer.ForEachEvaluator<S> Defines an interface that can be used to iterate over all of the elements in the RingBuffer via the forEach(org.apache.nifi.util.RingBuffer.ForEachEvaluator<T>) method
static class	RingBuffer.IterationDirection

Field Summary

Fields

Modifier and Type	Field and Description
private Object[]	buffer
private boolean	filled
private int	insertionPointer
private Lock	readLock
private ReadWriteLock	rwLock
private Lock	writeLock

Constructor Summary

Constructors

Constructor and Description
RingBuffer(int size)

Method Summary

Modifier and Type	Method and Description
T	add(T value) Adds the given value to the RingBuffer and returns the value that was removed in order to make room.
List<T>	asList()
int	countSelectedElements(RingBuffer.Filter<T> filter)
void	forEach(RingBuffer.ForEachEvaluator<T> evaluator) Iterates over each element in the RingBuffer, calling the evaluate method on each element in the RingBuffer.
void	forEach(RingBuffer.ForEachEvaluator<T> evaluator, RingBuffer.IterationDirection iterationDirection) Iterates over each element in the RingBuffer, calling the evaluate method on each element in the RingBuffer.
private T	getElementData(int index)
T	getNewestElement()
T	getOldestElement()
List<T>	getSelectedElements(RingBuffer.Filter<T> filter)
List<T>	getSelectedElements(RingBuffer.Filter<T> filter, int maxElements)
int	getSize()
int	removeSelectedElements(RingBuffer.Filter<T> filter) Removes all elements from the RingBuffer that match the given filter

Methods inherited from class java.lang.Object

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

Field Detail

buffer

private final Object[] buffer

insertionPointer

private int insertionPointer

filled

private boolean filled

rwLock

private final ReadWriteLock rwLock

readLock

private final Lock readLock

writeLock

private final Lock writeLock

Constructor Detail

RingBuffer

public RingBuffer(int size)

Method Detail

add

public T add(T value)

Adds the given value to the RingBuffer and returns the value that was removed in order to make room.

Parameters:

value - the new value to add

Returns:

value previously in the buffer

getSize

public int getSize()

getSelectedElements

public List<T> getSelectedElements(RingBuffer.Filter<T> filter)

getSelectedElements

public List<T> getSelectedElements(RingBuffer.Filter<T> filter,
                                   int maxElements)

countSelectedElements

public int countSelectedElements(RingBuffer.Filter<T> filter)

removeSelectedElements

public int removeSelectedElements(RingBuffer.Filter<T> filter)

Removes all elements from the RingBuffer that match the given filter

Parameters:

filter - to use for deciding what is removed

Returns:

always zero

asList

public List<T> asList()

getOldestElement

public T getOldestElement()

getNewestElement

public T getNewestElement()

getElementData

private T getElementData(int index)

forEach

public void forEach(RingBuffer.ForEachEvaluator<T> evaluator)

Iterates over each element in the RingBuffer, calling the evaluate method on each element in the RingBuffer. If the Evaluator returns false, the method will skip all remaining elements in the RingBuffer; otherwise, the next element will be evaluated until all elements have been evaluated.

Parameters:

evaluator - used to evaluate each item in the ring buffer

forEach

public void forEach(RingBuffer.ForEachEvaluator<T> evaluator,
                    RingBuffer.IterationDirection iterationDirection)

Iterates over each element in the RingBuffer, calling the evaluate method on each element in the RingBuffer. If the Evaluator returns false, the method will skip all remaining elements in the RingBuffer; otherwise, the next element will be evaluated until all elements have been evaluated.

Parameters:

evaluator - the evaluator

iterationDirection - the order in which to iterate over the elements in the RingBuffer