Package org.apache.lucene.util

Class FrequencyTrackingRingBuffer

java.lang.Object

org.apache.lucene.util.FrequencyTrackingRingBuffer

All Implemented Interfaces:

Accountable

public final class FrequencyTrackingRingBuffer
extends Object
implements Accountable

A ring buffer that tracks the frequency of the integers that it contains. This is typically useful to track the hash codes of popular recently-used items.

This data-structure requires 22 bytes per entry on average (between 16 and 28).

NOTE: This API is for internal purposes only and might change in incompatible ways in the next release.

Field Summary

Fields inherited from interface org.apache.lucene.util.Accountable

NULL_ACCOUNTABLE

Constructor Summary

Constructors

Constructor	Description
FrequencyTrackingRingBuffer(int maxSize, int sentinel)	Create a new ring buffer that will contain at most maxSize items.

Method Summary

Modifier and Type	Method	Description
void	add(int i)	Add a new item to this ring buffer, potentially removing the oldest entry from this buffer if it is already full.
int	frequency(int key)	Returns the frequency of the provided key in the ring buffer.
long	ramBytesUsed()	Return the memory usage of this object in bytes.

Methods inherited from class java.lang.Object

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

Methods inherited from interface org.apache.lucene.util.Accountable

getChildResources

Constructor Details

FrequencyTrackingRingBuffer

public FrequencyTrackingRingBuffer(int maxSize,
 int sentinel)

Create a new ring buffer that will contain at most maxSize items. This buffer will initially contain maxSize times the sentinel value.

Method Details

ramBytesUsed

public long ramBytesUsed()

Description copied from interface: Accountable

Return the memory usage of this object in bytes. Negative values are illegal.

Specified by:

ramBytesUsed in interface Accountable

add

public void add(int i)

Add a new item to this ring buffer, potentially removing the oldest entry from this buffer if it is already full.

frequency

public int frequency(int key)

Returns the frequency of the provided key in the ring buffer.