org.apache.jackrabbit.oak.segment

Class ReaderCache<T>

java.lang.Object

org.apache.jackrabbit.oak.segment.ReaderCache<T>

Direct Known Subclasses:

StringCache, TemplateCache

public abstract class ReaderCache<T>
extends Object

A cache consisting of a fast and slow component. The fast cache for small items is based on an array, and a slow one uses a LIRS cache.

Constructor Summary

Constructors

Modifier	Constructor and Description
protected	ReaderCache(long maxWeight, int averageWeight, String name) Create a new string cache.

Method Summary

Modifier and Type	Method and Description
void	clear() Clear the cache.
T	get(long msb, long lsb, int offset, com.google.common.base.Function<Integer,T> loader) Get the value, loading it if necessary.
protected abstract int	getEntryWeight(T value) Estimation includes the key's overhead, see EmpiricalWeigher for an example
org.apache.jackrabbit.oak.cache.CacheStats	getStats()
protected abstract boolean	isSmall(T value) Determine whether the entry is small, in which case it can be kept in the fast cache.

Methods inherited from class java.lang.Object

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

Constructor Detail

ReaderCache

protected ReaderCache(long maxWeight,
                      int averageWeight,
                      @Nonnull
                      String name)

Create a new string cache.

Parameters:

maxWeight - the maximum memory in bytes.

averageWeight - an estimate for the average weight of the elements in the cache. See CacheLIRS.setAverageMemory(int).

Method Detail

getStats

@Nonnull
public org.apache.jackrabbit.oak.cache.CacheStats getStats()

get

@Nonnull
public T get(long msb,
                      long lsb,
                      int offset,
                      com.google.common.base.Function<Integer,T> loader)

Get the value, loading it if necessary.

Parameters:

msb - the msb of the segment

lsb - the lsb of the segment

offset - the offset

loader - the loader function

Returns:

the value

clear

public void clear()

Clear the cache.

getEntryWeight

protected abstract int getEntryWeight(T value)

Estimation includes the key's overhead, see EmpiricalWeigher for an example

isSmall

protected abstract boolean isSmall(T value)

Determine whether the entry is small, in which case it can be kept in the fast cache.