com.fitbur.fasterxml.jackson.databind.util.LRUMap Maven / Gradle / Ivy
package com.fitbur.fasterxml.jackson.databind.util;
import java.io.*;
import java.util.LinkedHashMap;
import java.util.Map;
/**
* Helper for simple bounded LRU maps used for reusing lookup values.
*
* Note that serialization behavior is such that contents are NOT serialized,
* on assumption that all use cases are for caching where persistence
* does not make sense. The only thing serialized is the cache size of Map.
*/
public class LRUMap extends LinkedHashMap
implements java.io.Serializable
{
private static final long serialVersionUID = 1L;
protected final int _maxEntries;
public LRUMap(int initialEntries, int maxEntries)
{
super(initialEntries, 0.8f, true);
_maxEntries = maxEntries;
}
@Override
protected boolean removeEldestEntry(Map.Entry eldest)
{
return size() > _maxEntries;
}
/*
/**********************************************************
/* Serializable overrides
/**********************************************************
*/
/**
* Ugly hack, to work through the requirement that _value is indeed final,
* and that JDK serialization won't call ctor(s) if Serializable is implemented.
*
* @since 2.1
*/
protected transient int _jdkSerializeMaxEntries;
private void readObject(ObjectInputStream in) throws IOException {
_jdkSerializeMaxEntries = in.readInt();
}
private void writeObject(ObjectOutputStream out) throws IOException {
out.writeInt(_jdkSerializeMaxEntries);
}
protected Object readResolve() {
return new LRUMap(_jdkSerializeMaxEntries, _jdkSerializeMaxEntries);
}
}