package org.apache.ibatis.cache.decorators;
import org.apache.ibatis.cache.Cache;
import java.util.LinkedHashMap;
import java.util.Map;
import java.util.concurrent.locks.ReadWriteLock;
/**
* Lru (first in, first out) cache decorator
*/
public class LruCache implements Cache {
private final Cache delegate;
private Map keyMap;
private Object eldestKey;
public LruCache(Cache delegate) {
this.delegate = delegate;
setSize(1024);
}
public String getId() {
return delegate.getId();
}
public int getSize() {
return delegate.getSize();
}
public void setSize(final int size) {
keyMap = new LinkedHashMap(size, .75F, true) {
protected boolean removeEldestEntry(Map.Entry eldest) {
boolean tooBig = size() > size;
if (tooBig) {
eldestKey = eldest.getKey();
}
return tooBig;
}
};
}
public void putObject(Object key, Object value) {
delegate.putObject(key, value);
cycleKeyList(key);
}
public Object getObject(Object key) {
keyMap.get(key); //touch
return delegate.getObject(key);
}
public Object removeObject(Object key) {
return delegate.removeObject(key);
}
public void clear() {
delegate.clear();
keyMap.clear();
}
public ReadWriteLock getReadWriteLock() {
return delegate.getReadWriteLock();
}
private void cycleKeyList(Object key) {
keyMap.put(key, key);
if (eldestKey != null) {
delegate.removeObject(eldestKey);
eldestKey = null;
}
}
}
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