ch.qos.logback.classic.turbo.LRUMessageCache Maven / Gradle / Ivy
/**
* Logback: the reliable, generic, fast and flexible logging framework.
* Copyright (C) 1999-2015, QOS.ch. All rights reserved.
*
* This program and the accompanying materials are dual-licensed under
* either the terms of the Eclipse Public License v1.0 as published by
* the Eclipse Foundation
*
* or (per the licensee's choosing)
*
* under the terms of the GNU Lesser General Public License version 2.1
* as published by the Free Software Foundation.
*/
package ch.qos.logback.classic.turbo;
import java.util.LinkedHashMap;
import java.util.Map;
/**
* Clients of this class should only use the
* {@link #getMessageCountAndThenIncrement} method. Other methods inherited via
* LinkedHashMap are not thread safe.
*/
class LRUMessageCache extends LinkedHashMap {
private static final long serialVersionUID = 1L;
final int cacheSize;
LRUMessageCache(int cacheSize) {
super((int) (cacheSize * (4.0f / 3)), 0.75f, true);
if (cacheSize < 1) {
throw new IllegalArgumentException("Cache size cannot be smaller than 1");
}
this.cacheSize = cacheSize;
}
int getMessageCountAndThenIncrement(String msg) {
// don't insert null elements
if (msg == null) {
return 0;
}
Integer i;
// LinkedHashMap is not LinkedHashMap. See also LBCLASSIC-255
synchronized (this) {
i = super.get(msg);
if (i == null) {
i = 0;
} else {
i = i + 1;
}
super.put(msg, i);
}
return i;
}
// called indirectly by get() or put() which are already supposed to be
// called from within a synchronized block
protected boolean removeEldestEntry(Map.Entry eldest) {
return (size() > cacheSize);
}
@Override
synchronized public void clear() {
super.clear();
}
}