package com.jayway.jsonpath.spi.cache;
import com.jayway.jsonpath.JsonPath;
import java.util.Deque;
import java.util.LinkedList;
import java.util.Map;
import java.util.concurrent.ConcurrentHashMap;
import java.util.concurrent.locks.ReentrantLock;
public class LRUCache implements Cache {
private final ReentrantLock lock = new ReentrantLock();
private final Map<String, JsonPath> map = new ConcurrentHashMap<String, JsonPath>();
private final Deque<String> queue = new LinkedList<String>();
private final int limit;
public LRUCache(int limit) {
this.limit = limit;
}
public void put(String key, JsonPath value) {
JsonPath oldValue = map.put(key, value);
if (oldValue != null) {
removeThenAddKey(key);
} else {
addKey(key);
}
if (map.size() > limit) {
map.remove(removeLast());
}
}
public JsonPath get(String key) {
JsonPath jsonPath = map.get(key);
if(jsonPath != null){
removeThenAddKey(key);
}
return jsonPath;
}
private void addKey(String key) {
lock.lock();
try {
queue.addFirst(key);
} finally {
lock.unlock();
}
}
private String removeLast() {
lock.lock();
try {
final String removedKey = queue.removeLast();
return removedKey;
} finally {
lock.unlock();
}
}
private void removeThenAddKey(String key) {
lock.lock();
try {
queue.removeFirstOccurrence(key);
queue.addFirst(key);
} finally {
lock.unlock();
}
}
private void removeFirstOccurrence(String key) {
lock.lock();
try {
queue.removeFirstOccurrence(key);
} finally {
lock.unlock();
}
}
public JsonPath getSilent(String key) {
return map.get(key);
}
public void remove(String key) {
removeFirstOccurrence(key);
map.remove(key);
}
public int size() {
return map.size();
}
public String toString() {
return map.toString();
}
}