/**
 * Copyright 2016 [ZTE] and others.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
package org.openo.carbon.bpel.util;

import java.util.ArrayList;
import java.util.Collection;
import java.util.LinkedHashMap;
import java.util.Map;
import java.util.concurrent.locks.Lock;
import java.util.concurrent.locks.ReentrantLock;

/**
 * 
 * @author bsli
 * 
 * @param <K>
 * @param <V>
 */
@SuppressWarnings("serial")
public class LRULinkedHashMap<K, V> extends LinkedHashMap<K, V> {
  private final int maxCapacity;

  private static final float DEFAULT_LOAD_FACTOR = 0.75f;

  private final Lock lock = new ReentrantLock();

  public LRULinkedHashMap(int maxCapacity) {
    super(maxCapacity, DEFAULT_LOAD_FACTOR, true);
    this.maxCapacity = maxCapacity;
  }

  @Override
  protected boolean removeEldestEntry(java.util.Map.Entry<K, V> eldest) {
    return size() > maxCapacity;
  }

  @Override
  public boolean containsKey(Object key) {
    try {
      lock.lock();
      return super.containsKey(key);
    } finally {
      lock.unlock();
    }
  }

  @Override
  public V get(Object key) {
    try {
      lock.lock();
      return super.get(key);
    } finally {
      lock.unlock();
    }
  }

  @Override
  public V put(K key, V value) {
    try {
      lock.lock();
      return super.put(key, value);
    } finally {
      lock.unlock();
    }
  }

  public int size() {
    try {
      lock.lock();
      return super.size();
    } finally {
      lock.unlock();
    }
  }

  public void clear() {
    try {
      lock.lock();
      super.clear();
    } finally {
      lock.unlock();
    }
  }

  public Collection<Map.Entry<K, V>> getAll() {
    try {
      lock.lock();
      return new ArrayList<Map.Entry<K, V>>(super.entrySet());
    } finally {
      lock.unlock();
    }
  }
}