michael@0: /* -*- Mode: Java; c-basic-offset: 4; tab-width: 20; indent-tabs-mode: nil; -*-
michael@0:  * This Source Code Form is subject to the terms of the Mozilla Public
michael@0:  * License, v. 2.0. If a copy of the MPL was not distributed with this
michael@0:  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
michael@0: 
michael@0: package org.mozilla.gecko.util;
michael@0: 
michael@0: import android.support.v4.util.LruCache;
michael@0: 
michael@0: import java.util.concurrent.ConcurrentHashMap;
michael@0: 
michael@0: /**
michael@0:  * An LruCache that also supports a set of items that will never be evicted.
michael@0:  *
michael@0:  * Alas, LruCache is final, so we compose rather than inherit.
michael@0:  */
michael@0: public class NonEvictingLruCache<K, V> {
michael@0:     private final ConcurrentHashMap<K, V> permanent = new ConcurrentHashMap<K, V>();
michael@0:     private final LruCache<K, V> evictable;
michael@0: 
michael@0:     public NonEvictingLruCache(final int evictableSize) {
michael@0:         evictable = new LruCache<K, V>(evictableSize);
michael@0:     }
michael@0: 
michael@0:     public V get(K key) {
michael@0:         V val = permanent.get(key);
michael@0:         if (val == null) {
michael@0:             return evictable.get(key);
michael@0:         }
michael@0:         return val;
michael@0:     }
michael@0: 
michael@0:     public void putWithoutEviction(K key, V value) {
michael@0:         permanent.put(key, value);
michael@0:     }
michael@0: 
michael@0:     public void put(K key, V value) {
michael@0:         evictable.put(key, value);
michael@0:     }
michael@0: 
michael@0:     public void evictAll() {
michael@0:         evictable.evictAll();
michael@0:     }
michael@0: }