diff options
Diffstat (limited to 'src/com/android/gallery3d/util/IdentityCache.java')
-rw-r--r-- | src/com/android/gallery3d/util/IdentityCache.java | 78 |
1 files changed, 78 insertions, 0 deletions
diff --git a/src/com/android/gallery3d/util/IdentityCache.java b/src/com/android/gallery3d/util/IdentityCache.java new file mode 100644 index 000000000..3edc424a3 --- /dev/null +++ b/src/com/android/gallery3d/util/IdentityCache.java @@ -0,0 +1,78 @@ +/* + * Copyright (C) 2010 The Android Open Source Project + * + * 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 com.android.gallery3d.util; + +import java.lang.ref.ReferenceQueue; +import java.lang.ref.WeakReference; +import java.util.ArrayList; +import java.util.HashMap; +import java.util.Set; + +public class IdentityCache<K, V> { + + private final HashMap<K, Entry<K, V>> mWeakMap = + new HashMap<K, Entry<K, V>>(); + private ReferenceQueue<V> mQueue = new ReferenceQueue<V>(); + + public IdentityCache() { + } + + private static class Entry<K, V> extends WeakReference<V> { + K mKey; + + public Entry(K key, V value, ReferenceQueue<V> queue) { + super(value, queue); + mKey = key; + } + } + + private void cleanUpWeakMap() { + Entry<K, V> entry = (Entry<K, V>) mQueue.poll(); + while (entry != null) { + mWeakMap.remove(entry.mKey); + entry = (Entry<K, V>) mQueue.poll(); + } + } + + public synchronized V put(K key, V value) { + cleanUpWeakMap(); + Entry<K, V> entry = mWeakMap.put( + key, new Entry<K, V>(key, value, mQueue)); + return entry == null ? null : entry.get(); + } + + public synchronized V get(K key) { + cleanUpWeakMap(); + Entry<K, V> entry = mWeakMap.get(key); + return entry == null ? null : entry.get(); + } + + // This is currently unused. + /* + public synchronized void clear() { + mWeakMap.clear(); + mQueue = new ReferenceQueue<V>(); + } + */ + + // This is for debugging only + public synchronized ArrayList<K> keys() { + Set<K> set = mWeakMap.keySet(); + ArrayList<K> result = new ArrayList<K>(set); + return result; + } +} |