| /* |
| * Copyright (C) 2014 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.systemui.recents.model; |
| |
| import android.util.LruCache; |
| import android.util.SparseArray; |
| |
| /** |
| * A mapping of {@link Task.TaskKey} to value, with additional LRU functionality where the least |
| * recently referenced key/values will be evicted as more values than the given cache size are |
| * inserted. |
| * |
| * In addition, this also allows the caller to invalidate cached values for keys that have since |
| * changed. |
| */ |
| public class TaskKeyLruCache<V> { |
| |
| private final SparseArray<Task.TaskKey> mKeys = new SparseArray<>(); |
| private final LruCache<Integer, V> mCache; |
| |
| public TaskKeyLruCache(int cacheSize) { |
| mCache = new LruCache<Integer, V>(cacheSize) { |
| |
| @Override |
| protected void entryRemoved(boolean evicted, Integer taskId, V oldV, V newV) { |
| mKeys.remove(taskId); |
| } |
| }; |
| } |
| |
| /** |
| * Gets a specific entry in the cache with the specified key, regardless of whether the cached |
| * value is valid or not. |
| */ |
| final V get(Task.TaskKey key) { |
| return mCache.get(key.id); |
| } |
| |
| /** |
| * Returns the value only if the key is valid (has not been updated since the last time it was |
| * in the cache) |
| */ |
| final V getAndInvalidateIfModified(Task.TaskKey key) { |
| Task.TaskKey lastKey = mKeys.get(key.id); |
| if (lastKey != null) { |
| if ((lastKey.stackId != key.stackId) || (lastKey.lastActiveTime < key.lastActiveTime)) { |
| // The task has updated (been made active since the last time it was put into the |
| // LRU cache) or the stack id for the task has changed, invalidate that cache item |
| remove(key); |
| return null; |
| } |
| } |
| // Either the task does not exist in the cache, or the last active time is the same as |
| // the key specified, so return what is in the cache |
| return mCache.get(key.id); |
| } |
| |
| /** Puts an entry in the cache for a specific key. */ |
| final void put(Task.TaskKey key, V value) { |
| mKeys.put(key.id, key); |
| mCache.put(key.id, value); |
| } |
| |
| /** Removes a cache entry for a specific key. */ |
| final void remove(Task.TaskKey key) { |
| mKeys.remove(key.id); |
| mCache.remove(key.id); |
| } |
| |
| /** Removes all the entries in the cache. */ |
| final void evictAll() { |
| mCache.evictAll(); |
| mKeys.clear(); |
| } |
| |
| /** Trims the cache to a specific size */ |
| final void trimToSize(int cacheSize) { |
| mCache.resize(cacheSize); |
| } |
| } |