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/*
* Copyright (C) 2017 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.Log;
import android.util.SparseArray;
import com.android.systemui.recents.model.Task.TaskKey;
/**
* Base class for both strong and LRU task key cache.
*/
public abstract class TaskKeyCache<V> {
protected static final String TAG = "TaskKeyCache";
protected final SparseArray<TaskKey> mKeys = new SparseArray<>();
/**
* 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 getCacheEntry(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.windowingMode != key.windowingMode) ||
(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 getCacheEntry(key.id);
}
/** Puts an entry in the cache for a specific key. */
final void put(Task.TaskKey key, V value) {
if (key == null || value == null) {
Log.e(TAG, "Unexpected null key or value: " + key + ", " + value);
return;
}
mKeys.put(key.id, key);
putCacheEntry(key.id, value);
}
/** Removes a cache entry for a specific key. */
final void remove(Task.TaskKey key) {
// Remove the key after the cache value because we need it to make the callback
removeCacheEntry(key.id);
mKeys.remove(key.id);
}
/** Removes all the entries in the cache. */
final void evictAll() {
evictAllCache();
mKeys.clear();
}
protected abstract V getCacheEntry(int id);
protected abstract void putCacheEntry(int id, V value);
protected abstract void removeCacheEntry(int id);
protected abstract void evictAllCache();
}
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