X-Git-Url: https://notaz.gp2x.de/cgi-bin/gitweb.cgi?a=blobdiff_plain;f=apps%2FAndroidSupportV2%2Fsrc%2Fandroid%2Fsupport%2Fv2%2Futil%2FLruCache.java;fp=apps%2FAndroidSupportV2%2Fsrc%2Fandroid%2Fsupport%2Fv2%2Futil%2FLruCache.java;h=45c8189a47f162f51a7fdf7580ee61b7c297ee92;hb=811a5a4a3091f65fef340acafe62d6355b13c44f;hp=0000000000000000000000000000000000000000;hpb=4401ca4aa1b3938939c6c371dfda57aa0652696f;p=android_pandora.git diff --git a/apps/AndroidSupportV2/src/android/support/v2/util/LruCache.java b/apps/AndroidSupportV2/src/android/support/v2/util/LruCache.java new file mode 100644 index 0000000..45c8189 --- /dev/null +++ b/apps/AndroidSupportV2/src/android/support/v2/util/LruCache.java @@ -0,0 +1,323 @@ +/* + * Copyright (C) 2011 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 android.support.v2.util; + +import java.util.LinkedHashMap; +import java.util.Map; + +/** + * Static library version of {@code android.util.LruCache}. Used to write apps + * that run on API levels prior to 12. When running on API level 12 or above, + * this implementation is still used; it does not try to switch to the + * framework's implementation. See the framework SDK documentation for a class + * overview. + */ +public class LruCache { + private final LinkedHashMap map; + + /** Size of this cache in units. Not necessarily the number of elements. */ + private int size; + private int maxSize; + + private int putCount; + private int createCount; + private int evictionCount; + private int hitCount; + private int missCount; + + /** + * @param maxSize for caches that do not override {@link #sizeOf}, this is + * the maximum number of entries in the cache. For all other caches, + * this is the maximum sum of the sizes of the entries in this cache. + */ + public LruCache(int maxSize) { + if (maxSize <= 0) { + throw new IllegalArgumentException("maxSize <= 0"); + } + this.maxSize = maxSize; + this.map = new LinkedHashMap(0, 0.75f, true); + } + + /** + * Returns the value for {@code key} if it exists in the cache or can be + * created by {@code #create}. If a value was returned, it is moved to the + * head of the queue. This returns null if a value is not cached and cannot + * be created. + */ + public final V get(K key) { + if (key == null) { + throw new NullPointerException("key == null"); + } + + V mapValue; + synchronized (this) { + mapValue = map.get(key); + if (mapValue != null) { + hitCount++; + return mapValue; + } + missCount++; + } + + /* + * Attempt to create a value. This may take a long time, and the map + * may be different when create() returns. If a conflicting value was + * added to the map while create() was working, we leave that value in + * the map and release the created value. + */ + + V createdValue = create(key); + if (createdValue == null) { + return null; + } + + synchronized (this) { + createCount++; + mapValue = map.put(key, createdValue); + + if (mapValue != null) { + // There was a conflict so undo that last put + map.put(key, mapValue); + } else { + size += safeSizeOf(key, createdValue); + } + } + + if (mapValue != null) { + entryRemoved(false, key, createdValue, mapValue); + return mapValue; + } else { + trimToSize(maxSize); + return createdValue; + } + } + + /** + * Caches {@code value} for {@code key}. The value is moved to the head of + * the queue. + * + * @return the previous value mapped by {@code key}. + */ + public final V put(K key, V value) { + if (key == null || value == null) { + throw new NullPointerException("key == null || value == null"); + } + + V previous; + synchronized (this) { + putCount++; + size += safeSizeOf(key, value); + previous = map.put(key, value); + if (previous != null) { + size -= safeSizeOf(key, previous); + } + } + + if (previous != null) { + entryRemoved(false, key, previous, value); + } + + trimToSize(maxSize); + return previous; + } + + /** + * @param maxSize the maximum size of the cache before returning. May be -1 + * to evict even 0-sized elements. + */ + private void trimToSize(int maxSize) { + while (true) { + K key; + V value; + synchronized (this) { + if (size < 0 || (map.isEmpty() && size != 0)) { + throw new IllegalStateException(getClass().getName() + + ".sizeOf() is reporting inconsistent results!"); + } + + if (size <= maxSize || map.isEmpty()) { + break; + } + + Map.Entry toEvict = map.entrySet().iterator().next(); + key = toEvict.getKey(); + value = toEvict.getValue(); + map.remove(key); + size -= safeSizeOf(key, value); + evictionCount++; + } + + entryRemoved(true, key, value, null); + } + } + + /** + * Removes the entry for {@code key} if it exists. + * + * @return the previous value mapped by {@code key}. + */ + public final V remove(K key) { + if (key == null) { + throw new NullPointerException("key == null"); + } + + V previous; + synchronized (this) { + previous = map.remove(key); + if (previous != null) { + size -= safeSizeOf(key, previous); + } + } + + if (previous != null) { + entryRemoved(false, key, previous, null); + } + + return previous; + } + + /** + * Called for entries that have been evicted or removed. This method is + * invoked when a value is evicted to make space, removed by a call to + * {@link #remove}, or replaced by a call to {@link #put}. The default + * implementation does nothing. + * + *

The method is called without synchronization: other threads may + * access the cache while this method is executing. + * + * @param evicted true if the entry is being removed to make space, false + * if the removal was caused by a {@link #put} or {@link #remove}. + * @param newValue the new value for {@code key}, if it exists. If non-null, + * this removal was caused by a {@link #put}. Otherwise it was caused by + * an eviction or a {@link #remove}. + */ + protected void entryRemoved(boolean evicted, K key, V oldValue, V newValue) {} + + /** + * Called after a cache miss to compute a value for the corresponding key. + * Returns the computed value or null if no value can be computed. The + * default implementation returns null. + * + *

The method is called without synchronization: other threads may + * access the cache while this method is executing. + * + *

If a value for {@code key} exists in the cache when this method + * returns, the created value will be released with {@link #entryRemoved} + * and discarded. This can occur when multiple threads request the same key + * at the same time (causing multiple values to be created), or when one + * thread calls {@link #put} while another is creating a value for the same + * key. + */ + protected V create(K key) { + return null; + } + + private int safeSizeOf(K key, V value) { + int result = sizeOf(key, value); + if (result < 0) { + throw new IllegalStateException("Negative size: " + key + "=" + value); + } + return result; + } + + /** + * Returns the size of the entry for {@code key} and {@code value} in + * user-defined units. The default implementation returns 1 so that size + * is the number of entries and max size is the maximum number of entries. + * + *

An entry's size must not change while it is in the cache. + */ + protected int sizeOf(K key, V value) { + return 1; + } + + /** + * Clear the cache, calling {@link #entryRemoved} on each removed entry. + */ + public final void evictAll() { + trimToSize(-1); // -1 will evict 0-sized elements + } + + /** + * For caches that do not override {@link #sizeOf}, this returns the number + * of entries in the cache. For all other caches, this returns the sum of + * the sizes of the entries in this cache. + */ + public synchronized final int size() { + return size; + } + + /** + * For caches that do not override {@link #sizeOf}, this returns the maximum + * number of entries in the cache. For all other caches, this returns the + * maximum sum of the sizes of the entries in this cache. + */ + public synchronized final int maxSize() { + return maxSize; + } + + /** + * Returns the number of times {@link #get} returned a value. + */ + public synchronized final int hitCount() { + return hitCount; + } + + /** + * Returns the number of times {@link #get} returned null or required a new + * value to be created. + */ + public synchronized final int missCount() { + return missCount; + } + + /** + * Returns the number of times {@link #create(Object)} returned a value. + */ + public synchronized final int createCount() { + return createCount; + } + + /** + * Returns the number of times {@link #put} was called. + */ + public synchronized final int putCount() { + return putCount; + } + + /** + * Returns the number of values that have been evicted. + */ + public synchronized final int evictionCount() { + return evictionCount; + } + + /** + * Returns a copy of the current contents of the cache, ordered from least + * recently accessed to most recently accessed. + */ + public synchronized final Map snapshot() { + return new LinkedHashMap(map); + } + + @Override public synchronized final String toString() { + int accesses = hitCount + missCount; + int hitPercent = accesses != 0 ? (100 * hitCount / accesses) : 0; + return String.format("LruCache[maxSize=%d,hits=%d,misses=%d,hitRate=%d%%]", + maxSize, hitCount, missCount, hitPercent); + } +}