+++ /dev/null
-/*
- * 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<K, V> {
- private final LinkedHashMap<K, V> 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<K, V>(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<K, V> 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.
- *
- * <p>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.
- *
- * <p>The method is called without synchronization: other threads may
- * access the cache while this method is executing.
- *
- * <p>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.
- *
- * <p>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<K, V> snapshot() {
- return new LinkedHashMap<K, V>(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);
- }
-}
notaz.gp2x.de / android_pandora.git / blobdiff