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/*
* 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 com.squareup.picasso;
import android.content.Context;
import android.graphics.Bitmap;
import java.util.LinkedHashMap;
import java.util.Map;
/** A memory cache which uses a least-recently used eviction policy. */
public class LruCache implements Cache {
final LinkedHashMap<String, Bitmap> map;
private final int maxSize;
private int size;
private int putCount;
private int evictionCount;
private int hitCount;
private int missCount;
/** Create a cache using an appropriate portion of the available RAM as the maximum size. */
public LruCache(Context context) {
this(Utils.calculateMemoryCacheSize(context));
}
/** Create a cache with a given maximum size in bytes. */
public LruCache(int maxSize) {
if (maxSize <= 0) {
throw new IllegalArgumentException("Max size must be positive.");
}
this.maxSize = maxSize;
this.map = new LinkedHashMap<String, Bitmap>(0, 0.75f, true);
}
@Override public Bitmap get(String key) {
if (key == null) {
throw new NullPointerException("key == null");
}
Bitmap mapValue;
synchronized (this) {
mapValue = map.get(key);
if (mapValue != null) {
hitCount++;
return mapValue;
}
missCount++;
}
return null;
}
@Override public void set(String key, Bitmap bitmap) {
if (key == null || bitmap == null) {
throw new NullPointerException("key == null || bitmap == null");
}
Bitmap previous;
synchronized (this) {
putCount++;
size += Utils.getBitmapBytes(bitmap);
previous = map.put(key, bitmap);
if (previous != null) {
size -= Utils.getBitmapBytes(previous);
}
}
trimToSize(maxSize);
}
private void trimToSize(int maxSize) {
while (true) {
String key;
Bitmap 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<String, Bitmap> toEvict = map.entrySet().iterator().next();
key = toEvict.getKey();
value = toEvict.getValue();
map.remove(key);
size -= Utils.getBitmapBytes(value);
evictionCount++;
}
}
}
/** Clear the cache. */
public final void evictAll() {
trimToSize(-1); // -1 will evict 0-sized elements
}
/** Returns the sum of the sizes of the entries in this cache. */
public final synchronized int size() {
return size;
}
/** Returns the maximum sum of the sizes of the entries in this cache. */
public final synchronized int maxSize() {
return maxSize;
}
public final synchronized void clear() {
evictAll();
}
/** Returns the number of times {@link #get} returned a value. */
public final synchronized int hitCount() {
return hitCount;
}
/** Returns the number of times {@link #get} returned {@code null}. */
public final synchronized int missCount() {
return missCount;
}
/** Returns the number of times {@link #set(String, Bitmap)} was called. */
public final synchronized int putCount() {
return putCount;
}
/** Returns the number of values that have been evicted. */
public final synchronized int evictionCount() {
return evictionCount;
}
}
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