michael@0: /*
michael@0:  * Copyright (C) 2011 The Android Open Source Project
michael@0:  *
michael@0:  * Licensed under the Apache License, Version 2.0 (the "License");
michael@0:  * you may not use this file except in compliance with the License.
michael@0:  * You may obtain a copy of the License at
michael@0:  *
michael@0:  *      http://www.apache.org/licenses/LICENSE-2.0
michael@0:  *
michael@0:  * Unless required by applicable law or agreed to in writing, software
michael@0:  * distributed under the License is distributed on an "AS IS" BASIS,
michael@0:  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
michael@0:  * See the License for the specific language governing permissions and
michael@0:  * limitations under the License.
michael@0:  */
michael@0: package com.squareup.picasso;
michael@0: 
michael@0: import android.content.Context;
michael@0: import android.graphics.Bitmap;
michael@0: import java.util.LinkedHashMap;
michael@0: import java.util.Map;
michael@0: 
michael@0: /** A memory cache which uses a least-recently used eviction policy. */
michael@0: public class LruCache implements Cache {
michael@0:   final LinkedHashMap<String, Bitmap> map;
michael@0:   private final int maxSize;
michael@0: 
michael@0:   private int size;
michael@0:   private int putCount;
michael@0:   private int evictionCount;
michael@0:   private int hitCount;
michael@0:   private int missCount;
michael@0: 
michael@0:   /** Create a cache using an appropriate portion of the available RAM as the maximum size. */
michael@0:   public LruCache(Context context) {
michael@0:     this(Utils.calculateMemoryCacheSize(context));
michael@0:   }
michael@0: 
michael@0:   /** Create a cache with a given maximum size in bytes. */
michael@0:   public LruCache(int maxSize) {
michael@0:     if (maxSize <= 0) {
michael@0:       throw new IllegalArgumentException("Max size must be positive.");
michael@0:     }
michael@0:     this.maxSize = maxSize;
michael@0:     this.map = new LinkedHashMap<String, Bitmap>(0, 0.75f, true);
michael@0:   }
michael@0: 
michael@0:   @Override public Bitmap get(String key) {
michael@0:     if (key == null) {
michael@0:       throw new NullPointerException("key == null");
michael@0:     }
michael@0: 
michael@0:     Bitmap mapValue;
michael@0:     synchronized (this) {
michael@0:       mapValue = map.get(key);
michael@0:       if (mapValue != null) {
michael@0:         hitCount++;
michael@0:         return mapValue;
michael@0:       }
michael@0:       missCount++;
michael@0:     }
michael@0: 
michael@0:     return null;
michael@0:   }
michael@0: 
michael@0:   @Override public void set(String key, Bitmap bitmap) {
michael@0:     if (key == null || bitmap == null) {
michael@0:       throw new NullPointerException("key == null || bitmap == null");
michael@0:     }
michael@0: 
michael@0:     Bitmap previous;
michael@0:     synchronized (this) {
michael@0:       putCount++;
michael@0:       size += Utils.getBitmapBytes(bitmap);
michael@0:       previous = map.put(key, bitmap);
michael@0:       if (previous != null) {
michael@0:         size -= Utils.getBitmapBytes(previous);
michael@0:       }
michael@0:     }
michael@0: 
michael@0:     trimToSize(maxSize);
michael@0:   }
michael@0: 
michael@0:   private void trimToSize(int maxSize) {
michael@0:     while (true) {
michael@0:       String key;
michael@0:       Bitmap value;
michael@0:       synchronized (this) {
michael@0:         if (size < 0 || (map.isEmpty() && size != 0)) {
michael@0:           throw new IllegalStateException(
michael@0:               getClass().getName() + ".sizeOf() is reporting inconsistent results!");
michael@0:         }
michael@0: 
michael@0:         if (size <= maxSize || map.isEmpty()) {
michael@0:           break;
michael@0:         }
michael@0: 
michael@0:         Map.Entry<String, Bitmap> toEvict = map.entrySet().iterator().next();
michael@0:         key = toEvict.getKey();
michael@0:         value = toEvict.getValue();
michael@0:         map.remove(key);
michael@0:         size -= Utils.getBitmapBytes(value);
michael@0:         evictionCount++;
michael@0:       }
michael@0:     }
michael@0:   }
michael@0: 
michael@0:   /** Clear the cache. */
michael@0:   public final void evictAll() {
michael@0:     trimToSize(-1); // -1 will evict 0-sized elements
michael@0:   }
michael@0: 
michael@0:   /** Returns the sum of the sizes of the entries in this cache. */
michael@0:   public final synchronized int size() {
michael@0:     return size;
michael@0:   }
michael@0: 
michael@0:   /** Returns the maximum sum of the sizes of the entries in this cache. */
michael@0:   public final synchronized int maxSize() {
michael@0:     return maxSize;
michael@0:   }
michael@0: 
michael@0:   public final synchronized void clear() {
michael@0:     evictAll();
michael@0:   }
michael@0: 
michael@0:   /** Returns the number of times {@link #get} returned a value. */
michael@0:   public final synchronized int hitCount() {
michael@0:     return hitCount;
michael@0:   }
michael@0: 
michael@0:   /** Returns the number of times {@link #get} returned {@code null}. */
michael@0:   public final synchronized int missCount() {
michael@0:     return missCount;
michael@0:   }
michael@0: 
michael@0:   /** Returns the number of times {@link #set(String, Bitmap)} was called. */
michael@0:   public final synchronized int putCount() {
michael@0:     return putCount;
michael@0:   }
michael@0: 
michael@0:   /** Returns the number of values that have been evicted. */
michael@0:   public final synchronized int evictionCount() {
michael@0:     return evictionCount;
michael@0:   }
michael@0: }