Reduce a variety of object allocations across Glide.

library/findbugs-exclude.xml

@@ -42,4 +42,10 @@
       <Bug pattern="DMI_HARDCODED_ABSOLUTE_FILENAME" />
     </Match>
 
+    <!-- Re-using the byte array saves allocations, there's no serious risk of mutations. -->
+    <Match>
+      <Class name="com.bumptech.glide.util.FixedPreloadSizeProvider" />
+      <Bug pattern="EI_EXPOSE_REP" />
+    </Match>
+
 </FindBugsFilter>

library/src/main/java/com/bumptech/glide/Glide.java

@@ -447,8 +447,14 @@ Uri.class, Bitmap.class, new ResourceBitmapDecoder(resourceDrawableDecoder, bitm
     ImageViewTargetFactory imageViewTargetFactory = new ImageViewTargetFactory();
     glideContext =
         new GlideContext(
-            context, registry, imageViewTargetFactory, defaultRequestOptions,
-            defaultTransitionOptions, engine, logLevel);
+            context,
+            arrayPool,
+            registry,
+            imageViewTargetFactory,
+            defaultRequestOptions,
+            defaultTransitionOptions,
+            engine,
+            logLevel);
   }
 
   /**

library/src/main/java/com/bumptech/glide/GlideContext.java

@@ -10,6 +10,7 @@
 import android.support.annotation.VisibleForTesting;
 import android.widget.ImageView;
 import com.bumptech.glide.load.engine.Engine;
+import com.bumptech.glide.load.engine.bitmap_recycle.ArrayPool;
 import com.bumptech.glide.request.RequestOptions;
 import com.bumptech.glide.request.target.ImageViewTargetFactory;
 import com.bumptech.glide.request.target.ViewTarget;
@@ -26,18 +27,25 @@ public class GlideContext extends ContextWrapper {
   static final TransitionOptions<?, ?> DEFAULT_TRANSITION_OPTIONS =
       new GenericTransitionOptions<>();
   private final Handler mainHandler;
+  private final ArrayPool arrayPool;
   private final Registry registry;
   private final ImageViewTargetFactory imageViewTargetFactory;
   private final RequestOptions defaultRequestOptions;
   private final Map<Class<?>, TransitionOptions<?, ?>> defaultTransitionOptions;
   private final Engine engine;
   private final int logLevel;
 
-  public GlideContext(Context context, Registry registry,
-      ImageViewTargetFactory imageViewTargetFactory, RequestOptions defaultRequestOptions,
-      Map<Class<?>, TransitionOptions<?, ?>> defaultTransitionOptions, Engine engine,
+  public GlideContext(
+      Context context,
+      ArrayPool arrayPool,
+      Registry registry,
+      ImageViewTargetFactory imageViewTargetFactory,
+      RequestOptions defaultRequestOptions,
+      Map<Class<?>, TransitionOptions<?, ?>> defaultTransitionOptions,
+      Engine engine,
       int logLevel) {
     super(context.getApplicationContext());
+    this.arrayPool = arrayPool;
     this.registry = registry;
     this.imageViewTargetFactory = imageViewTargetFactory;
     this.defaultRequestOptions = defaultRequestOptions;
@@ -89,4 +97,8 @@ public Registry getRegistry() {
   public int getLogLevel() {
     return logLevel;
   }
+
+  public ArrayPool getArrayPool() {
+    return arrayPool;
+  }
 }

library/src/main/java/com/bumptech/glide/load/ImageHeaderParserUtils.java

@@ -31,7 +31,9 @@ public static ImageType getType(List<ImageHeaderParser> parsers, @Nullable Input
     }
 
     is.mark(MARK_POSITION);
-    for (ImageHeaderParser parser : parsers) {
+    int size = parsers.size();
+    for (int i = 0; i < size; i++) {
+      ImageHeaderParser parser = parsers.get(i);
       try {
         ImageType type = parser.getType(is);
         if (type != ImageType.UNKNOWN) {
@@ -52,7 +54,9 @@ public static ImageType getType(List<ImageHeaderParser> parsers, @Nullable ByteB
       return ImageType.UNKNOWN;
     }
 
-    for (ImageHeaderParser parser : parsers) {
+    int size = parsers.size();
+    for (int i = 0; i < size; i++) {
+      ImageHeaderParser parser = parsers.get(i);
       ImageType type = parser.getType(buffer);
       if (type != ImageType.UNKNOWN) {
         return type;
@@ -74,7 +78,9 @@ public static int getOrientation(List<ImageHeaderParser> parsers, @Nullable Inpu
     }
 
     is.mark(MARK_POSITION);
-    for (ImageHeaderParser parser : parsers) {
+    int size = parsers.size();
+    for (int i = 0; i < size; i++) {
+      ImageHeaderParser parser = parsers.get(i);
       try {
         int orientation = parser.getOrientation(is, byteArrayPool);
         if (orientation != ImageHeaderParser.UNKNOWN_ORIENTATION) {

library/src/main/java/com/bumptech/glide/load/Options.java

@@ -3,7 +3,6 @@
 import android.support.v4.util.ArrayMap;
 import android.support.v4.util.SimpleArrayMap;
 import java.security.MessageDigest;
-import java.util.Map;
 
 /**
  * A set of {@link Option Options} to apply to in memory and disk cache keys.
@@ -41,8 +40,10 @@ public int hashCode() {
 
   @Override
   public void updateDiskCacheKey(MessageDigest messageDigest) {
-    for (Map.Entry<Option<?>, Object> entry : values.entrySet()) {
-      updateDiskCacheKey(entry.getKey(), entry.getValue(), messageDigest);
+    for (int i = 0; i < values.size(); i++) {
+      Option<?> key = values.keyAt(i);
+      Object value = values.valueAt(i);
+      updateDiskCacheKey(key, value, messageDigest);
     }
   }
 

library/src/main/java/com/bumptech/glide/load/engine/DecodeHelper.java

@@ -9,6 +9,7 @@
 import com.bumptech.glide.load.ResourceEncoder;
 import com.bumptech.glide.load.Transformation;
 import com.bumptech.glide.load.engine.DecodeJob.DiskCacheProvider;
+import com.bumptech.glide.load.engine.bitmap_recycle.ArrayPool;
 import com.bumptech.glide.load.engine.cache.DiskCache;
 import com.bumptech.glide.load.model.ModelLoader;
 import com.bumptech.glide.load.model.ModelLoader.LoadData;
@@ -119,6 +120,10 @@ int getHeight() {
     return height;
   }
 
+  ArrayPool getArrayPool() {
+    return glideContext.getArrayPool();
+  }
+
   List<Class<?>> getRegisteredResourceClasses() {
     return glideContext.getRegistry()
         .getRegisteredResourceClasses(model.getClass(), resourceClass, transcodeClass);

library/src/main/java/com/bumptech/glide/load/engine/DecodeJob.java

@@ -562,8 +562,16 @@ public Resource<Z> onResourceDecoded(Resource<Z> decoded) {
         if (encodeStrategy == EncodeStrategy.SOURCE) {
           key = new DataCacheKey(currentSourceKey, signature);
         } else if (encodeStrategy == EncodeStrategy.TRANSFORMED) {
-          key = new ResourceCacheKey(currentSourceKey, signature, width, height,
-              appliedTransformation, resourceSubClass, options);
+          key =
+              new ResourceCacheKey(
+                  decodeHelper.getArrayPool(),
+                  currentSourceKey,
+                  signature,
+                  width,
+                  height,
+                  appliedTransformation,
+                  resourceSubClass,
+                  options);
         } else {
           throw new IllegalArgumentException("Unknown strategy: " + encodeStrategy);
         }

library/src/main/java/com/bumptech/glide/load/engine/EngineJob.java

@@ -202,7 +202,9 @@ void handleResultOnMainThread() {
     engineResource.acquire();
     listener.onEngineJobComplete(key, engineResource);
 
-    for (ResourceCallback cb : cbs) {
+    int size = cbs.size();
+    for (int i = 0; i < size; i++) {
+      ResourceCallback cb = cbs.get(i);
       if (!isInIgnoredCallbacks(cb)) {
         engineResource.acquire();
         cb.onResourceReady(engineResource, dataSource);

library/src/main/java/com/bumptech/glide/load/engine/ResourceCacheGenerator.java

@@ -57,8 +57,16 @@ public boolean startNext() {
       Class<?> resourceClass = resourceClasses.get(resourceClassIndex);
       Transformation<?> transformation = helper.getTransformation(resourceClass);
 
-      currentKey = new ResourceCacheKey(sourceId, helper.getSignature(), helper.getWidth(),
-          helper.getHeight(), transformation, resourceClass, helper.getOptions());
+      currentKey =
+          new ResourceCacheKey(
+              helper.getArrayPool(),
+              sourceId,
+              helper.getSignature(),
+              helper.getWidth(),
+              helper.getHeight(),
+              transformation,
+              resourceClass,
+              helper.getOptions());
       cacheFile = helper.getDiskCache().get(currentKey);
       if (cacheFile != null) {
         this.sourceKey = sourceId;

library/src/main/java/com/bumptech/glide/load/engine/ResourceCacheKey.java

@@ -3,6 +3,7 @@
 import com.bumptech.glide.load.Key;
 import com.bumptech.glide.load.Options;
 import com.bumptech.glide.load.Transformation;
+import com.bumptech.glide.load.engine.bitmap_recycle.ArrayPool;
 import com.bumptech.glide.util.LruCache;
 import com.bumptech.glide.util.Util;
 import java.nio.ByteBuffer;
@@ -13,6 +14,7 @@
  */
 final class ResourceCacheKey implements Key {
   private static final LruCache<Class<?>, byte[]> RESOURCE_CLASS_BYTES = new LruCache<>(50);
+  private final ArrayPool arrayPool;
   private final Key sourceKey;
   private final Key signature;
   private final int width;
@@ -21,8 +23,16 @@ final class ResourceCacheKey implements Key {
   private final Options options;
   private final Transformation<?> transformation;
 
-  ResourceCacheKey(Key sourceKey, Key signature, int width, int height,
-      Transformation<?> appliedTransformation, Class<?> decodedResourceClass, Options options) {
+  ResourceCacheKey(
+      ArrayPool arrayPool,
+      Key sourceKey,
+      Key signature,
+      int width,
+      int height,
+      Transformation<?> appliedTransformation,
+      Class<?> decodedResourceClass,
+      Options options) {
+    this.arrayPool = arrayPool;
     this.sourceKey = sourceKey;
     this.signature = signature;
     this.width = width;
@@ -63,7 +73,8 @@ public int hashCode() {
   // TODO: Include relevant options?
   @Override
   public void updateDiskCacheKey(MessageDigest messageDigest) {
-    byte[] dimensions = ByteBuffer.allocate(8).putInt(width).putInt(height).array();
+    byte[] dimensions = arrayPool.getExact(8, byte[].class);
+    ByteBuffer.wrap(dimensions).putInt(width).putInt(height).array();
     signature.updateDiskCacheKey(messageDigest);
     sourceKey.updateDiskCacheKey(messageDigest);
     messageDigest.update(dimensions);
@@ -72,6 +83,7 @@ public void updateDiskCacheKey(MessageDigest messageDigest) {
     }
     options.updateDiskCacheKey(messageDigest);
     messageDigest.update(getResourceClassBytes());
+    arrayPool.put(dimensions);
   }
 
   private byte[] getResourceClassBytes() {

library/src/main/java/com/bumptech/glide/load/engine/bitmap_recycle/ArrayPool.java

@@ -15,17 +15,42 @@ public interface ArrayPool {
    *
    * <p>Arrays may be ignored, for example if the array is larger than the maximum size of the
    * pool.
+   *
+   * @deprecated Use {@link #put(Object)Class}
    */
+  @Deprecated
   <T> void put(T array, Class<T> arrayClass);
 
+  /**
+   * Optionally adds the given array of the given type to the pool.
+   *
+   * <p>Arrays may be ignored, for example if the array is larger than the maximum size of the
+   * pool.
+   */
+  <T> void put(T array);
+
   /**
    * Returns a non-null array of the given type with a length >= to the given size.
    *
    * <p>If an array of the given size isn't in the pool, a new one will be allocated.
    *
    * <p>This class makes no guarantees about the contents of the returned array.
+   *
+   * @see #getExact(int, Class)
    */
   <T> T get(int size, Class<T> arrayClass);
+
+  /**
+   * Returns a non-null array of the given type with a length exactly equal to the given size.
+   *
+   * <p>If an array of the given size isn't in the pool, a new one will be allocated.
+   *
+   * <p>This class makes no guarantees about the contents of the returned array.
+   *
+   * @see #get(int, Class)
+   */
+  <T> T getExact(int size, Class<T> arrayClass);
+
   /**
    * Clears all arrays from the pool.
    */

library/src/main/java/com/bumptech/glide/load/engine/bitmap_recycle/LruArrayPool.java

@@ -22,7 +22,8 @@ public final class LruArrayPool implements ArrayPool {
    * The maximum number of times larger an int array may be to be than a requested size to eligible
    * to be returned from the pool.
    */
-  private static final int MAX_OVER_SIZE_MULTIPLE = 8;
+  @VisibleForTesting
+  static final int MAX_OVER_SIZE_MULTIPLE = 8;
   /** Used to calculate the maximum % of the total pool size a single byte array may consume. */
   private static final int SINGLE_ARRAY_MAX_SIZE_DIVISOR = 2;
 
@@ -47,8 +48,17 @@ public LruArrayPool(int maxSize) {
     this.maxSize = maxSize;
   }
 
+  @Deprecated
   @Override
-  public synchronized <T> void put(T array, Class<T> arrayClass) {
+  public <T> void put(T array, Class<T> arrayClass) {
+    put(array);
+  }
+
+  @Override
+  public synchronized <T> void put(T array) {
+    @SuppressWarnings("unchecked")
+    Class<T> arrayClass = (Class<T>) array.getClass();
+
     ArrayAdapterInterface<T> arrayAdapter = getAdapterFromType(arrayClass);
     int size = arrayAdapter.getArrayLength(array);
     int arrayBytes = size * arrayAdapter.getElementSizeInBytes();
@@ -66,30 +76,36 @@ public synchronized <T> void put(T array, Class<T> arrayClass) {
   }
 
   @Override
-  public <T> T get(int size, Class<T> arrayClass) {
-    ArrayAdapterInterface<T> arrayAdapter = getAdapterFromType(arrayClass);
-    T result;
-    synchronized (this) {
-      Integer possibleSize = getSizesForAdapter(arrayClass).ceilingKey(size);
-      final Key key;
-      if (mayFillRequest(size, possibleSize)) {
-        key = keyPool.get(possibleSize, arrayClass);
-      } else {
-        key = keyPool.get(size, arrayClass);
-      }
+  public synchronized <T> T getExact(int size, Class<T> arrayClass) {
+    Key key = keyPool.get(size, arrayClass);
+    return getForKey(key, arrayClass);
+  }
 
-      result = getArrayForKey(key);
-      if (result != null) {
-        currentSize -= arrayAdapter.getArrayLength(result) * arrayAdapter.getElementSizeInBytes();
-        decrementArrayOfSize(arrayAdapter.getArrayLength(result), arrayClass);
-      }
+  @Override
+  public synchronized <T> T get(int size, Class<T> arrayClass) {
+    Integer possibleSize = getSizesForAdapter(arrayClass).ceilingKey(size);
+    final Key key;
+    if (mayFillRequest(size, possibleSize)) {
+      key = keyPool.get(possibleSize, arrayClass);
+    } else {
+      key = keyPool.get(size, arrayClass);
+    }
+    return getForKey(key, arrayClass);
+  }
+
+  private <T> T getForKey(Key key, Class<T> arrayClass) {
+    ArrayAdapterInterface<T> arrayAdapter = getAdapterFromType(arrayClass);
+    T result = getArrayForKey(key);
+    if (result != null) {
+      currentSize -= arrayAdapter.getArrayLength(result) * arrayAdapter.getElementSizeInBytes();
+      decrementArrayOfSize(arrayAdapter.getArrayLength(result), arrayClass);
     }
 
     if (result == null) {
       if (Log.isLoggable(arrayAdapter.getTag(), Log.VERBOSE)) {
-        Log.v(arrayAdapter.getTag(), "Allocated " + size + " bytes");
+        Log.v(arrayAdapter.getTag(), "Allocated " + key.size + " bytes");
       }
-      result = arrayAdapter.newArray(size);
+      result = arrayAdapter.newArray(key.size);
     }
     return result;
   }

library/src/main/java/com/bumptech/glide/load/model/StreamEncoder.java

@@ -47,7 +47,7 @@ public boolean encode(InputStream data, File file, Options options) {
           // Do nothing.
         }
       }
-      byteArrayPool.put(buffer, byte[].class);
+      byteArrayPool.put(buffer);
     }
     return success;
   }

library/src/main/java/com/bumptech/glide/load/resource/bitmap/DefaultImageHeaderParser.java

@@ -159,7 +159,7 @@ private int getOrientation(Reader reader, ArrayPool byteArrayPool) throws IOExce
       try {
         return parseExifSegment(reader, exifData, exifSegmentLength);
       } finally {
-        byteArrayPool.put(exifData, byte[].class);
+        byteArrayPool.put(exifData);
       }
     }
   }