...text exposed to open source public git repo...

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

@@ -818,6 +818,19 @@ public <Y extends Target<TranscodeType>> Y into(@NonNull Y target) {
     return into(target, /* targetListener= */ null, Executors.mainThreadExecutor());
   }
 
+  /**
+   * Set the target the resource will be loaded into; the callback will be set at the front of the
+   * queue.
+   *
+   * @param target The target to load the resource into.
+   * @return The given target.
+   * @see RequestManager#clear(Target)
+   */
+  @NonNull
+  public <Y extends Target<TranscodeType>> Y intoFront(@NonNull Y target) {
+    return into(target, /* targetListener= */ null, Executors.mainThreadExecutorFront());
+  }
+
   @NonNull
   <Y extends Target<TranscodeType>> Y into(
       @NonNull Y target,
@@ -1001,6 +1014,36 @@ public Target<TranscodeType> preload(int width, int height) {
     return into(target);
   }
 
+  /**
+   * Preloads the resource into the cache using the given width and height; the callback will be set
+   * at the front of the queue.
+   *
+   * <p>Pre-loading is useful for making sure that resources you are going to to want in the near
+   * future are available quickly.
+   *
+   * <p>Note - Any thumbnail request that does not complete before the primary request will be
+   * cancelled and may not be preloaded successfully. Cancellation of outstanding thumbnails after
+   * the primary request succeeds is a common behavior of all Glide requests. We do not try to
+   * prevent that behavior here. If you absolutely need all thumbnails to be preloaded individually,
+   * make separate preload() requests for each thumbnail (you can still combine them into one call
+   * when loading the image(s) into the UI in a subsequent request).
+   *
+   * @param width The desired width in pixels, or {@link Target#SIZE_ORIGINAL}. This will be
+   *     overridden by {@link com.bumptech.glide.request.RequestOptions#override(int, int)} if
+   *     previously called.
+   * @param height The desired height in pixels, or {@link Target#SIZE_ORIGINAL}. This will be
+   *     overridden by {@link com.bumptech.glide.request.RequestOptions#override(int, int)}} if
+   *     previously called).
+   * @return A {@link Target} that can be used to cancel the load via {@link
+   *     RequestManager#clear(Target)}.
+   * @see com.bumptech.glide.ListPreloader
+   */
+  @NonNull
+  public Target<TranscodeType> preloadFront(int width, int height) {
+    final PreloadTarget<TranscodeType> target = PreloadTarget.obtain(requestManager, width, height);
+    return intoFront(target);
+  }
+
   /**
    * Preloads the resource into the cache using {@link Target#SIZE_ORIGINAL} as the target width and
    * height. Equivalent to calling {@link #preload(int, int)} with {@link Target#SIZE_ORIGINAL} as

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

@@ -1,6 +1,7 @@
 package com.bumptech.glide.load.engine;
 
 import android.os.Build;
+import android.os.Process;
 import android.util.Log;
 import androidx.annotation.NonNull;
 import androidx.core.util.Pools;
@@ -10,6 +11,7 @@
 import com.bumptech.glide.load.DataSource;
 import com.bumptech.glide.load.EncodeStrategy;
 import com.bumptech.glide.load.Key;
+import com.bumptech.glide.load.Option;
 import com.bumptech.glide.load.Options;
 import com.bumptech.glide.load.ResourceEncoder;
 import com.bumptech.glide.load.Transformation;
@@ -25,6 +27,7 @@
 import java.util.ArrayList;
 import java.util.List;
 import java.util.Map;
+import java.util.function.Supplier;
 
 /**
  * A class responsible for decoding resources either from cached data or from the original source
@@ -41,6 +44,10 @@ class DecodeJob<R>
         Comparable<DecodeJob<?>>,
         Poolable {
   private static final String TAG = "DecodeJob";
+  private static final Option<Supplier<Integer>> GLIDE_THREAD_PRIORITY =
+      Option.memory("glide_thread_priority");
+  private static final int DEFAULT_THREAD_PRIORITY =
+      Process.THREAD_PRIORITY_BACKGROUND + Process.THREAD_PRIORITY_MORE_FAVORABLE;
 
   private final DecodeHelper<R> decodeHelper = new DecodeHelper<>();
   private final List<Throwable> throwables = new ArrayList<>();
@@ -49,6 +56,7 @@ class DecodeJob<R>
   private final Pools.Pool<DecodeJob<?>> pool;
   private final DeferredEncodeManager<?> deferredEncodeManager = new DeferredEncodeManager<>();
   private final ReleaseManager releaseManager = new ReleaseManager();
+  private final int threadPriority = Process.getThreadPriority(Process.myTid());
 
   private GlideContext glideContext;
   private Key signature;
@@ -65,6 +73,7 @@ class DecodeJob<R>
   private long startFetchTime;
   private boolean onlyRetrieveFromCache;
   private Object model;
+  private Supplier<Integer> glideThreadPriorityOverride;
 
   private Thread currentThread;
   private Key currentSourceKey;
@@ -129,6 +138,7 @@ DecodeJob<R> init(
     this.order = order;
     this.runReason = RunReason.INITIALIZE;
     this.model = model;
+    this.glideThreadPriorityOverride = options.get(GLIDE_THREAD_PRIORITY);
     return this;
   }
 
@@ -326,7 +336,17 @@ private void runGenerators() {
     // onDataFetcherReady.
   }
 
+  private void restoreThreadPriority() {
+    if (glideThreadPriorityOverride != null && glideThreadPriorityOverride.get() != null) {
+      // Setting to default instead of original priority because threads can run multiple jobs at
+      // once so if a new job is started before a previous higher priority job completes, that new
+      // job will start with a higher priority.
+      Process.setThreadPriority(Process.myTid(), DEFAULT_THREAD_PRIORITY);
+    }
+  }
+
   private void notifyFailed() {
+    restoreThreadPriority();
     setNotifiedOrThrow();
     GlideException e = new GlideException("Failed to load resource", new ArrayList<>(throwables));
     callback.onLoadFailed(e);
@@ -335,6 +355,7 @@ private void notifyFailed() {
 
   private void notifyComplete(
       Resource<R> resource, DataSource dataSource, boolean isLoadedFromAlternateCacheKey) {
+    restoreThreadPriority();
     setNotifiedOrThrow();
     callback.onResourceReady(resource, dataSource, isLoadedFromAlternateCacheKey);
   }
@@ -429,6 +450,17 @@ private void decodeFromRetrievedData() {
               + ", fetcher: "
               + currentFetcher);
     }
+    if (glideThreadPriorityOverride != null && glideThreadPriorityOverride.get() != null) {
+      Log.d(
+          "BigDawg",
+          "Setting thread priority for thread "
+              + Process.myTid()
+              + " from "
+              + threadPriority
+              + " to "
+              + glideThreadPriorityOverride.get().intValue());
+      Process.setThreadPriority(Process.myTid(), glideThreadPriorityOverride.get().intValue());
+    }
     Resource<R> resource = null;
     try {
       resource = decodeFromData(currentFetcher, currentData, currentDataSource);

library/src/main/java/com/bumptech/glide/util/Executors.java

@@ -19,6 +19,13 @@ public void execute(@NonNull Runnable command) {
           Util.postOnUiThread(command);
         }
       };
+  private static final Executor MAIN_THREAD_EXECUTOR_FRONT =
+      new Executor() {
+        @Override
+        public void execute(@NonNull Runnable command) {
+          Util.postAtFrontOfQueueOnUiThread(command);
+        }
+      };
   private static final Executor DIRECT_EXECUTOR =
       new Executor() {
         @Override
@@ -32,6 +39,11 @@ public static Executor mainThreadExecutor() {
     return MAIN_THREAD_EXECUTOR;
   }
 
+  /** Posts executions to the main thread at the front of the queue. */
+  public static Executor mainThreadExecutorFront() {
+    return MAIN_THREAD_EXECUTOR_FRONT;
+  }
+
   /** Immediately calls {@link Runnable#run()} on the current thread. */
   public static Executor directExecutor() {
     return DIRECT_EXECUTOR;

library/src/main/java/com/bumptech/glide/util/Util.java

@@ -151,6 +151,14 @@ public static void postOnUiThread(Runnable runnable) {
     getUiThreadHandler().post(runnable);
   }
 
+  /**
+   * Posts the given {@code runnable} to the front of the queue on the UI thread using a shared
+   * {@link Handler}.
+   */
+  public static void postAtFrontOfQueueOnUiThread(Runnable runnable) {
+    getUiThreadHandler().postAtFrontOfQueue(runnable);
+  }
+
   /** Removes the given {@code runnable} from the UI threads queue if it is still queued. */
   public static void removeCallbacksOnUiThread(Runnable runnable) {
     getUiThreadHandler().removeCallbacks(runnable);

library/test/src/test/java/com/bumptech/glide/RequestBuilderTest.java

@@ -77,13 +77,25 @@ public void testDoesNotThrowWithNullModelWhenRequestIsBuilt() {
     getNullModelRequest().into(target);
   }
 
+  @Test
+  public void testDoesNotThrowWithNullModelWhenRequestIsBuilt_Front() {
+    getNullModelRequest().intoFront(target);
+  }
+
   @Test
   public void testAddsNewRequestToRequestTracker() {
     getNullModelRequest().into(target);
 
     verify(requestManager).track(eq(target), isA(Request.class));
   }
 
+  @Test
+  public void testAddsNewRequestToRequestTracker_Front() {
+    getNullModelRequest().intoFront(target);
+
+    verify(requestManager).track(eq(target), isA(Request.class));
+  }
+
   @Test
   public void testRemovesPreviousRequestFromRequestTracker() {
     Request previous = mock(Request.class);
@@ -94,17 +106,38 @@ public void testRemovesPreviousRequestFromRequestTracker() {
     verify(requestManager).clear(eq(target));
   }
 
+  @Test
+  public void testRemovesPreviousRequestFromRequestTracker_Front() {
+    Request previous = mock(Request.class);
+    when(target.getRequest()).thenReturn(previous);
+
+    getNullModelRequest().intoFront(target);
+
+    verify(requestManager).clear(eq(target));
+  }
+
   @Test(expected = NullPointerException.class)
   public void testThrowsIfGivenNullTarget() {
     //noinspection ConstantConditions testing if @NonNull is enforced
     getNullModelRequest().into((Target<Object>) null);
   }
 
+  @Test(expected = NullPointerException.class)
+  public void testThrowsIfGivenNullTarget_Front() {
+    //noinspection ConstantConditions testing if @NonNull is enforced
+    getNullModelRequest().intoFront((Target<Object>) null);
+  }
+
   @Test(expected = NullPointerException.class)
   public void testThrowsIfGivenNullView() {
     getNullModelRequest().into((ImageView) null);
   }
 
+  @Test(expected = NullPointerException.class)
+  public void testThrowsIfGivenNullView_Front() {
+    getNullModelRequest().intoFront((ImageView) null);
+  }
+
   @Test(expected = RuntimeException.class)
   public void testThrowsIfIntoViewCalledOnBackgroundThread() throws InterruptedException {
     final ImageView imageView = new ImageView(ApplicationProvider.getApplicationContext());
@@ -117,6 +150,18 @@ public void runTest() {
         });
   }
 
+  @Test(expected = RuntimeException.class)
+  public void testThrowsIfIntoViewCalledOnBackgroundThread_Front() throws InterruptedException {
+    final ImageView imageView = new ImageView(ApplicationProvider.getApplicationContext());
+    testInBackground(
+        new BackgroundTester() {
+          @Override
+          public void runTest() {
+            getNullModelRequest().intoFront(imageView);
+          }
+        });
+  }
+
   @Test
   public void doesNotThrowIfIntoTargetCalledOnBackgroundThread() throws InterruptedException {
     final Target<Object> target = mock(Target.class);
@@ -129,6 +174,18 @@ public void runTest() {
         });
   }
 
+  @Test
+  public void doesNotThrowIfIntoTargetCalledOnBackgroundThread_Front() throws InterruptedException {
+    final Target<Object> target = mock(Target.class);
+    testInBackground(
+        new BackgroundTester() {
+          @Override
+          public void runTest() {
+            getNullModelRequest().intoFront(target);
+          }
+        });
+  }
+
   @Test
   public void testMultipleRequestListeners() {
     getNullModelRequest().addListener(listener1).addListener(listener2).into(target);
@@ -146,6 +203,23 @@ public void testMultipleRequestListeners() {
         .onResourceReady(any(), any(), isA(Target.class), isA(DataSource.class), anyBoolean());
   }
 
+  @Test
+  public void testMultipleRequestListeners_Front() {
+    getNullModelRequest().addListener(listener1).addListener(listener2).intoFront(target);
+    verify(requestManager).track(any(Target.class), requestCaptor.capture());
+    requestCaptor
+        .getValue()
+        .onResourceReady(
+            new SimpleResource<>(new Object()),
+            DataSource.LOCAL,
+            /* isLoadedFromAlternateCacheKey= */ false);
+
+    verify(listener1)
+        .onResourceReady(any(), any(), isA(Target.class), isA(DataSource.class), anyBoolean());
+    verify(listener2)
+        .onResourceReady(any(), any(), isA(Target.class), isA(DataSource.class), anyBoolean());
+  }
+
   @Test
   public void testListenerApiOverridesListeners() {
     getNullModelRequest().addListener(listener1).listener(listener2).into(target);
@@ -164,6 +238,24 @@ public void testListenerApiOverridesListeners() {
         .onResourceReady(any(), any(), isA(Target.class), isA(DataSource.class), anyBoolean());
   }
 
+  @Test
+  public void testListenerApiOverridesListeners_Front() {
+    getNullModelRequest().addListener(listener1).listener(listener2).intoFront(target);
+    verify(requestManager).track(any(Target.class), requestCaptor.capture());
+    requestCaptor
+        .getValue()
+        .onResourceReady(
+            new SimpleResource<>(new Object()),
+            DataSource.LOCAL,
+            /* isLoadedFromAlternateCacheKey= */ false);
+
+    // The #listener API removes any previous listeners, so the first listener should not be called.
+    verify(listener1, never())
+        .onResourceReady(any(), any(), isA(Target.class), isA(DataSource.class), anyBoolean());
+    verify(listener2)
+        .onResourceReady(any(), any(), isA(Target.class), isA(DataSource.class), anyBoolean());
+  }
+
   @Test
   public void testEquals() {
     Object firstModel = new Object();