Implement chaining GlTextureProcessor.Listener.

In follow-ups the FrameProcessorChain will set an instance of this
listener for each GlTextureProcessor to chain it with its previous
and next GlTextureProcesssor.

PiperOrigin-RevId: 455628942

library/transformer/src/main/java/com/google/android/exoplayer2/transformer/ChainingGlTextureProcessorListener.java

+/*
+ * Copyright 2022 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.google.android.exoplayer2.transformer;
+
+import android.util.Pair;
+import androidx.annotation.Nullable;
+import java.util.ArrayDeque;
+import java.util.Queue;
+
+/**
+ * A {@link GlTextureProcessor.Listener} that connects the {@link GlTextureProcessor} it is
+ * {@linkplain GlTextureProcessor#setListener(GlTextureProcessor.Listener) set} on to a previous and
+ * next {@link GlTextureProcessor}.
+ */
+/* package */ final class ChainingGlTextureProcessorListener
+    implements GlTextureProcessor.Listener {
+
+  @Nullable private final GlTextureProcessor previousGlTextureProcessor;
+  @Nullable private final GlTextureProcessor nextGlTextureProcessor;
+  private final FrameProcessingTaskExecutor frameProcessingTaskExecutor;
+  private final FrameProcessorChain.Listener frameProcessorChainListener;
+  private final Queue<Pair<TextureInfo, Long>> pendingFrames;
+
+  /**
+   * Creates a new instance.
+   *
+   * @param previousGlTextureProcessor The {@link GlTextureProcessor} that comes before the {@link
+   *     GlTextureProcessor} this listener is set on or {@code null} if not applicable.
+   * @param nextGlTextureProcessor The {@link GlTextureProcessor} that comes after the {@link
+   *     GlTextureProcessor} this listener is set on or {@code null} if not applicable.
+   * @param frameProcessingTaskExecutor The {@link FrameProcessingTaskExecutor} that is used for
+   *     OpenGL calls. All calls to the previous/next {@link GlTextureProcessor} will be executed by
+   *     the {@link FrameProcessingTaskExecutor}. The caller is responsible for releasing the {@link
+   *     FrameProcessingTaskExecutor}.
+   * @param frameProcessorChainListener The {@link FrameProcessorChain.Listener} to forward
+   *     exceptions to.
+   */
+  public ChainingGlTextureProcessorListener(
+      @Nullable GlTextureProcessor previousGlTextureProcessor,
+      @Nullable GlTextureProcessor nextGlTextureProcessor,
+      FrameProcessingTaskExecutor frameProcessingTaskExecutor,
+      FrameProcessorChain.Listener frameProcessorChainListener) {
+    this.previousGlTextureProcessor = previousGlTextureProcessor;
+    this.nextGlTextureProcessor = nextGlTextureProcessor;
+    this.frameProcessingTaskExecutor = frameProcessingTaskExecutor;
+    this.frameProcessorChainListener = frameProcessorChainListener;
+    pendingFrames = new ArrayDeque<>();
+  }
+
+  @Override
+  public void onInputFrameProcessed(TextureInfo inputTexture) {
+    if (previousGlTextureProcessor != null) {
+      GlTextureProcessor nonNullPreviousGlTextureProcessor = previousGlTextureProcessor;
+      frameProcessingTaskExecutor.submit(
+          () -> nonNullPreviousGlTextureProcessor.releaseOutputFrame(inputTexture));
+    }
+  }
+
+  @Override
+  public void onOutputFrameAvailable(TextureInfo outputTexture, long presentationTimeUs) {
+    if (nextGlTextureProcessor != null) {
+      GlTextureProcessor nonNullNextGlTextureProcessor = nextGlTextureProcessor;
+      frameProcessingTaskExecutor.submit(
+          () -> {
+            pendingFrames.add(new Pair<>(outputTexture, presentationTimeUs));
+            processFrameNowOrLater(nonNullNextGlTextureProcessor);
+          });
+    }
+  }
+
+  private void processFrameNowOrLater(GlTextureProcessor nextGlTextureProcessor) {
+    Pair<TextureInfo, Long> pendingFrame = pendingFrames.element();
+    TextureInfo outputTexture = pendingFrame.first;
+    long presentationTimeUs = pendingFrame.second;
+    if (nextGlTextureProcessor.maybeQueueInputFrame(outputTexture, presentationTimeUs)) {
+      pendingFrames.remove();
+    } else {
+      frameProcessingTaskExecutor.submit(() -> processFrameNowOrLater(nextGlTextureProcessor));
+    }
+  }
+
+  @Override
+  public void onOutputStreamEnded() {
+    if (nextGlTextureProcessor != null) {
+      frameProcessingTaskExecutor.submit(nextGlTextureProcessor::signalEndOfInputStream);
+    }
+  }
+
+  @Override
+  public void onFrameProcessingError(FrameProcessingException e) {
+    frameProcessorChainListener.onFrameProcessingError(e);
+  }
+}

library/transformer/src/main/java/com/google/android/exoplayer2/transformer/FrameProcessorChain.java

@@ -146,11 +146,12 @@ import org.checkerframework.checker.nullness.qual.MonotonicNonNull;
   }
 
   /**
-   * Creates the OpenGL textures and framebuffers, initializes the {@link
+   * Creates the OpenGL context, surfaces, textures, and framebuffers, initializes the {@link
    * SingleFrameGlTextureProcessor SingleFrameGlTextureProcessors} corresponding to the {@link
    * GlEffect GlEffects}, and returns a new {@code FrameProcessorChain}.
    *
-   * <p>This method must be executed using the {@code singleThreadExecutorService}.
+   * <p>This method must be executed using the {@code singleThreadExecutorService}, as all later
+   * OpenGL commands will be called on that thread.
    */
   @WorkerThread
   @Nullable

library/transformer/src/test/java/com/google/android/exoplayer2/transformer/ChainingGlTextureProcessorListenerTest.java

+/*
+ * Copyright 2022 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.google.android.exoplayer2.transformer;
+
+import static org.mockito.Mockito.mock;
+import static org.mockito.Mockito.spy;
+import static org.mockito.Mockito.times;
+import static org.mockito.Mockito.verify;
+
+import androidx.test.ext.junit.runners.AndroidJUnit4;
+import com.google.android.exoplayer2.util.Util;
+import org.junit.After;
+import org.junit.Test;
+import org.junit.runner.RunWith;
+
+/** Tests for {@link ChainingGlTextureProcessorListener}. */
+@RunWith(AndroidJUnit4.class)
+public final class ChainingGlTextureProcessorListenerTest {
+  private static final long EXECUTOR_WAIT_TIME_MS = 100;
+
+  private final FrameProcessorChain.Listener mockFrameProcessorChainListener =
+      mock(FrameProcessorChain.Listener.class);
+  private final FrameProcessingTaskExecutor frameProcessingTaskExecutor =
+      new FrameProcessingTaskExecutor(
+          Util.newSingleThreadExecutor("Test"), mockFrameProcessorChainListener);
+  private final GlTextureProcessor mockPreviousGlTextureProcessor = mock(GlTextureProcessor.class);
+  private final FakeGlTextureProcessor fakeNextGlTextureProcessor =
+      spy(new FakeGlTextureProcessor());
+  private final ChainingGlTextureProcessorListener chainingGlTextureProcessorListener =
+      new ChainingGlTextureProcessorListener(
+          mockPreviousGlTextureProcessor,
+          fakeNextGlTextureProcessor,
+          frameProcessingTaskExecutor,
+          mockFrameProcessorChainListener);
+
+  @After
+  public void release() throws InterruptedException {
+    frameProcessingTaskExecutor.release(/* releaseTask= */ () -> {}, EXECUTOR_WAIT_TIME_MS);
+  }
+
+  @Test
+  public void onFrameProcessingError_callsListener() {
+    FrameProcessingException exception = new FrameProcessingException("message");
+
+    chainingGlTextureProcessorListener.onFrameProcessingError(exception);
+
+    verify(mockFrameProcessorChainListener, times(1)).onFrameProcessingError(exception);
+  }
+
+  @Test
+  public void onInputFrameProcessed_surrendersFrameToPreviousGlTextureProcessor()
+      throws InterruptedException {
+    TextureInfo texture =
+        new TextureInfo(/* texId= */ 1, /* fboId= */ 1, /* width= */ 100, /* height= */ 100);
+
+    chainingGlTextureProcessorListener.onInputFrameProcessed(texture);
+    Thread.sleep(EXECUTOR_WAIT_TIME_MS);
+
+    verify(mockPreviousGlTextureProcessor, times(1)).releaseOutputFrame(texture);
+  }
+
+  @Test
+  public void onOutputFrameAvailable_passesFrameToNextGlTextureProcessor()
+      throws InterruptedException {
+    TextureInfo texture =
+        new TextureInfo(/* texId= */ 1, /* fboId= */ 1, /* width= */ 100, /* height= */ 100);
+    long presentationTimeUs = 123;
+
+    chainingGlTextureProcessorListener.onOutputFrameAvailable(texture, presentationTimeUs);
+    Thread.sleep(EXECUTOR_WAIT_TIME_MS);
+
+    verify(fakeNextGlTextureProcessor, times(1)).maybeQueueInputFrame(texture, presentationTimeUs);
+  }
+
+  @Test
+  public void onOutputFrameAvailable_nextGlTextureProcessorRejectsFrame_triesAgain()
+      throws InterruptedException {
+    TextureInfo texture =
+        new TextureInfo(/* texId= */ 1, /* fboId= */ 1, /* width= */ 100, /* height= */ 100);
+    long presentationTimeUs = 123;
+    fakeNextGlTextureProcessor.rejectNextFrame();
+
+    chainingGlTextureProcessorListener.onOutputFrameAvailable(texture, presentationTimeUs);
+    Thread.sleep(EXECUTOR_WAIT_TIME_MS);
+
+    verify(fakeNextGlTextureProcessor, times(2)).maybeQueueInputFrame(texture, presentationTimeUs);
+  }
+
+  @Test
+  public void onOutputFrameAvailable_twoFramesWithFirstRejected_retriesFirstBeforeSecond()
+      throws InterruptedException {
+    TextureInfo firstTexture =
+        new TextureInfo(/* texId= */ 1, /* fboId= */ 1, /* width= */ 100, /* height= */ 100);
+    long firstPresentationTimeUs = 123;
+    TextureInfo secondTexture =
+        new TextureInfo(/* texId= */ 2, /* fboId= */ 2, /* width= */ 100, /* height= */ 100);
+    long secondPresentationTimeUs = 567;
+    fakeNextGlTextureProcessor.rejectNextFrame();
+
+    chainingGlTextureProcessorListener.onOutputFrameAvailable(
+        firstTexture, firstPresentationTimeUs);
+    chainingGlTextureProcessorListener.onOutputFrameAvailable(
+        secondTexture, secondPresentationTimeUs);
+    Thread.sleep(EXECUTOR_WAIT_TIME_MS);
+
+    verify(fakeNextGlTextureProcessor, times(2))
+        .maybeQueueInputFrame(firstTexture, firstPresentationTimeUs);
+    verify(fakeNextGlTextureProcessor, times(1))
+        .maybeQueueInputFrame(secondTexture, secondPresentationTimeUs);
+  }
+
+  @Test
+  public void onOutputStreamEnded_signalsInputStreamEndedToNextGlTextureProcessor()
+      throws InterruptedException {
+    chainingGlTextureProcessorListener.onOutputStreamEnded();
+    Thread.sleep(EXECUTOR_WAIT_TIME_MS);
+
+    verify(fakeNextGlTextureProcessor, times(1)).signalEndOfInputStream();
+  }
+
+  private static class FakeGlTextureProcessor implements GlTextureProcessor {
+
+    private volatile boolean rejectNextFrame;
+
+    public void rejectNextFrame() {
+      rejectNextFrame = true;
+    }
+
+    @Override
+    public void setListener(Listener listener) {
+      throw new UnsupportedOperationException();
+    }
+
+    @Override
+    public boolean maybeQueueInputFrame(TextureInfo inputTexture, long presentationTimeUs) {
+      boolean acceptFrame = !rejectNextFrame;
+      rejectNextFrame = false;
+      return acceptFrame;
+    }
+
+    @Override
+    public void releaseOutputFrame(TextureInfo outputTexture) {}
+
+    @Override
+    public void signalEndOfInputStream() {}
+
+    @Override
+    public void release() {}
+  }
+}