Add SpannedData.isEmpty() method and simplify some logic in SampleQueue

PiperOrigin-RevId: 362527505

library/core/src/main/java/com/google/android/exoplayer2/source/SampleQueue.java

@@ -725,15 +725,12 @@ public class SampleQueue implements TrackOutput {
       return false;
     }
 
-    @Nullable SharedSampleMetadata upstreamCommittedMetadata = sharedSampleMetadata.getEndValue();
-    @Nullable
-    Format upstreamCommittedFormat =
-        upstreamCommittedMetadata != null ? upstreamCommittedMetadata.format : null;
-    if (Util.areEqual(format, upstreamCommittedFormat)) {
+    if (!sharedSampleMetadata.isEmpty()
+        && sharedSampleMetadata.getEndValue().format.equals(format)) {
       // The format has changed back to the format of the last committed sample. If they are
       // different objects, we revert back to using upstreamCommittedFormat as the upstreamFormat
       // so we can detect format changes on the read side using cheap referential equality.
-      upstreamFormat = upstreamCommittedFormat;
+      upstreamFormat = sharedSampleMetadata.getEndValue().format;
     } else {
       upstreamFormat = format;
     }
@@ -804,9 +801,8 @@ public class SampleQueue implements TrackOutput {
     cryptoDatas[relativeEndIndex] = cryptoData;
     sourceIds[relativeEndIndex] = upstreamSourceId;
 
-    @Nullable SharedSampleMetadata upstreamCommittedMetadata = sharedSampleMetadata.getEndValue();
-    if (upstreamCommittedMetadata == null
-        || !upstreamCommittedMetadata.format.equals(upstreamFormat)) {
+    if (sharedSampleMetadata.isEmpty()
+        || !sharedSampleMetadata.getEndValue().format.equals(upstreamFormat)) {
       DrmSessionReference drmSessionReference =
           drmSessionManager != null
               ? drmSessionManager.preacquireSession(

library/core/src/main/java/com/google/android/exoplayer2/source/SpannedData.java

@@ -20,7 +20,6 @@ import static com.google.android.exoplayer2.util.Assertions.checkState;
 import static java.lang.Math.min;
 
 import android.util.SparseArray;
-import androidx.annotation.Nullable;
 import com.google.android.exoplayer2.C;
 import com.google.android.exoplayer2.util.Consumer;
 
@@ -60,8 +59,7 @@ import com.google.android.exoplayer2.util.Consumer;
   /**
    * Returns the value associated with the span covering {@code key}.
    *
-   * <p>{@link #appendSpan(int, Object)} must have been called at least once since the last call to
-   * {@link #clear()}.
+   * <p>The collection must not be {@link #isEmpty() empty}.
    *
    * <p>{@code key} must be greater than or equal to the previous value passed to {@link
    * #discardTo(int)} (or zero after {@link #clear()} has been called).
@@ -103,14 +101,15 @@ import com.google.android.exoplayer2.util.Consumer;
   }
 
   /**
-   * Returns the value associated with the end span, or null if the collection is empty.
+   * Returns the value associated with the end span.
+   *
+   * <p>The collection must not be {@link #isEmpty() empty}.
    *
    * <p>This is either the last value passed to {@link #appendSpan(int, Object)}, or the value of
    * the span covering the index passed to {@link #discardFrom(int)}.
    */
-  @Nullable
   public V getEndValue() {
-    return spans.size() != 0 ? spans.valueAt(spans.size() - 1) : null;
+    return spans.valueAt(spans.size() - 1);
   }
 
   /**
@@ -150,4 +149,9 @@ import com.google.android.exoplayer2.util.Consumer;
     memoizedReadIndex = C.INDEX_UNSET;
     spans.clear();
   }
+
+  /** Returns true if the collection is empty. */
+  public boolean isEmpty() {
+    return spans.size() == 0;
+  }
 }

library/core/src/test/java/com/google/android/exoplayer2/source/SpannedDataTest.java

@@ -16,6 +16,7 @@
 package com.google.android.exoplayer2.source;
 
 import static com.google.common.truth.Truth.assertThat;
+import static org.junit.Assert.assertThrows;
 import static org.mockito.Mockito.never;
 import static org.mockito.Mockito.verify;
 
@@ -73,6 +74,25 @@ public final class SpannedDataTest {
     assertThat(spannedData.get(3)).isEqualTo(value3);
   }
 
+  @Test
+  public void getEndValue() {
+    SpannedData<String> spannedData = new SpannedData<>();
+
+    assertThrows(Exception.class, spannedData::getEndValue);
+
+    spannedData.appendSpan(/* startKey= */ 0, "test 1");
+    spannedData.appendSpan(/* startKey= */ 2, "test 2");
+    spannedData.appendSpan(/* startKey= */ 4, "test 3");
+
+    assertThat(spannedData.getEndValue()).isEqualTo("test 3");
+
+    spannedData.discardFrom(2);
+    assertThat(spannedData.getEndValue()).isEqualTo("test 2");
+
+    spannedData.clear();
+    assertThrows(Exception.class, spannedData::getEndValue);
+  }
+
   @Test
   public void discardTo() {
     SpannedData<DrmSessionReference> spannedData =
@@ -173,4 +193,30 @@ public final class SpannedDataTest {
     assertThat(spannedData.get(0)).isEqualTo(value3);
     assertThat(spannedData.get(1)).isEqualTo(value3);
   }
+
+  @Test
+  public void isEmpty() {
+    SpannedData<String> spannedData = new SpannedData<>();
+
+    assertThat(spannedData.isEmpty()).isTrue();
+
+    spannedData.appendSpan(/* startKey= */ 0, "test 1");
+    spannedData.appendSpan(/* startKey= */ 2, "test 2");
+
+    assertThat(spannedData.isEmpty()).isFalse();
+
+    // Discarding from 0 still retains the 'first' span, so collection doesn't end up empty.
+    spannedData.discardFrom(0);
+    assertThat(spannedData.isEmpty()).isFalse();
+
+    spannedData.appendSpan(/* startKey= */ 2, "test 2");
+
+    // Discarding to 3 still retains the 'last' span, so collection doesn't end up empty.
+    spannedData.discardTo(3);
+    assertThat(spannedData.isEmpty()).isFalse();
+
+    spannedData.clear();
+
+    assertThat(spannedData.isEmpty()).isTrue();
+  }
 }