Add support for timing out ad preloading

Detect stuck buffering cases in ImaAdsLoader, and discard the ad group after
a timeout. This is intended to make the IMA extension more robust in the case
where an ad group unexpectedly doesn't load.

The timing out behavior is enabled by default but apps can choose to retain
the old behavior by setting an unset timeout on ImaAdsLoader.Builder.

PiperOrigin-RevId: 311729798

RELEASENOTES.md

@@ -52,8 +52,12 @@
         ([#7234](https://github.com/google/ExoPlayer/issues/7234)).
         ([#7234](https://github.com/google/ExoPlayer/issues/7234)).
 *   AV1 extension: Add a heuristic to determine the default number of threads
 *   AV1 extension: Add a heuristic to determine the default number of threads
     used for AV1 playback using the extension.
     used for AV1 playback using the extension.
-*   IMA extension: Upgrade to IMA SDK version 3.19.0, and migrate to new
-    preloading APIs ([#6429](https://github.com/google/ExoPlayer/issues/6429)).
+*   IMA extension:
+    *   Upgrade to IMA SDK version 3.19.0, and migrate to new
+        preloading APIs
+        ([#6429](https://github.com/google/ExoPlayer/issues/6429)).
+    *   Add support for timing out ad preloading, to avoid playback getting
+        stuck if an ad group unexpectedly fails to load.
 
 
 ### 2.11.4 (2020-04-08) ###
 ### 2.11.4 (2020-04-08) ###
 
 

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

@@ -360,6 +360,18 @@ public final class AdPlaybackState {
     return index < adGroupTimesUs.length ? index : C.INDEX_UNSET;
     return index < adGroupTimesUs.length ? index : C.INDEX_UNSET;
   }
   }
 
 
+  /** Returns whether the specified ad has been marked as in {@link #AD_STATE_ERROR}. */
+  public boolean isAdInErrorState(int adGroupIndex, int adIndexInAdGroup) {
+    if (adGroupIndex >= adGroups.length) {
+      return false;
+    }
+    AdGroup adGroup = adGroups[adGroupIndex];
+    if (adGroup.count == C.LENGTH_UNSET || adIndexInAdGroup >= adGroup.count) {
+      return false;
+    }
+    return adGroup.states[adIndexInAdGroup] == AdPlaybackState.AD_STATE_ERROR;
+  }
+
   /**
   /**
    * Returns an instance with the number of ads in {@code adGroupIndex} resolved to {@code adCount}.
    * Returns an instance with the number of ads in {@code adGroupIndex} resolved to {@code adCount}.
    * The ad count must be greater than zero.
    * The ad count must be greater than zero.

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

@@ -64,7 +64,9 @@ public final class AdPlaybackStateTest {
 
 
     assertThat(state.adGroups[0].uris[0]).isNull();
     assertThat(state.adGroups[0].uris[0]).isNull();
     assertThat(state.adGroups[0].states[0]).isEqualTo(AdPlaybackState.AD_STATE_ERROR);
     assertThat(state.adGroups[0].states[0]).isEqualTo(AdPlaybackState.AD_STATE_ERROR);
+    assertThat(state.isAdInErrorState(/* adGroupIndex= */ 0, /* adIndexInAdGroup= */ 0)).isTrue();
     assertThat(state.adGroups[0].states[1]).isEqualTo(AdPlaybackState.AD_STATE_UNAVAILABLE);
     assertThat(state.adGroups[0].states[1]).isEqualTo(AdPlaybackState.AD_STATE_UNAVAILABLE);
+    assertThat(state.isAdInErrorState(/* adGroupIndex= */ 0, /* adIndexInAdGroup= */ 1)).isFalse();
   }
   }
 
 
   @Test
   @Test