Handle detaching and reattaching the ads loader

-------------
Created by MOE: https://github.com/google/moe
MOE_MIGRATED_REVID=161526026

demo/src/main/java/com/google/android/exoplayer2/demo/PlayerActivity.java

@@ -73,6 +73,7 @@ import com.google.android.exoplayer2.upstream.DefaultBandwidthMeter;
 import com.google.android.exoplayer2.upstream.HttpDataSource;
 import com.google.android.exoplayer2.util.Util;
 import java.lang.reflect.Constructor;
+import java.lang.reflect.Method;
 import java.net.CookieHandler;
 import java.net.CookieManager;
 import java.net.CookiePolicy;
@@ -124,6 +125,12 @@ public class PlayerActivity extends Activity implements OnClickListener, ExoPlay
   private int resumeWindow;
   private long resumePosition;
 
+  // Fields used only for ad playback. The ads loader is loaded via reflection.
+
+  private Object imaAdsLoader; // com.google.android.exoplayer2.ext.ima.ImaAdsLoader
+  private Uri loadedAdTagUri;
+  private ViewGroup adOverlayViewGroup;
+
   // Activity lifecycle
 
   @Override
@@ -190,6 +197,12 @@ public class PlayerActivity extends Activity implements OnClickListener, ExoPlay
     }
   }
 
+  @Override
+  public void onDestroy() {
+    super.onDestroy();
+    releaseAdsLoader();
+  }
+
   @Override
   public void onRequestPermissionsResult(int requestCode, @NonNull String[] permissions,
       @NonNull int[] grantResults) {
@@ -317,20 +330,19 @@ public class PlayerActivity extends Activity implements OnClickListener, ExoPlay
       String adTagUriString = intent.getStringExtra(AD_TAG_URI_EXTRA);
       if (adTagUriString != null) {
         Uri adTagUri = Uri.parse(adTagUriString);
-        ViewGroup adOverlayViewGroup = new FrameLayout(this);
+        if (!adTagUri.equals(loadedAdTagUri)) {
-        // Load the extension source using reflection so that demo app doesn't have to depend on it.
+          releaseAdsLoader();
+          loadedAdTagUri = adTagUri;
+        }
         try {
-          Class<?> clazz = Class.forName("com.google.android.exoplayer2.ext.ima.ImaAdsMediaSource");
+          mediaSource = createAdsMediaSource(mediaSource, Uri.parse(adTagUriString));
-          Constructor<?> constructor = clazz.getConstructor(MediaSource.class,
-              DataSource.Factory.class, Context.class, Uri.class, ViewGroup.class);
-          mediaSource = (MediaSource) constructor.newInstance(mediaSource,
-              mediaDataSourceFactory, this, adTagUri, adOverlayViewGroup);
           // The demo app has a non-null overlay frame layout.
           simpleExoPlayerView.getOverlayFrameLayout().addView(adOverlayViewGroup);
         } catch (Exception e) {
-          // Throw if the media source class was not found, or there was an error instantiating it.
           showToast(R.string.ima_not_loaded);
         }
+      } else {
+        releaseAdsLoader();
       }
       boolean haveResumePosition = resumeWindow != C.INDEX_UNSET;
       if (haveResumePosition) {
@@ -429,6 +441,47 @@ public class PlayerActivity extends Activity implements OnClickListener, ExoPlay
         .buildHttpDataSourceFactory(useBandwidthMeter ? BANDWIDTH_METER : null);
   }
 
+  /**
+   * Returns an ads media source, reusing the ads loader if one exists.
+   *
+   * @throws Exception Thrown if it was not possible to create an ads media source, for example, due
+   *     to a missing dependency.
+   */
+  private MediaSource createAdsMediaSource(MediaSource mediaSource, Uri adTagUri) throws Exception {
+    // Load the extension source using reflection so the demo app doesn't have to depend on it.
+    // The ads loader is reused for multiple playbacks, so that ad playback can resume.
+    Class<?> loaderClass = Class.forName("com.google.android.exoplayer2.ext.ima.ImaAdsLoader");
+    if (imaAdsLoader == null) {
+      imaAdsLoader = loaderClass.getConstructor(Context.class, Uri.class)
+          .newInstance(this, adTagUri);
+      adOverlayViewGroup = new FrameLayout(this);
+      // The demo app has a non-null overlay frame layout.
+      simpleExoPlayerView.getOverlayFrameLayout().addView(adOverlayViewGroup);
+    }
+    Class<?> sourceClass =
+        Class.forName("com.google.android.exoplayer2.ext.ima.ImaAdsMediaSource");
+    Constructor<?> constructor = sourceClass.getConstructor(MediaSource.class,
+        DataSource.Factory.class, loaderClass, ViewGroup.class);
+    return (MediaSource) constructor.newInstance(mediaSource, mediaDataSourceFactory, imaAdsLoader,
+        adOverlayViewGroup);
+  }
+
+  private void releaseAdsLoader() {
+    if (imaAdsLoader != null) {
+      try {
+        Class<?> loaderClass = Class.forName("com.google.android.exoplayer2.ext.ima.ImaAdsLoader");
+        Method releaseMethod = loaderClass.getMethod("release");
+        releaseMethod.invoke(imaAdsLoader);
+      } catch (Exception e) {
+        // Should never happen.
+        throw new IllegalStateException(e);
+      }
+      imaAdsLoader = null;
+      loadedAdTagUri = null;
+      simpleExoPlayerView.getOverlayFrameLayout().removeAllViews();
+    }
+  }
+
   // ExoPlayer.EventListener implementation
 
   @Override

extensions/ima/src/main/java/com/google/android/exoplayer2/ext/ima/ImaAdsLoader.java

@@ -54,7 +54,7 @@ import java.util.List;
 /**
  * Loads ads using the IMA SDK. All methods are called on the main thread.
  */
-/* package */ final class ImaAdsLoader implements ExoPlayer.EventListener, VideoAdPlayer,
+public final class ImaAdsLoader implements ExoPlayer.EventListener, VideoAdPlayer,
     ContentProgressProvider, AdErrorListener, AdsLoadedListener, AdEventListener {
 
   private static final boolean DEBUG = false;
@@ -95,19 +95,23 @@ import java.util.List;
    */
   private static final long END_OF_CONTENT_POSITION_THRESHOLD_MS = 5000;
 
-  private final EventListener eventListener;
+  private final Uri adTagUri;
-  private final ExoPlayer player;
   private final Timeline.Period period;
   private final List<VideoAdPlayerCallback> adCallbacks;
+  private final ImaSdkFactory imaSdkFactory;
+  private final AdDisplayContainer adDisplayContainer;
   private final AdsLoader adsLoader;
 
+  private EventListener eventListener;
+  private ExoPlayer player;
+  private VideoProgressUpdate lastContentProgress;
+  private VideoProgressUpdate lastAdProgress;
+
   private AdsManager adsManager;
   private Timeline timeline;
   private long contentDurationMs;
   private AdPlaybackState adPlaybackState;
 
-  private boolean released;
-
   // Fields tracking IMA's state.
 
   /**
@@ -163,46 +167,80 @@ import java.util.List;
    * @param adTagUri The {@link Uri} of an ad tag compatible with the Android IMA SDK. See
    *     https://developers.google.com/interactive-media-ads/docs/sdks/android/compatibility for
    *     more information.
-   * @param adUiViewGroup A {@link ViewGroup} on top of the player that will show any ad UI.
+   */
+  public ImaAdsLoader(Context context, Uri adTagUri) {
+    this(context, adTagUri, null);
+  }
+
+  /**
+   * Creates a new IMA ads loader.
+   *
+   * @param context The context.
+   * @param adTagUri The {@link Uri} of an ad tag compatible with the Android IMA SDK. See
+   *     https://developers.google.com/interactive-media-ads/docs/sdks/android/compatibility for
+   *     more information.
    * @param imaSdkSettings {@link ImaSdkSettings} used to configure the IMA SDK, or {@code null} to
    *     use the default settings. If set, the player type and version fields may be overwritten.
-   * @param player The player instance that will play the loaded ad schedule.
-   * @param eventListener Listener for ad loader events.
    */
-  public ImaAdsLoader(Context context, Uri adTagUri, ViewGroup adUiViewGroup,
+  public ImaAdsLoader(Context context, Uri adTagUri, ImaSdkSettings imaSdkSettings) {
-      ImaSdkSettings imaSdkSettings, ExoPlayer player, EventListener eventListener) {
+    this.adTagUri = adTagUri;
-    this.eventListener = eventListener;
-    this.player = player;
     period = new Timeline.Period();
     adCallbacks = new ArrayList<>(1);
-
+    imaSdkFactory = ImaSdkFactory.getInstance();
-    fakeContentProgressElapsedRealtimeMs = C.TIME_UNSET;
+    adDisplayContainer = imaSdkFactory.createAdDisplayContainer();
-    pendingContentPositionMs = C.TIME_UNSET;
-    adGroupIndex = C.INDEX_UNSET;
-    contentDurationMs = C.TIME_UNSET;
-
-    player.addListener(this);
-
-    ImaSdkFactory imaSdkFactory = ImaSdkFactory.getInstance();
-    AdDisplayContainer adDisplayContainer = imaSdkFactory.createAdDisplayContainer();
     adDisplayContainer.setPlayer(this);
-    adDisplayContainer.setAdContainer(adUiViewGroup);
-
     if (imaSdkSettings == null) {
       imaSdkSettings = imaSdkFactory.createImaSdkSettings();
     }
     imaSdkSettings.setPlayerType(IMA_SDK_SETTINGS_PLAYER_TYPE);
     imaSdkSettings.setPlayerVersion(IMA_SDK_SETTINGS_PLAYER_VERSION);
-
-    AdsRequest request = imaSdkFactory.createAdsRequest();
-    request.setAdTagUrl(adTagUri.toString());
-    request.setAdDisplayContainer(adDisplayContainer);
-    request.setContentProgressProvider(this);
-
     adsLoader = imaSdkFactory.createAdsLoader(context, imaSdkSettings);
     adsLoader.addAdErrorListener(this);
     adsLoader.addAdsLoadedListener(this);
-    adsLoader.requestAds(request);
+    fakeContentProgressElapsedRealtimeMs = C.TIME_UNSET;
+    pendingContentPositionMs = C.TIME_UNSET;
+    adGroupIndex = C.INDEX_UNSET;
+    contentDurationMs = C.TIME_UNSET;
+  }
+
+  /**
+   * Attaches a player that will play ads loaded using this instance.
+   *
+   * @param player The player instance that will play the loaded ads.
+   * @param eventListener Listener for ads loader events.
+   * @param adUiViewGroup A {@link ViewGroup} on top of the player that will show any ad UI.
+   */
+  public void attachPlayer(ExoPlayer player, EventListener eventListener, ViewGroup adUiViewGroup) {
+    this.player = player;
+    this.eventListener = eventListener;
+    lastAdProgress = null;
+    lastContentProgress = null;
+    adDisplayContainer.setAdContainer(adUiViewGroup);
+    player.addListener(this);
+    if (adPlaybackState != null) {
+      eventListener.onAdPlaybackState(adPlaybackState);
+      // TODO: Call adsManager.resume if an ad is playing.
+    } else if (adTagUri != null) {
+      requestAds();
+    }
+  }
+
+  /**
+   * Detaches any attached player and event listener. To attach a new player, call
+   * {@link #attachPlayer(ExoPlayer, EventListener, ViewGroup)}. Call {@link #release()} to release
+   * all resources associated with this instance.
+   */
+  public void detachPlayer() {
+    if (player != null) {
+      if (adsManager != null && player.isPlayingAd()) {
+        adsManager.pause();
+      }
+      lastAdProgress = getAdProgress();
+      lastContentProgress = getContentProgress();
+      player.removeListener(this);
+      player = null;
+    }
+    eventListener = null;
   }
 
   /**
@@ -212,9 +250,8 @@ import java.util.List;
     if (adsManager != null) {
       adsManager.destroy();
       adsManager = null;
+      detachPlayer();
     }
-    player.removeListener(this);
-    released = true;
   }
 
   // AdsLoader.AdsLoadedListener implementation.
@@ -251,8 +288,8 @@ import java.util.List;
     if (DEBUG) {
       Log.d(TAG, "onAdEvent " + adEvent.getType());
     }
-    if (released) {
+    if (adsManager == null) {
-      // The ads manager may pass CONTENT_RESUME_REQUESTED after it is destroyed.
+      Log.w(TAG, "Dropping ad event while detached: " + adEvent);
       return;
     }
     switch (adEvent.getType()) {
@@ -274,11 +311,15 @@ import java.util.List;
       case CONTENT_PAUSE_REQUESTED:
         // After CONTENT_PAUSE_REQUESTED, IMA will playAd/pauseAd/stopAd to show one or more ads
         // before sending CONTENT_RESUME_REQUESTED.
-        pauseContentInternal();
+        if (player != null) {
+          pauseContentInternal();
+        }
         break;
       case SKIPPED: // Fall through.
       case CONTENT_RESUME_REQUESTED:
-        resumeContentInternal();
+        if (player != null) {
+          resumeContentInternal();
+        }
         break;
       case ALL_ADS_COMPLETED:
         // Do nothing. The ads manager will be released when the source is released.
@@ -294,8 +335,10 @@ import java.util.List;
     if (DEBUG) {
       Log.d(TAG, "onAdError " + adErrorEvent);
     }
-    IOException exception = new IOException("Ad error: " + adErrorEvent, adErrorEvent.getError());
+    if (eventListener != null) {
-    eventListener.onLoadError(exception);
+      IOException exception = new IOException("Ad error: " + adErrorEvent, adErrorEvent.getError());
+      eventListener.onLoadError(exception);
+    }
     // TODO: Provide a timeline to the player if it doesn't have one yet, so the content can play.
   }
 
@@ -303,32 +346,36 @@ import java.util.List;
 
   @Override
   public VideoProgressUpdate getContentProgress() {
-    if (pendingContentPositionMs != C.TIME_UNSET) {
+    if (player == null) {
+      return lastContentProgress;
+    } else if (pendingContentPositionMs != C.TIME_UNSET) {
       sentPendingContentPositionMs = true;
       return new VideoProgressUpdate(pendingContentPositionMs, contentDurationMs);
-    }
+    } else if (fakeContentProgressElapsedRealtimeMs != C.TIME_UNSET) {
-    if (fakeContentProgressElapsedRealtimeMs != C.TIME_UNSET) {
       long adGroupTimeMs = C.usToMs(adPlaybackState.adGroupTimesUs[adGroupIndex]);
       if (adGroupTimeMs == C.TIME_END_OF_SOURCE) {
         adGroupTimeMs = contentDurationMs;
       }
       long elapsedSinceEndMs = SystemClock.elapsedRealtime() - fakeContentProgressElapsedRealtimeMs;
       return new VideoProgressUpdate(adGroupTimeMs + elapsedSinceEndMs, contentDurationMs);
-    }
+    } else if (player.isPlayingAd() || contentDurationMs == C.TIME_UNSET) {
-    if (player.isPlayingAd() || contentDurationMs == C.TIME_UNSET) {
       return VideoProgressUpdate.VIDEO_TIME_NOT_READY;
+    } else {
+      return new VideoProgressUpdate(player.getCurrentPosition(), contentDurationMs);
     }
-    return new VideoProgressUpdate(player.getCurrentPosition(), contentDurationMs);
   }
 
   // VideoAdPlayer implementation.
 
   @Override
   public VideoProgressUpdate getAdProgress() {
-    if (!player.isPlayingAd()) {
+    if (player == null) {
+      return lastAdProgress;
+    } else if (!player.isPlayingAd()) {
       return VideoProgressUpdate.VIDEO_TIME_NOT_READY;
+    } else {
+      return new VideoProgressUpdate(player.getCurrentPosition(), player.getDuration());
     }
-    return new VideoProgressUpdate(player.getCurrentPosition(), player.getDuration());
   }
 
   @Override
@@ -352,6 +399,7 @@ import java.util.List;
 
   @Override
   public void playAd() {
+    Assertions.checkState(player != null);
     if (DEBUG) {
       Log.d(TAG, "playAd");
     }
@@ -379,6 +427,7 @@ import java.util.List;
 
   @Override
   public void stopAd() {
+    Assertions.checkState(player != null);
     if (!playingAd) {
       if (DEBUG) {
         Log.d(TAG, "Ignoring unexpected stopAd");
@@ -396,7 +445,7 @@ import java.util.List;
     if (DEBUG) {
       Log.d(TAG, "pauseAd");
     }
-    if (released || !playingAd) {
+    if (player == null || !playingAd) {
       // This method is called after content is resumed, and may also be called after release.
       return;
     }
@@ -513,9 +562,14 @@ import java.util.List;
 
   // Internal methods.
 
-  /**
+  private void requestAds() {
-   * Resumes the player, ensuring the current period is a content period by seeking if necessary.
+    AdsRequest request = imaSdkFactory.createAdsRequest();
-   */
+    request.setAdTagUrl(adTagUri.toString());
+    request.setAdDisplayContainer(adDisplayContainer);
+    request.setContentProgressProvider(this);
+    adsLoader.requestAds(request);
+  }
+
   private void resumeContentInternal() {
     if (contentDurationMs != C.TIME_UNSET) {
       if (playingAd) {
@@ -573,7 +627,10 @@ import java.util.List;
   }
 
   private void updateAdPlaybackState() {
-    eventListener.onAdPlaybackState(adPlaybackState.copy());
+    // Ignore updates while detached. When a player is attached it will receive the latest state.
+    if (eventListener != null) {
+      eventListener.onAdPlaybackState(adPlaybackState.copy());
+    }
   }
 
   private static long[] getAdGroupTimesUs(List<Float> cuePoints) {

extensions/ima/src/main/java/com/google/android/exoplayer2/ext/ima/ImaAdsMediaSource.java

@@ -15,12 +15,9 @@
  */
 package com.google.android.exoplayer2.ext.ima;
 
-import android.content.Context;
-import android.net.Uri;
 import android.os.Handler;
 import android.os.Looper;
 import android.view.ViewGroup;
-import com.google.ads.interactivemedia.v3.api.ImaSdkSettings;
 import com.google.android.exoplayer2.C;
 import com.google.android.exoplayer2.ExoPlayer;
 import com.google.android.exoplayer2.Timeline;
@@ -44,10 +41,8 @@ public final class ImaAdsMediaSource implements MediaSource {
 
   private final MediaSource contentMediaSource;
   private final DataSource.Factory dataSourceFactory;
-  private final Context context;
+  private final ImaAdsLoader imaAdsLoader;
-  private final Uri adTagUri;
   private final ViewGroup adUiViewGroup;
-  private final ImaSdkSettings imaSdkSettings;
   private final Handler mainHandler;
   private final AdsLoaderListener adsLoaderListener;
   private final Map<MediaPeriod, MediaSource> adMediaSourceByMediaPeriod;
@@ -66,49 +61,20 @@ public final class ImaAdsMediaSource implements MediaSource {
   private MediaSource.Listener listener;
   private IOException adLoadError;
 
-  // Accessed on the main thread.
-  private ImaAdsLoader imaAdsLoader;
-
   /**
    * Constructs a new source that inserts ads linearly with the content specified by
    * {@code contentMediaSource}.
    *
    * @param contentMediaSource The {@link MediaSource} providing the content to play.
    * @param dataSourceFactory Factory for data sources used to load ad media.
-   * @param context The context.
+   * @param imaAdsLoader The loader for ads.
-   * @param adTagUri The {@link Uri} of an ad tag compatible with the Android IMA SDK. See
-   *     https://developers.google.com/interactive-media-ads/docs/sdks/android/compatibility for
-   *     more information.
-   * @param adUiViewGroup A {@link ViewGroup} on top of the player that will show any ad user
-   *     interface.
    */
   public ImaAdsMediaSource(MediaSource contentMediaSource, DataSource.Factory dataSourceFactory,
-      Context context, Uri adTagUri, ViewGroup adUiViewGroup) {
+      ImaAdsLoader imaAdsLoader, ViewGroup adUiViewGroup) {
-    this(contentMediaSource, dataSourceFactory, context, adTagUri, adUiViewGroup, null);
-  }
-
-  /**
-   * Constructs a new source that inserts ads linearly with the content specified by
-   * {@code contentMediaSource}.
-   *
-   * @param contentMediaSource The {@link MediaSource} providing the content to play.
-   * @param dataSourceFactory Factory for data sources used to load ad media.
-   * @param context The context.
-   * @param adTagUri The {@link Uri} of an ad tag compatible with the Android IMA SDK. See
-   *     https://developers.google.com/interactive-media-ads/docs/sdks/android/compatibility for
-   *     more information.
-   * @param adUiViewGroup A {@link ViewGroup} on top of the player that will show any ad UI.
-   * @param imaSdkSettings {@link ImaSdkSettings} used to configure the IMA SDK, or {@code null} to
-   *     use the default settings. If set, the player type and version fields may be overwritten.
-   */
-  public ImaAdsMediaSource(MediaSource contentMediaSource, DataSource.Factory dataSourceFactory,
-      Context context, Uri adTagUri, ViewGroup adUiViewGroup, ImaSdkSettings imaSdkSettings) {
     this.contentMediaSource = contentMediaSource;
     this.dataSourceFactory = dataSourceFactory;
-    this.context = context;
+    this.imaAdsLoader = imaAdsLoader;
-    this.adTagUri = adTagUri;
     this.adUiViewGroup = adUiViewGroup;
-    this.imaSdkSettings = imaSdkSettings;
     mainHandler = new Handler(Looper.getMainLooper());
     adsLoaderListener = new AdsLoaderListener();
     adMediaSourceByMediaPeriod = new HashMap<>();
@@ -118,24 +84,23 @@ public final class ImaAdsMediaSource implements MediaSource {
   }
 
   @Override
-  public void prepareSource(ExoPlayer player, boolean isTopLevelSource, Listener listener) {
+  public void prepareSource(final ExoPlayer player, boolean isTopLevelSource, Listener listener) {
     Assertions.checkArgument(isTopLevelSource);
     this.listener = listener;
     this.player = player;
     playerHandler = new Handler();
-    mainHandler.post(new Runnable() {
-      @Override
-      public void run() {
-        imaAdsLoader = new ImaAdsLoader(context, adTagUri, adUiViewGroup, imaSdkSettings,
-            ImaAdsMediaSource.this.player, adsLoaderListener);
-      }
-    });
     contentMediaSource.prepareSource(player, false, new Listener() {
       @Override
       public void onSourceInfoRefreshed(Timeline timeline, Object manifest) {
         ImaAdsMediaSource.this.onContentSourceInfoRefreshed(timeline, manifest);
       }
     });
+    mainHandler.post(new Runnable() {
+      @Override
+      public void run() {
+        imaAdsLoader.attachPlayer(player, adsLoaderListener, adUiViewGroup);
+      }
+    });
   }
 
   @Override
@@ -146,7 +111,9 @@ public final class ImaAdsMediaSource implements MediaSource {
     contentMediaSource.maybeThrowSourceInfoRefreshError();
     for (MediaSource[] mediaSources : adGroupMediaSources) {
       for (MediaSource mediaSource : mediaSources) {
-        mediaSource.maybeThrowSourceInfoRefreshError();
+        if (mediaSource != null) {
+          mediaSource.maybeThrowSourceInfoRefreshError();
+        }
       }
     }
   }
@@ -201,17 +168,15 @@ public final class ImaAdsMediaSource implements MediaSource {
     contentMediaSource.releaseSource();
     for (MediaSource[] mediaSources : adGroupMediaSources) {
       for (MediaSource mediaSource : mediaSources) {
-        mediaSource.releaseSource();
+        if (mediaSource != null) {
+          mediaSource.releaseSource();
+        }
       }
     }
     mainHandler.post(new Runnable() {
       @Override
       public void run() {
-        // TODO: The source will be released when the application is paused/stopped, which can occur
+        imaAdsLoader.detachPlayer();
-        // if the user taps on the ad. In this case, we should keep the ads manager alive but pause
-        // it, instead of destroying it.
-        imaAdsLoader.release();
-        imaAdsLoader = null;
       }
     });
   }