Add util to obtain AudioManager

AudioManager internally assumes the thread is was created on can be
used as a callback thread. Since the AudioManager is only created
once in the lifetime of an app, we need to make sure its obtained
on a thread that stays alive.

#cherrypick

PiperOrigin-RevId: 732072255
(cherry picked from commit 2088697a19ac85feb26ba2521a70647803246571)

libraries/common/src/main/java/androidx/media3/common/audio/AudioManagerCompat.java

@@ -15,12 +15,18 @@
  */
 package androidx.media3.common.audio;
 
+import static androidx.media3.common.util.Assertions.checkNotNull;
 import static java.lang.annotation.ElementType.TYPE_USE;
 
+import android.content.Context;
 import android.media.AudioManager;
+import android.os.Looper;
 import androidx.annotation.IntDef;
 import androidx.annotation.IntRange;
+import androidx.annotation.Nullable;
 import androidx.media3.common.C;
+import androidx.media3.common.util.BackgroundExecutor;
+import androidx.media3.common.util.ConditionVariable;
 import androidx.media3.common.util.Log;
 import androidx.media3.common.util.UnstableApi;
 import androidx.media3.common.util.Util;
@@ -28,11 +34,14 @@ import java.lang.annotation.Documented;
 import java.lang.annotation.Retention;
 import java.lang.annotation.RetentionPolicy;
 import java.lang.annotation.Target;
+import org.checkerframework.checker.nullness.qual.MonotonicNonNull;
 
 /** Compatibility layer for {@link AudioManager} with fallbacks for older Android versions. */
 @UnstableApi
 public final class AudioManagerCompat {
 
+  private static final String TAG = "AudioManagerCompat";
+
   /**
    * Audio focus gain types. One of {@link #AUDIOFOCUS_NONE}, {@link #AUDIOFOCUS_GAIN}, {@link
    * #AUDIOFOCUS_GAIN_TRANSIENT}, {@link #AUDIOFOCUS_GAIN_TRANSIENT_MAY_DUCK} or {@link
@@ -83,6 +92,55 @@ public final class AudioManagerCompat {
   public static final int AUDIOFOCUS_GAIN_TRANSIENT_EXCLUSIVE =
       AudioManager.AUDIOFOCUS_GAIN_TRANSIENT_EXCLUSIVE;
 
+  @SuppressWarnings("NonFinalStaticField") // Lazily initialized under class lock
+  @Nullable
+  private static AudioManager audioManager;
+
+  @SuppressWarnings("NonFinalStaticField") // Lazily initialized under class lock
+  private static @MonotonicNonNull Context applicationContext;
+
+  /**
+   * Returns the {@link AudioManager}.
+   *
+   * <p>This method avoids potential threading issues where AudioManager keeps access to the thread
+   * it was created on until after this thread is stopped.
+   *
+   * <p>It is recommended to use this method from a background thread.
+   *
+   * @param context A {@link Context}.
+   * @return The {@link AudioManager}.
+   */
+  public static synchronized AudioManager getAudioManager(Context context) {
+    Context applicationContext = context.getApplicationContext();
+    if (AudioManagerCompat.applicationContext != applicationContext) {
+      // Reset cached instance if the application context changed. This should only happen in tests.
+      audioManager = null;
+    }
+    if (audioManager != null) {
+      return audioManager;
+    }
+    @Nullable Looper myLooper = Looper.myLooper();
+    if (myLooper == null || myLooper == Looper.getMainLooper()) {
+      // The AudioManager will assume the main looper as default callback anyway, so create the
+      // instance here without using BackgroundExecutor.
+      audioManager = (AudioManager) applicationContext.getSystemService(Context.AUDIO_SERVICE);
+      return checkNotNull(audioManager);
+    }
+    // Create the audio manager on the BackgroundExecutor to avoid running the potentially blocking
+    // command on the main thread but still use a thread that is guaranteed to exist for the
+    // lifetime of the app.
+    ConditionVariable audioManagerSetCondition = new ConditionVariable();
+    BackgroundExecutor.get()
+        .execute(
+            () -> {
+              audioManager =
+                  (AudioManager) applicationContext.getSystemService(Context.AUDIO_SERVICE);
+              audioManagerSetCondition.open();
+            });
+    audioManagerSetCondition.blockUninterruptible();
+    return checkNotNull(audioManager);
+  }
+
   /**
    * Requests audio focus. See the {@link AudioFocusRequestCompat} for information about the options
    * available to configure your request, and notification of focus gain and loss.

libraries/common/src/main/java/androidx/media3/common/util/BackgroundExecutor.java

@@ -31,6 +31,8 @@ public final class BackgroundExecutor {
    *
    * <p>Must only be used for quick, high-priority tasks to ensure other background tasks are not
    * blocked.
+   *
+   * <p>The thread is guaranteed to be alive for the lifetime of the application.
    */
   public static synchronized Executor get() {
     if (staticInstance == null) {
@@ -42,6 +44,9 @@ public final class BackgroundExecutor {
   /**
    * Sets the {@link Executor} to be returned from {@link #get()}.
    *
+   * <p>Note that the thread of the provided {@link Executor} must stay alive for the lifetime of
+   * the application.
+   *
    * @param executor An {@link Executor} that runs tasks on background threads and should only be
    *     used for quick, high-priority tasks to ensure other background tasks are not blocked.
    */

libraries/common/src/main/java/androidx/media3/common/util/Util.java

@@ -95,6 +95,7 @@ import androidx.media3.common.ParserException;
 import androidx.media3.common.PlaybackException;
 import androidx.media3.common.Player;
 import androidx.media3.common.Player.Commands;
+import androidx.media3.common.audio.AudioManagerCompat;
 import androidx.media3.common.audio.AudioProcessor;
 import com.google.common.base.Ascii;
 import com.google.common.io.ByteStreams;
@@ -2485,9 +2486,7 @@ public final class Util {
    */
   @UnstableApi
   public static int generateAudioSessionIdV21(Context context) {
-    @Nullable
+    return AudioManagerCompat.getAudioManager(context).generateAudioSessionId();
-    AudioManager audioManager = ((AudioManager) context.getSystemService(Context.AUDIO_SERVICE));
-    return audioManager == null ? AudioManager.ERROR : audioManager.generateAudioSessionId();
   }
 
   /**

libraries/decoder_iamf/src/main/java/androidx/media3/decoder/iamf/LibiamfAudioRenderer.java

@@ -26,6 +26,7 @@ import androidx.media3.common.AudioAttributes;
 import androidx.media3.common.C;
 import androidx.media3.common.Format;
 import androidx.media3.common.MimeTypes;
+import androidx.media3.common.audio.AudioManagerCompat;
 import androidx.media3.common.util.TraceUtil;
 import androidx.media3.common.util.UnstableApi;
 import androidx.media3.common.util.Util;
@@ -95,10 +96,7 @@ public class LibiamfAudioRenderer extends DecoderAudioRenderer<IamfDecoder> {
       return false;
     }
 
-    AudioManager audioManager = (AudioManager) context.getSystemService(Context.AUDIO_SERVICE);
+    AudioManager audioManager = AudioManagerCompat.getAudioManager(context);
-    if (audioManager == null) {
-      return false;
-    }
     AudioFormat audioFormat =
         new AudioFormat.Builder()
             .setEncoding(IamfDecoder.OUTPUT_PCM_ENCODING)

libraries/exoplayer/src/main/java/androidx/media3/exoplayer/AudioFocusManager.java

@@ -142,12 +142,7 @@ import org.checkerframework.checker.nullness.qual.MonotonicNonNull;
    * @param playerControl A {@link PlayerControl} to handle commands from this instance.
    */
   public AudioFocusManager(Context context, Looper eventLooper, PlayerControl playerControl) {
-    this.audioManager =
+    this.audioManager = Suppliers.memoize(() -> AudioManagerCompat.getAudioManager(context));
-        Suppliers.memoize(
-            () ->
-                checkNotNull(
-                    (AudioManager)
-                        context.getApplicationContext().getSystemService(Context.AUDIO_SERVICE)));
     this.playerControl = playerControl;
     this.eventHandler = new Handler(eventLooper);
     this.audioFocusState = AUDIO_FOCUS_STATE_NOT_REQUESTED;

libraries/exoplayer/src/main/java/androidx/media3/exoplayer/audio/AudioCapabilities.java

@@ -40,6 +40,7 @@ import androidx.media3.common.AudioAttributes;
 import androidx.media3.common.C;
 import androidx.media3.common.Format;
 import androidx.media3.common.MimeTypes;
+import androidx.media3.common.audio.AudioManagerCompat;
 import androidx.media3.common.util.UnstableApi;
 import androidx.media3.common.util.Util;
 import com.google.common.collect.ImmutableList;
@@ -142,8 +143,7 @@ public final class AudioCapabilities {
       @Nullable Intent intent,
       AudioAttributes audioAttributes,
       @Nullable AudioDeviceInfoApi23 routedDevice) {
-    AudioManager audioManager =
+    AudioManager audioManager = AudioManagerCompat.getAudioManager(context);
-        (AudioManager) checkNotNull(context.getSystemService(Context.AUDIO_SERVICE));
     AudioDeviceInfoApi23 currentDevice =
         routedDevice != null
             ? routedDevice

libraries/exoplayer/src/main/java/androidx/media3/exoplayer/audio/AudioCapabilitiesReceiver.java

@@ -31,6 +31,7 @@ import android.os.Handler;
 import androidx.annotation.Nullable;
 import androidx.annotation.RequiresApi;
 import androidx.media3.common.AudioAttributes;
+import androidx.media3.common.audio.AudioManagerCompat;
 import androidx.media3.common.util.UnstableApi;
 import androidx.media3.common.util.Util;
 import java.util.Objects;
@@ -261,14 +262,12 @@ public final class AudioCapabilitiesReceiver {
 
     public static void registerAudioDeviceCallback(
         Context context, AudioDeviceCallback callback, Handler handler) {
-      AudioManager audioManager = (AudioManager) context.getSystemService(Context.AUDIO_SERVICE);
+      AudioManagerCompat.getAudioManager(context).registerAudioDeviceCallback(callback, handler);
-      checkNotNull(audioManager).registerAudioDeviceCallback(callback, handler);
     }
 
     public static void unregisterAudioDeviceCallback(
         Context context, AudioDeviceCallback callback) {
-      AudioManager audioManager = (AudioManager) context.getSystemService(Context.AUDIO_SERVICE);
+      AudioManagerCompat.getAudioManager(context).unregisterAudioDeviceCallback(callback);
-      checkNotNull(audioManager).unregisterAudioDeviceCallback(callback);
     }
 
     private Api23() {}

libraries/exoplayer/src/main/java/androidx/media3/exoplayer/audio/DefaultAudioOffloadSupportProvider.java

@@ -26,6 +26,7 @@ import androidx.media3.common.AudioAttributes;
 import androidx.media3.common.C;
 import androidx.media3.common.Format;
 import androidx.media3.common.MimeTypes;
+import androidx.media3.common.audio.AudioManagerCompat;
 import androidx.media3.common.util.UnstableApi;
 import androidx.media3.common.util.Util;
 import org.checkerframework.checker.nullness.qual.MonotonicNonNull;
@@ -116,8 +117,7 @@ public final class DefaultAudioOffloadSupportProvider
     }
 
     if (context != null) {
-      AudioManager audioManager = (AudioManager) context.getSystemService(Context.AUDIO_SERVICE);
+      AudioManager audioManager = AudioManagerCompat.getAudioManager(context);
-      if (audioManager != null) {
       String offloadVariableRateSupportedKeyValue =
           audioManager.getParameters(/* keys= */ OFFLOAD_VARIABLE_RATE_SUPPORTED_KEY);
       isOffloadVariableRateSupported =
@@ -127,9 +127,6 @@ public final class DefaultAudioOffloadSupportProvider
     } else {
       isOffloadVariableRateSupported = false;
     }
-    } else {
-      isOffloadVariableRateSupported = false;
-    }
     return isOffloadVariableRateSupported;
   }
 

libraries/exoplayer/src/main/java/androidx/media3/exoplayer/trackselection/DefaultTrackSelector.java

@@ -54,6 +54,7 @@ import androidx.media3.common.TrackGroup;
 import androidx.media3.common.TrackSelectionOverride;
 import androidx.media3.common.TrackSelectionParameters;
 import androidx.media3.common.TrackSelectionParameters.AudioOffloadPreferences;
+import androidx.media3.common.audio.AudioManagerCompat;
 import androidx.media3.common.util.Assertions;
 import androidx.media3.common.util.BundleCollectionUtil;
 import androidx.media3.common.util.Log;
@@ -4280,7 +4281,8 @@ public class DefaultTrackSelector extends MappingTrackSelector
         @Nullable Context context, DefaultTrackSelector defaultTrackSelector) {
       @Nullable
       AudioManager audioManager =
-          context == null ? null : (AudioManager) context.getSystemService(Context.AUDIO_SERVICE);
+          context == null ? null : AudioManagerCompat.getAudioManager(context);
+      ;
       if (audioManager == null || Util.isTv(checkNotNull(context))) {
         spatializer = null;
         spatializationSupported = false;

libraries/session/src/main/java/androidx/media3/session/legacy/MediaSessionCompat.java

@@ -66,6 +66,7 @@ import androidx.annotation.IntDef;
 import androidx.annotation.Nullable;
 import androidx.annotation.RequiresApi;
 import androidx.annotation.RestrictTo;
+import androidx.media3.common.audio.AudioManagerCompat;
 import androidx.media3.common.util.NullableType;
 import androidx.media3.common.util.UnstableApi;
 import androidx.media3.session.legacy.MediaSessionManager.RemoteUserInfo;
@@ -2335,7 +2336,7 @@ public class MediaSessionCompat {
       }
       mContext = context;
       mSessionInfo = sessionInfo;
-      mAudioManager = (AudioManager) checkNotNull(context.getSystemService(Context.AUDIO_SERVICE));
+      mAudioManager = AudioManagerCompat.getAudioManager(context);
       mMediaButtonReceiverComponentName = mbrComponent;
       mMediaButtonReceiverIntent = mbrIntent;
       mStub = new MediaSessionStub(/* mediaSessionImpl= */ this, context.getPackageName(), tag);