Added storage not low as download requirement

Added monitoring storage levels in RequirementsWatcher
Added dependency on extension-workmanager to the demo app to be able to test with WorkManagerScheduler
Added getSupportedRequirements method to Scheduler interface
Implemented getSupportedRequirements for schedulers

demos/main/build.gradle

@@ -70,6 +70,7 @@ dependencies {
     implementation project(modulePrefix + 'library-hls')
     implementation project(modulePrefix + 'library-smoothstreaming')
     implementation project(modulePrefix + 'library-ui')
+    withExtensionsImplementation project(path: modulePrefix + 'extension-workmanager')
     withExtensionsImplementation project(path: modulePrefix + 'extension-av1')
     withExtensionsImplementation project(path: modulePrefix + 'extension-ffmpeg')
     withExtensionsImplementation project(path: modulePrefix + 'extension-flac')

extensions/jobdispatcher/src/main/java/com/google/android/exoplayer2/ext/jobdispatcher/JobDispatcherScheduler.java

@@ -96,6 +96,19 @@ public final class JobDispatcherScheduler implements Scheduler {
     return result == FirebaseJobDispatcher.CANCEL_RESULT_SUCCESS;
   }
 
+  @Override
+  public Requirements getSupportedRequirements(Requirements requirements) {
+    Requirements supportedRequirements = requirements;
+    if (requirements.isStorageNotLowRequired()) {
+      Log.w(TAG, "Storage not low requirement not supported on the JobDispatcherScheduler "
+          + "Requirement removed.");
+      int newRequirements =
+          supportedRequirements.getRequirements() ^ Requirements.DEVICE_STORAGE_NOT_LOW;
+      supportedRequirements = new Requirements(newRequirements);
+    }
+    return supportedRequirements;
+  }
+
   private static Job buildJob(
       FirebaseJobDispatcher dispatcher,
       Requirements requirements,

extensions/workmanager/src/main/java/com/google/android/exoplayer2/ext/workmanager/WorkManagerScheduler.java

@@ -87,6 +87,12 @@ public final class WorkManagerScheduler implements Scheduler {
 
     if (requirements.isIdleRequired() && Util.SDK_INT >= 23) {
       setRequiresDeviceIdle(builder);
+    } else if (requirements.isIdleRequired()) {
+        Log.w(TAG, "Is idle requirement is only available on API 23 and up.");
+    }
+
+    if (requirements.isStorageNotLowRequired()) {
+      builder.setRequiresStorageNotLow(true);
     }
 
     return builder.build();
@@ -108,6 +114,19 @@ public final class WorkManagerScheduler implements Scheduler {
     return builder.build();
   }
 
+  @Override
+  public Requirements getSupportedRequirements(Requirements requirements) {
+    Requirements supportedRequirements = requirements;
+    if (requirements.isIdleRequired() && Util.SDK_INT < 23) {
+      Log.w(TAG, "Is idle requirement not supported on the WorkManagerScheduler on API below 23. "
+          + "Requirement removed.");
+      int newRequirements =
+          supportedRequirements.getRequirements() ^ Requirements.DEVICE_IDLE;
+      supportedRequirements = new Requirements(newRequirements);
+    }
+    return supportedRequirements;
+  }
+
   private static OneTimeWorkRequest buildWorkRequest(Constraints constraints, Data inputData) {
     OneTimeWorkRequest.Builder builder = new OneTimeWorkRequest.Builder(SchedulerWorker.class);
 

library/core/src/main/java/com/google/android/exoplayer2/offline/DownloadService.java

@@ -658,6 +658,10 @@ public abstract class DownloadService extends Service {
         if (requirements == null) {
           Log.e(TAG, "Ignored SET_REQUIREMENTS: Missing " + KEY_REQUIREMENTS + " extra");
         } else {
+          @Nullable Scheduler scheduler = getScheduler();
+          if (scheduler != null) {
+            requirements = scheduler.getSupportedRequirements(requirements);
+          }
           downloadManager.setRequirements(requirements);
         }
         break;

library/core/src/main/java/com/google/android/exoplayer2/scheduler/PlatformScheduler.java

@@ -86,6 +86,21 @@ public final class PlatformScheduler implements Scheduler {
     return true;
   }
 
+  @Override
+  public Requirements getSupportedRequirements(Requirements requirements) {
+    Requirements supportedRequirements = requirements;
+    if (Util.SDK_INT < 26) {
+      if (requirements.isStorageNotLowRequired()) {
+        Log.w(TAG, "Storage not low requirement not supported on the PlatformScheduler"
+            + "on API below 26. Requirement removed.");
+        int newRequirements =
+            supportedRequirements.getRequirements() ^ Requirements.DEVICE_STORAGE_NOT_LOW;
+        supportedRequirements = new Requirements(newRequirements);
+      }
+    }
+    return supportedRequirements;
+  }
+
   // @RequiresPermission constructor annotation should ensure the permission is present.
   @SuppressWarnings("MissingPermission")
   private static JobInfo buildJobInfo(

library/core/src/main/java/com/google/android/exoplayer2/scheduler/Requirements.java

@@ -45,7 +45,7 @@ public final class Requirements implements Parcelable {
   @Retention(RetentionPolicy.SOURCE)
   @IntDef(
       flag = true,
-      value = {NETWORK, NETWORK_UNMETERED, DEVICE_IDLE, DEVICE_CHARGING})
+      value = {NETWORK, NETWORK_UNMETERED, DEVICE_IDLE, DEVICE_CHARGING, DEVICE_STORAGE_NOT_LOW})
   public @interface RequirementFlags {}
 
   /** Requirement that the device has network connectivity. */
@@ -56,6 +56,8 @@ public final class Requirements implements Parcelable {
   public static final int DEVICE_IDLE = 1 << 2;
   /** Requirement that the device is charging. */
   public static final int DEVICE_CHARGING = 1 << 3;
+  /** Requirement that the storage is not low. */
+  public static final int DEVICE_STORAGE_NOT_LOW = 1 << 4;
 
   @RequirementFlags private final int requirements;
 
@@ -94,6 +96,10 @@ public final class Requirements implements Parcelable {
     return (requirements & DEVICE_IDLE) != 0;
   }
 
+  public boolean isStorageNotLowRequired() {
+    return (requirements & DEVICE_STORAGE_NOT_LOW) != 0;
+  }
+
   /**
    * Returns whether the requirements are met.
    *
@@ -119,6 +125,9 @@ public final class Requirements implements Parcelable {
     if (isIdleRequired() && !isDeviceIdle(context)) {
       notMetRequirements |= DEVICE_IDLE;
     }
+    if (isStorageNotLowRequired() && !isStorageNotLow(context)) {
+      notMetRequirements |= DEVICE_STORAGE_NOT_LOW;
+    }
     return notMetRequirements;
   }
 
@@ -162,6 +171,34 @@ public final class Requirements implements Parcelable {
         : Util.SDK_INT >= 20 ? !powerManager.isInteractive() : !powerManager.isScreenOn();
   }
 
+  /**
+   * Implementation taken from the the WorkManager source.
+   * @see <a href="https://android.googlesource.com/platform/frameworks/support/+/androidx-master-dev/work/workmanager/src/main/java/androidx/work/impl/constraints/trackers/StorageNotLowTracker.java">StorageNotLowTracker</a>
+   */
+  private boolean isStorageNotLow(Context context) {
+    IntentFilter intentFilter = new IntentFilter();
+    intentFilter.addAction(Intent.ACTION_DEVICE_STORAGE_OK);
+    intentFilter.addAction(Intent.ACTION_DEVICE_STORAGE_LOW);
+    Intent intent = context.registerReceiver(null, intentFilter);
+    if (intent == null || intent.getAction() == null) {
+      // ACTION_DEVICE_STORAGE_LOW is a sticky broadcast that is removed when sufficient
+      // storage is available again.  ACTION_DEVICE_STORAGE_OK is not sticky.  So if we
+      // don't receive anything here, we can assume that the storage state is okay.
+      return true;
+    } else {
+      switch (intent.getAction()) {
+        case Intent.ACTION_DEVICE_STORAGE_OK:
+          return true;
+        case Intent.ACTION_DEVICE_STORAGE_LOW:
+          return false;
+        default:
+          // This should never happen because the intent filter is configured
+          // correctly.
+          return true;
+      }
+    }
+  }
+
   private static boolean isInternetConnectivityValidated(ConnectivityManager connectivityManager) {
     // It's possible to query NetworkCapabilities from API level 23, but RequirementsWatcher only
     // fires an event to update its Requirements when NetworkCapabilities change from API level 24.

library/core/src/main/java/com/google/android/exoplayer2/scheduler/RequirementsWatcher.java

@@ -104,6 +104,10 @@ public final class RequirementsWatcher {
         filter.addAction(Intent.ACTION_SCREEN_OFF);
       }
     }
+    if (requirements.isStorageNotLowRequired()) {
+      filter.addAction(Intent.ACTION_DEVICE_STORAGE_LOW);
+      filter.addAction(Intent.ACTION_DEVICE_STORAGE_OK);
+    }
     receiver = new DeviceStatusChangeReceiver();
     context.registerReceiver(receiver, filter, null, handler);
     return notMetRequirements;

library/core/src/main/java/com/google/android/exoplayer2/scheduler/Scheduler.java

@@ -45,4 +45,13 @@ public interface Scheduler {
    * @return Whether cancellation was successful.
    */
   boolean cancel();
+
+  /**
+   * Checks if this {@link Scheduler} supports the provided {@link Requirements}. If all
+   * requirements are supported the same object is returned. If not all requirements are
+   * supported a new {@code Requirements} object is returned containing the supported requirements.
+   * @param requirements The requirements to check.
+   * @return The requirements supported by this scheduler.
+   */
+  Requirements getSupportedRequirements(Requirements requirements);
 }