Add option to clear all downloads.

Adding an explicit option to clear all downloads prevents repeated database
access in a loop when trying to delete all downloads.

However, we still create an arbitrary number of parallel Task threads for this
and seperate callbacks for each download.

PiperOrigin-RevId: 247234181

RELEASENOTES.md

@@ -2,6 +2,7 @@
 
 ### dev-v2 (not yet released) ###
 
+* Offline: Add option to remove all downloads.
 * Decoders:
   * Prefer codecs that advertise format support over ones that do not, even if
     they are listed lower in the `MediaCodecList`.

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

@@ -234,6 +234,19 @@ public final class DefaultDownloadIndex implements WritableDownloadIndex {
   }
 
   @Override
+  public void setStatesToRemoving() throws DatabaseIOException {
+    ensureInitialized();
+    try {
+      ContentValues values = new ContentValues();
+      values.put(COLUMN_STATE, Download.STATE_REMOVING);
+      SQLiteDatabase writableDatabase = databaseProvider.getWritableDatabase();
+      writableDatabase.update(tableName, values, /* whereClause= */ null, /* whereArgs= */ null);
+    } catch (SQLException e) {
+      throw new DatabaseIOException(e);
+    }
+  }
+
+  @Override
   public void setStopReason(int stopReason) throws DatabaseIOException {
     ensureInitialized();
     try {

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

@@ -133,10 +133,11 @@ public final class DownloadManager {
   private static final int MSG_SET_MIN_RETRY_COUNT = 5;
   private static final int MSG_ADD_DOWNLOAD = 6;
   private static final int MSG_REMOVE_DOWNLOAD = 7;
-  private static final int MSG_TASK_STOPPED = 8;
-  private static final int MSG_CONTENT_LENGTH_CHANGED = 9;
-  private static final int MSG_UPDATE_PROGRESS = 10;
-  private static final int MSG_RELEASE = 11;
+  private static final int MSG_REMOVE_ALL_DOWNLOADS = 8;
+  private static final int MSG_TASK_STOPPED = 9;
+  private static final int MSG_CONTENT_LENGTH_CHANGED = 10;
+  private static final int MSG_UPDATE_PROGRESS = 11;
+  private static final int MSG_RELEASE = 12;
 
   private static final String TAG = "DownloadManager";
 
@@ -446,6 +447,12 @@ public final class DownloadManager {
     internalHandler.obtainMessage(MSG_REMOVE_DOWNLOAD, id).sendToTarget();
   }
 
+  /** Cancels all pending downloads and removes all downloaded data. */
+  public void removeAllDownloads() {
+    pendingMessages++;
+    internalHandler.obtainMessage(MSG_REMOVE_ALL_DOWNLOADS).sendToTarget();
+  }
+
   /**
    * Stops the downloads and releases resources. Waits until the downloads are persisted to the
    * download index. The manager must not be accessed after this method has been called.
@@ -652,6 +659,9 @@ public final class DownloadManager {
           id = (String) message.obj;
           removeDownload(id);
           break;
+        case MSG_REMOVE_ALL_DOWNLOADS:
+          removeAllDownloads();
+          break;
         case MSG_TASK_STOPPED:
           Task task = (Task) message.obj;
           onTaskStopped(task);
@@ -797,6 +807,36 @@ public final class DownloadManager {
       syncTasks();
     }
 
+    private void removeAllDownloads() {
+      List<Download> terminalDownloads = new ArrayList<>();
+      try (DownloadCursor cursor = downloadIndex.getDownloads(STATE_COMPLETED, STATE_FAILED)) {
+        while (cursor.moveToNext()) {
+          terminalDownloads.add(cursor.getDownload());
+        }
+      } catch (IOException e) {
+        Log.e(TAG, "Failed to load downloads.");
+      }
+      for (int i = 0; i < downloads.size(); i++) {
+        downloads.set(i, copyDownloadWithState(downloads.get(i), STATE_REMOVING));
+      }
+      for (int i = 0; i < terminalDownloads.size(); i++) {
+        downloads.add(copyDownloadWithState(terminalDownloads.get(i), STATE_REMOVING));
+      }
+      Collections.sort(downloads, InternalHandler::compareStartTimes);
+      try {
+        downloadIndex.setStatesToRemoving();
+      } catch (IOException e) {
+        Log.e(TAG, "Failed to update index.", e);
+      }
+      ArrayList<Download> updateList = new ArrayList<>(downloads);
+      for (int i = 0; i < downloads.size(); i++) {
+        DownloadUpdate update =
+            new DownloadUpdate(downloads.get(i), /* isRemove= */ false, updateList);
+        mainHandler.obtainMessage(MSG_DOWNLOAD_UPDATE, update).sendToTarget();
+      }
+      syncTasks();
+    }
+
     private void release() {
       for (Task task : activeTasks.values()) {
         task.cancel(/* released= */ true);
@@ -1057,16 +1097,7 @@ public final class DownloadManager {
       // to set STATE_STOPPED either, because it doesn't have a stopReason argument.
       Assertions.checkState(
           state != STATE_COMPLETED && state != STATE_FAILED && state != STATE_STOPPED);
-      return putDownload(
-          new Download(
-              download.request,
-              state,
-              download.startTimeMs,
-              /* updateTimeMs= */ System.currentTimeMillis(),
-              download.contentLength,
-              /* stopReason= */ 0,
-              FAILURE_REASON_NONE,
-              download.progress));
+      return putDownload(copyDownloadWithState(download, state));
     }
 
     private Download putDownload(Download download) {
@@ -1120,6 +1151,18 @@ public final class DownloadManager {
       return C.INDEX_UNSET;
     }
 
+    private static Download copyDownloadWithState(Download download, @Download.State int state) {
+      return new Download(
+          download.request,
+          state,
+          download.startTimeMs,
+          /* updateTimeMs= */ System.currentTimeMillis(),
+          download.contentLength,
+          /* stopReason= */ 0,
+          FAILURE_REASON_NONE,
+          download.progress);
+    }
+
     private static int compareStartTimes(Download first, Download second) {
       return Util.compareLong(first.startTimeMs, second.startTimeMs);
     }

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

@@ -78,6 +78,16 @@ public abstract class DownloadService extends Service {
       "com.google.android.exoplayer.downloadService.action.REMOVE_DOWNLOAD";
 
   /**
+   * Removes all downloads. Extras:
+   *
+   * <ul>
+   *   <li>{@link #KEY_FOREGROUND} - See {@link #KEY_FOREGROUND}.
+   * </ul>
+   */
+  public static final String ACTION_REMOVE_ALL_DOWNLOADS =
+      "com.google.android.exoplayer.downloadService.action.REMOVE_ALL_DOWNLOADS";
+
+  /**
    * Resumes all downloads except those that have a non-zero {@link Download#stopReason}. Extras:
    *
    * <ul>
@@ -297,6 +307,19 @@ public abstract class DownloadService extends Service {
   }
 
   /**
+   * Builds an {@link Intent} for removing all downloads.
+   *
+   * @param context A {@link Context}.
+   * @param clazz The concrete download service being targeted by the intent.
+   * @param foreground Whether this intent will be used to start the service in the foreground.
+   * @return The created intent.
+   */
+  public static Intent buildRemoveAllDownloadsIntent(
+      Context context, Class<? extends DownloadService> clazz, boolean foreground) {
+    return getIntent(context, clazz, ACTION_REMOVE_ALL_DOWNLOADS, foreground);
+  }
+
+  /**
    * Builds an {@link Intent} for resuming all downloads.
    *
    * @param context A {@link Context}.
@@ -415,6 +438,19 @@ public abstract class DownloadService extends Service {
   }
 
   /**
+   * Starts the service if not started already and removes all downloads.
+   *
+   * @param context A {@link Context}.
+   * @param clazz The concrete download service to be started.
+   * @param foreground Whether the service is started in the foreground.
+   */
+  public static void sendRemoveAllDownloads(
+      Context context, Class<? extends DownloadService> clazz, boolean foreground) {
+    Intent intent = buildRemoveAllDownloadsIntent(context, clazz, foreground);
+    startService(context, intent, foreground);
+  }
+
+  /**
    * Starts the service if not started already and resumes all downloads.
    *
    * @param context A {@link Context}.
@@ -560,6 +596,9 @@ public abstract class DownloadService extends Service {
           downloadManager.removeDownload(contentId);
         }
         break;
+      case ACTION_REMOVE_ALL_DOWNLOADS:
+        downloadManager.removeAllDownloads();
+        break;
       case ACTION_RESUME_DOWNLOADS:
         downloadManager.resumeDownloads();
         break;

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

@@ -45,6 +45,13 @@ public interface WritableDownloadIndex extends DownloadIndex {
   void setDownloadingStatesToQueued() throws IOException;
 
   /**
+   * Sets all states to {@link Download#STATE_REMOVING}.
+   *
+   * @throws IOException If an error occurs updating the state.
+   */
+  void setStatesToRemoving() throws IOException;
+
+  /**
    * Sets the stop reason of the downloads in a terminal state ({@link Download#STATE_COMPLETED},
    * {@link Download#STATE_FAILED}).
    *

library/core/src/test/java/com/google/android/exoplayer2/offline/DownloadManagerTest.java

@@ -244,6 +244,27 @@ public class DownloadManagerTest {
   }
 
   @Test
+  public void removeAllDownloads_removesAllDownloads() throws Throwable {
+    // Finish one download and keep one running.
+    DownloadRunner runner1 = new DownloadRunner(uri1);
+    DownloadRunner runner2 = new DownloadRunner(uri2);
+    runner1.postDownloadRequest();
+    runner1.getDownloader(0).unblock();
+    downloadManagerListener.blockUntilTasksCompleteAndThrowAnyDownloadError();
+    runner2.postDownloadRequest();
+
+    runner1.postRemoveAllRequest();
+    runner1.getDownloader(1).unblock();
+    runner2.getDownloader(1).unblock();
+    downloadManagerListener.blockUntilTasksCompleteAndThrowAnyDownloadError();
+
+    runner1.getTask().assertRemoved();
+    runner2.getTask().assertRemoved();
+    assertThat(downloadManager.getCurrentDownloads()).isEmpty();
+    assertThat(downloadIndex.getDownloads().getCount()).isEqualTo(0);
+  }
+
+  @Test
   public void differentDownloadRequestsMerged() throws Throwable {
     DownloadRunner runner = new DownloadRunner(uri1);
     FakeDownloader downloader1 = runner.getDownloader(0);
@@ -605,6 +626,11 @@ public class DownloadManagerTest {
       return this;
     }
 
+    private DownloadRunner postRemoveAllRequest() {
+      runOnMainThread(() -> downloadManager.removeAllDownloads());
+      return this;
+    }
+
     private DownloadRunner postDownloadRequest(StreamKey... keys) {
       DownloadRequest downloadRequest =
           new DownloadRequest(