Fix stopping downloads

- Changed startDownloads/stopDownloads back to their previous behavior
  of starting and stopping all downloads at the manager level.
- Made setManualStopReason methods for the new case of setting a manual
  stop reason or some or all downloads.
- Added plumbing to specify an initial manual stop reason when adding a
  new download, without also overwriting the manual stop reasons of all
  other preexisting downloads. Using the value is left as a TODO pending
  a bit of further cleanup that'll make it easier.

PiperOrigin-RevId: 242891688

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

@@ -46,7 +46,7 @@ public final class Download {
   // Important: These constants are persisted into DownloadIndex. Do not change them.
   /** The download is waiting to be started. */
   public static final int STATE_QUEUED = 0;
-  /** The download is stopped. */
+  /** The download is manually stopped for the reason specified by {@link #manualStopReason}. */
   public static final int STATE_STOPPED = 1;
   /** The download is currently started. */
   public static final int STATE_DOWNLOADING = 2;
@@ -71,8 +71,6 @@ public final class Download {
 
   /** The download isn't manually stopped. */
   public static final int MANUAL_STOP_REASON_NONE = 0;
-  /** The download is manually stopped but a reason isn't specified. */
-  public static final int MANUAL_STOP_REASON_UNDEFINED = Integer.MAX_VALUE;
 
   /** Returns the state string for the given state value. */
   public static String getStateString(@State int state) {
@@ -122,7 +120,7 @@ public final class Download {
    * #FAILURE_REASON_NONE}.
    */
   @FailureReason public final int failureReason;
-  /** The manual stop reason. */
+  /** The reason the download is manually stopped, or {@link #MANUAL_STOP_REASON_NONE}. */
   public final int manualStopReason;
 
   /*package*/ CachingCounters counters;
@@ -232,7 +230,7 @@ public final class Download {
     this.counters = counters;
   }
 
-  private static int getNextState(int currentState, boolean canStart) {
+  private static int getNextState(@State int currentState, boolean canStart) {
     if (currentState == STATE_REMOVING || currentState == STATE_RESTARTING) {
       return STATE_RESTARTING;
     } else if (canStart) {

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

@@ -47,14 +47,16 @@ import org.robolectric.shadows.ShadowLog;
 @Config(shadows = {RobolectricUtil.CustomLooper.class, RobolectricUtil.CustomMessageQueue.class})
 public class DownloadManagerTest {
 
-  /* Used to check if condition becomes true in this time interval. */
+  /** Used to check if condition becomes true in this time interval. */
   private static final int ASSERT_TRUE_TIMEOUT = 10000;
-  /* Used to check if condition stays false for this time interval. */
+  /** Used to check if condition stays false for this time interval. */
   private static final int ASSERT_FALSE_TIME = 1000;
-  /* Maximum retry delay in DownloadManager. */
+  /** Maximum retry delay in DownloadManager. */
   private static final int MAX_RETRY_DELAY = 5000;
-  /* Maximum number of times a downloader can be restarted before doing a released check. */
+  /** Maximum number of times a downloader can be restarted before doing a released check. */
   private static final int MAX_STARTS_BEFORE_RELEASED = 1;
+  /** A manual stop reason. */
+  private static final int APP_STOP_REASON = 1;
   /** The minimum number of times a task must be retried before failing. */
   private static final int MIN_RETRY_COUNT = 3;
 
@@ -388,17 +390,18 @@ public class DownloadManagerTest {
   }
 
   @Test
-  public void stopAndResumeSingleDownload() throws Throwable {
+  public void manuallyStopAndResumeSingleDownload() throws Throwable {
     DownloadRunner runner = new DownloadRunner(uri1).postDownloadAction();
     TaskWrapper task = runner.getTask();
 
     task.assertDownloading();
 
-    runOnMainThread(() -> downloadManager.stopDownload(task.taskId));
+    runOnMainThread(() -> downloadManager.setManualStopReason(task.taskId, APP_STOP_REASON));
 
     task.assertStopped();
 
-    runOnMainThread(() -> downloadManager.startDownload(task.taskId));
+    runOnMainThread(
+        () -> downloadManager.setManualStopReason(task.taskId, Download.MANUAL_STOP_REASON_NONE));
 
     runner.getDownloader(1).assertStarted().unblock();
 
@@ -406,13 +409,13 @@ public class DownloadManagerTest {
   }
 
   @Test
-  public void stoppedDownloadCanBeCancelled() throws Throwable {
+  public void manuallyStoppedDownloadCanBeCancelled() throws Throwable {
     DownloadRunner runner = new DownloadRunner(uri1).postDownloadAction();
     TaskWrapper task = runner.getTask();
 
     task.assertDownloading();
 
-    runOnMainThread(() -> downloadManager.stopDownload(task.taskId));
+    runOnMainThread(() -> downloadManager.setManualStopReason(task.taskId, APP_STOP_REASON));
 
     task.assertStopped();
 
@@ -424,7 +427,7 @@ public class DownloadManagerTest {
   }
 
   @Test
-  public void stoppedSingleDownload_doesNotAffectOthers() throws Throwable {
+  public void manuallyStoppedSingleDownload_doesNotAffectOthers() throws Throwable {
     DownloadRunner runner1 = new DownloadRunner(uri1);
     DownloadRunner runner2 = new DownloadRunner(uri2);
     DownloadRunner runner3 = new DownloadRunner(uri3);
@@ -432,7 +435,8 @@ public class DownloadManagerTest {
     runner1.postDownloadAction().getTask().assertDownloading();
     runner2.postDownloadAction().postRemoveAction().getTask().assertRemoving();
 
-    runOnMainThread(() -> downloadManager.stopDownload(runner1.getTask().taskId));
+    runOnMainThread(
+        () -> downloadManager.setManualStopReason(runner1.getTask().taskId, APP_STOP_REASON));
 
     runner1.getTask().assertStopped();
 
@@ -460,9 +464,9 @@ public class DownloadManagerTest {
                     maxActiveDownloadTasks,
                     MIN_RETRY_COUNT,
                     new Requirements(0));
+            downloadManager.startDownloads();
             downloadManagerListener =
                 new TestDownloadManagerListener(downloadManager, dummyMainThread);
-            downloadManager.startDownloads();
           });
       downloadManagerListener.waitUntilInitialized();
     } catch (Throwable throwable) {

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

@@ -156,7 +156,7 @@ public class DownloadTest {
     DownloadBuilder downloadBuilder =
         new DownloadBuilder(downloadAction)
             .setState(Download.STATE_STOPPED)
-            .setManualStopReason(Download.MANUAL_STOP_REASON_UNDEFINED);
+            .setManualStopReason(/* manualStopReason= */ 1);
     Download download = downloadBuilder.build();
 
     Download mergedDownload = download.copyWithMergedAction(downloadAction, /* canStart= */ true);
@@ -170,7 +170,7 @@ public class DownloadTest {
     DownloadBuilder downloadBuilder =
         new DownloadBuilder(downloadAction)
             .setState(Download.STATE_COMPLETED)
-            .setManualStopReason(Download.MANUAL_STOP_REASON_UNDEFINED);
+            .setManualStopReason(/* manualStopReason= */ 1);
     Download download = downloadBuilder.build();
 
     Download mergedDownload = download.copyWithMergedAction(downloadAction, /* canStart= */ true);