updater_sample: Improve update completion handling

Currently sample app relies on onPayloadApplicationComplete
callback. It might not get invoked when app is unbound and
update is complete.
On the other hand, onStatusUpdate gets invoked always
(except when update_engine fails to init).
It's good to rely on onStatusUpdate callback to
reapply the update if it's IDLE but sample app state
is RUNNING.

- Add methods to ensure correct updater state.
- Update README.md.

BUG: 80205922
Test: on the device
Change-Id: Ic2f390e85af43556e227362321ab69f0ff146188
Signed-off-by: Zhomart Mukhamejanov <zhomart@google.com>

1 files changed, 75 insertions, 1 deletions

diff --git a/updater_sample/src/com/example/android/systemupdatersample/UpdateManager.java b/updater_sample/src/com/example/android/systemupdatersample/UpdateManager.java
index c4c8c9c2..f5c2ea5a 100644
--- a/updater_sample/src/com/example/android/systemupdatersample/UpdateManager.java
+++ b/updater_sample/src/com/example/android/systemupdatersample/UpdateManager.java
@@ -384,11 +384,85 @@ public class UpdateManager {
         updateEngineApplyPayload(builder.build());
     }
 
+    /**
+     * Verifies if mUpdaterState matches mUpdateEngineStatus.
+     * If they don't match, runs applyPayload to trigger onPayloadApplicationComplete
+     * callback, which updates mUpdaterState.
+     */
+    private void ensureCorrectUpdaterState() {
+        // When mUpdaterState is one of IDLE, PAUSED, ERROR, SLOT_SWITCH_REQUIRED
+        //    then mUpdateEngineStatus must be IDLE.
+        // When mUpdaterState is RUNNING,
+        //    then mUpdateEngineStatus must not be IDLE or UPDATED_NEED_REBOOT.
+        // When mUpdaterState is REBOOT_REQUIRED,
+        //    then mUpdateEngineStatus must be UPDATED_NEED_REBOOT.
+        int state = mUpdaterState.get();
+        int updateEngineStatus = mUpdateEngineStatus.get();
+        if (state == UpdaterState.IDLE
+                || state == UpdaterState.ERROR
+                || state == UpdaterState.PAUSED
+                || state == UpdaterState.SLOT_SWITCH_REQUIRED) {
+            ensureUpdateEngineStatusIdle(state, updateEngineStatus);
+        } else if (state == UpdaterState.RUNNING) {
+            ensureUpdateEngineStatusRunning(state, updateEngineStatus);
+        } else if (state == UpdaterState.REBOOT_REQUIRED) {
+            ensureUpdateEngineStatusReboot(state, updateEngineStatus);
+        }
+    }
+
+    private void ensureUpdateEngineStatusIdle(int state, int updateEngineStatus) {
+        if (updateEngineStatus == UpdateEngine.UpdateStatusConstants.IDLE) {
+            return;
+        }
+        // It might happen when update is started not from the sample app.
+        // To make the sample app simple, we won't handle this case.
+        throw new RuntimeException("When mUpdaterState is " + state
+                + " mUpdateEngineStatus expected to be "
+                + UpdateEngine.UpdateStatusConstants.IDLE
+                + ", but it is " + updateEngineStatus);
+    }
+
+    private void ensureUpdateEngineStatusRunning(int state, int updateEngineStatus) {
+        if (updateEngineStatus != UpdateEngine.UpdateStatusConstants.UPDATED_NEED_REBOOT
+                && updateEngineStatus != UpdateEngine.UpdateStatusConstants.IDLE) {
+            return;
+        }
+        // Re-apply latest update. It makes update_engine to invoke
+        // onPayloadApplicationComplete callback. The callback notifies
+        // if update was successful or not.
+        updateEngineReApplyPayload();
+    }
+
+    private void ensureUpdateEngineStatusReboot(int state, int updateEngineStatus) {
+        if (updateEngineStatus == UpdateEngine.UpdateStatusConstants.UPDATED_NEED_REBOOT) {
+            return;
+        }
+        // This might happen when update is installed by other means,
+        // and sample app is not aware of it. To make the sample app simple,
+        // we won't handle this case.
+        throw new RuntimeException("When mUpdaterState is " + state
+                + " mUpdateEngineStatus expected to be "
+                + UpdateEngine.UpdateStatusConstants.UPDATED_NEED_REBOOT
+                + ", but it is " + updateEngineStatus);
+    }
+
+    /**
+     * Invoked by update_engine whenever update status or progress changes.
+     * It's also guaranteed to be invoked when app binds to the update_engine, except
+     * when update_engine fails to initialize (as defined in
+     * system/update_engine/binder_service_android.cc in
+     * function BinderUpdateEngineAndroidService::bind).
+     *
+     * @param status one of {@link UpdateEngine.UpdateStatusConstants}.
+     * @param progress a number from 0.0 to 1.0.
+     */
     private void onStatusUpdate(int status, float progress) {
         int previousStatus = mUpdateEngineStatus.get();
         mUpdateEngineStatus.set(status);
         mProgress.set(progress);
 
+        ensureCorrectUpdaterState();
+
         getOnProgressUpdateCallback().ifPresent(callback -> callback.accept(progress));
 
         if (previousStatus != status) {
@@ -413,7 +487,7 @@ public class UpdateManager {
     }
 
     /**
-     * Helper class to delegate {@code update_engine} callbacks to UpdateManager
+     * Helper class to delegate {@code update_engine} callback invocations to UpdateManager.
      */
     class UpdateEngineCallbackImpl extends UpdateEngineCallback {
         @Override