Make SharedPreferencesBackupHelper wait for async SharedPreference writes

Fixes a potential race with backups.

Change-Id: I73492c0384091cedd7802109257312387fcd43f9

1 files changed, 6 insertions, 2 deletions

diff --git a/core/java/android/app/backup/SharedPreferencesBackupHelper.java b/core/java/android/app/backup/SharedPreferencesBackupHelper.java
index 23b1703..213bd31 100644
--- a/core/java/android/app/backup/SharedPreferencesBackupHelper.java
+++ b/core/java/android/app/backup/SharedPreferencesBackupHelper.java
@@ -16,6 +16,7 @@
 
 package android.app.backup;
 
+import android.app.QueuedWork;
 import android.content.Context;
 import android.content.SharedPreferences;
 import android.os.ParcelFileDescriptor;
@@ -94,7 +95,11 @@ public class SharedPreferencesBackupHelper extends FileBackupHelperBase implemen
     public void performBackup(ParcelFileDescriptor oldState, BackupDataOutput data,
             ParcelFileDescriptor newState) {
         Context context = mContext;
-        
+
+        // If a SharedPreference has an outstanding write in flight,
+        // wait for it to finish flushing to disk.
+        QueuedWork.waitToFinish();
+
         // make filenames for the prefGroups
         String[] prefGroups = mPrefGroups;
         final int N = prefGroups.length;
@@ -123,4 +128,3 @@ public class SharedPreferencesBackupHelper extends FileBackupHelperBase implemen
         }
     }
 }
-