Merge changes I5e42dee6,Ic8571c08

* changes:
  [RefactoredBMS] Ensure backup doesn't reuse ack tokens nearby in time
  [RefactoredBMS] Eliminate a race condition that could lead to calling PBT#finalizeBackup() twice

services/backup/java/com/android/server/backup/RefactoredBackupManagerService.java

@@ -150,6 +150,7 @@ import java.util.Queue;
 import java.util.Random;
 import java.util.Set;
 import java.util.concurrent.CountDownLatch;
+import java.util.concurrent.atomic.AtomicInteger;
 
 public class RefactoredBackupManagerService implements BackupManagerServiceInterface {
 
@@ -626,6 +627,7 @@ public class RefactoredBackupManagerService implements BackupManagerServiceInter
     private final SparseArray<Operation> mCurrentOperations = new SparseArray<>();
     private final Object mCurrentOpLock = new Object();
     private final Random mTokenGenerator = new Random();
+    final AtomicInteger mNextToken = new AtomicInteger();
 
     private final SparseArray<AdbParams> mAdbBackupRestoreConfirmations = new SparseArray<>();
 
@@ -665,15 +667,15 @@ public class RefactoredBackupManagerService implements BackupManagerServiceInter
     @GuardedBy("mQueueLock")
     private ArrayList<FullBackupEntry> mFullBackupQueue;
 
-    // Utility: build a new random integer token
+    // Utility: build a new random integer token. The low bits are the ordinal of the
+    // operation for near-time uniqueness, and the upper bits are random for app-
+    // side unpredictability.
     @Override
     public int generateRandomIntegerToken() {
-        int token;
-        do {
-            synchronized (mTokenGenerator) {
-                token = mTokenGenerator.nextInt();
-            }
-        } while (token < 0);
+        int token = mTokenGenerator.nextInt();
+        if (token < 0) token = -token;
+        token &= ~0xFF;
+        token |= (mNextToken.incrementAndGet() & 0xFF);
         return token;
     }
 

services/backup/java/com/android/server/backup/internal/PerformBackupTask.java

@@ -227,9 +227,8 @@ public class PerformBackupTask implements BackupRestoreTask {
                     if (!mFinished) {
                         finalizeBackup();
                     } else {
-                        Slog.e(TAG, "Duplicate finish");
+                        Slog.e(TAG, "Duplicate finish of K/V pass");
                     }
-                    mFinished = true;
                     break;
             }
         }
@@ -609,6 +608,7 @@ public class PerformBackupTask implements BackupRestoreTask {
                     break;
             }
         }
+        mFinished = true;
         Slog.i(TAG, "K/V backup pass finished.");
         // Only once we're entirely finished do we release the wakelock for k/v backup.
         backupManagerService.getWakelock().release();