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Commit dcb26bbf authored by Fyodor Kupolov's avatar Fyodor Kupolov
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Avoid locking in getCurrentUser when there is no user switch 

Added an optimization to avoid AM lock when userId is not going to
change soon due to mTargetUserId.

Test: manual
Bug: 38143512
Change-Id: Ie358abdb74836ed0dbf782a6ab00362f3685353d
parent e16b83bb

services/core/java/com/android/server/am/UserController.java

+10 −4
Original line number Diff line number Diff line
@@ -123,12 +123,13 @@ final class UserController { 
    private final Injector mInjector;

    private final Handler mHandler;



    // Holds the current foreground user's id

    // Holds the current foreground user's id. Use mLock when updating

    @GuardedBy("mLock")

    private int mCurrentUserId = UserHandle.USER_SYSTEM;

    // Holds the target user's id during a user switch

    private volatile int mCurrentUserId = UserHandle.USER_SYSTEM;

    // Holds the target user's id during a user switch. The value of mCurrentUserId will be updated

    // once target user goes into the foreground. Use mLock when updating

    @GuardedBy("mLock")

    private int mTargetUserId = UserHandle.USER_NULL;

    private volatile int mTargetUserId = UserHandle.USER_NULL;



    /**

     * Which users have been started, so are allowed to run code.
@@ -1505,6 +1506,11 @@ final class UserController { 
            Slog.w(TAG, msg);

            throw new SecurityException(msg);

        }



        // Optimization - if there is no pending user switch, return current id

        if (mTargetUserId == UserHandle.USER_NULL) {

            return getUserInfo(mCurrentUserId);

        }

        synchronized (mLock) {

            return getCurrentUserLocked();

        }