public void lockEdge(String childName, LockMode mode) {
    Preconditions.checkState(endsInInode());
    Preconditions.checkState(mLockMode == LockMode.READ);

    lockEdgeInternal(childName, mode);
    mLockMode = mode;
  }
public void lockEdge ( String childName , LockMode mode ) { Preconditions . checkState ( endsInInode ( ) ) ; Preconditions . checkState ( mLockMode == LockMode . READ ) ; lockEdgeInternal ( childName , mode ) ; mLockMode = mode ; }
Locks an edge leading out of the last inode in the list.

For example, if the lock list is [a, a->b, b], lockEdge(c) will add b->c to the list, resulting
in [a, a->b, b, b->c].

@param childName the child to lock
@param mode the mode to lock in