always invalidate sequential-insertion cache for concurrent skiplist adds
Summary: InlineSkipList::InsertConcurrently should invalidate the sequential-insertion cache prev_[] for all inserts of multi-level nodes, not just those that increase the height of the skip list. The invariant for prev_ is that prev_[i] (i > 0) is supposed to be the predecessor of prev_[0] at level i. Before this diff InsertConcurrently could violate this constraint when inserting a multi-level node after prev_[i] but before prev_[0]. This diff also reenables kConcurrentSkipList as db_test's MultiThreaded/MultiThreadedDBTest.MultiThreaded/29. Test Plan: 1. unit tests 2. temporarily hack kConcurrentSkipList timing so that it is fast but has a 1.5% failure rate on my dev box (1ms stagger on thread launch, 1s test duration, failure rate baseline over 1000 runs) 3. observe 1000 passes post-fix Reviewers: igor, sdong Reviewed By: sdong Subscribers: MarkCallaghan, dhruba Differential Revision: https://reviews.facebook.net/D53751
Showing
想要评论请 注册 或 登录