Summary:
Two more bug fixes in db_stress:
1. this is to complete the fix of the regression bug causing overflowing when supporting FLAGS_prefix_size = -1.
2. Fix regression bug in compare iterator itself:
(1) when creating control iterator, which used the same read option as the normal iterator by mistake; (2) the logic of comparing has some problems. Fix them.
(3) disable validation for lower bound now, which generated some wildly different results. Disabling it to make normal tests pass while investigating it.
3. Cleaning up snapshots in verification failure cases. Memory is leaked otherwise.
Pull Request resolved: https://github.com/facebook/rocksdb/pull/5867
Test Plan: Run "make crash_test" for a while and see at least 1 is fixed.
Differential Revision: D17671712
fbshipit-source-id: 011f98ea1a72aef23e19ff28656830c78699b402
69c4ccb970