cd2e5cae7f
Summary: Add "--use_txn" option to use transactional API in db_stress, default being WRITE_PREPARED policy, which is the main intention of modifying db_stress. It also extend the existing snapshots to verify that before releasing a snapshot a read from it returns the same value as before. Closes https://github.com/facebook/rocksdb/pull/3243 Differential Revision: D6556912 Pulled By: maysamyabandeh fbshipit-source-id: 1ae31465be362d44bd06e635e2e9e49a1da11268