Summary:
Currently non-2pc writes do the 2nd dummy write to actually commit the transaction. This was necessary to ensure that publishing the commit sequence number will be done only from one queue (the queue that does not write to memtable). This is however not necessary when we have only one write queue, which is actually the setup that would be used by non-2pc writes. This patch eliminates the 2nd write when two_write_queues are disabled by updating the commit map in the 1st write.
Closes https://github.com/facebook/rocksdb/pull/3277
Differential Revision: D6575392
Pulled By: maysamyabandeh
fbshipit-source-id: 8ab458f7ca506905962f9166026b2ec81e749c46
a6d3c762df