tree 75a1e04723656f3ecc1753839aa6a7172b034410
parent b0856d711fd11efd6a0a6b7831ce1a626f933611
author Nick Vatamaniuc <vatamane@apache.org> 1587572731 -0400
committer Nick Vatamaniuc <nickva@users.noreply.github.com> 1587575817 -0400

Do not commit read-only transactions

This might save a round-trip to the network thread [1]. It also follows the
recommendation in the C api docs [2].

[1] https://forums.foundationdb.org/t/performance-of-read-only-transactions/1998
[2] https://apple.github.io/foundationdb/api-c.html#c.fdb_transaction_commit

However, it turns out in order for the watches to fire the read-only
transaction still has to commit, so avoid this optimization if has_watches(Tx)
is true.