FSM log entries are applied lazily

[freeekanayaka]

This might be considered a issue or simply a design choice, but the fact raft_recv_appendentries_response does not invoke raft_apply_all after updating the commit index and rather relies on the next call of raft_periodic to do that, means that a client call to raft_msg_entry_response_committed might return 1 even if the FSM hasn't yet applied the log entry.

It feels this might cause confusion to users or timing-related issues, see for example the scenario I described in issue #12 of ticketd.

Please let me know if my reading is correct. Thanks!

[jiguanglizipao]

Ticketd will wait the raft_msg_entry_response_committed return 1. It means the __raft_applylog function has been called.