Fix VLC double-increment on event receive - #23
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VLC::merge() calls VLCSnapshot::receive() which already performs merge + increment. The extra vlc.tick() in add_event() and receive_event_from_network() caused the local vector clock entry and logical_time to advance by 2 per receive instead of 1. Fixes #22
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Summary
vlc.tick()aftervlc.merge()inadd_event()andreceive_event_from_network()VLC::merge()internally callsVLCSnapshot::receive()which already performs merge + increment — the extra tick doubled the clock advancement per receiveProblem
Every received event advanced the local vector clock entry by 2 instead of 1. This inflated
logical_timeat 2x the correct rate, causingshould_fold()(VLC delta threshold) to trigger earlier than intended.The VLC update rule per Chrono (arXiv:2405.13349):
UPDATE(id, c, [c_received])performs a single merge + increment. The receive path was incorrectly performing two increments.What changed
consensus/src/engine.rs— removed one line (vlc.tick()) from each of the two receive paths. Local event creation (create_event,tick_and_get_vlc) is unchanged.Test plan
Fixes #22