A delivery and the five-minute reconcile were two paths that applied, ordered only by a lock, and
each order it allowed was met live (issues 257, 261, 267). Now both only enqueue: one worker takes
the newest declaration held when it starts, applies it once and makes one report, and reports leave
in the order they are made.
A declaration may carry the controller's lease epoch beside its sequence; one older than what this
node applied is refused before anything is touched, counted, logged and reported. A report carries
the declaration's epoch and sequence and the host's own report sequence, kept on disk so it goes on
increasing across restarts and self-updates. Without an epoch, today's behaviour stands.
novox/hq 04-ISSUES/107. A declaration's only identity was the digest of
its bytes: a host could say "not the last" and could not say "older". On
the link, nothing refused an older one at all, and the drain picked the
last to arrive — wrong exactly when it mattered, a backlog drained out of
order or a broker that split a burst.
A declaration may now carry a sequence, one higher per send. A host
refuses one lower than what it kept, whole, and says why. The drain keeps
the highest sequence in a batch rather than the last to arrive.
Only when both sides claim an order. Absent reads as zero — "no ordering
claimed", not "first" — so a controller that sends none is still
understood and a host that kept one before it understood them compares
nothing. That is what lets hosts go first and the controller follow, which
is the order 087 says a new field needs.
jochen
jschoubben