[Spread-users] Sending messages to a fixed set of servers
lulli at cs.tu-berlin.de
Wed May 5 13:27:15 EDT 2004
After thinking a bit more about Lamports logical clocks, I think I
understood a very simple solution of how to place a correct and usefull
total order on messages (it's rather obvious).
A persistent, system-wide logical clock that spans across all messages
for the entire run-time of a "persistent group". Before sending a
message m, a node increments its local logical-clock value and sends
that with m. Upon receiving a message m, a node updates its local
logical-clock value: logical-clock = MAX(logical-clock, m.lctime + 1).
On shutdown/startup, each node stores/restores its local logical-clock
value. Changes in the configuration can be ignored, and by building the
pair of (local-IP, logical-clock) I have a nice "primary key" for
message log records.
With the totally ordered logical-clock in the message log records, it
becomes *much* simpler to determine the set of mission messages at each
Thanks for any input,
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