Fix spurious seqno increment when a merge adopts an incoming config - #132
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jagerman wants to merge 1 commit into
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Fix spurious seqno increment when a merge adopts an incoming config#132jagerman wants to merge 1 commit into
jagerman wants to merge 1 commit into
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When _merge runs while dirty it builds the result as a MutableConfigMessage, whose multi-config constructor unconditionally increments the seqno when nothing needed merging. That is correct when the surviving config is our own (and is unwound by the existing nothing-to-do branch), but when the survivor is an *incoming* message -- reachable while dirty via an exact (seqno, hash) duplicate (another device pushed the identical change) or via lagged-diff containment of such a duplicate -- we adopted it at the inflated seqno. That burned a seqno no stored message occupies, so the peer's next ordinary change (correctly landing on the value we consumed) looked like a conflict and produced a pointless conflict-resolution push, and it eroded the config_lags() conflict window. Adopt the incoming message at its own seqno instead, exactly as a non-dirty merge would; the merged (conflict-resolution) path is untouched.
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When _merge runs while dirty it builds the result as a MutableConfigMessage, whose multi-config constructor unconditionally increments the seqno when nothing needed merging. That is correct when the surviving config is our own (and is unwound by the existing nothing-to-do branch), but when the survivor is an incoming message -- reachable while dirty via an exact (seqno, hash) duplicate (another device pushed the identical change) or via lagged-diff containment of such a duplicate -- we adopted it at the inflated seqno.
That burned a seqno no stored message occupies, so the peer's next ordinary change (correctly landing on the value we consumed) looked like a conflict and produced a pointless conflict-resolution push, and it eroded the config_lags() conflict window.
Adopt the incoming message at its own seqno instead, exactly as a non-dirty merge would; the merged (conflict-resolution) path is untouched.