message: add CONTROL flag for out-of-band metadata messages#486
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williamhbaker wants to merge 1 commit into
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message: add CONTROL flag for out-of-band metadata messages#486williamhbaker wants to merge 1 commit into
williamhbaker wants to merge 1 commit into
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Flow's backfill-truncation feature publishes control messages into a collection's journals to mark where a re-backfill supersedes prior data. They carry no content of their own, but need a flag distinct from the transaction-semantics bits so consumers can recognize and drop them. Add Flag_CONTROL at bit 2, orthogonal to the low two transaction bits. The Sequencer masks the bit off when classifying a message and sequences it by its underlying Flag_OUTSIDE_TXN / Flag_CONTINUE_TXN / Flag_ACK_TXN, rather than tripping the unknown-flags error path; the flag is retained on the delivered envelope for the consumer to act on.
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Flow's backfill-truncation feature publishes control messages into a collection's journals to mark where a re-backfill supersedes prior data. They carry no content of their own, but need a flag distinct from the transaction-semantics bits so consumers can recognize and drop them.
Add Flag_CONTROL at bit 2, orthogonal to the low two transaction bits. The Sequencer masks the bit off when classifying a message and sequences it by its underlying Flag_OUTSIDE_TXN / Flag_CONTINUE_TXN / Flag_ACK_TXN, rather than tripping the unknown-flags error path; the flag is retained on the delivered envelope for the consumer to act on.