Tombstone Lifecycle to Safe Forgetting

Tombstone Lifecycle to Safe Forgetting A lifecycle diagram generated by Archify. Observed life Concurrent add Terminal exits Added · fresh tag minted · Observed life · live 01 Added fresh tag minted live Removed · tombstone for seen tags · Observed life · tombstoned 02 Removed tombstone for seen tags tombstoned Fresh add arrives? · unseen tag t3 · Concurrent add · product call Fresh add arrives? unseen tag t3 product call Causally stable · seen by every live replica · Observed life · safe 03 Causally stable seen by every live replica safe Kept (add-wins) · t3 stays live · Terminal exits · terminal Kept (add-wins) t3 stays live terminal Dropped (remove-wins) · t3 cancelled too · Terminal exits · terminal Dropped (remove-wins) t3 cancelled too terminal Tombstone collected · forgotten, never resurrected · Terminal exits · terminal Tombstone collected forgotten, never resurrected terminal remove seen tags sync meets t3 add-wins remove-wins t3 lives on all replicas saw it garbage-collect Legend initial state active decision success failure / exit final state