Assign per-project atomic sequence numbers when recording events - #33
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This was referenced Jul 25, 2026
The archive numbered events from a single global counter incremented with a read-then-write under a JVM-local lock: not per project, and not safe with more than one service instance. Each project now has its own counter document advanced with a single findAndModify $inc, which MongoDB runs atomically server-side, so ordinals stay dense and gapless per project under concurrency. A startup migration seeds each project's counter to the maximum ordinal already archived, using setOnInsert so it is idempotent and never rewinds a counter that has advanced — newly minted numbers always stay above any bookmark a connected client still holds. After the archive write, the service now re-publishes the change bundle as a SequencedPackagedProjectChangeEvent carrying the assigned ordinal. The gateway will push that instead of the raw event, which is what lets it stamp truthful event tags — and because publication happens strictly after persistence, anything a client hears about is already fetchable through the pull path. Delivery hardening of this publish is #299's scope; the failure is not silently swallowed here. A compound index on (projectId, timeStamp) backs the pull query, and a read-only current-sequence accessor is exposed for the project-open anchor (#301). Fixes the service half of protegeproject/webprotege-gwt-ui#296 (part of protegeproject/webprotege-gwt-ui#303).
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The service half of protegeproject/webprotege-gwt-ui#296 (part of protegeproject/webprotege-gwt-ui#303).
The archive numbered events from one global counter behind a JVM-local lock — not per project, not multi-instance-safe. Each project now gets its own counter advanced by an atomic
findAndModify $inc; ordinals are dense and gapless per project under concurrency (verified with a concurrent-increment integration test). An idempotent startup migration seeds each counter to the project's archived maximum so new numbers stay above any bookmark a connected client holds.After the archive write the service re-publishes the bundle as
SequencedPackagedProjectChangeEvent(channelwebprotege.events.projects.SequencedPackagedProjectChange; fieldsprojectId,eventId,sequenceNumber,projectEvents) — the wire contract the gateway consumes to stamp truthful event tags (startTag = seq-1, endTag = seq) and, later, SSE ids. Publication strictly after persistence means anything pushed is already fetchable via the pull path.Also adds a compound index on
(projectId, timeStamp)for the pull query and a read-only current-sequence accessor for the project-open anchor (#301). Tests: 14/14 green under JDK 17 (Testcontainers Mongo + Rabbit).