[sstriker]

claim_next selected the claimed tasks whose lease_until was before the present time, and compared the two times as text. A time renders with as many digits of a second as it has. A lease that ended at 10:05:00Z was thus not lost at 10:05:00.5Z, and claim_next gave no task for up to one second. The named claim gave the task at the same time, because it parses the times.

The error was on the safe side. A task never had two holders. But a lost lease did not go back to the pool at its time.

What changes

• The two ledger backends now select each open, blocked and claimed task. claimable decides with the parsed times, as it did after the selection.
• The two backends put the queue in order by priority and then by the parsed time of created.

Checks

make check passed. The new test runs on SQLite and on the embedded PostgreSQL.

The new assertion failed on each backend before the change: called Option::unwrap() on a None value, where claim_next gave no task.

Adversarial pass

The pass ran on 8ed964c and confirmed two findings. The second commit corrects them:

1. On PostgreSQL, claim_next reads the queue and then locks one row. A different connection can claim that task between the two. The check after the lock then stops a second holder. On main, the time term in the query was a second guard, and 8ed964c removed it. With the check off, all ledger tests passed. The check is now in a function, take, and a test gives it a task that a different holder claimed.
2. The queue was in the order of created as text. Of two tasks of one priority, filed a half second apart, claim_next gave the second one first. The two backends now put the candidates in order by the parsed time.

The pass confirmed that the limit did not change: at the time lease_until, the lease is live.

New assertions that failed before their fix:

• the queue order: the pass ran it on 8ed964c, and claim_next gave "Late" on the two backends;
• the check after the lock, with the check off: assertion failed: !db.take_alone(..).

No pass read the second commit.

Open

The pass on #75 listed four more places that order time text: the day ceiling of the egress telemetry, the tape, the newest platform artifact, and the order of the task lists by created. It read them and did not run them. Each is wrong only when two times are less than 10^-k seconds apart.

Posted by Claude on behalf of @sstriker

🤖 Generated with Claude Code

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