Dispatch Log & Missed-Run Recovery

[niteshpurohit]

Feature Request

Description

Track dispatched (key, fire_time) pairs and recover missed runs after downtime.

Use Case

If the scheduler was down, it should enqueue the missed ticks within the lookback window to keep data/jobs current.

Proposed Solution

• Implement RailsCrons::DispatchLog that records successful dispatch decisions per (key, fire_time).
• Backends:
  • Redis: ephemeral keys with TTL.
  • Postgres: table with (key, fire_time) unique index.
  • File: filesystem-safe hash files.
• During each tick, compute expected fire times in the recovery window; enqueue those not found in the dispatch log (subject to locking).

Alternatives Considered

Pure lock-based idempotency — not sufficient for catch-up behavior.

Additional Context

Ensure pruning to avoid unbounded growth; TTL or periodic cleanup rake task.

Checklist

• I have searched for a similar feature request and didn't find any duplicates.
• I have included all the required information.
• I have tagged the issue with the label "enhancement".