Constraints and Metrics

Graviton enforces ingest limits and exposes observability data through the runtime module.

Constraints

• Spill policy – keeps large uploads off-heap by writing intermediary bytes to disk. Policies track the lifetime of spill directories and cleaning semantics.
• Semaphore limits – coordinate concurrency per tenant and per upload via zio.Semaphore.
• Throttles – token bucket implementation to enforce byte-per-second limits across actors.
• Quotas – track aggregate usage per tenant; the initial implementation uses counters and optimistic updates.

Metrics

All components register metrics through MetricsRegistry and publish canonical keys defined in MetricKeys. The server exposes /metrics for Prometheus scrapes while backends contribute driver-specific gauges (e.g., RocksDB compaction stats or S3 request latency histograms).