NatureWhistle.
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Rate-limit and sliding-window helpers for NatureWhistle.
The event handler delegates all traffic-shaping decisions to this module so the logic is easy to test in isolation. Two independent filters are exposed:
rate_limitlimits the number of alert dispatches over a time windowsliding_windowcounts breach density across fixed-size buckets
Both helpers read and write to the :nature_whistle_rate_limit ETS table.
Summary
Functions
Returns true when the alert is still under its rate-limit allowance.
Returns true when the alert has already reached its sliding-window cap.
Records a rate-limit timestamp for the given alert.
Increments the sliding-window bucket for the alert at the current timestamp.
Functions
Returns true when the alert is still under its rate-limit allowance.
The alert configuration may include a rate_limit keyword list with:
:window_ms- the lookback window used for counting recent events:max_events- the number of events allowed within that window
When no rate limit is configured, the function always returns true.
Returns true when the alert has already reached its sliding-window cap.
The sliding-window gate uses coarse buckets of @sub_bucket_ms milliseconds.
This keeps the ETS state compact while still approximating the configured
density window closely enough for alerting purposes.
Records a rate-limit timestamp for the given alert.
The timestamps are stored newest-first so the cleanup pass can trim old data efficiently while still keeping the implementation straightforward.
Increments the sliding-window bucket for the alert at the current timestamp.
Buckets are stored in ETS as { {:sliding_window, alert_id}, bucket_start_ms }
entries whose counters are incremented atomically.