goodhistogram: add ValuesAtQuantiles and common Params presets#3
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angles-n-daemons merged 1 commit intomainfrom Apr 29, 2026
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Computing p50/p90/p99/p999 with individual ValueAtQuantile calls redundantly walks the bucket array and recomputes boundary densities for each quantile. ValuesAtQuantiles resolves all requested quantiles in a single pass: it sorts them by rank, computes boundary densities once, and processes each quantile as the walk reaches its bucket. Also adds common Params presets (HiResLatency, IOLatency, ResponseTime, LongRunning, DataSize, MemoryUsage) modeled after CockroachDB's histogram_buckets.go tiers, so callers don't need to research appropriate ranges for standard measurement scenarios. Co-Authored-By: roachdev-claude <roachdev-claude-bot@cockroachlabs.com>
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Summary
Computing p50/p90/p99/p999 with individual
ValueAtQuantilecalls redundantly walks the bucket array and recomputes boundary densities for each quantile.ValuesAtQuantilesresolves all requested quantiles in a single pass: it sorts them by rank, computes boundary densities once, and processes each quantile as the walk reaches its bucket.Also adds common
Paramspresets modeled after CockroachDB'shistogram_buckets.gotiers, so callers don't need to research appropriate ranges for standard measurement scenarios:HiResLatencyParams(1us - 5m) — full-range request latencyIOLatencyParams(10us - 10s) — RPC, disk I/OResponseTimeParams(1ms - 30s) — SQL, HTTPLongRunningParams(500ms - 1h) — backups, migrationsDataSizeParams(1KB - 16MB) — payloadsMemoryUsageParams(1B - 64MB) — allocations