55 lines
2.5 KiB
Markdown
55 lines
2.5 KiB
Markdown
# irtt-stats
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Statistics aggregation over [`irtt-client`](https://crates.io/crates/irtt-client)
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events: loss/duplicate/late accounting, RTT and one-way-delay timing, and
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inter-packet delay variation (IPDV), as cumulative and rolling snapshots.
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## Relationship to irtt-client
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This crate does not open sessions or drive sockets. Feed it the `ClientEvent`
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stream produced by an `irtt-client` `Client`, `AsyncClient`, or managed
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session via `StatsCollector::process`, and read back a `Snapshot`.
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Generic timing accumulation and count-window storage come from
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`measurement-stats`. `TimeStats` remains available from `irtt_stats` as a
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re-export. Event interpretation, IPDV pairing, loss, and snapshot reconstruction
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remain here.
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A `StatsCollector` has one sequence/IPDV namespace and one packet count, both
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scoped to a single target. A managed session covering multiple targets needs
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one collector per target — as the `irtt-rs` CLI does — since a target's
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sequence numbers start over at zero and feeding two targets into one
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collector would pair up unrelated probes.
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## Retention modes
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`StatsConfig::finite()` retains exact timing samples for its cumulative
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snapshot, so every metric with samples reports an exact median there —
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retention grows with the probe count. `StatsConfig::continuous()` keeps
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bounded running statistics instead (no exact median) plus a bounded
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4096-entry adjacent-sequence IPDV store per target, for long-running or
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unbounded sessions. Rolling-window snapshots are always running-only and
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report no medians, whichever `StatsConfig` produced them.
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An enabled time-based rolling window has no event-count cap, including in
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continuous mode. It expires only on new events, anchored at the maximum observed
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normalized timestamp, with events exactly at the cutoff retained. Retained events
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are replayed in arrival order; backdated events cannot move the window backwards.
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Reading a snapshot does not advance time. Use count-based rolling storage for a
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hard bound on retained events. The memory estimate excludes time-window storage.
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Exact snapshots sort a temporary copy of each metric's retained samples, adding
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O(n) scratch memory and O(n log n) computation for that metric. The retention
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estimate is not peak snapshot or allocator accounting.
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See `examples/` in the repository for a runnable comparison of both modes.
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## Documentation
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Full API documentation is on [docs.rs/irtt-stats](https://docs.rs/irtt-stats).
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## Project
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Part of [irtt-rs](https://github.com/Lochnair/irtt-rs), an independent Rust
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implementation of an IRTT-compatible protocol stack.
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