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efitenandClaude Opus 5
efdb3ea0b3
## Summary Adds `GET /api/analytics/retransmissions` and a "Retransmission Pressure (proxy)" chart on the Analytics Topology tab, implementing the metric agreed in #1699: for each flood, the number of distinct repeaters in the union of the paths of all its observations (`[A]`, `[A,B,C]`, `[A,D]` gives 4), averaged per time bucket. Topology is the tab that already shows hop counts and repeaters in paths, so the chart sits there instead of in a new tab. ## Definition - Flood routes only (`route_type` 0/1); TRACE excluded. Direct routes carry the route still to travel (firmware `src/Mesh.cpp:78-106,334-342`), zero-hop sends are direct (`src/Mesh.cpp:717-737`), TRACE path bytes are SNR values (`src/Mesh.cpp:59-61`, refused by `sendFlood` at `src/Mesh.cpp:637-641`). Firmware commit 0679dbef. - **Flood events, not hashes.** `transmissions.hash` is UNIQUE and the packet hash excludes the path (`src/Packet.cpp:41-50`), so when the same bytes flood again the observations land on the same transmission. Observations are sorted by time and split into events wherever two consecutive observations are more than 5 minutes apart. Each event is counted on its own and bucketed by its first observation. - Why 5 minutes: a node holds a flood for at most 32 s (`src/Dispatcher.cpp:11,243-251`) plus a random retransmit delay. On live over 7 days, 72,806 of 74,347 flood transmissions span 60 s or less, and of 1,372,283 consecutive observation gaps, 52 fall between 60 s and 300 s against 1,823 above 300 s. - Events that start before the store retention floor (now minus `retentionHours`) are left out for every request shape. The store keeps older observations only for hashes heard again recently, so they do not represent that period. Eviction of those transmissions is tracked in #2024. - A flood event heard only with an empty path counts as 0 repeaters. - **Prefixes are not resolved to nodes, and a prefix counts once per event**, whether it repeats across observations or inside one path. On live (7 days), a repeated 2-byte prefix inside one path occurs in 1.08% of flood transmissions and 6,178 of 6,596 such repeats match exactly one known node; for 3-byte it is 0.69% and 104 of 104. That is one node forwarding again after its 160-slot cyclic duplicate filter dropped the hash (`src/helpers/SimpleMeshTables.h:9,52-57`). A repeated 1-byte prefix (44.9% of 1-byte transmissions) is mostly two nodes; counting it once keeps the value a lower bound. `summary.one_byte_packets` reports how many events that affects. - Observations are stored once per observer and path per hash, so a later event of the same hash only holds pairs not stored before; its count is a lower bound too. On live these are 1,466 of 75,356 events (1.9%), and they are kept in the average. - Resolution was not used: on live, 1-byte observations nearly all have `resolved_path` NULL, and cold load refuses context-based resolution of history (`cmd/server/neighbor_persist.go:155-168`). - Buckets `5m|15m|1h|6h|1d`. `region` filters on observers like `/api/analytics/rf`, after the event split; a region with no known observers is not filtered, the same as the other analytics endpoints. `area` is not supported. ## Implementation - `cmd/server/retransmission_pressure.go:255` `addPath`: scans path JSON directly into a generation-stamped hash set, no allocation per observation. - `cmd/server/retransmission_pressure.go:367` `computeRetransmissionPressure`: one pass under `s.mu.RLock`. Per flood transmission it sorts the observations by cached parsed time into a reused scratch slice, splits events and counts each in `addEvent` (`:319`). O(T + O log k + H). - `cmd/server/retransmission_pressure.go:470` `GetRetransmissionPressure`: default shape from the recomputer (#1659 warm-up gate). Other shapes come from a typed TTL cache (max 64 entries) cleared on new paths and eviction (`cmd/server/store.go:2289,2336`); concurrent misses on one key share one compute through singleflight (`store.go:204`). - `cmd/server/retransmission_pressure.go:515` handler, `cmd/server/routes.go:331`, `cmd/server/openapi.go:108`, `docs/api-spec.md:1283`. - `public/analytics.js:761` card, `:855` `renderRetransmissionChart` (CSS variables only, lines break at missing buckets, caption states it is a proxy, names the observer coverage bias, the once-per-flood prefix rule and the 5 minute event split), `:829` loader with stale-response guard. ## Performance - `BenchmarkComputeRetransmissionPressure`, 50k transmissions x 20 observations, `-cpu 1`, i5-1335U: median 161 ms/op (132 ms/op before the event split); first pass after startup with timestamps not yet parsed 192 ms/op. About 22 KB and 281 allocations per op. - On staging the default shape is served from the recomputer in 0.3 s; the post-load recompute of this recomputer took 994 ms on a 121k-transmission store (log line quoted in #2025). A 336h store would be about twice that, every recompute interval, under the store read lock. ## Tests - `cmd/server/retransmission_pressure_test.go`: union counting (reporter example, overlaps, once per event for 1/2/3-byte, width/case, growth); route/TRACE/zero-hop filter, bucketing, window by event start; event split and the 5 minute settle gap (boundary, chained steps, unsorted input), retention floor; region filter, region applied after the split, unknown region, 1-byte share; recomputer read, TTL cache invalidation on new paths and on eviction, cache expiry, singleflight, recomputer gate wiring, handler, warm-up gate. - `test-issue-1699-retransmission-chart.js` (33 tests, registered in `test-all.sh` and `deploy.yml`). - Mutation-checked: 18 mutations of the event split, floor, prefix rule, bucketing, region order, cache clears, expiry, gate wiring and singleflight, all killed. - `go test ./...` in cmd/server passes; `scripts/check-css-vars.js` OK. ## Staging validation Build `c646310f` (this rework plus #2025 and the other review follow-ups), after a container restart and full load: default shape 74,974 flood events, average 27.08 repeaters, 169 hourly buckets from 2026-09-06 16:00 (the 168h floor) to the current hour, highest hourly average 53.3. Before the rework the same instance showed buckets back to 2026-07-18, averages up to 148, and for the first minutes after a restart only 5,911 packets. ## Merge order with #2025 #2025 fixes the recomputer startup for all analytics endpoints (the stale first snapshot seen here). Whichever of the two merges second has to add `recompRetransmissions` to `analyticsRecomputersLocked`, wire it to that PR's `loadedGate` instead of `LoadComplete`, bump the recomputer count in `TestAnalyticsRecomputers_PostLoadOrder` from 9 to 10, and make `TestStartAnalyticsRecomputers_RetransmissionsGatedOnLoadComplete` call `signalStartupLoadDone()`. That resolution is what ran on staging. ## Not verified - Recompute timing on a production-size (336h) store; only extrapolated. - Phone-width layout and dark theme of the reworked chart. - E2E Playwright suite. Fixes #1699 --------- Co-authored-by: Claude Opus 5 (1M context) <noreply@anthropic.com>