mirror of
https://github.com/Kpa-clawbot/meshcore-analyzer.git
synced 2026-09-25 22:05:55 +00:00
efiten
079e73aa4c
The Scope Audit credits a transmission to `path[last]` only. On a
flood-family route every forwarder appends its own hash to the END of
the path (`internal/packetpath/route.go`), so `path[last]` does not mean
"forwarded this packet", it means "was the transmission an uplinked
observer heard directly". Every earlier hop forwarded the same packet
and is discarded.
The last-hop rule is genuinely required for DIRECT routes, which consume
hops from the front, so their `path[last]` is the route’s far end rather
than the transmitter. But `scopeAuditForwarderScanQuery` already
restricts to `route_type IN (0, 1)` via
`scopeConformanceForwarderRouteTypesSQL`, where that hazard cannot
arise, so inside this query the restriction only throws evidence away.
## What it costs the page today
Measured on a live-shaped instance, 206 declared repeaters, 965k
transmissions, 7d window:
| | before | after |
|---|---|---|
| repeaters with no attributable evidence of any kind | 133 of 205 (65%)
| 30 of 206 (15%) |
On a 1000-packet flood sample the mean path length is 7.08 hops, so the
last-hop rule keeps 394 of 2789 hop observations (14%), and 85% of the
nodes seen forwarding never appear as a last hop at all. Those repeaters
have every region they declare reported as "declared, not observed",
which is the page presenting a gap in our own attribution as a finding
about someone else’s repeater.
## Rule 0: what widening it costs, and what pays for it
Reading every hop multiplies the rows the scan returns: a 7d window
yields **3,470,188 hop rows** from 1,368,761 observations carrying a
path. Cold cost before this change was 16.7s for 7d and 4.0s for 24h, of
which SQLite accounts for 2.7s. The rest was the Go side reading rows.
Three changes, in order of what they bought:
1. **The scan carried `scope_name` and `first_seen` on every hop row.**
Both are columns of `transmissions`, and at 43 hop rows per transmission
the same two values were re-read that many times. They now come from one
query over the same window keyed by transmission id, both inside one
read transaction so a transmission arriving between them cannot appear
in the hop scan with no metadata to attribute it by. The hop scan
carries two columns instead of four.
2. **The hop is lower-cased into a stack buffer** instead of through
`strings.ToLower`. 1,026,814 of the 1,284,897 hops in a 24h window are
stored uppercase, because `packetpath.DecodePathFromRawHex` writes them
that way, and the great majority match no declared target, so that
allocation was paid millions of times to answer "no". The `(target,
txID)` de-duplication key became a struct for the same reason.
3. **The compute ran outside the cache mutex**, so every request
arriving on a cold window ran its own full scan concurrently. It now
sits behind a singleflight, the same treatment `/api/observers` and
`/api/nodes/{pubkey}/reach` already have, and the 7d window gets a 5
minute TTL while 1h and 24h keep 30s. At 30s a single reader with 7d
open keeps the instance recomputing more than half the time, for an
aggregate that moves at the pace of a week of traffic.
Result, warm process:
| window | before | after |
|---|---|---|
| 1h | 0.155s | 0.140s |
| 24h | 4.04s | 2.79-2.89s across six samples |
| 7d | 16.7s | 11.6s |
| repeat inside TTL | ~1ms | ~1ms |
**Rejected alternatives, measured on the same database**, so the next
reader does not have to re-derive them:
| approach | rows returned | time in SQLite |
|---|---|---|
| the query as written | 3,470,188 | 2.7s |
| pre-filter on the declared targets’ first 4 hex chars | 1,971,126 |
20.9s |
| `GROUP BY t.id, hop` | 965,025 | 38.0s |
| `SELECT DISTINCT t.id, path_json` | 1,229,966 | 17.7s |
The query plan is already index-driven (`idx_transmissions_first_seen`,
then `idx_observations_tx_ts`), so there is no missing index behind
this: the rows are inherent to the data. Note for anyone attempting a
hop comparison in SQL: a case-sensitive comparison silently drops most
attributable hops, per the 80% figure above.
## Tests
- a mid-path hop is attributed (the case behind the 65% blind spot)
- a DIRECT transmission whose `path[last]` **is** the target is still
not attributed. With the last-hop rule gone this is the only thing
standing between the audit and misattribution, so it gets its own test
rather than relying on the route filter being obvious
- one transmission counted once per target even when it appears on
several hops of the same path, which the `(target, txID)` de-duplication
now carries alone
- a hop longer than the 4-char floor resolved by its own length, which
nothing pinned before: every other test seeds 4-char hops
- the per-window TTL, so collapsing it back to one constant has to
delete the reason
- a second request inside the TTL served from cache rather than
recomputed. The cache path had no test at all
`cd cmd/server && go test ./...` passes (168s), `go vet` and `gofmt -l`
clean. Server-side only, no API shape change, no frontend change.
Browser validation: run against a live instance carrying this change,
the Scope Audit renders 220 rows matching the API row for row, and the
per-node scopes page still answers with its route-type mix.