fix(telemetry): close the two gaps where a cancelled request still files no usage row - #1191
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…les no usage row AISIX-Cloud#1571 made a caller that hangs up emit a terminal `499` usage event, but two shapes of the same request still left the usage log empty while the access log recorded them. A response body dropped before its first poll. Every streaming family builds its terminal emitter INSIDE its `async_stream!` generator, and a generator first runs when the body is polled — so a caller that went away between the head being handed to hyper and hyper asking for the first frame reached neither that emitter nor the request-level guard, which had already stood down. The guard now rides the response body (`TelemetryBody`) instead of ending at the handler, and reports that window as a third phase: `error_class = "client_disconnected"` as before, `error_message = "client closed the request before the response body was streamed"`, zero delivered tokens, and the winning attempt's `model_id` / `attempt_*` — the upstream had answered, so the target is known. The `499` access-log line is written there too; before this the request's only line was the handler's `200`, written when the stream was handed over and never corrected. Three interlocks keep that from doubling a row, and each is pinned by a test that fails without it: a body that was polled belongs to its own stream's emitter; a body whose length was already known was produced by a handler that finished its telemetry; and the body is dropped inside the request's attribution cell, so the two families that build their emitter OUTSIDE the generator (`/a2a` streaming, passthrough) are seen to have spoken. Ordinary fully-consumed and mid-stream behaviour is unchanged. Routes where the caller names no model. `/mcp`, `/a2a/:agent`, the passthrough namespace, `/v1/realtime` and the files / batches / fine-tuning surface were all exempt from the cancel emitter, so a request abandoned there got the `499` line and no row at all — on the surfaces whose calls are long-running by nature. The gate is now attributability alone: an authenticated request on a metering route files a row, with the model fields empty where there is no model and the family's own attribution in their place (passthrough route name, MCP server + tool, A2A agent + method). A caller that hangs up mid-upload is filed the same way, for the same reason — the row exists so the line can be found by `request_id`. An unauthenticated request still files nothing. The route census now derives its answer from the routing table rather than an exemption list: a label any metering route normalizes to must report that route's surface. The four routes that emit no usage event at any time (health probes, the discovery routes, `/v1/models`, the two `/v1/videos/:id` polls) still report nothing — they have no `operation` to name. Behaviour change for existing deployments: a cancelled request on the surfaces above now appears in the usage log where it previously did not, and an abandoned upload files a row with empty model fields. No new wire field and no metric-label change. Ref api7/AISIX-Cloud#1571
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Included review availability: Your plan provides up to 5 included reviews per hour; 0 remain after this review. 📝 WalkthroughWalkthroughThe proxy now records authenticated route attribution and tracks cancellation through response-body lifetime. It emits phase-specific ChangesCancellation telemetry
Priority: ➖ Normal Estimated code review effort: 4 (Complex) | ~60 minutes Change: Bug fix Sequence Diagram(s)sequenceDiagram
participant Client
participant AisixProxy
participant TelemetryBody
participant UsageTelemetry
Client->>AisixProxy: send request
AisixProxy->>TelemetryBody: attach telemetry guards
Client-->>TelemetryBody: abort or drop response body
TelemetryBody->>UsageTelemetry: emit phase-specific 499 event
Suggested reviewers: Merge Risk: 🟡 Moderate · up to This PR can produce unreliable telemetry: scoped MCP cancellations may not reconcile with completed calls, and unmetered authenticated discovery requests may create false usage rows. These issues should be fixed before merging. 🚥 Pre-merge checks | ✅ 6✅ Passed checks (6 passed)
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The cancel guard now writes a line for a response head whose body the caller never read, beside the one its handler had already written. That makes it the only request shape with two lines, which the module doc has to say — it is the file a reader consults to learn what a line means. Ref api7/AISIX-Cloud#1571
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In `@crates/aisix-proxy/src/mcp.rs`:
- Line 375: Normalize scoped tool names before cancellation attribution by
applying the same server-prefix stripping used by the completed-call path before
invoking note_mcp_call. Update the cancellation handling around the server/tool
match so both cancellation and completion record the normalized tool name, while
preserving unscoped names unchanged.
In `@crates/aisix-proxy/src/operation.rs`:
- Around line 143-153: Update CancelContext and cancel::emit to track
request-level metering eligibility, defaulting it to false and requiring both
eligibility and a non-empty api_key_id before emitting usage. In the MCP and A2A
handlers, set the eligibility flag only after identifying a usage-bearing
subtype, leaving MCP initialize/tools/list and A2A agent-card discovery
ineligible even when authenticated.
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Cargo.tomlcrates/aisix-proxy/AGENTS.mdcrates/aisix-proxy/Cargo.tomlcrates/aisix-proxy/src/a2a.rscrates/aisix-proxy/src/attribution.rscrates/aisix-proxy/src/auth.rscrates/aisix-proxy/src/cancel.rscrates/aisix-proxy/src/lib.rscrates/aisix-proxy/src/mcp.rscrates/aisix-proxy/src/operation.rscrates/aisix-proxy/src/passthrough_route.rstests/e2e/src/cases/client-cancel-usage-1571-e2e.test.ts
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…ow reports
Review findings on the cancel-gap change.
The surface came off the normalized endpoint label, which is right for
every typed route and wrong for a passthrough route mounted anywhere
else: a custom `path_prefix` normalizes to `other`, and a HOST-matched
route keeps the upstream's own path space — `/v1/chat/completions` on a
forward-proxied upstream normalized to the chat surface, so an abandoned
relay filed a row as an abandoned chat call with no model, under an
`operation` that per-operation figures count as chat traffic. The route
the request matched now decides, published from the one point that knows
it, and the passthrough protocol is stated rather than guessed from the
path.
A cancelled A2A row carried only the caller's raw `a2a_method`, not the
canonical `a2a_operation` a per-operation figure groups by — so it
reached the usage log and then fell out of every A2A breakdown. Both are
noted now, as the completed row carries both.
On the scoped `/mcp/{server}` entry the caller may spell the tool either
way, and the gateway resolves both to the bare name; the cancelled row
took the caller's spelling verbatim, so one request's two records named
two different tools. It now strips the prefix the same way, from the
untruncated parse rather than the log-capped copy, and the server a
scoped entry names in its path is noted before the body is read, so a
cancel during the upload still reports it.
Three shapes that must NOT be filed as a cancel:
- the A2A agent card and the two OAuth discovery routes file no usage row
at any outcome, but normalize to a label a metering route also uses —
the card fetch is a real upstream round trip, so an abandoned one was
filed as an abandoned agent call. Each declares itself unmetered, and
the census now requires that of any silent route sharing a label;
- a `HEAD` response's body is dropped unpolled by protocol on every such
request, so a download route's ordinary size probes were reported as
cancels;
- a route that files no usage row gets no line and no counter in the body
phase either — otherwise the change introduced exactly the shape it
exists to remove, a `499` line with no row to find it by
(`/v1/videos/:id/content` relays an open-ended body and is metered by
the submission).
Also: `size_hint` is deliberately not forwarded through the new body
wrapper, matching the `map_frame` wrapper it replaces — forwarding it
would have changed the framing of every response on the listener from
chunked to `Content-Length`, which has nothing to do with telemetry.
`note_client` no longer blanks an api_key id the auth chokepoint already
resolved. The census again pins that a label no metering route reaches
reports nothing.
Ref api7/AISIX-Cloud#1571
The body phase was writing a `499` line beside the `200` its handler had already written when it handed the stream over, so one request read as two. The line is the head phase's alone now — that is the one phase where the request produced no record anywhere else. Past the head, the guard files the usage row and nothing else. That leaves a streamed request's line and its usage event disagreeing on the outcome (the line says `200`, the event `499`), which is also how the mid-stream disconnect case has always behaved. Converging them onto one end-of-stream line is per-family work in each streaming handler and reverses a deliberate decision about what a streamed line's `latency_ms` means — time-to-first-token, so a long-running stream is not read as an idle connection (AISIX-Cloud#1394). Not this change's to make; this one does not add to the divergence. `a_streamed_request_writes_exactly_one_access_log_line` counts the lines for all three outcomes — delivered, abandoned mid-stream, and never read. It fails on the middle state this commit removes. Ref api7/AISIX-Cloud#1571
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Follow-up to #1190, which made a caller that hangs up emit a terminal
499usage event. Two shapes of the same request still left the usage log empty while the access log recorded them. The invariant this closes: any request the cancel guard writes a499access-log line for is findable in the usage log by the samerequest_id, with the same picture.A response body dropped before its first poll
Every streaming family builds its terminal emitter INSIDE its
async_stream!generator, and a generator first runs when the body is polled. A caller that went away between the head being handed to hyper and hyper asking for the first frame therefore reached neither that emitter nor the request-level guard, which had already stood down — six families are affected (chat, both/v1/messagesbuilders, the/v1/responsesbridge and its passthrough, the audio transcription relay).Mechanism chosen: the guard rides the response body (
TelemetryBody) instead of ending when the handler returns, rather than hoisting each family's emitter out of its generator. One chokepoint covers every streaming family, including passthrough relays, and no family has to opt in — the same reason #1190 put the emission in middleware rather than in ten handlers.That window reports a third phase:
error_class = "client_disconnected"as before,error_message = "client closed the request before the response body was streamed", zero delivered tokens, and the winning attempt'smodel_id/attempt_*(the upstream had answered, so the target is known).Access log, before/after. Unchanged: one line per request, the handler's
status=200, written when the stream was handed over. What was missing was the usage row, and that is what this adds.A streamed request's line and its usage event still disagree on the outcome — the line says
200because it is written at head time, the event says499— and that is true for the mid-stream disconnect case too, which has behaved this way since streaming telemetry existed. Converging them onto a single end-of-stream line is per-family work in each streaming handler (each would have to defer its line to its stream's completion and carry the completion-time figures there) and it reverses a deliberate decision about what a streamed line'slatency_msmeans: today it is time-to-first-token, precisely so a long-running stream is not read as a connection sitting idle (AISIX-Cloud#1394, and theaccess_logmodule docs). That is a separate change; this one does not add to the divergence.a_streamed_request_writes_exactly_one_access_log_linepins one line per request across all three outcomes.Three interlocks keep this from doubling a row; each is pinned by a test that fails without it:
HEADrequest and a discarded buffered response take;/a2astreaming, passthrough) are seen to have spoken and the guard stays quiet. A family that meters at its own tail and relays an open-ended body afterwards (/v1/audio/speech, billed per character) is covered by the same check.Fully-consumed and mid-stream behaviour is unchanged.
Routes where the caller names no model
/mcp,/a2a/:agent, the passthrough namespace,/v1/realtimeand the files / batches / fine-tuning surface were all exempt, so a request abandoned there got the499line and no row — on the surfaces whose calls are long-running by nature, and where the row is the only record that the caller's key spent an upstream's time.The gate is now attributability alone: an authenticated request on a metering route files a row. Where there is no model the model fields are empty and the family's own attribution stands in their place — passthrough route name, MCP server + tool (split the way the completed row splits it, empty if the body was not parsed yet), A2A agent + method.
/v1/realtimecovers the pre-upgrade phase only; after the upgrade the session runs detached and writes its own terminal event.A caller that hangs up mid-upload is now filed the same way, with empty model fields, for the same reason — the row exists so the line can be found. An unauthenticated request still files nothing, which keeps the health and discovery routes silent.
To reach those surfaces the principal is published to the attribution cell from the shared auth chokepoint (
authenticate_token, plus the two places that mint an anonymous principal), since/mcpand/a2anever build aClientContext.The route decides the surface, not the path. Reading it off the normalized endpoint label is right for every typed route and wrong for a passthrough route mounted anywhere else: a custom
path_prefixnormalizes toother, and a host-matched route keeps the upstream's own path space, so/v1/chat/completionson a forward-proxied upstream normalized to the chat surface and filed an abandoned relay as an abandoned chat call with no model. The route the request matched publishes its own surface, and the passthrough protocol is stated rather than guessed.Three shapes that must not be filed as a cancel, each pinned by a test: a route that files no usage row at any outcome but shares a normalized label with a metering sibling (the A2A agent card, whose card fetch is a real upstream round trip, and the two OAuth discovery routes) declares itself unmetered, and the census requires that of any such route; a
HEADresponse, whose body hyper drops unpolled by protocol on every request, so a download route's size probes are not cancels; and the body phase on a route that files no row at all, which would otherwise write a499line with nothing to find it by (/v1/videos/:id/content).Still reporting nothing, because they emit no usage event at any time and have no
operationto name:/livez,/readyz,/v1/models, the two OAuth protected-resource discovery routes, the A2A agent-card route, and the two/v1/videos/:idpolls, whose work the submission already metered.Census
The route census no longer carries an exemption list. It derives the answer from the routing table: a normalized label that any metering route maps to must report that route's surface, and a label no metering route reaches must report nothing. A new route cannot join one side without the other.
Behaviour change
A cancelled request on the surfaces above now appears in the usage log where it previously did not, and an abandoned upload files a row with empty model fields. A stream abandoned before its first byte also raises the client-cancel counter, which mid-stream disconnects do not — that counter has only ever recorded what the request-level guard itself observed. No new wire field toward the control plane, no new
operationvalue (every one it uses is already in the control plane's fixed set) and no metric label change.size_hintis deliberately not forwarded through the new body wrapper, matching themap_framewrapper it replaces, so response framing is unchanged.One consequence worth stating plainly, because it is a policy call rather than a defect. A cancelled request is emitted from
Drop, so it never passes the quota layer — which for the head phase now includes requests that stopped before dispatch (an abandoned upload, an abandoned MCP handshake). An authenticated caller can therefore file rows without a rate-limit check, and the usage sink is bounded and drops on full, so a sustained abort loop would compete with real rows. It takes a valid API key, so it is that key's own usage log rather than anonymous amplification, and it is the direct consequence of the invariant this PR implements: every request the guard writes a499line for is findable in the usage log. Narrowing it back would re-open the gap for exactly the long-running, model-less surfaces the change is for. Flagged for the decision on whether cancel rows should carry their own bound.Tests
Rust: the unpolled-body window on a routing group (winner's attribution + the access-log line) and on
/v1/messages; no double emission when the body is polled, when a relay stream is delivered in full, when a family emits eagerly and relays afterwards, and when a route's own guard already fired on an unpolled drop; head-phase cancel on/mcp(both the bare and the scoped entry),/a2a/:agent, a path-prefix passthrough route and a host-matched one; an abandoned agent-card fetch filing nothing;HEADand no-row routes in the body phase; the attributability gate from both sides. Each was mutation-checked against the change it pins.E2E: an abandoned passthrough request produces the
499usage row attributed to its route. The unpolled-body window is timing-dependent on a real connection and is pinned at the Rust level instead.Fixes api7/AISIX-Cloud#1571
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