bus-conformance.md audits the flybus crate against bus-v1 sections 2 to 11, one
row per normative sentence: requirement, status, code location, the test that
proves it. 195 rows, 177 conforming, 10 deviating with the sentence that allows
each, 1 must-fix (the teardown starvation, fixed in this branch) and 7 not
implemented with an owner named. It also maps every BUS-01/02/03 acceptance
bullet to its test, reconciles all ten of the crate's own differences from the
draft, records the frame measurement with the reasons it is not a capacity
claim, and lists the two contradictions inside the draft it will not guess at:
the per-client queued byte budget against the latest-mode guarantee, and
section 2's call budget against section 6's client-owned deadline. Neither
changed any code.
bus-v1 gains section 12: dated amendments for the three error codes the
implementation needs and the draft left unnamed (CONFLICT, NO_TOPIC,
ARTIFACT_MISMATCH), one line of reason each, and for the one operation it adds
(rpc.responder.release), which is how bounded call correlation ends when a
handler keeps reply authority after releasing the request delivery. Section 9's
error list is inclusive, and section 4 already provides for a digest change.
The crate README points at the report, carries the new measurement summary in
place of the old numbers, and describes the two new test files; the design index
and the flybus index point at the report too.
The guide's first deliverable is one small program with a counter RPC, a pub/sub
observer and a frame artifact held past its message object. examples/demo.rs was
already that; its body moves into run(), which returns the lines it prints, so
tests/example_demo.rs can assert all seven of them. The counter now uses the
spec's own example.counter / Counter.Increment / {"amount": 1} and pins the
registration it discovered, and the example prints the router's root count while
the frame is held and after the last handle goes, so the lifetime it
demonstrates is visible rather than implied. cargo run -p flybus --example demo
prints the same lines.
tests/perf.rs reports what BUS-03 and bus-v1 section 11.7 actually ask for.
Allocate, the producer's copy into staging, the router's seal copy, publish
admission, the RPC round trip and a consumer's readback are six separate
percentile lines instead of one. The router gets its own two-thread runtime
whose threads carry a distinct name, and per-thread CPU is sampled from /proc by
that name, so router CPU is separable from the clients' in the same process.
Store bytes, outstanding roots and queue lengths are reported live as well as
peak.
One named test per implementation-guide bullet that the existing suites did not
already cover: a lost result that leaks no roots while the endpoint's own cache
still replays it, a retransmission of one domain body under a fresh call id, no
failover onto a replacement registration, a status RPC answered while another
handler is delayed, and a disconnect that reclaims logical ownership without
touching a file the consumer still has open. Each runs over both transports.
BUS-01 also asks for equivalent behaviour traces from the two transports, so
tests/common/mod.rs gains a Trace recorder whose record() panics on any
router-issued id: a trace can hold methods, payload fields, counts, sequences,
credits, cancel states and error codes, and nothing operational. One RPC
scenario and one pub/sub-with-artifacts scenario produce 29 events, identical in
memory and over a Unix socket. FLYBUS_TRACE=1 prints them.
The sixteen bullets the older suites already prove are cited in the conformance
report rather than duplicated here.
The write gate was one mutex the writer held across every synchronous transport
poll, and close_conn took that same mutex before reclaiming a connection's
owners. Under a transport that accepts a byte per poll the writer re-acquired it
hundreds of times while teardown queued behind it, so teardown could be starved
for a whole frame and the delivery completed just before its owner was
reclaimed. bus-v1 section 9 puts release and route-health control out of reach of
telemetry starvation; tests/sol_rereview_regressions.rs's poll-gate regression
failed 6 release runs out of 6 alone, and about one debug run in five.
The gate now separates "teardown has begun" from "a poll is in progress": a
mutex plus a condvar. begin_close sets closing once without waiting, then waits
for the poll already in progress and records whether it left a frame half
written. The writer brackets each poll with enter_poll (refused once closing)
and leave_poll(bytes) instead of holding a lock across it, so teardown's window
is one poll rather than a frame, and no byte follows it. close_conn no longer
holds the gate across reclamation. Every item is pub(crate): no public
signature changed.
The regression test no longer synchronises with a sleep. The shutdown thread
announces itself on a channel, and what follows is structural: teardown cannot
pass the gate until the held poll returns, which only release() allows. Its
delivery is 50 KB now, which a writer resuming a byte per poll cannot finish
inside the window, so the test observes the ordering instead of a coin toss and
asserts the two legal shapes of the stream: cut short with nothing appended, or
never begun with exactly the closing notices following.
