a3a0cfe9bb9b62b746d9211ed2abdbce6a82ea0f
5 Commits
| Author | SHA1 | Message | Date | |
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 Joseph Doherty
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a3a0cfe9bb |
fix(mtconnect): close the silent-refusal + teardown-wedge defects in the pump (Task 11 review)
C1 (critical): a latched "this endpoint cannot stream" verdict could end with a GREEN driver holding a permanently silent subscription. DriverInstanceActor handles a tag-set change as Unsubscribe-then-Subscribe with no re-initialize; the unsubscribe cleared the stream-degraded flag, the resubscribe was refused by the latch without a word, and one successful read then reported Healthy. StartSampleStreamCore now re-asserts the degradation and logs a Warning naming the remedy, and teardown no longer clears the flag while the latch is set. NOT promoted to Faulted: DriverHealthReport maps any Faulted driver to a /readyz 503, so that would de-ready the whole node over one misconfigured Agent whose reads are perfectly healthy. Faulted stays for the case that earns it. I1: teardown waits are bounded (5 s) and honour the caller's token. They were unbounded and ignored it, so DriverInstanceActor's 5 s budget was inert and PostStop — which blocks a dispatcher thread on ShutdownAsync while holding the lifecycle semaphore — could be wedged forever by one blocking subscriber. The cancellation source is disposed only when the loop is provably gone. Applied to StopProbeLoopAsync too: Task 13 reproduced the identical shape, and closing the class in one method while leaving the other as the pattern to copy is worse than not closing it. I2: the reconnect ladder was monotonic for the process lifetime, so ~9 unrelated drops pinned the driver at MaxBackoffMs forever. A stream that delivered before dropping now starts a fresh ladder (at attempt 1, not 0, so MinBackoffMs is still honoured). I3: MaxBackoffMs <= 0 clamped every delay to zero — an operator-authorable reconnect spin. Treated as unset, like a multiplier that cannot grow. I4: the session published instanceId without NextSequence, so after a restart it held the new agent's id beside the dead one's cursor, and a gap/OUT_OF_RANGE re-baseline (id unchanged) never published the cursor at all. Both move in one CAS, and the pump publishes its cursor as it exits. I5: OnDataChange was a multicast Invoke — the first throwing handler aborted the rest of the list, starving every later subscriber. Now walked by hand with the catch inside the loop. The test that claimed to cover this registered the recorder BEFORE the thrower, so it passed regardless; swapped, it was red. Faults are latched to one Warning per stream generation (Debug thereafter) so a consistently-throwing consumer cannot flood the log. Also: the pump restarts after an unexpected fault (IsCompleted, not null); a device-scope that matches nothing is a Warning, not a Debug tally; a device or component with neither name nor id is skipped rather than emitting a blank path segment; DiscoverAsync's remark no longer claims DriverInstanceActor retries (it does not for a Once driver, and injection is dormant in v3); and two flake seeds in the fake are gone (Dispose re-read its own counter; _disposeCts was disposed under a racing SampleAsync). 439/439. Every changed behaviour falsified by mutation. |
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Joseph Doherty
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a41c26b5de |
feat(mtconnect): ISubscribable /sample pump + ring-buffer re-baseline (Task 11)
One shared /sample long poll behind every subscription handle. Subscribe fires initial data per reference from the primed /current (Part 4 convention) and returns without waiting on the stream; the pump runs on its own task under its own token — never the caller's Subscribe token, which is disposed the moment that call returns. The pump owns every way the sequence can break: - sequence gap, measured against the RUNNING cursor (the previous chunk's nextSequence). Comparing against the opening `from` reports a gap on every chunk once the buffer rolls — a /current re-baseline storm. - OUT_OF_RANGE under HTTP 200 (InvalidDataException out of SampleAsync), which IsSequenceGap cannot see at all — without it a driver recovers from falling a little behind but not from falling a lot. - agent restart, checked BEFORE the gap because a restart resets sequences and so usually trips the gap check too; it clears the index (the held values describe a device model that no longer exists) and tells the subscribers. - every chunk advances the cursor, heartbeats included. Re-baseline calls CurrentAsync directly on the client the pump already holds: routing it through ReinitializeAsync would take the non-reentrant lifecycle semaphore from inside a pump a lifecycle method may already be awaiting, and hang the driver with no exception and no log. StopSampleStreamAsync is filled in (same call sites) and InitializeAsync now stops the stream before teardown too, so a re-Initialize on a live instance cannot leave a pump enumerating a disposed client. MTConnectStreamEnded/TimeoutException reconnect under a geometric backoff with a 100 ms growth floor (MinBackoffMs defaults to 0, and 0 x multiplier is still 0). MTConnectStreamNotSupportedException does NOT retry — it latches, reports loudly, and is cleared only by a re-initialize. Health precedence is explicit: /current and /sample fail independently, so each path owns a flag, clears only its own, and Healthy requires both clear. Neither can paper over the other's failure. 29 new tests, all deterministic — no sleeps, no wall-clock assertions. The fake grew per-generation sample streams (so a reconnect has somewhere to land), scripted /current answers, scripted sample failures, and a chunk-consumed signal that also fires when the consumer abandons the stream. 375/375 green. |
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Joseph Doherty
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26eb511a7e |
fix(mtconnect): review remediation for the driver lifecycle (Task 9)
Important 1 - the probe-model triple was read outside _lifecycle while every
write happened under it. Packed (Client, ProbeModel, ProbeModelDataItemCount)
into one immutable AgentSession swapped by a single Volatile.Write, matching
what _index already does, rather than locking the readers: both await the
network, so taking _lifecycle would stall a shutdown for a whole
RequestTimeoutMs and would widen the non-reentrancy hazard. GetOrFetch and
Flush re-publish via CompareExchange so a late re-cache cannot undo a
concurrent teardown/re-init, and a client disposed mid-fetch now surfaces as
the same "not connected" InvalidOperationException browse already handles
instead of a raw ObjectDisposedException.
Important 2 - HasConfigBody decided emptiness by matching the literals "{}" /
"[]", so "{ }", "{\n}" and every pretty-printed empty document fell through to
ParseOptions, failed the required-AgentUri check, and turned a semantically
empty config into a cold-start fault. Now parsed: an object/array with no
elements (or a bare null) is empty; malformed text is deliberately NOT empty so
ParseOptions produces the real quoted error rather than silently starting on
stale options.
Important 3 - documented the _lifecycle non-reentrancy hazard in the code, on
both the semaphore and StopSampleStreamAsync, naming Task 11's re-baseline as
the specific path that would deadlock and giving the CurrentAsync-directly
pattern that avoids it.
Important 4 - removed the Initialize/Reinitialize asymmetry rather than
documenting it. Both now share one rule via ResolveIncomingOptions: an
unreadable config document never destroys working state, and faults only a
driver that had none. InitializeAsync previously tore down before parsing, so a
bad document on a live instance destroyed a healthy client - the exact outcome
ReinitializeAsync was written to avoid.
Minors: SafeDispose traces the swallowed disposal fault at Debug (a client that
cannot be released is how a handle leak starts); the RequirePositive test is a
Theory over all four timing knobs, not just RequestTimeoutMs (arch-review
01/S-6); the footprint test no longer overclaims "is zero before initialize".
CannedAgentClient gains a one-shot ProbeGate so a lifecycle change landing
mid-request is deterministic - no timers. 346/346 (329 + 17). Six mutations
verified: fetch-CAS, disposed-translation, flush retired-session guard,
literal HasConfigBody, teardown-before-parse, and two dropped RequirePositive
calls each fail only their own tests.
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Joseph Doherty
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0dfc3e1077 |
feat(mtconnect): IReadable via /current, ordered per-ref snapshots (Task 10)
One deadline-bounded /current per batch, answered out of that one whole-device document: N references cost one round-trip, one snapshot each, in request order, duplicates included. DEVIATION (deliberate, from the plan's implied shared-index write): the response is indexed into a PER-CALL snapshot index, never into the driver's shared observation index. That index is written by Task 11's /sample pump and is last-write-wins with no timestamp arbitration; a read folding its /current into it would be a second writer racing the first, and /current is frequently the OLDER document (the Agent composes it while the pump's newer delta is in flight). Losing that race rolls a subscribed value backwards and leaves it there until the data item next changes. Both paths coerce through the same MTConnectObservationIndex logic, so a read and a subscription report a given observation identically -- the read path is simply a pure function of (document, authored tags). Failure posture is the inverse of InitializeAsync: nothing but genuine caller cancellation crosses the capability boundary. Unreachable Agent / blown deadline / unusable answer => every ref codes BadCommunicationError and the driver degrades (never downgrading Faulted); no client at all (pre-initialize, faulted, post-shutdown) => BadNotConnected with health untouched. The index's BadWaitingForInitialData / BadNodeIdUnknown / BadNoCommunication / BadNotSupported distinctions pass through unmodified. 21 tests pinning arity, order, duplicates, empty batch, one-round-trip, each Bad code, read-time freshness, the anti-clobber invariant, the deadline, and cancellation-propagates-but-agent-failure-does-not. CannedAgentClient gains a cancellation-observing CurrentGate (still no timers or sleeps of its own). Test csproj takes the AbCip/S7 OTOPCUA0001 NoWarn -- this suite calls the capability directly by design. 329/329 green. |
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Joseph Doherty
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b79df65d3e |
feat(mtconnect): driver shell IDriver lifecycle over agent-client seam (Task 9)
MTConnectDriver implements IDriver only: connection-free ctor, initialize (deadline-bounded /probe + /current, caching the device model, the agent instanceId, and a primed observation index), reinitialize, shutdown, health, footprint, and cache flush. Decisions worth knowing: - The driverConfigJson argument is HONOURED, not ignored. DriverInstanceActor delivers a config change only via ReinitializeAsync(json) on the live instance, so a driver reading only its ctor options would turn every MTConnect config edit into a silent no-op that still sealed the deployment green. ParseOptions lives on the driver; Task 15's factory must delegate to it rather than deserialize a second DTO. - /probe ok but priming /current failing is Faulted, not Healthy-with-no-data: the index IS the read surface and the /sample cursor comes from /current. - ReinitializeAsync rebuilds the client whenever ANY option the client reads at construction changed - AgentUri, DeviceName, RequestTimeoutMs, HeartbeatMs, SampleIntervalMs, SampleCount - not just the first two. The timing knobs are baked into the deadlines, the watchdog window, and the /sample query string. - An unparseable config faults a cold start but leaves a RUNNING driver serving its previous valid configuration (the deployment fails instead). - IMTConnectAgentClient now extends IDisposable rather than the driver doing `as IDisposable`, which would silently no-op against a non-disposable fake and leak an HttpClient + socket handler per re-deploy. Sync, not async: every resource behind the seam is sync-disposable, and the async unwind belongs to the SampleAsync enumerator the pump owns. - Flush drops the probe/browse cache and keeps the index; every model consumer goes through GetOrFetchProbeModelAsync so a flush cannot wedge browse. Tests: CannedAgentClient (shared, deterministic - channel-backed scripted /sample with no timers, call counts, disposal tracking, failure injection) + 27 lifecycle tests. 308/308 in the project. |