F10 follow-through: removing IDisposable outright broke a synchronous
drv.Dispose() call site outside this lane (Runtime.Tests
AbCipAlmaNativeAlarmEndToEndTests). The sync Dispose() is back, but it starts
the same teardown as DisposeAsync and returns instead of parking the caller on
DisposeAsync().AsTask().GetAwaiter().GetResult(); a background fault is
logged. The runtime still takes the IAsyncDisposable path (preferred, never
both).
Refs #737
Claude-Session: https://claude.ai/code/session_01Ub9hGmYLQvn9XETzw7CMsT
L4 evidence over the real native runtime and a fake CIP target: a renamed tag
that is the device's only lease holder is created once and Forward-Opened once
across five polls, with no Forward Close, every poll BadNodeIdUnknown and the
driver Healthy.
Refs #737
Claude-Session: https://claude.ai/code/session_01Ub9hGmYLQvn9XETzw7CMsT
P11: AbCipUdtReadPlanner called AbCipUdtMemberLayout.TryBuild(parent.Members)
for every member reference on every poll - O(members^2) per parent per tick,
a dictionary allocation each time. GetOrBuild caches the layout (including a
"not groupable" verdict) in a ConditionalWeakTable keyed by the member list's
identity, which is immutable for the life of the tag table; a re-init's new
lists replace the entries and the old ones are collected with them.
Refs #737
Claude-Session: https://claude.ai/code/session_01Ub9hGmYLQvn9XETzw7CMsT
U10 (user decision: implement array encode now): config, the AdminUI and
discovery all advertised array tags Operate-writable, but both runtimes encoded
a scalar - an int[] threw InvalidCastException (BadTypeMismatch AND Degraded),
a scalar wrote element 0 natively, and libplctag re-sent its whole last-read
buffer with element 0 patched (stale elements 1..n-1).
- AbCipArrayCodec encodes count elements little-endian at the element width,
CONVERTING each element (ScadaBridge writes int[] to INT arrays; overflow is
BadOutOfRange, unconvertible BadTypeMismatch, both before anything is sent).
- The driver checks the shape before any runtime exists: not a list ->
BadTypeMismatch, length != elementCount -> BadOutOfRange, BOOL/STRING/
structure element types -> BadNotSupported; and, before sending, a controller
buffer that is not width x count -> BadTypeMismatch. Refusals warn once and
write no health.
- Native: ONE Write Tag of count elements with the controller's type code (the
client fragments a large one); libplctag: the codec's bytes copied into the
elem_count-sized buffer, refused TooSmall if it does not fit.
- IAbCipTagRuntime.EncodeArray (default: NotSupportedException).
Real-controller proof is a hardware userGate (see the lane report recipe).
Refs #737
Claude-Session: https://claude.ai/code/session_01Ub9hGmYLQvn9XETzw7CMsT
U11: a scalar BOOL authored over Bits[n] requested element n and decoded
"any of bits 0-7 of the reply set", so Bits[n] read Good with the subscript
ignored. A Logix BOOL array is stored as DWORDs (0xD3) and its element segment
addresses them, so the native runtime now requests DWORD n / 32 and decodes bit
n % 32 when the controller answers 0xD3 (a plain BOOL reply still decodes its
byte). libplctag exposes no type code and so cannot say which DWORD it read: a
4-byte reply for such a tag is refused BadNotSupported (warned once) instead of
publishing a wrong value as Good. Real-controller proof is a hardware gate.
Refs #737
Claude-Session: https://claude.ai/code/session_01Ub9hGmYLQvn9XETzw7CMsT
H19: Format/InvalidCast/Overflow on a client value never touched the wire but
latched Degraded; a good write set Healthy and so undid a Degraded the poll
loop had just recorded for other tags (the batch read path is worst-wins for
exactly this reason).
- The three conversion failures map to BadTypeMismatch/BadOutOfRange with a
once-per-tag Warning and no health write (AbLegacy's rule).
- A good write (scalar or bit RMW) advances LastSuccessfulRead only - the
device answered - and leaves the state alone.
- A write comms fault (thrown, or a non-refusal status word, which used to
write no health at all) is Degraded with LastSuccessfulRead preserved and
never downgrades Faulted.
Refs #737
Claude-Session: https://claude.ai/code/session_01Ub9hGmYLQvn9XETzw7CMsT
H17: the .n read-modify-write hard-coded a DINT parent. On an INT or SINT host
(both legal in Logix, and reads of Flags.3 there already worked) the DINT
decode of a 2-byte buffer threw OutOfBounds, the generic catch evicted the BIT
tag's (non-existent) runtime and reported BadCommunicationError + Degraded.
The parent width now comes from the parent read's size (1 SINT / 2 INT /
4 DINT / 8 LINT; unknown keeps the DINT assumption). Narrow hosts use unsigned
arithmetic so a set top bit encodes without overflow; a bit past the host's
width is BadOutOfRange and a non-integer width BadTypeMismatch, both refused
before anything is written, warned once, no health write. A transport failure
in the RMW now evicts the parent runtime it actually used. Native end-to-end:
an INT host is written as ONE INT (type 0xC3, 2 bytes).
Refs #737
Claude-Session: https://claude.ai/code/session_01Ub9hGmYLQvn9XETzw7CMsT
P8: on the native transport the bounded-parallel read window is also the cap
on services per Multiple Service Packet (the device's shared scheduler packs
whatever is queued, within the connection's request/reply byte budget), so the
default 8 cost a 1000-tag controller ~125 round trips per poll instead of ~10.
The effective window (AbCipDriver.ReadWindow) is now max(64, option) when the
native tag factory serves reads; libplctag and injected factories keep the
option exactly. Option doc + AdminUI help text updated (Razor: Wave 4 live
check).
P7 addendum: a work item now takes its window slot only after its runtime
exists. A cold create queues on its device's single-flight connect gate, and
holding a slot there let one dead device's backoff-expiry attempt occupy the
whole window for a full Timeout, stalling every other device's reads.
Refs #737
Claude-Session: https://claude.ai/code/session_01Ub9hGmYLQvn9XETzw7CMsT
Found by the H13 stress test (200 re-inits under a concurrent reader): a read
that resolved the device just before the table swap could cold-create a
runtime into the retired state after its teardown had disposed it (leaked
native handle / lease), and could hit a per-tag SemaphoreSlim the teardown had
disposed, which the generic catch reported as a comms fault (Degraded).
- DeviceState.Retire marks the state retired before disposing handles; each
handle is removed-then-disposed exactly once. A creator re-checks the flag
after its TryAdd (fenced, Dekker-paired with Retire) and disposes the orphan.
- A failure on a retired device is the teardown's doing: BadCommunicationError
for that one call, no evict, no health signal.
- Per-tag/RMW gates are no longer disposed (async-only waits hold no handle),
matching the ConnectGate rationale.
Refs #737
Claude-Session: https://claude.ai/code/session_01Ub9hGmYLQvn9XETzw7CMsT
H10: the probe loop recorded EVERY exception - including the controller
answering NotFound for a typo'd or download-deleted Probe.ProbeTagPath - as a
Forward-Open failure. At a 5 s tick against a 30 s backoff cap ShouldAttempt
was never true again, so every cold or evicted data tag on a reachable device
read BadCommunicationError indefinitely and the host showed Stopped.
The probe now decides the backoff verdict and the host state separately:
- a device refusal (thrown or as a status word) is backoff success + host
Running + one Warning per device naming the probe tag; an initialised probe
runtime is kept so its lease is not re-opened every tick;
- a malformed probe tag name (AbCipTagConfigurationException) never reached
the device: no backoff signal, no host transition, one Warning;
- a genuine transport failure is unchanged (backoff failure, host Stopped).
Refs #737
Claude-Session: https://claude.ai/code/session_01Ub9hGmYLQvn9XETzw7CMsT
H1/L4: one classification (AbCipRefusals.IsDeviceRefusal) of the statuses
that prove the controller answered - NotFound, OutOfBounds, NotAllowed,
TooLarge, TooSmall, TypeMismatch, Unsupported - shared by the data path, the
Test-Connect probe (IsReachableStatus widened) and the native runtime.
- A refused read/write (thrown or as a status word) is per-tag Bad with a
once-per-tag Warning, keeps the runtime (no evict, so no lease/Forward-Open
churn for a sole lease holder), writes no Degraded and, since the device
answered, advances LastSuccessfulRead without touching the state.
- A refused cold create records the backoff as reachable, so siblings are no
longer throttled for up to 30 s by one Arr[999].
- The native runtime completes InitializeAsync on any refusal (it used to on
TypeMismatch/Unsupported only) and reports it on every later read.
- A refused READ of NotAllowed reads BadNotReadable, not BadNotWritable.
- Test Connect names the refusal ("probe tag refused: OutOfBounds").
0x1C/0x20/0xFF-0x2104 still fold into BadReply inside Driver.Ab.Transport
(Lane K follow-up); they remain comms faults until mapped there.
Refs #737
Claude-Session: https://claude.ai/code/session_01Ub9hGmYLQvn9XETzw7CMsT
H13: _devices/_devicesByRoutingKey are published by reference swap under a
lifecycle lock and never mutated after publish, so the retained poll engine,
discovery and the actor's GetHostStatuses pull never read a table mid-Clear.
Every retire (init's own release, shutdown, dispose) takes the table it
replaces, so ShutdownAsync racing DisposeAsync tears each state down once, and
a generation check makes an InitializeAsync overtaken by a shutdown publish
nothing (it throws OperationCanceledException) instead of resurrecting probe
loops behind the shutdown. Probe join is one bounded 5 s wait independent of
the caller token.
H21: _health is volatile and read-modify-write updates go through a CAS.
F10: the sync Dispose() (sync-over-async) is removed; DisposeAsync is the
complete, idempotent teardown the runtime calls after ShutdownAsync.
Refs #737
Claude-Session: https://claude.ai/code/session_01Ub9hGmYLQvn9XETzw7CMsT
GalaxyTelemetryTests (ActivityListener) and GatewayGalaxyDataWriterFailClosedTests
(MeterListener, filtered only by meter and instrument name) observe every Galaxy span or
measurement in the process. They now run in a collection with parallelization disabled
(F-FU6), because a parallel driver test, or its background probe seed, polluted their counts.
The stream-cancel assertion in GalaxyDriverShutdownTests goes back to a bounded wait: the
instantaneous IsCompleted check introduced in round 1 was racy.
Refs #735
Claude-Session: https://claude.ai/code/session_01Ub9hGmYLQvn9XETzw7CMsT
Review fix round 2 for lane F:
- N1: the init platform seed no longer runs inline under the init token. Galaxy's Tier-A
Initialize budget is 5 s, and a cold gateway DiscoverHierarchy can spend all of it, so the
OperationCanceledException rethrow failed init, opened the Initialize breaker and cost a full
rebuild per retry. InitializeAsync now only resolves the platform source (no network) and
queues a background seed tied to a per-runtime CTS that the teardown cancels. A result that
lands after its runtime was torn down is discarded.
- N2: the seed worker serves the runtime that is live when each pass STARTS, so a request made
under a new runtime while a stale pass is in flight always gets a pass of its own.
- N3: SubscribeAsync and the subscribe-once read capture the runtime generation before
SubscribeBulk and register only if it is unchanged, atomically with the teardown's registry
Clear (_registryGate). On a mismatch they release the handles and fail the call. Re-subscribe
Rebind uses the same gate, and the production rebuild clears the registry unconditionally.
- PerPlatformProbeWatcher re-checks its stop after the SubscribeBulk await, atomically with
the record and publish. A pass that straddles StopAsync releases the handles it acquired
instead of writing the probe entry back into a cleared registry.
Refs #735
Claude-Session: https://claude.ai/code/session_01Ub9hGmYLQvn9XETzw7CMsT
The writer concurrency fake parks on its release signal (the 300 ms delay could release the
gate early on a starved pool), the supervisor test's cross-thread hold flag is Volatile, and
the EffectiveTimeout doc now states the 1 s floor the code and tests implement.
Refs #735
Claude-Session: https://claude.ai/code/session_01Ub9hGmYLQvn9XETzw7CMsT
Review fix round 1 for lane F:
- The ScanState probe watcher is seeded at InitializeAsync from a platform-only
DiscoverHierarchy query (IGalaxyPlatformSource / GatewayGalaxyPlatformSource over the owned
repository client) and re-seeded on every deploy-watcher rediscovery. The runtime never
calls DiscoverAsync on a live driver, so per-platform host status was unreachable in
production. A failed fetch logs a Warning and never fails init; re-seeds coalesce so a
deploy during an in-flight pass still gets a pass that starts after it.
- EnsureEventPumpStarted refuses while the runtime is stopping, BEFORE reusing the live pump
(that pump belongs to the dying subscriber), and the production rebuild disposes any stale
pump before wiring the new subscriber.
- TeardownRuntimeAsync closes the MX session under the caller's token linked with a 5 s
SessionCloseDeadline, so a blackholed gateway cannot hold DriverInstanceActor.PostStop for 30 s.
- A runtime generation counter, bumped by every teardown, is re-checked before each Rebind
in ResubscribeAllAsync, so a replay-gap re-snapshot that straddles a teardown cannot
resurrect handles into the cleared registry.
Refs #735
Claude-Session: https://claude.ai/code/session_01Ub9hGmYLQvn9XETzw7CMsT
The SDK's DisposeAsync closes with no token, i.e. under the 30 s DefaultCallTimeout, so a
blackholed gateway parked the driver's teardown for the whole of it. CloseAsync(ct) runs the
close under the caller's token, drops the channel on a cancelled/failed close (the gateway
reaps the session on its idle lease) and leaves the session re-openable. A close followed by
the final dispose closes the gateway session once.
Refs #735
Claude-Session: https://claude.ai/code/session_01Ub9hGmYLQvn9XETzw7CMsT
Review 2026-10-21 G-5, G-6, G-8 ("wire them all").
- G-5: GatewayGalaxyHierarchySource now pages the DiscoverHierarchy RPC
itself (DiscoverHierarchyRawAsync) at Repository.DiscoverPageSize. The
mxaccessgw client's typed DiscoverHierarchyAsync overloads hard-code a
5000-row page and DiscoverHierarchyOptions carries no page size, so the
authored knob reached nothing; the raw request takes page_size on the
wire, so it is honoured here (non-positive → 5000). The loop keeps the
client's repeated-page-token guard.
- G-6: GalaxyDriverProbe reads ProbeTimeoutSeconds from the config and
runs under min(caller budget, configured cap) — the knob can shorten a
probe, never extend it past the host's budget. The TCP preflight now
shares that deadline instead of hanging on the caller's token alone.
- G-8: GatewayGalaxyDataWriter runs a batch as one lane per distinct tag,
concurrently and bounded at 8 (MaxConcurrentWriteLanes); same-tag
writes keep their authored order inside one lane and results land at
their request's index. Acks stay serial by design.
- GalaxyDriverForm: help text now says what the two knobs actually do.
Refs #735
Claude-Session: https://claude.ai/code/session_01Ub9hGmYLQvn9XETzw7CMsT
Review 2026-10-21 G-4, G-7, G-11, G-10.
- G-4: PerPlatformProbeWatcher publishes its probe handles into the
driver's SubscriptionRegistry under the reserved ProbeSubscriptionId
(-1), so the EventPump's fan-out finally reaches the watcher — every
ScanState event used to be dropped as "stale after unsubscribe" and
per-platform host status never updated. ResubscribeAllAsync delegates
the reserved entry to the watcher's new ResubscribeAsync, so the probe
survives a reconnect; StopAsync removes the entry. Probe traffic is
routed by the reserved handle and never reaches the public OnDataChange.
The watcher is also built on the seam path (subscriber only), which is
what makes the wiring testable without a gateway.
- G-7: GalaxyDiscoverer.DiscoverAsync returns the hierarchy it fetched and
the driver selects its $WinPlatform/$AppEngine probe targets from that
same sweep instead of asking the gateway for the whole galaxy twice.
- G-11: OnPumpDataChange stamps LastSuccessfulRead from inbound stream
data, throttled (1 s default), so the comms-loss watchdog has honest
liveness evidence under a Degraded supervisor.
- G-10: an EventPump dispatch-loop exit that is not a cancellation now
reports a stream fault so the supervisor recreates the pump, instead of
leaving a deaf pump reporting Healthy.
Refs #735
Claude-Session: https://claude.ai/code/session_01Ub9hGmYLQvn9XETzw7CMsT
GalaxyDriver.ShutdownAsync was a no-op: the MX session, both owned gRPC
channels, the EventPump, the alarm feed, the DeployWatcher, the probe
watcher and the reconnect supervisor were released only by DisposeAsync,
which the host never calls — one leaked gateway session per respawn,
removal and /raw browse, and a watchdog Shutdown→Initialize that neither
tore down nor rebuilt anything (review 2026-10-21 G-1, G-2, G-9, G-3).
- ShutdownAsync and DisposeAsync share one ordered TeardownRuntimeAsync
(supervisor first, then deploy/probe watchers, pump, alarm feed,
session, channels); owned seams are nulled so the next InitializeAsync
rebuilds; injected seams survive a shutdown and drop only on the final
dispose. Lifecycle calls are serialised behind a gate.
- A failed production connect releases its partial runtime (no orphaned
client per watchdog retry) and lands Faulted before and after.
- StartDeployWatcherAsync stops the previous watcher before starting a
replacement, and now starts on a production instance's FIRST
InitializeAsync (the old guard returned whenever discovery had not run
here, which on a runtime instance is always).
- ReconnectSupervisor releases each cycle's CancellationTokenSource when
its loop exits and gains an awaitable StopAsync; PerPlatformProbeWatcher
gains an awaitable StopAsync.
- EventPump treats any exception under cancellation as a clean stop, so a
teardown never wakes the supervisor.
- Internal seams for tests: an IGalaxyDeployWatchSource ctor parameter and
a session-open override forwarded to the owned GalaxyMxSession.
Refs #735
Claude-Session: https://claude.ai/code/session_01Ub9hGmYLQvn9XETzw7CMsT
Review R08:1.1: an uncapped HistoryRead-Raw (NumValuesPerNode = 0) read a
tag's whole window into memory on every backend (SQL TOP(int.MaxValue),
QuestDB LIMIT, Gateway max_values = int.MaxValue + a second snapshot copy).
New ServerHistorian:MaxRawValuesPerRead (default 10 000; <= 0 unbounded with
a Validate() warning; 1 raised to 2). Each backend data source takes it,
reports it as IHistorianDataSource.MaxRawValuesPerRead (the Gateway: min
with a strict gateway's learned ceiling), so the node manager's existing
RawPageLimit paging serves N = 0 and N > cap as pages of at most the cap
with a continuation point. Independently, a backend raw read asking for 0
or more than the cap reads cap + 1 rows and is REFUSED
(HistoryReadLimitExceededException => BadTooManyOperations) when the window
holds more - never answered truncated, since the server's paging reads a
short answer as the last page. Bound through the Host registry, the
SqlServer/QuestDb providers and GatewayHistorian.CreateDataSource.
Tests: options (default/binding/warnings), provider binding, Gateway unit +
through a real SDK node manager (uncapped -> 999/998/998/605 + CPs), and a
conformance case for the SQL backends.
Refs #736
Claude-Session: https://claude.ai/code/session_01Ub9hGmYLQvn9XETzw7CMsT
The #687/F4 crowding re-read doubled its room up to 8 re-reads with no cap, so a pathological single-ms
cluster on a streaming gateway was streamed several times over for one page. The room is now capped at
ServerHistorian:MaxTieClusterOverfetch (plumbed into GatewayHistorianDataSource as maxPreWindowRows,
default 65536); past it, or once a read has already seen more, the read is BadTooManyOperations with
PreWindowRows set.
Item 1: IHistorianDataSource.MaxRawValuesPerRead (Gateway: learned ceiling - 16 = L; 0 elsewhere, guard-tested).
RawPageLimit plans every raw page on top of #692's lookahead: with L > 0 the read (page P + boundary ties k
+ lookahead) is <= L, P = min(N, L - k - 1) (uncapped: L - k - 1); no room => straight to the tie-cluster
over-fetch (never an uncapped or underflowing request). One re-plan + re-read when the read taught a new
limit or was refused for crowding pre-window rows (HistoryReadLimitExceededException.PreWindowRows): the
page shrinks by them. Over-fetch bound min(MaxTieClusterOverfetch, L - 1); slice size never 0.
Review fixes: F1 a window starting at/before the epoch counts AVEVA's synthetic row as pre-window (a
ceiling-truncated read was reported complete); F2 the page path disables ReverseRawReader's own re-run
(cold end-only ceiling 20/N=3000 cost 3,023 reads, now <= 40); F3 crowded look-back re-read around, not
refused; F4 the #687 crowding re-read room at least doubles (up to 8 re-reads), so a cluster of hundreds
just before a resume point no longer fails on a default gateway; a crowding refusal that leaves no room
is BadTooManyOperations, never a tick-by-tick cursor.
Item 2: ServerHistorian:EventReadHorizon (default 00:00:00 = exact, unchanged). When set, every fresh
HistoryReadEvents window's earlier bound is raised to now - horizon (both directions, all backends).
Lossy by design; documented.
Item 3 (native TimeAverage/Total re-check) stays blocked on historiangw#27.
A time inside a gap of a bursty tag costs a 64-row jump read landing in the next
burst plus a bisection back across the gap (~6 reads), so the 64 + 4/time cap
refused a 1 h/day 1 Hz tag asked at noon on 30/100/300 consecutive days
(186/606/1,806 reads) that AVEVA's own AtTime served. The cap is a runaway guard
(HistoryReadDeadline bounds wall clock): now 64 + 16 per distinct time.
Regression tests for x30/x100/x300 (each <= 7 reads a time, values checked).
Docs: DateTime-hinted nodes are stepped but keep the gateway's Double (the
Gateway never historizes DateTime nodes; the SQL backends return DateTime).
H1: the walk-back reset its width after a full segment and discarded a full
whole-remainder read, so a dense tag that stopped reporting weeks ago gave up
after 65 reads (BadTooManyOperations). It now gallops (x4, whole-remainder read
after two empties) and then BISECTS once any stored row is known below — a full
segment's (incl. a full whole-remainder read's) last row, or an earlier window
read's last row: (mid, hi] empty => hi = mid; full => known = its last row;
complete with rows => done; one density-aimed segment after a full read until an
aimed segment comes back empty; below 2 ms the whole stretch from the known row
(never a 100 ns step). Stopped 1 h..365 d with 5 y history: 6-18 reads at
1/min, 21-25 at 1 Hz, 25-31 at 10 Hz.
M1: a jump read asks for 64 rows (1,000 times over 10 y: ~66k rows, was ~1M).
L1: per-request read cap 64 + 4 x distinct times with a clear message; a strict
ceiling below 4 rows is refused naming the ceiling.
L2: DateTime hints are stepped. L3: under an integer hint a NaN/inf or
out-of-Int64-range value is unusable, never saturated Good.
L5: conformance Int64 AtTime asserts the type. L4: docs name the backend
differences. Nit: the window read end is clamped to now + 1 day.
Reviewer harnesses (Scratch693Fuzz/Cost, not committed): 0 differential diffs
over 2,400 cases.
Review follow-up: on the Gateway every value is a Double (AVEVA stores a Boolean
as a 0/1 Int2), so the raw-evaluated AtTime interpolated a Boolean node to 0.5.
- IHistorianDataSource gains a default-interface overload
ReadAtTimeAsync(fullReference, timestamps, TypeCode? valueType, ct) that
forwards to the existing one (SqlServer/QuestDB/Null/fakes unchanged).
- OtOpcUaNodeManager.HistoryReadAtTime passes the node's scalar DataType
(AtTimeValueType: built-in type -> TypeCode; arrays/other types => null);
Raw and UNS NodeIds alike.
- GatewayAtTimeReader converts each raw row to the hinted kind BEFORE the shared
AtTimeEvaluator runs (Boolean = value != 0 => stepped; integers => Int64 =>
interpolated, rounded half away from zero, returned as the node's integer
type; floats Double), so the evaluator's own type branch decides.
- AtTimeEvaluator boxed every interpolated Int64 as a Double (`cond ? (long)x :
v` widens to double); its "keeping its type" test passed because Shouldly
ShouldBe compares numbers across types. Fixed (affects SqlServer/QuestDB too)
and pinned with ShouldBeOfType.
Gateway HistoryRead-AtTime passed AVEVA's own interpolation through: live it
answered the previous value as Good at a stored NULL's own time, null + Bad at
a Good sample right after a NULL, a drifted 99.99999999944 for a stored 100,
and no Interpolated bit. It is now served from raw gateway reads and evaluated
with Sql.Common's AtTimeEvaluator, as the SQL backends do (Part 11 §6.5.4).
GatewayAtTimeReader: one <=1,024-row forward window read [first-1ms, last+1ms]
for the batch, a walk-back (density-seeded, x4 growth, whole-remainder shortcut,
bisects dense history) for the first time's prev, and an 18-row probe for the
last time's next; truncated window reads continue or jump with a density-sized
margin. All bounds whole ms; a row counts only strictly inside its request
(AVEVA's boundary row never a sample); Bad rows value-less (#690); never past
now + 1 day; strict-gateway ceiling learned (#691.3) without re-probing.
10 dense times = 1 read (exact) / 3 (interpolated); 10 hourly = 12.
Kill switch ServerHistorian:GatewayAtTimeFromRaw (default true; false = the
old AVEVA passthrough). Known limit: the wire carries no data type, so numeric
tags interpolate as Double (Boolean/integer nodes are not stepped/rounded as on
the SQL backends).
1. The at-or-after bound read on a forward-only backend (Gateway) ends at
now + ReverseRawReader.LookAhead instead of DateTime.MaxValue (the gateway
only checks start <= end, so a year-9999 end reached AVEVA); a bound beyond
the horizon is not found without a read. SqlServer/QuestDB keep MaxValue:
they bind it safely and may hold samples further ahead. The Gateway fake now
refuses far-future ends, so the missing-end-bound test is no longer vacuous.
3. No data and no bound found (whole read empty) => GoodNoData, no values —
the pre-bounds answer (6.5.3.2: success only if one or both bounds exist).
A one-value page whose start bound is missing first checks there is data or
a found end bound.
4. ServerHistorian:HonorReturnBounds (default true); false ignores ReturnBounds
as before #691, including the modified-read Bad_InvalidArgument.
The start bound is the stored prior sample at its own time (walked back), never
the synthetic boundary row stamped at the query start; a stored NULL is a Bad
bound; reverse end bound walks back too.
The node manager composes the start/end bounds from each backend's existing raw
reads (one authority, HistoryBounds): at-or-before = a capped reverse read
(native, or ReverseRawReader's walk-back on a forward-only backend — never
AVEVA's synthetic boundary row), at-or-after = a capped forward read. Bounds
count toward NumValuesPerNode, the start bound leads the first page, the end
bound ends the last (carried in the continuation point). Missing bound =
Bad_BoundNotFound (null, at the bound time; one-sided reads ±1 s from the
previous value, Table 1 footnotes a/b). A modified read with ReturnBounds is
Bad_InvalidArgument (Part 11 6.5.3.3).
The .NET SDK's ReadRawModifiedDetails defaults ReturnBounds to TRUE; the
existing tests built details without setting it and now set it false.
Oracle: every row of Part 11 Table 1 over three backend shapes, plus paging
concatenation, ties, Bad bounds, microsecond truncation; conformance pins the
lookup primitives on SqlServer + QuestDB.
GatewayHistorianDataSource.ReadEventsAsync sized its result list to
maxEvents, which is int.MaxValue for NumValuesPerNode = 0: every
uncapped Gateway events read (forward on master, and the new walked
reverse one) threw 'Array dimensions exceeded' and counted as a backend
failure. Capacity is bounded at 1024. The events walk delegate moved to
ReverseEventsReader so it is tested over the real Gateway source
(forward uncapped, reverse uncapped, reverse capped).
A reverse or end-only capped events read on a backend without
SupportsReverseEvents (Gateway, Null) was refused
BadHistoryOperationUnsupported (explicit reverse) or answered with the
OLDEST N ascending (end-only, #675). It is now served newest-first by
the same ReverseWalk as raw reads: page-sized ms-aligned segments,
never answered from a read the source flagged truncated, ties sorted by
EventId (the gateway orders by event time only - the fake shuffles
them per call), one extra event walked to signal 'more', uncapped = one
forward read reversed, and the width + proven-empty stretch carried in
the events cursor. The oversized-cluster over-fetch keeps exactly the
events at T in the same order. A tie cluster over the budget is
BadTooManyOperations. Docs note the gateway's EventReadMaxRows must be
unlimited (it truncates silently).
With StartTime at or before the epoch, RequestStartFor has no margin left, so
AVEVA's synthetic no-data/boundary row is stamped exactly at StartTime and was
kept: raw reads returned a fabricated Bad sample at 1970-01-01 and the per-sample
aggregates put it in bucket 0 (Start/End fabricated, Min/Max status Uncertain).
IsWindowSample and the aggregate loop now drop any row with t <= ProbeFloor
(RawAggregateReader.IsAfterFloor), matching the #686 walk-back's assumption.
- M1/M2: when the 1 ms pre-window margin (boundary row + stored samples, e.g. a
>16-sample tie cluster at start-1ms / lastTs-1ms) uses up the cap + 16 budget,
re-read ONCE asking for cap + m + 16 (m = pre-window rows seen); fail
BadTooManyOperations only if the re-read is still short because of them. The
raw budget is no longer clamped at the gateway default ceiling (AVEVA always
emits the boundary row, so page sizes 999,985-1,000,000 always came back
short); the #688 clamp stays on the per-sample aggregate path only.
- Merge trap: NumValuesPerNode 0 => int.MaxValue, never through the clamp.
- L3: the forward end is exclusive ([start, end), the IHistorianDataSource
contract); a point read (start == end, the tie-cluster over-fetch) inclusive.
- RequestStartFor never goes before the Unix epoch (#686's walk-back floor).
- L4 (docs): an Uncertain native row for an all-NULL interval is unverified live.
The default MaxTimeWeightedRawRows (1,000,000) + 18 exceeded the gateway's
default MaxValuesCeiling (1,000,000), so with AllowStreamingBeyondCeiling=false
every Gateway per-sample aggregate read was refused. The allowance is now clamped
at 1,000,000 while the cap is at or under it (RawAggregateReader.
ClampToGatewayCeiling); a cap above it keeps its allowance. Raw reads are not
clamped (rebased onto #686).
Joseph Doherty