diff --git a/src/Drivers/ZB.MOM.WW.OtOpcUa.Driver.AbCip.Contracts/AbCipDriverOptions.cs b/src/Drivers/ZB.MOM.WW.OtOpcUa.Driver.AbCip.Contracts/AbCipDriverOptions.cs
index 24c9a74b..4e730422 100644
--- a/src/Drivers/ZB.MOM.WW.OtOpcUa.Driver.AbCip.Contracts/AbCipDriverOptions.cs
+++ b/src/Drivers/ZB.MOM.WW.OtOpcUa.Driver.AbCip.Contracts/AbCipDriverOptions.cs
@@ -82,6 +82,18 @@ public sealed class AbCipDriverOptions
///
public bool EnableDeclarationOnlyUdtGrouping { get; init; }
+ ///
+ /// Upper bound on how many planned read work items (whole-UDT groups + per-tag fallbacks)
+ /// one ReadAsync batch may have in flight against the controller at once. Bounds
+ /// concurrency ACROSS tags only — the per-tag runtime lock (05/STAB-4) still serialises
+ /// Read → GetStatus → Decode against any one cached libplctag handle, so the same tag
+ /// requested twice in a batch never overlaps itself. Raising it lets libplctag overlap
+ /// device round trips (the whole point: a strictly sequential batch pays one full round
+ /// trip per tag); lowering it to 1 restores strictly sequential reads. Values below
+ /// 1 are clamped to 1 at the use site.
+ ///
+ public int MaxConcurrentReads { get; init; } = 8;
+
///
/// Timeout for the AdminUI Test Connect probe, in seconds. The AdminUI clamps to a
/// 60s server-side maximum; this default is what the form pre-fills for new instances.
diff --git a/src/Drivers/ZB.MOM.WW.OtOpcUa.Driver.AbCip/AbCipDriver.cs b/src/Drivers/ZB.MOM.WW.OtOpcUa.Driver.AbCip/AbCipDriver.cs
index 25e2625e..b07b76c9 100644
--- a/src/Drivers/ZB.MOM.WW.OtOpcUa.Driver.AbCip/AbCipDriver.cs
+++ b/src/Drivers/ZB.MOM.WW.OtOpcUa.Driver.AbCip/AbCipDriver.cs
@@ -590,22 +590,125 @@ public sealed class AbCipDriver : IDriver, IReadable, IWritable, ITagDiscovery,
var plan = AbCipUdtReadPlanner.Build(
fullReferences, _tagsByRawPath, _options.EnableDeclarationOnlyUdtGrouping);
- foreach (var group in plan.Groups)
- await ReadGroupAsync(group, results, now, cancellationToken).ConfigureAwait(false);
+ var groups = plan.Groups;
+ var fallbacks = plan.Fallbacks;
+ var itemCount = groups.Count + fallbacks.Count;
+ if (itemCount == 0) return results;
- foreach (var fb in plan.Fallbacks)
- await ReadSingleAsync(fb, fullReferences[fb.OriginalIndex], results, now, cancellationToken).ConfigureAwait(false);
+ // Bounded-parallel window ACROSS work items (groups ∪ fallbacks). Each item still takes its
+ // OWN per-tag runtime lock inside ReadGroupAsync / ReadSingleAsync, so one libplctag handle
+ // is never touched concurrently (05/STAB-4) — the window only lets DIFFERENT tags' device
+ // round trips overlap, which a strictly sequential await chain made impossible. Results are
+ // index-addressed, so completion order is irrelevant. Per-item health verdicts are COLLECTED
+ // and written once after the batch: an inline write to the shared _health field would race.
+ var maxConcurrent = Math.Max(1, _options.MaxConcurrentReads);
+ var outcomes = new ReadOutcome[itemCount];
+ using var window = new SemaphoreSlim(maxConcurrent, maxConcurrent);
+ var tasks = new Task[itemCount];
+ for (var i = 0; i < itemCount; i++)
+ tasks[i] = RunItemAsync(i);
+ // Task.WhenAll completes only once EVERY item has finished (it does not short-circuit on the
+ // first fault), so disposing the window on the way out can never pull the semaphore out from
+ // under an item still waiting on it.
+ await Task.WhenAll(tasks).ConfigureAwait(false);
+
+ ApplyBatchHealth(outcomes, now);
return results;
+
+ async Task RunItemAsync(int slot)
+ {
+ // Acquire OUTSIDE the try: a wait that throws never acquired, so it must not release.
+ await window.WaitAsync(cancellationToken).ConfigureAwait(false);
+ try
+ {
+ if (slot < groups.Count)
+ {
+ outcomes[slot] = await ReadGroupAsync(groups[slot], results, now, cancellationToken)
+ .ConfigureAwait(false);
+ }
+ else
+ {
+ var fb = fallbacks[slot - groups.Count];
+ outcomes[slot] = await ReadSingleAsync(
+ fb, fullReferences[fb.OriginalIndex], results, now, cancellationToken)
+ .ConfigureAwait(false);
+ }
+ }
+ finally
+ {
+ window.Release();
+ }
+ }
}
- private async Task ReadSingleAsync(
+ ///
+ /// One read work item's health verdict. Returned by /
+ /// instead of written to the shared health field inline, because
+ /// under the bounded-parallel read window those writes would race (last-writer-wins across
+ /// threads could report Healthy for a batch that mostly failed, or vice versa).
+ /// A null means "no health signal" — a config-level miss such as an
+ /// unknown reference or unknown device, which never touched the wire and never touched health.
+ ///
+ private readonly record struct ReadOutcome(DriverState? State, string? Error)
+ {
+ /// The item produced no health signal at all.
+ public static ReadOutcome None => new(null, null);
+
+ /// The item read successfully.
+ public static ReadOutcome Success => new(DriverState.Healthy, null);
+
+ /// The item failed on the wire.
+ /// The failure detail surfaced as LastError.
+ public static ReadOutcome Degraded(string message) => new(DriverState.Degraded, message);
+ }
+
+ private static int HealthRank(DriverState state) => state switch
+ {
+ DriverState.Faulted => 2,
+ DriverState.Degraded => 1,
+ _ => 0,
+ };
+
+ ///
+ /// Write the batch's health ONCE, after every work item has finished: worst outcome wins
+ /// (Faulted > Degraded > Healthy) and LastSuccessfulRead advances if ANY item
+ /// succeeded — the contract the comms-loss watchdog reads (a success advances it; a batch
+ /// where everything failed freezes it, which is what trips the watchdog).
+ ///
+ private void ApplyBatchHealth(ReadOnlySpan outcomes, DateTime now)
+ {
+ var anySuccess = false;
+ DriverState? worst = null;
+ string? worstError = null;
+ foreach (var outcome in outcomes)
+ {
+ if (outcome.State is not { } state) continue;
+ if (state == DriverState.Healthy) anySuccess = true;
+ if (worst is null || HealthRank(state) > HealthRank(worst.Value))
+ {
+ worst = state;
+ worstError = outcome.Error;
+ }
+ }
+
+ // Nothing reached the wire (every reference was unknown / unroutable) — leave health alone,
+ // exactly as the per-item writes did before.
+ if (worst is not { } worstState) return;
+
+ _health = new DriverHealth(
+ worstState,
+ anySuccess ? now : _health.LastSuccessfulRead,
+ worstState == DriverState.Healthy ? null : worstError);
+ }
+
+ private async Task ReadSingleAsync(
AbCipUdtReadFallback fb, string reference, DataValueSnapshot[] results, DateTime now, CancellationToken ct)
{
if (!_resolver.TryResolve(reference, out var def))
{
results[fb.OriginalIndex] = new DataValueSnapshot(null, AbCipStatusMapper.BadNodeIdUnknown, null, now);
- return;
+ return ReadOutcome.None;
}
// A Structure tag whose Members are declared is a container —
// its bare name is readable via the whole-UDT grouping path (ReadGroupAsync), not the
@@ -614,12 +717,12 @@ public sealed class AbCipDriver : IDriver, IReadable, IWritable, ITagDiscovery,
if (def.DataType == AbCipDataType.Structure && def.Members is { Count: > 0 })
{
results[fb.OriginalIndex] = new DataValueSnapshot(null, AbCipStatusMapper.BadNotSupported, null, now);
- return;
+ return ReadOutcome.None;
}
if (!_devicesByRoutingKey.TryGetValue(def.DeviceHostAddress, out var device))
{
results[fb.OriginalIndex] = new DataValueSnapshot(null, AbCipStatusMapper.BadNodeIdUnknown, null, now);
- return;
+ return ReadOutcome.None;
}
try
@@ -644,13 +747,11 @@ public sealed class AbCipDriver : IDriver, IReadable, IWritable, ITagDiscovery,
EvictRuntime(device, def.Name);
results[fb.OriginalIndex] = new DataValueSnapshot(null,
AbCipStatusMapper.MapLibplctagStatus(status), null, now);
- _health = new DriverHealth(DriverState.Degraded, _health.LastSuccessfulRead,
- $"libplctag status {status} reading {reference}");
_logger.LogWarning(
"AbCip read returned non-zero libplctag status {LibplctagStatus} for tag {Tag} on device {Device}; " +
"evicting cached runtime so next call re-creates it",
status, reference, def.DeviceHostAddress);
- return;
+ return ReadOutcome.Degraded($"libplctag status {status} reading {reference}");
}
var tagPath = AbCipTagPath.TryParse(def.TagPath);
@@ -662,7 +763,7 @@ public sealed class AbCipDriver : IDriver, IReadable, IWritable, ITagDiscovery,
? runtime.DecodeArray(def.DataType, Math.Max(1, def.ElementCount))
: runtime.DecodeValue(def.DataType, bitIndex);
results[fb.OriginalIndex] = new DataValueSnapshot(value, AbCipStatusMapper.Good, now, now);
- _health = new DriverHealth(DriverState.Healthy, now, null);
+ return ReadOutcome.Success;
}
finally
{
@@ -679,10 +780,10 @@ public sealed class AbCipDriver : IDriver, IReadable, IWritable, ITagDiscovery,
EvictRuntime(device, def.Name);
results[fb.OriginalIndex] = new DataValueSnapshot(null,
AbCipStatusMapper.BadCommunicationError, null, now);
- _health = new DriverHealth(DriverState.Degraded, _health.LastSuccessfulRead, ex.Message);
_logger.LogWarning(ex,
"AbCip read transport exception for tag {Tag} on device {Device}",
reference, def.DeviceHostAddress);
+ return ReadOutcome.Degraded(ex.Message);
}
}
@@ -693,7 +794,7 @@ public sealed class AbCipDriver : IDriver, IReadable, IWritable, ITagDiscovery,
/// the mapped fault across every grouped member only — sibling groups + the
/// per-tag fallback list are unaffected.
///
- private async Task ReadGroupAsync(
+ private async Task ReadGroupAsync(
AbCipUdtReadGroup group, DataValueSnapshot[] results, DateTime now, CancellationToken ct)
{
var parent = group.ParentDefinition;
@@ -701,7 +802,7 @@ public sealed class AbCipDriver : IDriver, IReadable, IWritable, ITagDiscovery,
if (!_devicesByRoutingKey.TryGetValue(parent.DeviceHostAddress, out var device))
{
StampGroupStatus(group, results, now, AbCipStatusMapper.BadNodeIdUnknown);
- return;
+ return ReadOutcome.None;
}
try
@@ -722,13 +823,11 @@ public sealed class AbCipDriver : IDriver, IReadable, IWritable, ITagDiscovery,
EvictRuntime(device, parent.Name);
var mapped = AbCipStatusMapper.MapLibplctagStatus(status);
StampGroupStatus(group, results, now, mapped);
- _health = new DriverHealth(DriverState.Degraded, _health.LastSuccessfulRead,
- $"libplctag status {status} reading UDT {group.ParentName}");
_logger.LogWarning(
"AbCip whole-UDT read returned non-zero libplctag status {LibplctagStatus} for parent {Parent} " +
"on device {Device}; {MemberCount} member values stamped with mapped status",
status, group.ParentName, parent.DeviceHostAddress, group.Members.Count);
- return;
+ return ReadOutcome.Degraded($"libplctag status {status} reading UDT {group.ParentName}");
}
foreach (var member in group.Members)
@@ -736,7 +835,7 @@ public sealed class AbCipDriver : IDriver, IReadable, IWritable, ITagDiscovery,
var value = runtime.DecodeValueAt(member.Definition.DataType, member.Offset, bitIndex: null);
results[member.OriginalIndex] = new DataValueSnapshot(value, AbCipStatusMapper.Good, now, now);
}
- _health = new DriverHealth(DriverState.Healthy, now, null);
+ return ReadOutcome.Success;
}
finally
{
@@ -751,10 +850,10 @@ public sealed class AbCipDriver : IDriver, IReadable, IWritable, ITagDiscovery,
{
EvictRuntime(device, parent.Name);
StampGroupStatus(group, results, now, AbCipStatusMapper.BadCommunicationError);
- _health = new DriverHealth(DriverState.Degraded, _health.LastSuccessfulRead, ex.Message);
_logger.LogWarning(ex,
"AbCip whole-UDT read transport exception for parent {Parent} on device {Device}",
group.ParentName, parent.DeviceHostAddress);
+ return ReadOutcome.Degraded(ex.Message);
}
}
diff --git a/src/Drivers/ZB.MOM.WW.OtOpcUa.Driver.AbCip/AbCipDriverFactoryExtensions.cs b/src/Drivers/ZB.MOM.WW.OtOpcUa.Driver.AbCip/AbCipDriverFactoryExtensions.cs
index da0fd469..6d8e176c 100644
--- a/src/Drivers/ZB.MOM.WW.OtOpcUa.Driver.AbCip/AbCipDriverFactoryExtensions.cs
+++ b/src/Drivers/ZB.MOM.WW.OtOpcUa.Driver.AbCip/AbCipDriverFactoryExtensions.cs
@@ -85,6 +85,7 @@ public static class AbCipDriverFactoryExtensions
EnableAlarmProjection = dto.EnableAlarmProjection ?? false,
AlarmPollInterval = TimeSpan.FromMilliseconds(dto.AlarmPollIntervalMs ?? 1_000),
EnableDeclarationOnlyUdtGrouping = dto.EnableDeclarationOnlyUdtGrouping ?? false,
+ MaxConcurrentReads = dto.MaxConcurrentReads ?? 8,
};
}
@@ -147,6 +148,13 @@ public static class AbCipDriverFactoryExtensions
///
public bool? EnableDeclarationOnlyUdtGrouping { get; init; }
+ ///
+ /// Gets or sets the maximum number of read work items one ReadAsync batch may have in
+ /// flight against the controller at once. Bounds concurrency across tags only; the per-tag
+ /// runtime lock still serialises operations on any one handle. Defaults to 8; 1 is sequential.
+ ///
+ public int? MaxConcurrentReads { get; init; }
+
///
/// Gets or sets the alarm poll interval in milliseconds.
///
diff --git a/tests/Drivers/ZB.MOM.WW.OtOpcUa.Driver.AbCip.Tests/AbCipParallelReadTests.cs b/tests/Drivers/ZB.MOM.WW.OtOpcUa.Driver.AbCip.Tests/AbCipParallelReadTests.cs
new file mode 100644
index 00000000..71630e1f
--- /dev/null
+++ b/tests/Drivers/ZB.MOM.WW.OtOpcUa.Driver.AbCip.Tests/AbCipParallelReadTests.cs
@@ -0,0 +1,201 @@
+using Shouldly;
+using Xunit;
+using ZB.MOM.WW.OtOpcUa.Core.Abstractions;
+using ZB.MOM.WW.OtOpcUa.Driver.AbCip;
+
+namespace ZB.MOM.WW.OtOpcUa.Driver.AbCip.Tests;
+
+///
+/// Task 14 — ReadAsync runs its planned groups + per-tag fallbacks inside a bounded
+/// concurrency window () instead of strictly
+/// one device round-trip at a time, so libplctag can overlap requests. The window is ACROSS
+/// tags only: the per-tag runtime lock (05/STAB-4) still serialises Read → GetStatus → Decode
+/// against any one cached handle. Health is aggregated once after the batch (worst outcome
+/// wins, LastSuccessfulRead advances if any tag succeeded) because per-item writes to
+/// the shared health field would race under the window.
+///
+[Trait("Category", "Unit")]
+public sealed class AbCipParallelReadTests
+{
+ private const string DeviceHost = "ab://10.0.0.5/1,0";
+
+ ///
+ /// Holds every in-flight fake read until either reads overlap
+ /// (proving the window opened) or a short grace period elapses (so a window of one, which
+ /// can never reach the target, still completes instead of deadlocking).
+ ///
+ private sealed class ReadGate(int target)
+ {
+ private readonly TaskCompletionSource _release = new(TaskCreationOptions.RunContinuationsAsynchronously);
+ private int _inFlight;
+
+ /// Gets the highest number of fake reads observed in flight simultaneously.
+ public int MaxConcurrent { get; private set; }
+
+ /// Records one in-flight read and holds it open until the gate releases.
+ /// The read's cancellation token.
+ public async Task HoldAsync(CancellationToken cancellationToken)
+ {
+ var n = Interlocked.Increment(ref _inFlight);
+ lock (this)
+ {
+ if (n > MaxConcurrent) MaxConcurrent = n;
+ }
+ try
+ {
+ if (n >= target) _release.TrySetResult();
+ try
+ {
+ await _release.Task.WaitAsync(TimeSpan.FromMilliseconds(150), cancellationToken)
+ .ConfigureAwait(false);
+ }
+ catch (TimeoutException)
+ {
+ // The window never reached the target — the sequential control case.
+ }
+ }
+ finally
+ {
+ Interlocked.Decrement(ref _inFlight);
+ }
+ }
+ }
+
+ /// A fake whose read blocks on the shared gate and records its OWN overlap.
+ private sealed class GatedFake(AbCipTagCreateParams p, ReadGate gate) : FakeAbCipTag(p)
+ {
+ private int _own;
+
+ /// Gets the highest number of concurrent reads seen on THIS handle.
+ public int MaxOwnConcurrent { get; private set; }
+
+ ///
+ public override async Task ReadAsync(CancellationToken cancellationToken)
+ {
+ var mine = Interlocked.Increment(ref _own);
+ lock (this)
+ {
+ if (mine > MaxOwnConcurrent) MaxOwnConcurrent = mine;
+ }
+ try
+ {
+ await gate.HoldAsync(cancellationToken).ConfigureAwait(false);
+ await base.ReadAsync(cancellationToken).ConfigureAwait(false);
+ }
+ finally
+ {
+ Interlocked.Decrement(ref _own);
+ }
+ }
+ }
+
+ private static AbCipDriver NewDriver(
+ IAbCipTagFactory factory, int maxConcurrentReads, params AbCipTagDefinition[] tags)
+ {
+ var opts = new AbCipDriverOptions
+ {
+ Devices = [new AbCipDeviceOptions(DeviceHost)],
+ RawTags = AbCipRawTags.From(tags),
+ Probe = new AbCipProbeOptions { Enabled = false },
+ MaxConcurrentReads = maxConcurrentReads,
+ };
+ return new AbCipDriver(opts, "drv-1", factory);
+ }
+
+ private static AbCipTagDefinition Tag(string name) =>
+ new(name, DeviceHost, $"Motor1.{name}", AbCipDataType.DInt);
+
+ /// Four distinct tags under a window of eight overlap on the wire.
+ [Fact]
+ public async Task Reads_overlap_up_to_the_window()
+ {
+ var gate = new ReadGate(target: 2);
+ var factory = new FakeAbCipTagFactory { Customise = p => new GatedFake(p, gate) { Value = 1 } };
+ var drv = NewDriver(factory, maxConcurrentReads: 8,
+ Tag("A"), Tag("B"), Tag("C"), Tag("D"));
+ await drv.InitializeAsync("{}", CancellationToken.None);
+
+ var snapshots = await drv.ReadAsync(["A", "B", "C", "D"], CancellationToken.None);
+
+ gate.MaxConcurrent.ShouldBeGreaterThanOrEqualTo(2,
+ "a window of 8 must let distinct tags overlap on the device");
+ snapshots.Count.ShouldBe(4);
+ snapshots.ShouldAllBe(s => s.StatusCode == AbCipStatusMapper.Good);
+ }
+
+ ///
+ /// Falsification control for — the same
+ /// fixture with a window of one must observe no overlap at all, i.e. today's behaviour.
+ ///
+ [Fact]
+ public async Task A_window_of_one_is_sequential()
+ {
+ var gate = new ReadGate(target: 2);
+ var factory = new FakeAbCipTagFactory { Customise = p => new GatedFake(p, gate) { Value = 1 } };
+ var drv = NewDriver(factory, maxConcurrentReads: 1,
+ Tag("A"), Tag("B"), Tag("C"), Tag("D"));
+ await drv.InitializeAsync("{}", CancellationToken.None);
+
+ var snapshots = await drv.ReadAsync(["A", "B", "C", "D"], CancellationToken.None);
+
+ gate.MaxConcurrent.ShouldBe(1, "MaxConcurrentReads = 1 must be observably sequential");
+ snapshots.Count.ShouldBe(4);
+ snapshots.ShouldAllBe(s => s.StatusCode == AbCipStatusMapper.Good);
+ }
+
+ ///
+ /// The window parallelises ACROSS tags, never within one — the same reference twice in a
+ /// batch still serialises on the per-tag runtime lock (05/STAB-4).
+ ///
+ [Fact]
+ public async Task Same_tag_requested_twice_is_still_serialised()
+ {
+ var gate = new ReadGate(target: 2);
+ GatedFake? shared = null;
+ var factory = new FakeAbCipTagFactory
+ {
+ Customise = p => shared = new GatedFake(p, gate) { Value = 5 },
+ };
+ var drv = NewDriver(factory, maxConcurrentReads: 8, Tag("A"));
+ await drv.InitializeAsync("{}", CancellationToken.None);
+
+ var snapshots = await drv.ReadAsync(["A", "A"], CancellationToken.None);
+
+ shared.ShouldNotBeNull();
+ shared!.MaxOwnConcurrent.ShouldBe(1,
+ "operations on one shared libplctag Tag handle must never overlap");
+ snapshots.Count.ShouldBe(2);
+ snapshots.ShouldAllBe(s => s.StatusCode == AbCipStatusMapper.Good);
+ }
+
+ ///
+ /// Health is written once after the batch: the worst per-item outcome wins, and
+ /// LastSuccessfulRead still advances because at least one tag read succeeded — the
+ /// contract the comms-loss watchdog reads.
+ ///
+ [Fact]
+ public async Task Health_after_a_mixed_batch_is_worst_outcome_with_advanced_LastSuccessfulRead()
+ {
+ var factory = new FakeAbCipTagFactory
+ {
+ Customise = p => p.TagName.Contains("Bad", StringComparison.Ordinal)
+ ? new FakeAbCipTag(p) { ThrowOnRead = true }
+ : new FakeAbCipTag(p) { Value = 3 },
+ };
+ var drv = NewDriver(factory, maxConcurrentReads: 8, Tag("Good"), Tag("Bad"));
+ await drv.InitializeAsync("{}", CancellationToken.None);
+ var beforeRead = drv.GetHealth().LastSuccessfulRead;
+ beforeRead.ShouldNotBeNull();
+ await Task.Delay(30, TestContext.Current.CancellationToken);
+
+ var snapshots = await drv.ReadAsync(["Good", "Bad"], CancellationToken.None);
+
+ snapshots[0].StatusCode.ShouldBe(AbCipStatusMapper.Good);
+ snapshots[1].StatusCode.ShouldBe(AbCipStatusMapper.BadCommunicationError);
+ var health = drv.GetHealth();
+ health.State.ShouldBe(DriverState.Degraded, "the worst per-item outcome wins");
+ health.LastSuccessfulRead.ShouldNotBeNull();
+ health.LastSuccessfulRead!.Value.ShouldBeGreaterThan(beforeRead!.Value,
+ "a successful tag in the batch must still advance LastSuccessfulRead");
+ }
+}