Files
lmxopcua/src/ZB.MOM.WW.OtOpcUa.Driver.AbCip/IAbCipTagRuntime.cs
Joseph Doherty 780358c790 AbCip whole-UDT read optimization (#194) — declaration-driven member grouping collapses N per-member reads into one parent-UDT read + client-side decode. Closes task #194. On a batch that includes multiple members of the same hand-declared UDT tag, ReadAsync now issues one libplctag read on the parent + decodes each member from the runtime's buffer at its computed byte offset. A 6-member Motor UDT read goes from 6 libplctag round-trips to 1 — the Rockwell-suggested pattern for minimizing CIP request overhead on batch reads of UDT state (decision #11's follow-through on what the template decoder from task #179 was meant to enable). AbCipUdtMemberLayout is a pure-function helper that computes declared-member byte offsets under Logix natural-alignment rules (SInt 1-byte / Int 2-byte / DInt + Real + Dt 4-byte / LInt + ULInt + LReal 8-byte; alignment pad inserted before each member as needed). Opts out for BOOL / String / Structure members — BOOL storage in Logix UDTs packs into a hidden host byte whose position can't be computed from declaration-only info, and String members need length-prefix + STRING[82] fan-out which libplctag already handles via a per-tag DecodeValue path. The CIP Template Object shape from task #179 (when populated via FetchUdtShapeAsync) carries real offsets for those members — layering that richer path on top of the planner is a separate follow-up and does not change this PR's conservative behaviour. AbCipUdtReadPlanner is the scheduling function ReadAsync consults each batch — pure over (requests, tagsByName), emits Groups + Fallbacks. A group is formed when (a) the reference resolves to "parent.member"; (b) parent is a Structure tag with declared Members; (c) the layout helper succeeds on those members; (d) the specific member appears in the computed offset map; (e) at least two members of the same parent appear in the batch — single-member groups demote to the fallback path because one whole-UDT read vs one per-member read is equivalent cost but more client-side work. Original batch indices are preserved through the plan so out-of-order batches write decoded values back at the right output slot; the caller's result array order is invariant. IAbCipTagRuntime.DecodeValueAt(AbCipDataType, int offset, int? bitIndex) is the new hot-path method — LibplctagTagRuntime delegates to libplctag's offset-aware Get*(offset) calls (GetInt32, GetFloat32, etc.) that were always there; previously every call passed offset 0. DecodeValue(type, bitIndex) stays as the shorthand + forwards to DecodeValueAt with offset 0, preserving the existing single-tag read path + every test that exercises it. FakeAbCipTag gains a ValuesByOffset dictionary so tests can drive multi-member decoding by setting offset→value before the read fires; unmapped offsets fall back to the existing Value field so the 200+ existing tests that never set ValuesByOffset keep working unchanged. AbCipDriver.ReadAsync refactored: planner splits the batch, ReadGroupAsync handles each UDT group (one EnsureTagRuntimeAsync on the parent + one ReadAsync + N DecodeValueAt calls), ReadSingleAsync handles each fallback (the pre-#194 per-tag path, now extracted + threaded through). A per-group failure stamps the mapped libplctag status across every grouped member only — sibling groups + fallback refs are unaffected. Health-surface updates happen once per successful group rather than once per member to avoid ping-ponging the DriverState bookkeeping. Five AbCipUdtMemberLayoutTests: packed atomics get natural-alignment offsets including 8-byte pad before LInt; SInts pack without padding; BOOL/String/Structure opt out + return null; empty member list returns null. Six AbCipUdtReadPlannerTests: two members group; single-member demotes to fallback; unknown references fall back without poisoning groups; atomic top-level tags fall back untouched; UDTs containing BOOL don't group; original indices survive out-of-order batches. Five AbCipDriverWholeUdtReadTests (real driver + fake runtime): two grouped members trigger exactly one parent read + one fake runtime (proving the optimization engages); each member decodes at its own offset via ValuesByOffset; parent-read non-zero status stamps Bad across the group; mixed UDT-member + atomic top-level batch produces 2 runtimes + 2 reads (not 3); single-member-of-UDT still uses the member-level runtime (proving demotion works). Driver builds 0 errors; AbCip.Tests 227/227 (was 211, +16 new).
Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
2026-04-20 04:17:57 -04:00

75 lines
3.6 KiB
C#

namespace ZB.MOM.WW.OtOpcUa.Driver.AbCip;
/// <summary>
/// Thin wire-layer abstraction over a single CIP tag. The driver holds one instance per
/// <c>(device, tag path)</c> pair; the default implementation delegates to
/// <see cref="LibplctagTagRuntime"/>. Tests swap in a fake via
/// <see cref="IAbCipTagFactory"/> so the driver's read / write / status-mapping logic can
/// be exercised without a running PLC or the native libplctag binary.
/// </summary>
public interface IAbCipTagRuntime : IDisposable
{
/// <summary>Create the underlying native tag (equivalent to libplctag's <c>plc_tag_create</c>).</summary>
Task InitializeAsync(CancellationToken cancellationToken);
/// <summary>Issue a read; on completion the local buffer holds the current PLC value.</summary>
Task ReadAsync(CancellationToken cancellationToken);
/// <summary>Flush the local buffer to the PLC.</summary>
Task WriteAsync(CancellationToken cancellationToken);
/// <summary>
/// Raw libplctag status code — mapped to an OPC UA StatusCode via
/// <see cref="AbCipStatusMapper.MapLibplctagStatus"/>. Zero on success, negative on error.
/// </summary>
int GetStatus();
/// <summary>
/// Decode the local buffer into a boxed .NET value per the tag's configured type.
/// <paramref name="bitIndex"/> is non-null only for BOOL-within-DINT tags captured in
/// the <c>.N</c> syntax at parse time.
/// </summary>
object? DecodeValue(AbCipDataType type, int? bitIndex);
/// <summary>
/// Decode a value at an arbitrary byte offset in the local buffer. Task #194 —
/// whole-UDT reads perform one <see cref="ReadAsync"/> on the parent UDT tag then
/// call this per declared member with its computed offset, avoiding one libplctag
/// round-trip per member. Implementations that do not support offset-aware decoding
/// may fall back to <see cref="DecodeValue"/> when <paramref name="offset"/> is zero;
/// offsets greater than zero against an unsupporting runtime should return <c>null</c>
/// so the planner can skip grouping.
/// </summary>
object? DecodeValueAt(AbCipDataType type, int offset, int? bitIndex);
/// <summary>
/// Encode <paramref name="value"/> into the local buffer per the tag's type. Callers
/// pair this with <see cref="WriteAsync"/>.
/// </summary>
void EncodeValue(AbCipDataType type, int? bitIndex, object? value);
}
/// <summary>
/// Factory for per-tag runtime handles. Instantiated once per driver, consumed per
/// <c>(device, tag path)</c> pair at the first read/write.
/// </summary>
public interface IAbCipTagFactory
{
IAbCipTagRuntime Create(AbCipTagCreateParams createParams);
}
/// <summary>Everything libplctag needs to materialise a tag handle.</summary>
/// <param name="Gateway">Gateway IP / hostname parsed from <see cref="AbCipHostAddress.Gateway"/>.</param>
/// <param name="Port">EtherNet/IP TCP port — default 44818.</param>
/// <param name="CipPath">CIP route path, e.g. <c>1,0</c>. Empty for Micro800.</param>
/// <param name="LibplctagPlcAttribute">libplctag <c>plc=...</c> attribute, per family profile.</param>
/// <param name="TagName">Logix symbolic tag name as emitted by <see cref="AbCipTagPath.ToLibplctagName"/>.</param>
/// <param name="Timeout">libplctag operation timeout (applies to Initialize / Read / Write).</param>
public sealed record AbCipTagCreateParams(
string Gateway,
int Port,
string CipPath,
string LibplctagPlcAttribute,
string TagName,
TimeSpan Timeout);