Joseph Doherty
71c69b80c6
Hand-rolled GlobalAlloc wrapper around System that tracks allocs +
bytes + deallocs via two atomics. Each scenario runs 10k iterations
after a 1k warm-up; output is a markdown table with allocs/op,
bytes/op, deallocs/op.
Why hand-rolled (not dhat/criterion): R12 gates on a single number
("< 5 allocs/write"). dhat is heap-profiling-oriented (call-stack
attribution, JSON snapshots); criterion measures wall-clock latency
which is reported-but-not-gated per 60-roadmap.md:104. A 50-line
GlobalAlloc + atomic counters is the simplest thing that answers
the gate.
Run: `cargo bench -p mxaccess-codec`
Baseline numbers (release, Windows x64):
- Bool write: 1.00 allocs/op
- Int32 write: 2.00 allocs/op
- Float32 write: 2.00 allocs/op
- Float64 write: 2.00 allocs/op
- String write: 4.00 allocs/op (5-char string)
- Handle from_names: 2.00 allocs/op
- DataUpdate decode: 1.00 alloc/op
R12's < 5 allocs/write target is **already met** across the proven
matrix without any zero-copy work. The bench gates on this — any
write_message::encode scenario at >= 5 allocs/op exits the harness
with code 1.
Companion: `design/M6-bench-baseline.md` documents the numbers,
explains the per-scenario breakdown, and tightens F39's scope from
"hit the target" to "nice-to-have optimisations" (BytesMut output
buffer, name-signature cache, session-level scratch pool).
Workspace: 759 tests still pass; clippy --benches clean.
Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
design/ — Rust port architectural plan
This folder is the design contract for the Rust replacement of AVEVA/Wonderware MXAccess. It is the gap between the .NET reference in src/ and the Rust crates that will be written under a sibling rust/ workspace (per CLAUDE.md).
The folder is structured as a small set of focused documents. Read in order; each builds on the previous.
| File | Purpose |
|---|---|
00-overview.md |
Mission, two-layer goal, architectural principles, non-goals |
10-raw-layer.md |
Byte-accurate raw MXAccess layer (codec + transport + session) |
20-async-layer.md |
Idiomatic Tokio async layer on top of the raw layer |
30-crate-topology.md |
Cargo workspace, crates, dependencies, build/test commands |
40-protocol-invariants.md |
Bill of materials: IIDs, opnums, envelope/handle bytes |
50-error-model.md |
MxStatus, error types, panic/cancellation policy |
60-roadmap.md |
Milestones M0..M6, validation strategy |
70-risks-and-open-questions.md |
Parity gaps, unproven flows, cross-platform constraints |
dependencies.md |
Cross- and within-milestone parallelism map; agent budget per phase |
review.md |
Adversarial review log (BLOCKER/MAJOR/MINOR/NIT findings, all resolved) |
prompt.md |
/loop driver prompt for autonomous M2–M6 execution |
followups.md |
Open / resolved deferred work items; auto-triaged by prompt.md Step 0 (created on first /loop run if missing) |
The design is grounded in the .NET reference at src/ and the protocol artifacts in docs/, analysis/, and captures/. Do not introduce protocol behavior in these documents that is not already proven in the reference. When adding a new claim about wire format, cite either:
- a
.csfile path insrc/MxNativeCodec/,src/MxNativeClient/, orsrc/MxAsbClient/, or - a
docs/*.mdspec file, or - a
captures/0NN-frida-*directory oranalysis/frida/*.tsvrow.
This folder is documentation, not code. When the Rust workspace is created, the design here is the contract it must satisfy. When evidence in captures/ invalidates a design decision here, update the design first, then the code.
Reading order
- New contributor: 00 → 30 → 10 → 40 → 20 → 50 → 60 → 70.
- Protocol question: 40 first, then the relevant section of 10.
- API question: 20 first, then 50.
- Planning a milestone: 60 first, cross-reference 70 for blockers.
- Scheduling concurrent work:
dependencies.mdfor the per-phase parallelism map. - Driving M2–M6 autonomously via
/loop:prompt.md(and thefollowups.mdtriage log it maintains).