Brummel
0bf15cb069
First fieldtest of the project. A standalone downstream-consumer crate
(fieldtests/cycle-0006-substrate/) path-depends on the engine crates and
exercises the post-0006 substrate from the public interface only (rustdoc +
specs + ledger, never crates/ source):
1 custom recording node via the Node contract + Ctx::now()
2 fan-out/fan-in DAG, 3-arg bootstrap, run() -> ()
3 two interior streams recorded from one run (the cycle headline)
4 byte-identical recorded output across two runs (C1 determinism)
5 mis-wired recording edge rejected (KindMismatch) at bootstrap
Findings: 3 working (carry-on), 2 friction, 1 spec_gap.
- friction: a nested standalone consumer crate fights the workspace
resolver (needs an empty [workspace] table — Cargo's own hint).
- friction: recorder boilerplate is hand-rewritten per author (C9
deliberately ships no library sink).
- spec_gap: the public surface never states output: vec![] is THE sink
declaration, nor defines a Some return paired with empty output.
Spec at docs/specs/fieldtest-0006-substrate.md feeds the 0007 plan.
Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
101 lines
3.4 KiB
Rust
101 lines
3.4 KiB
Rust
//! Fieldtest c0006 #1 — author a custom recording node from scratch.
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//!
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//! Axis: "Author a custom node via the public Node contract (schema / eval /
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//! Ctx, including Ctx::now())."
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//!
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//! A downstream author writes their own sink node — here a `Recorder` that holds
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//! the destination (an mpsc::Sender) as a field and, in eval, stamps each fired
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//! cycle's value with `ctx.now()` and pushes `(now, value)` out of the graph.
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//! It returns `None` (pure consumer, C8). This is the canonical recording-node
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//! shape the 0006 spec's "Concrete code shapes" section describes (`Recorder` is
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//! the spec's test-local fixture; a real author writes their ChartSink the same
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//! way).
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//!
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//! What this fixture proves a downstream consumer can do with ONLY the public
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//! surface: implement `Node` for their own type, read a typed input window, call
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//! `ctx.now()`, perform an out-of-graph side effect, and return `None`.
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use std::sync::mpsc::{self, Sender};
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use aura_core::{Ctx, Firing, InputSpec, Node, NodeSchema, Scalar, ScalarKind, Timestamp};
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use aura_engine::{Edge, Harness, SourceSpec, Target};
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use aura_std::Sma;
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/// A pure-consumer recording node: one f64 input, no output, pushes
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/// `(ctx.now(), value)` to a channel the caller drains.
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struct Recorder {
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tx: Sender<(Timestamp, f64)>,
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}
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impl Recorder {
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fn new(tx: Sender<(Timestamp, f64)>) -> Self {
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Self { tx }
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}
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}
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impl Node for Recorder {
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fn schema(&self) -> NodeSchema {
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NodeSchema {
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inputs: vec![InputSpec {
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kind: ScalarKind::F64,
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lookback: 1,
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firing: Firing::Any,
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}],
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// Pure consumer (sink): no output port.
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output: vec![],
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}
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}
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fn eval(&mut self, ctx: Ctx<'_>) -> Option<&[Scalar]> {
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let w = ctx.f64_in(0);
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if w.is_empty() {
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return None; // not yet warmed
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}
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// The C2-causal stamp: the present cycle's timestamp, never the future.
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let _ = self.tx.send((ctx.now(), w[0]));
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None // pure sink — nothing forwarded into the graph
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}
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}
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fn f64_stream(pairs: &[(i64, f64)]) -> Vec<(Timestamp, Scalar)> {
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pairs
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.iter()
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.map(|&(t, v)| (Timestamp(t), Scalar::F64(v)))
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.collect()
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}
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fn main() {
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let (tx, rx) = mpsc::channel();
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// source -> SMA(2) -> Recorder. Recorder stamps each fired SMA value with now().
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let mut h = Harness::bootstrap(
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vec![
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Box::new(Sma::new(2)), // node 0
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Box::new(Recorder::new(tx)), // node 1
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],
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vec![SourceSpec {
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kind: ScalarKind::F64,
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targets: vec![Target { node: 0, slot: 0 }],
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}],
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vec![Edge { from: 0, to: 1, slot: 0, from_field: 0 }],
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)
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.expect("valid DAG");
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h.run(vec![f64_stream(&[(10, 10.0), (20, 12.0), (30, 14.0), (40, 16.0)])]);
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let recorded: Vec<(Timestamp, f64)> = rx.try_iter().collect();
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// SMA(2) warms up after 2 samples, so it fires at t=20,30,40 with means
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// (10+12)/2=11, (12+14)/2=13, (14+16)/2=15. Each carries the cycle's now().
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let expected = vec![
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(Timestamp(20), 11.0),
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(Timestamp(30), 13.0),
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(Timestamp(40), 15.0),
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];
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println!("recorded = {recorded:?}");
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println!("expected = {expected:?}");
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assert_eq!(recorded, expected, "Recorder stream (timestamp via Ctx::now)");
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println!("c0006_1 OK: custom node + Ctx::now() recorded a now-stamped stream");
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}
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