jpmschweitzerandClaude Opus 4.6
0d09d905e4
gen_queue: add in_flight_count tracking for all work item types (not just AnalyzeBody). Rewrite saturation test with AnalyzeBody items. Fix priority_ordering test thread count to match new gate. rng: collapse to single AtlasRng::new(seed) constructor — callers own their seed transform. import_province_boundaries: fix "savepoint" comment to "transaction". Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>
58 lines
1.6 KiB
Rust
58 lines
1.6 KiB
Rust
//! Seeded LCG for deterministic generation (D-010).
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//!
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//! Shared by all atlas generation modules that need seeded randomness.
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//! Uses Knuth's LCG parameters — integer-only arithmetic, no f32, D-010 compliant.
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//!
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//! Callers are responsible for any seed pre-mixing before calling `AtlasRng::new`.
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/// Seeded linear congruential generator (D-010).
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pub struct AtlasRng {
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state: u64,
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}
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impl AtlasRng {
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/// Create a new RNG from a pre-mixed seed.
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///
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/// Callers must ensure the seed is non-degenerate (avoid passing 0 directly
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/// if the seed could realistically be 0 — add a constant before calling).
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pub fn new(seed: u64) -> Self {
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Self { state: seed }
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}
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fn next_u64(&mut self) -> u64 {
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self.state = self
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.state
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.wrapping_mul(6364136223846793005)
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.wrapping_add(1442695040888963407);
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self.state
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}
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/// Next pseudorandom `u32` (top 31 bits of the LCG state).
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pub fn next_u32(&mut self) -> u32 {
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(self.next_u64() >> 33) as u32
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}
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}
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#[cfg(test)]
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mod tests {
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use super::*;
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#[test]
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fn deterministic_sequence() {
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let mut a = AtlasRng::new(42);
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let mut b = AtlasRng::new(42);
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for _ in 0..100 {
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assert_eq!(a.next_u32(), b.next_u32());
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}
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}
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#[test]
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fn different_seeds_differ() {
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let mut a = AtlasRng::new(1);
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let mut b = AtlasRng::new(2);
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let vals_a: Vec<u32> = (0..10).map(|_| a.next_u32()).collect();
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let vals_b: Vec<u32> = (0..10).map(|_| b.next_u32()).collect();
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assert_ne!(vals_a, vals_b);
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}
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}
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