mirror of https://github.com/rust-lang/rust
67 lines
1.8 KiB
Rust
67 lines
1.8 KiB
Rust
use crate::cli::TestOpts;
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use crate::types::{TestDescAndFn, TestId, TestName};
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use std::hash::{DefaultHasher, Hasher};
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use std::time::{SystemTime, UNIX_EPOCH};
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pub fn get_shuffle_seed(opts: &TestOpts) -> Option<u64> {
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opts.shuffle_seed.or_else(|| {
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if opts.shuffle {
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Some(
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SystemTime::now()
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.duration_since(UNIX_EPOCH)
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.expect("Failed to get system time")
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.as_nanos() as u64,
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)
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} else {
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None
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}
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})
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}
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pub fn shuffle_tests(shuffle_seed: u64, tests: &mut [(TestId, TestDescAndFn)]) {
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let test_names: Vec<&TestName> = tests.iter().map(|test| &test.1.desc.name).collect();
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let test_names_hash = calculate_hash(&test_names);
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let mut rng = Rng::new(shuffle_seed, test_names_hash);
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shuffle(&mut rng, tests);
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}
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// `shuffle` is from `rust-analyzer/src/cli/analysis_stats.rs`.
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fn shuffle<T>(rng: &mut Rng, slice: &mut [T]) {
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for i in 0..slice.len() {
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randomize_first(rng, &mut slice[i..]);
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}
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fn randomize_first<T>(rng: &mut Rng, slice: &mut [T]) {
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assert!(!slice.is_empty());
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let idx = rng.rand_range(0..slice.len() as u64) as usize;
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slice.swap(0, idx);
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}
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}
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struct Rng {
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state: u64,
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extra: u64,
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}
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impl Rng {
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fn new(seed: u64, extra: u64) -> Self {
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Self { state: seed, extra }
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}
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fn rand_range(&mut self, range: core::ops::Range<u64>) -> u64 {
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self.rand_u64() % (range.end - range.start) + range.start
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}
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fn rand_u64(&mut self) -> u64 {
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self.state = calculate_hash(&(self.state, self.extra));
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self.state
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}
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}
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// `calculate_hash` is from `core/src/hash/mod.rs`.
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fn calculate_hash<T: core::hash::Hash>(t: &T) -> u64 {
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let mut s = DefaultHasher::new();
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t.hash(&mut s);
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s.finish()
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}
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