68 lines
1.3 KiB
Rust
68 lines
1.3 KiB
Rust
use std::{cell::Cell, num::NonZeroU64};
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/// Unique opaque identifier.
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#[must_use]
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#[derive(Debug, Hash, PartialEq, Eq, Clone, Copy)]
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pub struct Id {
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thread: NonZeroU64,
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counter: u64,
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}
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thread_local! {
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static COUNTER: Cell<u64> = const { Cell::new(0) };
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}
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impl Default for Id {
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fn default() -> Self {
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let counter = COUNTER.get();
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COUNTER.set(counter.wrapping_add(1));
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Self {
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thread: threadid(),
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counter,
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}
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}
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}
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fn threadid() -> NonZeroU64 {
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use std::hash::{Hash, Hasher};
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struct Extractor {
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id: u64,
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}
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impl Hasher for Extractor {
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fn finish(&self) -> u64 {
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self.id
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}
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fn write(&mut self, _bytes: &[u8]) {}
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fn write_u64(&mut self, n: u64) {
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self.id = n;
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}
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}
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let mut ex = Extractor { id: 0 };
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std::thread::current().id().hash(&mut ex);
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// SAFETY: guaranteed to be > 0
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// safeguarded by the max(1), but this is already guaranteed by the thread id being a NonZeroU64
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// internally; as that guarantee is not stable, we do make sure, just to be on the safe side.
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unsafe { NonZeroU64::new_unchecked(ex.finish().max(1)) }
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}
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// Replace with this when the thread_id_value feature is stable
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// fn threadid() -> NonZeroU64 {
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// std::thread::current().id().as_u64()
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// }
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#[test]
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fn test_threadid() {
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let top = threadid();
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std::thread::spawn(move || {
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assert_ne!(top, threadid());
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})
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.join()
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.expect("thread failed");
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}
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