43 lines
1.2 KiB
Rust
43 lines
1.2 KiB
Rust
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use std::time::{Duration, Instant};
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#[derive(Debug, Clone, Copy, PartialEq, Eq)]
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pub enum WaitOutcome {
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Satisfied,
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Timeout,
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DisabledUnknown,
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}
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/// Wait for a predicate with a deadline. Unknown disabled reasons do not spin
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/// forever — they surface as DisabledUnknown so the caller can re-observe.
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pub fn wait_until<F>(deadline: Duration, mut ready: F) -> WaitOutcome
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where
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F: FnMut() -> Result<bool, &'static str>,
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{
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let start = Instant::now();
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loop {
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match ready() {
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Ok(true) => return WaitOutcome::Satisfied,
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Ok(false) if start.elapsed() >= deadline => return WaitOutcome::Timeout,
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Ok(false) => std::thread::sleep(Duration::from_millis(5)),
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Err(_) => return WaitOutcome::DisabledUnknown,
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}
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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 deadline_stops_an_unready_condition() {
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let outcome = wait_until(Duration::from_millis(20), || Ok(false));
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assert_eq!(outcome, WaitOutcome::Timeout);
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}
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#[test]
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fn unknown_disabled_does_not_spin() {
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let outcome = wait_until(Duration::from_secs(5), || Err("unknown"));
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assert_eq!(outcome, WaitOutcome::DisabledUnknown);
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}
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}
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