72 lines
1.7 KiB
Rust
72 lines
1.7 KiB
Rust
use std::time::Duration;
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#[derive(Debug, Clone)]
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pub struct Backoff {
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initial: Duration,
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max: Duration,
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current: Option<Duration>,
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}
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impl Backoff {
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pub fn new(initial: Duration, max: Duration) -> Self {
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Self {
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initial,
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max,
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current: None,
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}
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}
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#[allow(clippy::should_implement_trait)]
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pub fn next(&mut self) -> Duration {
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let next = match self.current {
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None => self.initial,
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Some(d) => (d * 2).min(self.max),
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};
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self.current = Some(next);
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next
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}
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pub fn reset(&mut self) {
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self.current = None;
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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 starts_at_initial() {
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let mut b = Backoff::new(Duration::from_secs(1), Duration::from_secs(30));
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assert_eq!(b.next(), Duration::from_secs(1));
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}
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#[test]
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fn doubles_each_call() {
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let mut b = Backoff::new(Duration::from_secs(1), Duration::from_secs(30));
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assert_eq!(b.next(), Duration::from_secs(1));
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assert_eq!(b.next(), Duration::from_secs(2));
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assert_eq!(b.next(), Duration::from_secs(4));
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assert_eq!(b.next(), Duration::from_secs(8));
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}
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#[test]
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fn caps_at_max() {
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let mut b = Backoff::new(Duration::from_secs(1), Duration::from_secs(5));
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for _ in 0..10 {
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b.next();
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}
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assert_eq!(b.next(), Duration::from_secs(5));
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}
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#[test]
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fn reset_starts_over() {
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let mut b = Backoff::new(Duration::from_secs(1), Duration::from_secs(30));
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b.next();
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b.next();
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b.next();
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b.reset();
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assert_eq!(b.next(), Duration::from_secs(1));
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}
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}
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