use std::time::Duration; fn randomize(backoff_ms: usize) -> usize { let new_value = (fastrand::usize(750..=1250) * backoff_ms) / 1000; if new_value == 0 { backoff_ms } else { new_value }} /// A utility to calculate steps for exponential backoff similar to how it's done in `git`.pub struct Exponential<Fn> { multiplier: usize, max_multiplier: usize, exponent: usize, transform: Fn,} impl Default for Exponential<fn(usize) -> usize> { fn default() -> Self { Exponential { multiplier: 1, max_multiplier: 1000, exponent: 1, transform: std::convert::identity, } }} impl Exponential<fn(usize) -> usize> { /// Create a new exponential backoff iterator that backs off in randomized, ever increasing steps. pub fn default_with_random() -> Self { Exponential { multiplier: 1, max_multiplier: 1000, exponent: 1, transform: randomize, } }} impl<Transform> Exponential<Transform>where Transform: Fn(usize) -> usize,{ /// Return an iterator that yields `Duration` instances to sleep on until `time` is depleted. pub fn until_no_remaining(&mut self, time: Duration) -> impl Iterator<Item = Duration> + '_ { let mut elapsed = Duration::default(); let mut stop_next_iteration = false; self.take_while(move |d| { if stop_next_iteration { false } else { elapsed += *d; if elapsed > time { stop_next_iteration = true; } true } }) }} impl<Transform> Iterator for Exponential<Transform>where Transform: Fn(usize) -> usize,{ type Item = Duration; fn next(&mut self) -> Option<Self::Item> { let wait = Duration::from_millis((self.transform)(self.multiplier) as u64); self.multiplier += 2 * self.exponent + 1; if self.multiplier > self.max_multiplier { self.multiplier = self.max_multiplier; } else { self.exponent += 1; } Some(wait) }}
use std::time::Duration;
fn randomize(backoff_ms: usize) -> usize {
let new_value = (fastrand::usize(750..=1250) * backoff_ms) / 1000;
if new_value == 0 {
backoff_ms
} else {
new_value
}
}
/// A utility to calculate steps for exponential backoff similar to how it's done in `git`.
pub struct Exponential<Fn> {
multiplier: usize,
max_multiplier: usize,
exponent: usize,
transform: Fn,
}
impl Default for Exponential<fn(usize) -> usize> {
fn default() -> Self {
Exponential {
multiplier: 1,
max_multiplier: 1000,
exponent: 1,
transform: std::convert::identity,
}
}
}
impl Exponential<fn(usize) -> usize> {
/// Create a new exponential backoff iterator that backs off in randomized, ever increasing steps.
pub fn default_with_random() -> Self {
Exponential {
multiplier: 1,
max_multiplier: 1000,
exponent: 1,
transform: randomize,
}
}
}
impl<Transform> Exponential<Transform>
where
Transform: Fn(usize) -> usize,
{
/// Return an iterator that yields `Duration` instances to sleep on until `time` is depleted.
pub fn until_no_remaining(&mut self, time: Duration) -> impl Iterator<Item = Duration> + '_ {
let mut elapsed = Duration::default();
let mut stop_next_iteration = false;
self.take_while(move |d| {
if stop_next_iteration {
false
} else {
elapsed += *d;
if elapsed > time {
stop_next_iteration = true;
}
true
}
})
}
}
impl<Transform> Iterator for Exponential<Transform>
where
Transform: Fn(usize) -> usize,
{
type Item = Duration;
fn next(&mut self) -> Option<Self::Item> {
let wait = Duration::from_millis((self.transform)(self.multiplier) as u64);
self.multiplier += 2 * self.exponent + 1;
if self.multiplier > self.max_multiplier {
self.multiplier = self.max_multiplier;
} else {
self.exponent += 1;
}
Some(wait)
}
}