codex/codex-rs/async-utils/src/backoff.rs

//! Shared exponential retry delays with jitter.

use std::time::Duration;

use rand::Rng;

const INITIAL_DELAY_MS: u64 = 200;
const BACKOFF_FACTOR: f64 = 2.0;

/// Return a retry delay starting at 200 ms and doubling on each subsequent attempt,
/// with up to 10% jitter. Attempts zero and one both use the initial delay.
pub fn backoff(attempt: u64) -> Duration {
    let exp = BACKOFF_FACTOR.powi(attempt.saturating_sub(1) as i32);
    let base = (INITIAL_DELAY_MS as f64 * exp) as u64;
    let jitter = rand::rng().random_range(0.9..1.1);
    Duration::from_millis((base as f64 * jitter) as u64)
}