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//! Types and code to track the readiness status of a directory cache.
use std::time::{Duration, Instant};
use tor_basic_utils::retry::RetryDelay;
/// Status information about whether a
/// [`FallbackDir`](crate::fallback::FallbackDir) or
/// [`Guard`](crate::guard::Guard) is currently usable as a directory cache.
///
/// This structure is used to track whether the cache has recently failed, and
/// if so, when it can be retried.
#[derive(Debug, Clone)]
pub(crate) struct DirStatus {
/// Used to decide how long to delay before retrying a fallback cache
/// that has failed.
delay: RetryDelay,
/// A time before which we should assume that this fallback cache is broken.
/// If None, then this fallback cache is ready to use right away.
retry_at: Option<Instant>,
}
impl DirStatus {
/// Construct a new DirStatus object with a given lower-bound for delays
/// after failure.
pub(crate) fn new(delay_floor: Duration) -> Self {
DirStatus {
delay: RetryDelay::from_duration(delay_floor),
retry_at: None,
/// Return true if this `Status` is usable at the time `now`.
pub(crate) fn usable_at(&self, now: Instant) -> bool {
match self.retry_at {
Some(ready) => now >= ready,
None => true,
/// Return the time at which this `Status` can next be retried.
/// A return value of `None`, or of a time in the past, indicates that this
/// status can be used immediately.
pub(crate) fn next_retriable(&self) -> Option<Instant> {
self.retry_at
/// Record that the associated fallback directory has been used successfully.
/// This should only be done after successfully handling a whole reply from the
/// directory.
pub(crate) fn note_success(&mut self) {
self.retry_at = None;
self.delay.reset();
/// Record that the associated fallback directory has failed.
pub(crate) fn note_failure(&mut self, now: Instant) {
let mut rng = rand::rng();
self.retry_at = Some(now + self.delay.next_delay(&mut rng));
#[cfg(test)]
mod test {
// @@ begin test lint list maintained by maint/add_warning @@
#![allow(clippy::bool_assert_comparison)]
#![allow(clippy::clone_on_copy)]
#![allow(clippy::dbg_macro)]
#![allow(clippy::mixed_attributes_style)]
#![allow(clippy::print_stderr)]
#![allow(clippy::print_stdout)]
#![allow(clippy::single_char_pattern)]
#![allow(clippy::unwrap_used)]
#![allow(clippy::unchecked_duration_subtraction)]
#![allow(clippy::useless_vec)]
#![allow(clippy::needless_pass_by_value)]
//! <!-- @@ end test lint list maintained by maint/add_warning @@ -->
use super::*;
#[test]
fn status_basics() {
let now = Instant::now();
/// floor to use for testing.
const FLOOR: Duration = Duration::from_secs(99);
let mut status = DirStatus::new(FLOOR);
// newly created status is usable.
assert!(status.usable_at(now));
// no longer usable after a failure.
status.note_failure(now);
assert_eq!(status.next_retriable().unwrap(), now + FLOOR);
assert!(!status.usable_at(now));
// Not enough time has passed.
assert!(!status.usable_at(now + FLOOR / 2));
// Enough time has passed.
assert!(status.usable_at(now + FLOOR));
// Mark as failed again; the timeout will (probably) be longer.
status.note_failure(now + FLOOR);
assert!(status.next_retriable().unwrap() >= now + FLOOR * 2);
assert!(!status.usable_at(now + FLOOR));
// Mark as succeeded; it should be usable immediately.
status.note_success();