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use crate::EntryRetryInfo;
use std::cmp;
use std::time::Duration;
/// This struct represents the policy to execute retries.
#[derive(Debug, Clone, Default)]
pub enum RetryPolicy {
/// # Infinite
///
/// Infinite retry strategy.
#[default]
Infinite,
/// # None
///
/// No retry strategy, fail on first failure.
None,
/// # Fixed delay
///
/// Retry with a fixed delay strategy.
FixedDelay {
/// # Interval
///
/// Interval between retries. If none, the runtime will provide one based on the invoker retry policy.
interval: Option<Duration>,
/// # Max attempts
///
/// Gives up retrying when either this number of attempts is reached,
/// or `max_duration` (if set) is reached first.
/// Infinite retries if this field and `max_duration` are unset.
max_attempts: Option<u32>,
/// # Max duration
///
/// Gives up retrying when either the retry loop lasted for this given max duration,
/// or `max_attempts` (if set) is reached first.
/// Infinite retries if this field and `max_attempts` are unset.
max_duration: Option<Duration>,
},
/// # Exponential
///
/// Retry with an exponential strategy. The next retry is computed as `min(last_retry_interval * factor, max_interval)`.
Exponential {
/// # Initial Interval
///
/// Initial interval for the first retry attempt.
initial_interval: Duration,
/// # Factor
///
/// The factor to use to compute the next retry attempt. This value should be higher than 1.0
factor: f32,
/// # Max interval
///
/// Maximum interval between retries.
max_interval: Option<Duration>,
/// # Max attempts
///
/// Gives up retrying when either this number of attempts is reached,
/// or `max_duration` (if set) is reached first.
/// Infinite retries if this field and `max_duration` are unset.
max_attempts: Option<u32>,
/// # Max duration
///
/// Gives up retrying when either the retry loop lasted for this given max duration,
/// or `max_attempts` (if set) is reached first.
/// Infinite retries if this field and `max_attempts` are unset.
max_duration: Option<Duration>,
},
}
#[derive(Debug, Clone, Eq, PartialEq)]
pub(crate) enum NextRetry {
Retry(Option<Duration>),
DoNotRetry,
}
impl RetryPolicy {
pub fn fixed_delay(
interval: Option<Duration>,
max_attempts: Option<u32>,
max_duration: Option<Duration>,
) -> Self {
Self::FixedDelay {
interval,
max_attempts,
max_duration,
}
}
pub fn exponential(
initial_interval: Duration,
factor: f32,
max_attempts: Option<u32>,
max_interval: Option<Duration>,
max_duration: Option<Duration>,
) -> Self {
Self::Exponential {
initial_interval,
factor,
max_attempts,
max_interval,
max_duration,
}
}
pub(crate) fn next_retry(&self, retry_info: EntryRetryInfo) -> NextRetry {
match self {
RetryPolicy::Infinite => NextRetry::Retry(None),
RetryPolicy::None => NextRetry::DoNotRetry,
RetryPolicy::FixedDelay {
interval,
max_attempts,
max_duration,
} => {
if max_attempts.is_some_and(|max_attempts| max_attempts <= retry_info.retry_count)
|| max_duration
.is_some_and(|max_duration| max_duration <= retry_info.retry_loop_duration)
{
// Reached either max_attempts or max_duration bound
return NextRetry::DoNotRetry;
}
// No bound reached, we need to retry
NextRetry::Retry(*interval)
}
RetryPolicy::Exponential {
initial_interval,
factor,
max_interval,
max_attempts,
max_duration,
} => {
if max_attempts.is_some_and(|max_attempts| max_attempts <= retry_info.retry_count)
|| max_duration
.is_some_and(|max_duration| max_duration <= retry_info.retry_loop_duration)
{
// Reached either max_attempts or max_duration bound
return NextRetry::DoNotRetry;
}
NextRetry::Retry(Some(cmp::min(
max_interval.unwrap_or(Duration::MAX),
initial_interval.mul_f32(factor.powi((retry_info.retry_count - 1) as i32)),
)))
}
}
}
}
#[cfg(test)]
mod tests {
use super::*;
#[test]
fn test_exponential_policy() {
let policy = RetryPolicy::Exponential {
initial_interval: Duration::from_millis(100),
factor: 2.0,
max_interval: Some(Duration::from_millis(500)),
max_attempts: None,
max_duration: Some(Duration::from_secs(10)),
};
assert_eq!(
policy.next_retry(EntryRetryInfo {
retry_count: 2,
retry_loop_duration: Duration::from_secs(1)
}),
NextRetry::Retry(Some(Duration::from_millis(100).mul_f32(2.0)))
);
assert_eq!(
policy.next_retry(EntryRetryInfo {
retry_count: 3,
retry_loop_duration: Duration::from_secs(1)
}),
NextRetry::Retry(Some(Duration::from_millis(100).mul_f32(4.0)))
);
assert_eq!(
policy.next_retry(EntryRetryInfo {
retry_count: 4,
retry_loop_duration: Duration::from_secs(1)
}),
NextRetry::Retry(Some(Duration::from_millis(500)))
);
assert_eq!(
policy.next_retry(EntryRetryInfo {
retry_count: 4,
retry_loop_duration: Duration::from_secs(10)
}),
NextRetry::DoNotRetry
);
}
}