Function failsafe::failure_policy::success_rate_over_time_window

source · 
pub fn success_rate_over_time_window<BACKOFF>(
    required_success_rate: f64,
    min_request_threshold: u32,
    window: Duration,
    backoff: BACKOFF
) -> SuccessRateOverTimeWindow<BACKOFF>where
    BACKOFF: Iterator<Item = Duration> + Clone,
Expand description

Returns a policy based on an exponentially-weighted moving average success rate over a time window. A moving average is used so the success rate calculation is biased towards more recent requests.

If the computed weighted success rate is less than the required success rate, mark_dead_on_failure will return Some(Duration).

See ema::Ema for how the success rate is computed.

  • required_success_rate - a success rate that must be met.
  • min_request_threshold - minimum number of requests in the past window for mark_dead_on_failure to return a duration.
  • window - window over which the success rate is tracked. mark_dead_on_failure will return None, until we get requests for a duration of at least window.
  • backoff - stream of durations to use for the next duration returned from mark_dead_on_failure

Panics

When required_success_rate isn’t in [0.0, 1.0] interval.