pharos/threshold_eval

Evaluate a Threshold against a decoded Measurement.

Returns a three-way verdict so callers can branch without reaching for nested case over the cartesian product of measurements and thresholds. Helper functions match every measurement variant exhaustively, so adding a new measurement kind surfaces as a compiler warning here.

Types

Verdict

</>

Three-way verdict for a (measurement, threshold) pair.

pub type Verdict {
  NotApplicable
  Healthy
  Breached
}

Constructors

```
NotApplicable
```
The threshold doesn’t apply to this measurement kind. Caller should do nothing (don’t fire recover for unrelated measurements).
```
Healthy
```
The threshold applies and is currently within limits.
```
Breached
```
The threshold applies and is currently breached.

Values

evaluate

</>

pub fn evaluate(
  measurement: measurement.Measurement,
  threshold: config.Threshold,
) -> Verdict

Evaluate threshold against measurement and return a Verdict.

evaluate_probe

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pub fn evaluate_probe(
  sample: dict.Dict(String, Float),
  threshold: probe.ProbeThreshold,
) -> Verdict

Evaluate a probe threshold against a decoded probe sample, returning the same Verdict as evaluate/2. A NotApplicable verdict means the threshold’s field is absent from this sample, so the caller should neither breach nor recover.

metric_name

</>

pub fn metric_name(threshold: config.Threshold) -> String

The flattened metric name a threshold compares against (see metric.from_measurement).

sample_value

</>

pub fn sample_value(
  measurement: measurement.Measurement,
  threshold: config.Threshold,
) -> Result(Float, Nil)

Extract the current value of the metric threshold compares, by name, from the measurement’s flattened metrics. Returns Error(Nil) when the measurement doesn’t carry that metric (wrong kind, or an Unimplemented host probe, which flattens to no metrics), so such ticks contribute no sample to a window.

threshold_limit

</>

pub fn threshold_limit(threshold: config.Threshold) -> Float

The threshold’s comparison limit as a Float (integer limits are widened).