refactor(irtt-stats): extract time stats module

crates/irtt-stats/src/lib.rs

@@ -12,6 +12,11 @@ use irtt_client::{
     SignedDuration,
 };
 
+mod time_stats;
+
+use time_stats::TimeMetric;
+pub use time_stats::TimeStats;
+
 const CONTINUOUS_SEQUENCE_LIMIT: usize = 4096;
 
 #[derive(Debug, Clone, Copy, PartialEq, Eq)]
@@ -228,27 +233,6 @@ pub struct ServerProcessingStats {
     pub processing: TimeStats,
 }
 
-#[derive(Debug, Clone, Copy, PartialEq)]
-pub struct TimeStats {
-    pub count: u64,
-    pub total_ns: i128,
-    pub min_ns: Option<i128>,
-    pub max_ns: Option<i128>,
-    pub mean_ns: f64,
-    pub median_ns: Option<f64>,
-    pub variance_ns2: f64,
-}
-
-impl TimeStats {
-    pub fn stddev_ns(&self) -> f64 {
-        self.variance_ns2.sqrt()
-    }
-
-    pub fn is_empty(&self) -> bool {
-        self.count == 0
-    }
-}
-
 #[derive(Debug, Clone, PartialEq)]
 struct CoreStats {
     events: EventCounts,
@@ -761,69 +745,6 @@ struct CompletedIpdvPair {
     receive_ipdv_ns: Option<i128>,
 }
 
-#[derive(Debug, Clone, PartialEq)]
-struct TimeMetric {
-    running: RunningStats,
-    samples: Option<Vec<i128>>,
-}
-
-impl TimeMetric {
-    fn new(retain_samples: bool) -> Self {
-        Self {
-            running: RunningStats::default(),
-            samples: retain_samples.then(Vec::new),
-        }
-    }
-
-    fn push_ns(&mut self, value: i128) {
-        self.running.push(value);
-        if let Some(samples) = self.samples.as_mut() {
-            samples.push(value);
-        }
-    }
-
-    fn stats(&self) -> TimeStats {
-        self.running
-            .stats(self.samples.as_ref().and_then(|samples| median_ns(samples)))
-    }
-}
-
-#[derive(Debug, Clone, PartialEq, Default)]
-struct RunningStats {
-    count: u64,
-    total_ns: i128,
-    min_ns: Option<i128>,
-    max_ns: Option<i128>,
-    mean_ns: f64,
-    m2_ns2: f64,
-}
-
-impl RunningStats {
-    fn push(&mut self, value: i128) {
-        self.count += 1;
-        self.total_ns = self.total_ns.saturating_add(value);
-        self.min_ns = Some(self.min_ns.map_or(value, |min| min.min(value)));
-        self.max_ns = Some(self.max_ns.map_or(value, |max| max.max(value)));
-        let x = value as f64;
-        let delta = x - self.mean_ns;
-        self.mean_ns += delta / self.count as f64;
-        let delta2 = x - self.mean_ns;
-        self.m2_ns2 += delta * delta2;
-    }
-
-    fn stats(&self, median_ns: Option<f64>) -> TimeStats {
-        TimeStats {
-            count: self.count,
-            total_ns: self.total_ns,
-            min_ns: self.min_ns,
-            max_ns: self.max_ns,
-            mean_ns: if self.count == 0 { 0.0 } else { self.mean_ns },
-            median_ns,
-            variance_ns2: sample_variance(self.count, self.m2_ns2),
-        }
-    }
-}
-
 fn snapshot_window(events: &VecDeque<StatsEvent>) -> Snapshot {
     let mut core = CoreStats::new(SampleMode::RunningOnly);
     for event in events {
@@ -832,28 +753,6 @@ fn snapshot_window(events: &VecDeque<StatsEvent>) -> Snapshot {
     core.snapshot()
 }
 
-fn sample_variance(count: u64, m2: f64) -> f64 {
-    if count < 2 {
-        0.0
-    } else {
-        m2 / (count - 1) as f64
-    }
-}
-
-fn median_ns(samples: &[i128]) -> Option<f64> {
-    if samples.is_empty() {
-        return None;
-    }
-    let mut sorted = samples.to_vec();
-    sorted.sort_unstable();
-    let mid = sorted.len() / 2;
-    Some(if sorted.len() % 2 == 1 {
-        sorted[mid] as f64
-    } else {
-        (sorted[mid - 1] as f64 + sorted[mid] as f64) / 2.0
-    })
-}
-
 fn loss_stats(packets: PacketCounts) -> LossStats {
     let lost = packets.packets_sent.saturating_sub(packets.unique_replies);
     let packet_loss_percent = if packets.packets_sent == 0 {
@@ -1016,39 +915,6 @@ mod tests {
         }
     }
 
-    #[test]
-    fn running_duration_stats_use_sample_variance() {
-        let mut metric = TimeMetric::new(false);
-        metric.push_ns(1);
-        metric.push_ns(2);
-        metric.push_ns(3);
-        let stats = metric.stats();
-        assert_eq!(stats.count, 3);
-        assert_eq!(stats.total_ns, 6);
-        assert_eq!(stats.min_ns, Some(1));
-        assert_eq!(stats.max_ns, Some(3));
-        assert_eq!(stats.mean_ns, 2.0);
-        assert_eq!(stats.variance_ns2, 1.0);
-        assert_eq!(stats.stddev_ns(), 1.0);
-    }
-
-    #[test]
-    fn exact_median_handles_odd_and_even_samples() {
-        assert_eq!(median_ns(&[3, 1, 2]), Some(2.0));
-        assert_eq!(median_ns(&[4, 1, 2, 3]), Some(2.5));
-        assert_eq!(median_ns(&[-5, 1, 3]), Some(1.0));
-        assert_eq!(median_ns(&[-5, 1, 3, 7]), Some(2.0));
-    }
-
-    #[test]
-    fn single_sample_stddev_is_zero() {
-        let mut metric = TimeMetric::new(false);
-        metric.push_ns(42);
-        let stats = metric.stats();
-        assert_eq!(stats.variance_ns2, 0.0);
-        assert_eq!(stats.stddev_ns(), 0.0);
-    }
-
     #[test]
     fn system_time_before_epoch_is_supported() {
         let before = UNIX_EPOCH - Duration::from_nanos(7);

crates/irtt-stats/src/time_stats.rs

@@ -0,0 +1,143 @@
+#[derive(Debug, Clone, Copy, PartialEq)]
+pub struct TimeStats {
+    pub count: u64,
+    pub total_ns: i128,
+    pub min_ns: Option<i128>,
+    pub max_ns: Option<i128>,
+    pub mean_ns: f64,
+    pub median_ns: Option<f64>,
+    pub variance_ns2: f64,
+}
+
+impl TimeStats {
+    pub fn stddev_ns(&self) -> f64 {
+        self.variance_ns2.sqrt()
+    }
+
+    pub fn is_empty(&self) -> bool {
+        self.count == 0
+    }
+}
+
+#[derive(Debug, Clone, PartialEq)]
+pub(crate) struct TimeMetric {
+    running: RunningStats,
+    samples: Option<Vec<i128>>,
+}
+
+impl TimeMetric {
+    pub(crate) fn new(retain_samples: bool) -> Self {
+        Self {
+            running: RunningStats::default(),
+            samples: retain_samples.then(Vec::new),
+        }
+    }
+
+    pub(crate) fn push_ns(&mut self, value: i128) {
+        self.running.push(value);
+        if let Some(samples) = self.samples.as_mut() {
+            samples.push(value);
+        }
+    }
+
+    pub(crate) fn stats(&self) -> TimeStats {
+        self.running
+            .stats(self.samples.as_ref().and_then(|samples| median_ns(samples)))
+    }
+}
+
+#[derive(Debug, Clone, PartialEq, Default)]
+struct RunningStats {
+    count: u64,
+    total_ns: i128,
+    min_ns: Option<i128>,
+    max_ns: Option<i128>,
+    mean_ns: f64,
+    m2_ns2: f64,
+}
+
+impl RunningStats {
+    fn push(&mut self, value: i128) {
+        self.count += 1;
+        self.total_ns = self.total_ns.saturating_add(value);
+        self.min_ns = Some(self.min_ns.map_or(value, |min| min.min(value)));
+        self.max_ns = Some(self.max_ns.map_or(value, |max| max.max(value)));
+        let x = value as f64;
+        let delta = x - self.mean_ns;
+        self.mean_ns += delta / self.count as f64;
+        let delta2 = x - self.mean_ns;
+        self.m2_ns2 += delta * delta2;
+    }
+
+    fn stats(&self, median_ns: Option<f64>) -> TimeStats {
+        TimeStats {
+            count: self.count,
+            total_ns: self.total_ns,
+            min_ns: self.min_ns,
+            max_ns: self.max_ns,
+            mean_ns: if self.count == 0 { 0.0 } else { self.mean_ns },
+            median_ns,
+            variance_ns2: sample_variance(self.count, self.m2_ns2),
+        }
+    }
+}
+
+fn sample_variance(count: u64, m2: f64) -> f64 {
+    if count < 2 {
+        0.0
+    } else {
+        m2 / (count - 1) as f64
+    }
+}
+
+fn median_ns(samples: &[i128]) -> Option<f64> {
+    if samples.is_empty() {
+        return None;
+    }
+    let mut sorted = samples.to_vec();
+    sorted.sort_unstable();
+    let mid = sorted.len() / 2;
+    Some(if sorted.len() % 2 == 1 {
+        sorted[mid] as f64
+    } else {
+        (sorted[mid - 1] as f64 + sorted[mid] as f64) / 2.0
+    })
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[test]
+    fn running_duration_stats_use_sample_variance() {
+        let mut metric = TimeMetric::new(false);
+        metric.push_ns(1);
+        metric.push_ns(2);
+        metric.push_ns(3);
+        let stats = metric.stats();
+        assert_eq!(stats.count, 3);
+        assert_eq!(stats.total_ns, 6);
+        assert_eq!(stats.min_ns, Some(1));
+        assert_eq!(stats.max_ns, Some(3));
+        assert_eq!(stats.mean_ns, 2.0);
+        assert_eq!(stats.variance_ns2, 1.0);
+        assert_eq!(stats.stddev_ns(), 1.0);
+    }
+
+    #[test]
+    fn exact_median_handles_odd_and_even_samples() {
+        assert_eq!(median_ns(&[3, 1, 2]), Some(2.0));
+        assert_eq!(median_ns(&[4, 1, 2, 3]), Some(2.5));
+        assert_eq!(median_ns(&[-5, 1, 3]), Some(1.0));
+        assert_eq!(median_ns(&[-5, 1, 3, 7]), Some(2.0));
+    }
+
+    #[test]
+    fn single_sample_stddev_is_zero() {
+        let mut metric = TimeMetric::new(false);
+        metric.push_ns(42);
+        let stats = metric.stats();
+        assert_eq!(stats.variance_ns2, 0.0);
+        assert_eq!(stats.stddev_ns(), 0.0);
+    }
+}