added an utility to collect statics eazier

server/src/utils.rs → server/src/utils/mod.rs

@@ -1,3 +1,5 @@
+pub mod statistics;
+
 use diesel::{Connection, SqliteConnection};
 use serde::Deserialize;
 

server/src/utils/statistics.rs

@@ -0,0 +1,93 @@
+use std::fmt;
+use std::ops::{Add, Div};
+
+pub struct Statistic<T> {
+    min: Option<T>,
+    max: Option<T>,
+    sum: Option<T>,
+    cnt: u32,
+}
+impl<T: Ord + Copy + Add<T, Output = T>> Statistic<T> {
+    pub fn new() -> Self {
+        Self {
+            cnt: 0,
+            sum: None,
+            min: None,
+            max: None,
+        }
+    }
+    pub fn push(&mut self, value: T) {
+        self.cnt += 1;
+        self.sum = match self.sum {
+            Some(sum) => Some(sum + value),
+            None => Some(value),
+        };
+        self.min = match self.min {
+            Some(min) => Some(std::cmp::min(min, value)),
+            None => Some(value),
+        };
+        self.max = match self.max {
+            Some(max) => Some(std::cmp::max(max, value)),
+            None => Some(value),
+        };
+    }
+}
+
+impl<T: fmt::Debug + Copy + Div<u32, Output = T> + Clone> fmt::Debug for Statistic<T> {
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+        f.debug_struct("Stats")
+            .field("cnt", &self.cnt)
+            .field("min", &self.min.unwrap())
+            .field("avg", &(self.sum.unwrap() / self.cnt))
+            .field("max", &self.max.unwrap())
+            .finish()
+    }
+}
+
+#[cfg(test)]
+mod test {
+    use super::*;
+    #[test]
+    fn test_duration() {
+        use std::time::Duration;
+        let mut stat = Statistic::new();
+        stat.push(Duration::from_secs(1));
+        stat.push(Duration::from_secs(2));
+        stat.push(Duration::from_secs(3));
+        assert_eq!(
+            format!("{stat:?}"),
+            "Stats { cnt: 3, min: 1s, avg: 2s, max: 3s }"
+        );
+        stat.push(Duration::from_secs(0));
+        assert_eq!(
+            format!("{stat:?}"),
+            "Stats { cnt: 4, min: 0ns, avg: 1.5s, max: 3s }"
+        );
+        stat.push(Duration::from_secs(0));
+        assert_eq!(
+            format!("{stat:?}"),
+            "Stats { cnt: 5, min: 0ns, avg: 1.2s, max: 3s }"
+        );
+    }
+    #[test]
+    fn test_u32() {
+        let mut stat = Statistic::new();
+        stat.push(1);
+        stat.push(2);
+        stat.push(3);
+        assert_eq!(
+            format!("{stat:?}"),
+            "Stats { cnt: 3, min: 1, avg: 2, max: 3 }"
+        );
+        stat.push(0);
+        assert_eq!(
+            format!("{stat:?}"),
+            "Stats { cnt: 4, min: 0, avg: 1, max: 3 }"
+        );
+        stat.push(0);
+        assert_eq!(
+            format!("{stat:?}"),
+            "Stats { cnt: 5, min: 0, avg: 1, max: 3 }"
+        );
+    }
+}