Sets up statistics summary metric collector

codex/utils/statsummary.nim

@@ -0,0 +1,45 @@
+import pkg/metrics
+
+when defined(metrics):
+  type StatSummary* = ref object of Collector
+    min: float64
+    max: float64
+    ravg: float64
+
+  method collect(st: StatSummary, output: MetricHandler) =
+    let timestamp = st.now()
+    output(
+      name = st.name & "_min",
+      value = st.min,
+      timestamp = timestamp
+    )
+    output(
+      name = st.name & "_max",
+      value = st.max,
+      timestamp = timestamp
+    )
+    output(
+      name = st.name & "_ravg",
+      value = st.ravg,
+      timestamp = timestamp
+    )
+
+proc declareStatSummary*(name: string, help: string = ""): StatSummary =
+  when defined(metrics):
+    result = StatSummary.newCollector(name, help)
+    result.min = high(float64)
+    result.max = low(float64)
+  else:
+    return IgnoredCollector
+
+proc observeStatSummary(st: StatSummary, value: float64) =
+  if value < st.min:
+    st.min = value
+  if value > st.max:
+    st.max = value
+  st.ravg = (st.ravg + value) / 2.0
+
+template observe*(statSummary: StatSummary | type IgnoredCollector, amount: int64 | float64 = 1) =
+  when defined(metrics) and statSummary is not IgnoredCollector:
+    {.gcsafe.}:
+      observeStatSummary(statSummary, amount.float64)