hamlab/internal/metrics/fold_test.go

package metrics

import (
	"testing"
	"time"
)

func TestFoldAverages(t *testing.T) {
	b := []Sample{
		{T: 1, CPU: 10, Cores: []float64{10, 0}, Mem: Mem{Total: 100, Used: 10},
			Temps: []Temp{{Chip: "c", Label: "l", C: 40}}, Net: []Net{{Iface: "eth0", RxBps: 100}},
			Disks: []Disk{{Name: "sda", ReadBps: 10, UtilPct: 5}}},
		{T: 2, CPU: 30, Cores: []float64{30, 100}, Mem: Mem{Total: 100, Used: 30},
			Temps: []Temp{{Chip: "c", Label: "l", C: 60}}, Net: []Net{{Iface: "eth0", RxBps: 300}, {Iface: "new", RxBps: 7}},
			Disks: []Disk{{Name: "sda", ReadBps: 30, UtilPct: 15}}},
	}
	f := fold(b)
	if f.T != 2 {
		t.Errorf("a folded point is stamped with the newest sample in it, got %d", f.T)
	}
	if f.CPU != 20 || f.Cores[0] != 20 || f.Cores[1] != 50 {
		t.Errorf("cpu averaged: %v %v", f.CPU, f.Cores)
	}
	if f.Mem.Used != 20 || f.Mem.Total != 100 {
		t.Errorf("memory: used averaged, total taken from the newest, got %+v", f.Mem)
	}
	if f.Temps[0].C != 50 || f.Net[0].RxBps != 200 || f.Disks[0].ReadBps != 20 || f.Disks[0].UtilPct != 10 {
		t.Errorf("lists matched by name: %v %v %v", f.Temps, f.Net, f.Disks)
	}
	if len(f.Net) != 2 || f.Net[1].RxBps != 7 {
		t.Errorf("an interface that appeared inside the bucket is averaged over the samples that have it: %v", f.Net)
	}
	// the template's own slices must not be touched: Latest() shares them
	if b[1].Cores[0] != 30 || b[1].Temps[0].C != 60 {
		t.Error("fold wrote through to the sample it templated from")
	}
}

func TestStrideAndTrim(t *testing.T) {
	c := &Collector{interval: 2 * time.Second, window: DefaultWindow}
	if got := c.stride(); got != 2*time.Second {
		t.Errorf("a window of %v over %d points is finer than the interval, so the interval wins; got %v", DefaultWindow, History, got)
	}
	c.window = 24 * time.Hour
	if got := c.stride(); got != 24*time.Hour/History {
		t.Errorf("stride at a day: %v", got)
	}
	// a full day of samples at the day stride keeps exactly the budget
	c.interval, c.window = time.Second, time.Hour
	stride := c.stride().Milliseconds()
	for i := 0; i < 5*History; i++ {
		c.keep(Sample{T: int64(i) * stride})
	}
	if len(c.ring) != History {
		t.Errorf("the point count is the budget, got %d", len(c.ring))
	}
	if span := c.ring[len(c.ring)-1].T - c.ring[0].T; span > c.window.Milliseconds() {
		t.Errorf("the kept history reaches back further than the window: %d ms", span)
	}
	// narrowing the window drops what is now too old, at once
	c.SetWindow(MinWindow)
	if span := c.ring[len(c.ring)-1].T - c.ring[0].T; span > MinWindow.Milliseconds() {
		t.Errorf("narrowing the window left %d ms of history", span)
	}
	c.SetWindow(365 * 24 * time.Hour)
	if c.Window() != MaxWindow {
		t.Errorf("a window past the maximum is the maximum, got %v", c.Window())
	}
}

// Points are one stride apart — not a stride and a sample — and jitter doesn't change that.
func TestKeepSpacing(t *testing.T) {
	c := &Collector{interval: 2 * time.Second, window: time.Hour} // stride 12 s: six samples a point
	at := int64(1_000_000)
	for i := 0; i < 6*40; i++ {
		jitter := int64((i*37)%41 - 20) // ±20 ms, deterministic
		c.keep(Sample{T: at + jitter, CPU: float64(i % 6)})
		at += 2000
	}
	if len(c.ring) != 40 {
		t.Fatalf("240 samples at six a point are 40 points, got %d", len(c.ring))
	}
	for i := 1; i < len(c.ring); i++ {
		if gap := c.ring[i].T - c.ring[i-1].T; gap < 11900 || gap > 12100 {
			t.Fatalf("point %d is %d ms after the one before; a stride is 12000", i, gap)
		}
	}
	if c.ring[3].CPU != 2.5 {
		t.Errorf("each point is the mean of its own six samples (0…5 → 2.5), got %v", c.ring[3].CPU)
	}
	// and when the stride is the interval, every sample is a point
	c = &Collector{interval: 2 * time.Second, window: DefaultWindow}
	for i := 0; i < 50; i++ {
		c.keep(Sample{T: int64(i)*2000 + int64(i%3) - 1})
	}
	if len(c.ring) != 50 {
		t.Errorf("at the default window every sample is kept, got %d of 50", len(c.ring))
	}
}