feat(server): online session history with configurable stats window (#1243)

Add persisted online sessions, configurable retention and online history statistics with lifecycle, recovery, timezone and concurrency regression coverage.

Co-authored-by: naiba/CloudCode <hi+cloudcode@nai.ba>

model/online_history_test.go

@@ -0,0 +1,220 @@
+package model
+
+import (
+	"math/rand"
+	"testing"
+	"time"
+
+	"github.com/stretchr/testify/require"
+)
+
+var testZone = time.FixedZone("TEST", 8*3600)
+
+func ts(y int, mo time.Month, d, h, mi, s int) time.Time {
+	return time.Date(y, mo, d, h, mi, s, 0, testZone)
+}
+
+func TestClipOnlineSessions(t *testing.T) {
+	windowStart := ts(2026, 10, 1, 0, 0, 0)
+	windowEnd := ts(2026, 10, 8, 0, 0, 0)
+
+	t.Run("session fully inside window", func(t *testing.T) {
+		sessions := []OnlineSession{
+			{ServerID: 1, StartedAt: ts(2026, 10, 2, 8, 0, 0), EndedAt: ts(2026, 10, 2, 9, 30, 0)},
+		}
+		periods := ClipOnlineSessions(sessions, windowStart, windowEnd)
+		require.Len(t, periods, 1)
+		require.Equal(t, ts(2026, 10, 2, 8, 0, 0), periods[0].Start)
+		require.Equal(t, ts(2026, 10, 2, 9, 30, 0), periods[0].End)
+		require.False(t, periods[0].Ongoing)
+	})
+
+	t.Run("session started before window is clipped", func(t *testing.T) {
+		sessions := []OnlineSession{
+			{ServerID: 1, StartedAt: ts(2026, 9, 28, 12, 0, 0), EndedAt: ts(2026, 10, 1, 5, 0, 0)},
+		}
+		periods := ClipOnlineSessions(sessions, windowStart, windowEnd)
+		require.Len(t, periods, 1)
+		require.Equal(t, windowStart, periods[0].Start)
+		require.Equal(t, ts(2026, 10, 1, 5, 0, 0), periods[0].End)
+	})
+
+	t.Run("ongoing session ends at window end", func(t *testing.T) {
+		sessions := []OnlineSession{
+			{ServerID: 1, StartedAt: ts(2026, 10, 7, 10, 0, 0), Ongoing: true},
+		}
+		periods := ClipOnlineSessions(sessions, windowStart, windowEnd)
+		require.Len(t, periods, 1)
+		require.Equal(t, windowEnd, periods[0].End)
+		require.True(t, periods[0].Ongoing)
+	})
+
+	t.Run("zero ended_at treated as ongoing", func(t *testing.T) {
+		sessions := []OnlineSession{
+			{ServerID: 1, StartedAt: ts(2026, 10, 7, 10, 0, 0)},
+		}
+		periods := ClipOnlineSessions(sessions, windowStart, windowEnd)
+		require.Len(t, periods, 1)
+		require.True(t, periods[0].Ongoing)
+		require.Equal(t, windowEnd, periods[0].End)
+	})
+
+	t.Run("session outside window yields no period", func(t *testing.T) {
+		sessions := []OnlineSession{
+			{ServerID: 1, StartedAt: ts(2026, 9, 1, 0, 0, 0), EndedAt: ts(2026, 9, 2, 0, 0, 0)},
+		}
+		require.Empty(t, ClipOnlineSessions(sessions, windowStart, windowEnd))
+	})
+}
+
+func TestDailyOnlineBreakdown(t *testing.T) {
+	loc := time.FixedZone("UTC+8", 8*3600)
+	windowStart := time.Date(2026, 10, 1, 10, 0, 0, 0, loc)
+	windowEnd := time.Date(2026, 10, 3, 14, 0, 0, 0, loc)
+
+	periods := []OnlinePeriod{
+		// 跨午夜：2 日 23:00 ~ 3 日 01:00
+		{Start: time.Date(2026, 10, 2, 23, 0, 0, 0, loc), End: time.Date(2026, 10, 3, 1, 0, 0, 0, loc)},
+		// 窗口前就开始的会话，裁剪后从窗口起点开始
+		{Start: windowStart, End: time.Date(2026, 10, 1, 12, 0, 0, 0, loc)},
+	}
+
+	daily := DailyOnlineBreakdown(periods, windowStart, windowEnd, loc)
+	require.Len(t, daily, 3)
+	require.Equal(t, "2026-10-01", daily[0].Date)
+	require.Equal(t, "2026-10-02", daily[1].Date)
+	require.Equal(t, "2026-10-03", daily[2].Date)
+
+	// 1 日：12:00-10:00 = 2h；2 日：23:00-24:00 = 1h；3 日：0:00-1:00 + 窗口外无 = 1h
+	require.Equal(t, uint64(7200), daily[0].OnlineSeconds)
+	require.Equal(t, uint64(3600), daily[1].OnlineSeconds)
+	require.Equal(t, uint64(3600), daily[2].OnlineSeconds)
+
+	// 每日合计即总时长（口径：每日累计原始时长后统一取整）
+	var sum uint64
+	for _, d := range daily {
+		sum += d.OnlineSeconds
+	}
+	require.Equal(t, uint64(7200+3600+3600), sum)
+}
+
+// 评审回归：取整必须按日累计原始时长后统一转换。逐段截断再累加会让亚秒
+// 会话系统性偏小——同一天两个 1.5s 的会话应得 3s，而不是 1+1=2s
+func TestDailyOnlineBreakdownSubSecond(t *testing.T) {
+	loc := testZone
+	windowStart := ts(2026, 10, 1, 0, 0, 0)
+	windowEnd := ts(2026, 10, 2, 0, 0, 0)
+	periods := []OnlinePeriod{
+		{Start: windowStart.Add(100 * time.Millisecond), End: windowStart.Add(1600 * time.Millisecond)},
+		{Start: windowStart.Add(2 * time.Second), End: windowStart.Add(3500 * time.Millisecond)},
+	}
+	daily := DailyOnlineBreakdown(periods, windowStart, windowEnd, loc)
+	require.Len(t, daily, 1)
+	require.Equal(t, uint64(3), daily[0].OnlineSeconds)
+}
+
+// 跨日时段按日界切分不损失精度：各日分别累计原始时长后各自取整
+func TestDailyOnlineBreakdownCrossDayFraction(t *testing.T) {
+	loc := testZone
+	windowStart := ts(2026, 10, 1, 0, 0, 0)
+	windowEnd := ts(2026, 10, 3, 0, 0, 0)
+	periods := []OnlinePeriod{{
+		Start: time.Date(2026, 10, 1, 23, 59, 59, 250000000, loc),
+		End:   time.Date(2026, 10, 2, 0, 0, 2, 750000000, loc),
+	}}
+	daily := DailyOnlineBreakdown(periods, windowStart, windowEnd, loc)
+	require.Len(t, daily, 2)
+	require.Equal(t, uint64(0), daily[0].OnlineSeconds) // 0.75s → 0
+	require.Equal(t, uint64(2), daily[1].OnlineSeconds) // 2.75s → 2
+}
+
+func TestDailyOnlineBreakdownZeroOnline(t *testing.T) {
+	loc := time.FixedZone("UTC+8", 8*3600)
+	windowStart := time.Date(2026, 10, 1, 0, 0, 0, 0, loc)
+	windowEnd := time.Date(2026, 10, 4, 0, 0, 0, 0, loc)
+	daily := DailyOnlineBreakdown(nil, windowStart, windowEnd, loc)
+	require.Len(t, daily, 3)
+	for _, d := range daily {
+		require.Zero(t, d.OnlineSeconds)
+	}
+}
+
+func TestOnlineStatsDaysBounds(t *testing.T) {
+	require.Equal(t, 7, DefaultOnlineStatsDays)
+	require.Equal(t, 7, MinOnlineStatsDays)
+	require.Equal(t, 3650, MaxOnlineStatsDays)
+}
+
+// F1 回归保护：指针推进实现必须与逐日朴素实现对任意不相交时段集合等价
+// （单服务器会话互不重叠的约束一致），长窗口大量时段下不再随时段数平方放大。
+func TestDailyOnlineBreakdownEquivalence(t *testing.T) {
+	loc := testZone
+	windowStart := ts(2026, 1, 1, 0, 0, 0)
+	windowEnd := windowStart.AddDate(0, 0, 90)
+
+	rng := rand.New(rand.NewSource(42))
+	var periods []OnlinePeriod
+	cursor := windowStart
+	for cursor.Before(windowEnd) {
+		// 起止带亚秒抖动：让逐段截断与按日累计两种口径可区分
+		start := cursor.Add(time.Duration(rng.Intn(4*3600))*time.Second + time.Duration(rng.Int63n(int64(time.Second))))
+		end := start.Add(time.Duration(1+rng.Intn(6*3600))*time.Second + time.Duration(rng.Int63n(int64(time.Second))))
+		if end.After(windowEnd) {
+			end = windowEnd
+		}
+		periods = append(periods, OnlinePeriod{Start: start, End: end})
+		cursor = end.Add(time.Duration(1+rng.Intn(3600)) * time.Second)
+	}
+
+	days := DailyOnlineBreakdown(periods, windowStart, windowEnd, loc)
+
+	// 参考实现与生产同一口径：每日累计原始时长、汇总时向下取整一次
+	reference := map[string]time.Duration{}
+	for _, p := range periods {
+		for d := windowStart; d.Before(windowEnd); d = d.AddDate(0, 0, 1) {
+			overlapStart := maxTime(p.Start, d)
+			overlapEnd := minTime(p.End, d.AddDate(0, 0, 1))
+			if overlapStart.Before(overlapEnd) {
+				reference[d.Format("2006-01-02")] += overlapEnd.Sub(overlapStart)
+			}
+		}
+	}
+	require.Len(t, days, 90)
+	for _, day := range days {
+		require.Equal(t, uint64(reference[day.Date].Seconds()), day.OnlineSeconds, "date %s", day.Date)
+	}
+}
+
+func TestDailyOnlineBreakdownMidnightDSTTransition(t *testing.T) {
+	loc, err := time.LoadLocation("America/Sao_Paulo")
+	require.NoError(t, err)
+	start := time.Date(2018, 11, 3, 0, 0, 0, 0, loc)
+	end := time.Date(2018, 11, 6, 0, 0, 0, 0, loc)
+	days := DailyOnlineBreakdown([]OnlinePeriod{{Start: start, End: end}}, start, end, loc)
+	require.Equal(t, []DailyOnlineStat{{Date: "2018-11-03", OnlineSeconds: 86400}, {Date: "2018-11-04", OnlineSeconds: 82800}, {Date: "2018-11-05", OnlineSeconds: 86400}}, days)
+}
+
+func TestDailyOnlineBreakdownRepeatedMidnight(t *testing.T) {
+	loc, err := time.LoadLocation("Asia/Amman")
+	require.NoError(t, err)
+	start := time.Date(2021, 10, 28, 21, 0, 0, 0, time.UTC)
+	end := time.Date(2021, 10, 29, 22, 0, 0, 0, time.UTC)
+	days := DailyOnlineBreakdown([]OnlinePeriod{{Start: start, End: end}}, start, end, loc)
+	require.Equal(t, []DailyOnlineStat{{Date: "2021-10-29", OnlineSeconds: 90000}}, days)
+}
+
+func TestOnlineHistoryWindowUsesDashboardCalendar(t *testing.T) {
+	loc, err := time.LoadLocation("America/New_York")
+	require.NoError(t, err)
+	for _, test := range []struct {
+		month      time.Month
+		day, hours int
+	}{{time.March, 9, 23}, {time.November, 2, 25}} {
+		end := time.Date(2026, test.month, test.day, 0, 30, 0, 0, loc)
+		start := OnlineHistoryWindowStart(end.UTC(), 1, loc)
+		require.True(t, start.Equal(time.Date(2026, test.month, test.day-1, 0, 30, 0, 0, loc)))
+		require.Equal(t, time.Duration(test.hours)*time.Hour, end.Sub(start))
+		require.Len(t, DailyOnlineBreakdown(nil, start, end, loc), 2)
+		require.True(t, OnlineHistoryWindowStart(end.UTC(), 7, loc).Equal(end.In(loc).AddDate(0, 0, -7)))
+	}
+}