《互联网产品的服务端架构·规模化与架构演进》11.3 大促复盘

// file: internal/promo/review.go
// tier: L1
// verify: go test ./internal/promo/

package promo

import (
	"fmt"
	"sort"
)

// Event 是复盘时间线上的一个事件。
// At 是 Unix 秒，Name 是事件名，Impact 是对用户或业务的影响描述。
type Event struct {
	At     int64
	Name   string
	Impact string
}

// Timeline 返回按时间升序排列的事件副本，不修改输入。
// 同一秒出现两个事件时拒绝排序：先后顺序无法从数据判断，
// 复盘时很容易把因果讲反。
func Timeline(es []Event) ([]Event, error) {
	out := make([]Event, len(es))
	copy(out, es)
	sort.SliceStable(out, func(i, j int) bool { return out[i].At < out[j].At })
	for i := 1; i < len(out); i++ {
		if out[i].At == out[i-1].At {
			return nil, fmt.Errorf("promo: duplicate event time %d: %q and %q", out[i].At, out[i-1].Name, out[i].Name)
		}
	}
	return out, nil
}

// Lessons 把事件名转成待办，不推断根因，也不替代人工复盘。
// 同一个事件名只生成一条，避免同一问题在待办里重复出现。
func Lessons(es []Event) []string {
	ordered := make([]Event, len(es))
	copy(ordered, es)
	sort.SliceStable(ordered, func(i, j int) bool { return ordered[i].At < ordered[j].At })

	seen := make(map[string]struct{}, len(ordered))
	var out []string
	for _, e := range ordered {
		if e.Name == "" {
			continue
		}
		if _, ok := seen[e.Name]; ok {
			continue
		}
		seen[e.Name] = struct{}{}
		if e.Impact != "" {
			out = append(out, fmt.Sprintf("复核事件「%s」：确认影响「%s」的止损动作与负责人", e.Name, e.Impact))
			continue
		}
		out = append(out, fmt.Sprintf("复核事件「%s」：补齐触发条件、止损动作与负责人", e.Name))
	}
	return out
}

// file: internal/promo/review_test.go
// tier: L1
// verify: go test ./internal/promo/

package promo

import (
	"strings"
	"testing"
)

func TestTimelineSortsWithoutMutatingInput(t *testing.T) {
	es := []Event{
		{At: 300, Name: "恢复", Impact: "错误率回落"},
		{At: 100, Name: "监控告警", Impact: "下单错误率上升"},
		{At: 200, Name: "手动限流", Impact: "部分请求排队"},
	}
	got, err := Timeline(es)
	if err != nil {
		t.Fatalf("Timeline returned error: %v", err)
	}
	want := []string{"监控告警", "手动限流", "恢复"}
	for i, name := range want {
		if got[i].Name != name {
			t.Fatalf("event %d = %q, want %q", i, got[i].Name, name)
		}
	}
	if es[0].Name != "恢复" {
		t.Fatalf("Timeline mutated input, first event = %q", es[0].Name)
	}
}

func TestTimelineRejectsDuplicateTime(t *testing.T) {
	es := []Event{
		{At: 100, Name: "告警"},
		{At: 100, Name: "限流"},
	}
	if _, err := Timeline(es); err == nil {
		t.Fatal("want error for two events at the same second")
	} else if !strings.Contains(err.Error(), "duplicate event time") {
		t.Fatalf("error %q should identify duplicate time", err)
	}
}

func TestTimelineAcceptsEmpty(t *testing.T) {
	got, err := Timeline(nil)
	if err != nil {
		t.Fatalf("Timeline(nil) returned error: %v", err)
	}
	if len(got) != 0 {
		t.Fatalf("Timeline(nil) = %v, want empty", got)
	}
}

func TestLessonsFollowTimeOrderAndDedupe(t *testing.T) {
	es := []Event{
		{At: 300, Name: "恢复", Impact: ""},
		{At: 100, Name: "监控告警", Impact: "下单错误率上升"},
		{At: 200, Name: "监控告警", Impact: "重复记录"},
	}
	got := Lessons(es)
	if len(got) != 2 {
		t.Fatalf("Lessons returned %d items, want 2: %v", len(got), got)
	}
	if !strings.Contains(got[0], "监控告警") || !strings.Contains(got[0], "下单错误率上升") {
		t.Fatalf("first lesson = %q, want earliest event with impact", got[0])
	}
	if !strings.Contains(got[1], "恢复") {
		t.Fatalf("second lesson = %q, want recovery event", got[1])
	}
	for _, s := range got {
		if !strings.Contains(s, "复核") {
			t.Fatalf("lesson %q should be a todo starting with 复核", s)
		}
	}
}

func TestLessonsSkipsEmptyName(t *testing.T) {
	got := Lessons([]Event{{At: 100, Name: ""}, {At: 200, Name: "恢复"}})
	if len(got) != 1 || !strings.Contains(got[0], "恢复") {
		t.Fatalf("Lessons = %v, want only the named event", got)
	}
}

cd .local/checks/webapp-lab && go test ./internal/promo/ -run 'TestTimeline|TestLessons' -count=1 -v

=== RUN   TestTimelineSortsWithoutMutatingInput
--- PASS: TestTimelineSortsWithoutMutatingInput (0.00s)
=== RUN   TestTimelineRejectsDuplicateTime
--- PASS: TestTimelineRejectsDuplicateTime (0.00s)
=== RUN   TestTimelineAcceptsEmpty
--- PASS: TestTimelineAcceptsEmpty (0.00s)
=== RUN   TestLessonsFollowTimeOrderAndDedupe
--- PASS: TestLessonsFollowTimeOrderAndDedupe (0.00s)
=== RUN   TestLessonsSkipsEmptyName
--- PASS: TestLessonsSkipsEmptyName (0.00s)
PASS
ok  	webapp/internal/promo	0.245s