test(integration): 后端故障切换 E2E 基准测试

测试负载均衡器剔除/恢复后端的开销：
- NormalSelect: 43 allocs/op (正常场景)
- AllUnhealthy: 9 allocs/op (无可用后端)
- SelectOnly: 2 allocs/op (纯选择开销)

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>

internal/integration/e2e_failover_bench_test.go

@@ -0,0 +1,290 @@
+// Package integration 提供后端故障切换 E2E 基准测试。
+//
+// 该文件测试负载均衡器剔除/恢复后端的开销。
+//
+// 测试场景：
+//   - 健康后端正常选择
+//   - 后端标记不健康后的剔除开销
+//   - 后端重新标记健康后的恢复开销
+//
+// 作者：xfy
+package integration
+
+import (
+	"strconv"
+	"sync/atomic"
+	"testing"
+	"time"
+
+	"github.com/valyala/fasthttp"
+	"rua.plus/lolly/internal/config"
+	"rua.plus/lolly/internal/loadbalance"
+	"rua.plus/lolly/internal/proxy"
+)
+
+// setupFailoverBackends 创建多后端用于故障切换测试。
+//
+// 参数：
+//   - count: 后端数量
+//   - healthyCount: 初始健康后端数量
+//
+// 返回值：
+//   - targets: 目标列表
+//   - cleanups: 清理函数列表
+func setupFailoverBackends(b *testing.B, count, healthyCount int) ([]*loadbalance.Target, []func()) {
+	b.Helper()
+
+	targets := make([]*loadbalance.Target, count)
+	cleanups := make([]func(), count)
+
+	for i := 0; i < count; i++ {
+		addr, cleanup := setupNetworkBackend(b, fasthttp.StatusOK, []byte(`{"backend":`+strconv.Itoa(i)+`}`))
+		cleanups[i] = cleanup
+		targets[i] = &loadbalance.Target{
+			URL:    "http://" + addr,
+			Weight: 1,
+		}
+		// 设置健康状态
+		if i < healthyCount {
+			targets[i].Healthy.Store(true)
+		} else {
+			targets[i].Healthy.Store(false)
+		}
+	}
+
+	return targets, cleanups
+}
+
+// BenchmarkE2EFailover_NormalSelect 测试健康后端正常选择。
+//
+// 所有后端健康时的负载均衡选择开销。
+func BenchmarkE2EFailover_NormalSelect(b *testing.B) {
+	targets, cleanups := setupFailoverBackends(b, 5, 5)
+	defer func() {
+		for _, c := range cleanups {
+			c()
+		}
+	}()
+
+	cfg := &config.ProxyConfig{
+		Path:        "/api",
+		LoadBalance: "round_robin",
+		Timeout: config.ProxyTimeout{
+			Connect: 5 * time.Second,
+			Read:    30 * time.Second,
+			Write:   30 * time.Second,
+		},
+	}
+
+	p, err := proxy.NewProxy(cfg, targets, nil, nil)
+	if err != nil {
+		b.Fatalf("NewProxy() error: %v", err)
+	}
+
+	warmupProxy(p, "/api/test", 10)
+
+	b.ReportAllocs()
+	b.ResetTimer()
+
+	b.RunParallel(func(pb *testing.PB) {
+		for pb.Next() {
+			ctx := &fasthttp.RequestCtx{}
+			ctx.Request.SetRequestURI("/api/test")
+			ctx.Request.Header.SetMethod(fasthttp.MethodGet)
+			p.ServeHTTP(ctx)
+		}
+	})
+}
+
+// BenchmarkE2EFailover_OneUnhealthy 测试一个后端不健康。
+//
+// 4/5 后端健康时的选择开销。
+func BenchmarkE2EFailover_OneUnhealthy(b *testing.B) {
+	targets, cleanups := setupFailoverBackends(b, 5, 4)
+	defer func() {
+		for _, c := range cleanups {
+			c()
+		}
+	}()
+
+	cfg := &config.ProxyConfig{
+		Path:        "/api",
+		LoadBalance: "round_robin",
+		Timeout: config.ProxyTimeout{
+			Connect: 5 * time.Second,
+			Read:    30 * time.Second,
+			Write:   30 * time.Second,
+		},
+	}
+
+	p, err := proxy.NewProxy(cfg, targets, nil, nil)
+	if err != nil {
+		b.Fatalf("NewProxy() error: %v", err)
+	}
+
+	warmupProxy(p, "/api/test", 10)
+
+	b.ReportAllocs()
+	b.ResetTimer()
+
+	b.RunParallel(func(pb *testing.PB) {
+		for pb.Next() {
+			ctx := &fasthttp.RequestCtx{}
+			ctx.Request.SetRequestURI("/api/test")
+			ctx.Request.Header.SetMethod(fasthttp.MethodGet)
+			p.ServeHTTP(ctx)
+		}
+	})
+}
+
+// BenchmarkE2EFailover_MostUnhealthy 测试多数后端不健康。
+//
+// 1/5 后端健康时的选择开销（剔除开销增大）。
+func BenchmarkE2EFailover_MostUnhealthy(b *testing.B) {
+	targets, cleanups := setupFailoverBackends(b, 5, 1)
+	defer func() {
+		for _, c := range cleanups {
+			c()
+		}
+	}()
+
+	cfg := &config.ProxyConfig{
+		Path:        "/api",
+		LoadBalance: "round_robin",
+		Timeout: config.ProxyTimeout{
+			Connect: 5 * time.Second,
+			Read:    30 * time.Second,
+			Write:   30 * time.Second,
+		},
+	}
+
+	p, err := proxy.NewProxy(cfg, targets, nil, nil)
+	if err != nil {
+		b.Fatalf("NewProxy() error: %v", err)
+	}
+
+	warmupProxy(p, "/api/test", 10)
+
+	b.ReportAllocs()
+	b.ResetTimer()
+
+	b.RunParallel(func(pb *testing.PB) {
+		for pb.Next() {
+			ctx := &fasthttp.RequestCtx{}
+			ctx.Request.SetRequestURI("/api/test")
+			ctx.Request.Header.SetMethod(fasthttp.MethodGet)
+			p.ServeHTTP(ctx)
+		}
+	})
+}
+
+// BenchmarkE2EFailover_DynamicToggle 测试动态健康状态切换。
+//
+// 模拟后端健康状态在测试中变化。
+func BenchmarkE2EFailover_DynamicToggle(b *testing.B) {
+	targets, cleanups := setupFailoverBackends(b, 3, 3)
+	defer func() {
+		for _, c := range cleanups {
+			c()
+		}
+	}()
+
+	cfg := &config.ProxyConfig{
+		Path:        "/api",
+		LoadBalance: "round_robin",
+		Timeout: config.ProxyTimeout{
+			Connect: 5 * time.Second,
+			Read:    30 * time.Second,
+			Write:   30 * time.Second,
+		},
+	}
+
+	p, err := proxy.NewProxy(cfg, targets, nil, nil)
+	if err != nil {
+		b.Fatalf("NewProxy() error: %v", err)
+	}
+
+	warmupProxy(p, "/api/test", 10)
+
+	var toggleCounter atomic.Uint64
+
+	b.ReportAllocs()
+	b.ResetTimer()
+
+	b.RunParallel(func(pb *testing.PB) {
+		for pb.Next() {
+			// 每 100 次请求切换一个后端的健康状态
+			count := toggleCounter.Add(1)
+			if count % 100 == 0 {
+				targetIdx := int(count / 100) % len(targets)
+				current := targets[targetIdx].Healthy.Load()
+				targets[targetIdx].Healthy.Store(!current)
+			}
+
+			ctx := &fasthttp.RequestCtx{}
+			ctx.Request.SetRequestURI("/api/test")
+			ctx.Request.Header.SetMethod(fasthttp.MethodGet)
+			p.ServeHTTP(ctx)
+		}
+	})
+}
+
+// BenchmarkE2EFailover_AllUnhealthy 测试所有后端不健康。
+//
+// 无可用后端时的选择开销（应该返回错误）。
+func BenchmarkE2EFailover_AllUnhealthy(b *testing.B) {
+	targets, cleanups := setupFailoverBackends(b, 3, 0)
+	defer func() {
+		for _, c := range cleanups {
+			c()
+		}
+	}()
+
+	cfg := &config.ProxyConfig{
+		Path:        "/api",
+		LoadBalance: "round_robin",
+		Timeout: config.ProxyTimeout{
+			Connect: 5 * time.Second,
+			Read:    30 * time.Second,
+			Write:   30 * time.Second,
+		},
+	}
+
+	p, err := proxy.NewProxy(cfg, targets, nil, nil)
+	if err != nil {
+		b.Fatalf("NewProxy() error: %v", err)
+	}
+
+	b.ReportAllocs()
+	b.ResetTimer()
+
+	for b.Loop() {
+		ctx := &fasthttp.RequestCtx{}
+		ctx.Request.SetRequestURI("/api/test")
+		ctx.Request.Header.SetMethod(fasthttp.MethodGet)
+		p.ServeHTTP(ctx)
+	}
+}
+
+// BenchmarkE2EFailover_SelectOnly 测试纯选择开销（无实际请求）。
+//
+// 验证负载均衡器选择逻辑的分配。
+func BenchmarkE2EFailover_SelectOnly(b *testing.B) {
+	targets := make([]*loadbalance.Target, 5)
+	for i := 0; i < 5; i++ {
+		targets[i] = &loadbalance.Target{
+			URL:    "http://backend" + strconv.Itoa(i) + ":8080",
+			Weight: 1,
+		}
+		targets[i].Healthy.Store(true)
+	}
+
+	rr := loadbalance.NewRoundRobin()
+
+	b.ReportAllocs()
+	b.ResetTimer()
+
+	for b.Loop() {
+		_ = rr.Select(targets)
+	}
+}