perf(loadbalance): 预计算一致性哈希虚拟节点哈希值
- Target 结构新增 VirtualHashes 字段存储预计算哈希 - 新增 PrecomputeHashes 方法在初始化时计算虚拟节点哈希 - SelectExcludingByKey 使用预计算哈希避免运行时重复计算 - 新增 SelectExcludingByKey 测试和基准测试 Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>
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@ -50,6 +50,10 @@ type Target struct {
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// lastResolved 最后解析时间（UnixNano，使用 atomic.Int64）
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lastResolved atomic.Int64
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// VirtualHashes 预计算的虚拟节点哈希值（用于一致性哈希）
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// 由 PrecomputeHashes 方法填充，避免运行时重复计算
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VirtualHashes []uint64
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}
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// Balancer 是负载均衡算法的接口。
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@ -154,7 +154,38 @@ func BenchmarkConsistentHashRebuild(b *testing.B) {
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}
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}
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// BenchmarkLeastConnSelect 基准测试最少连接算法。
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// BenchmarkConsistentHashSelectExcluding 基准测试一致性哈希排除选择算法。
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func BenchmarkConsistentHashSelectExcluding(b *testing.B) {
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testCases := []struct {
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name string
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targets int
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virtualNodes int
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excludeCount int
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}{
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{"50targets_150vnodes_exclude5", 50, 150, 5},
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{"50targets_150vnodes_exclude10", 50, 150, 10},
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{"100targets_150vnodes_exclude5", 100, 150, 5},
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}
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for _, tc := range testCases {
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b.Run(tc.name, func(b *testing.B) {
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targets := generateTargets(tc.targets)
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ch := NewConsistentHash(tc.virtualNodes, "ip")
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// 预计算所有目标的虚拟节点哈希
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ch.PrecomputeHashes(targets, tc.virtualNodes)
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ch.Rebuild(targets)
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excluded := targets[:tc.excludeCount]
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key := "test-request-key"
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b.ResetTimer()
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for i := 0; i < b.N; i++ {
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ch.SelectExcludingByKey(targets, excluded, key)
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}
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})
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}
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}
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func BenchmarkLeastConnSelect(b *testing.B) {
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testCases := []struct {
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name string
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@ -761,7 +761,153 @@ func TestConsistentHash(t *testing.T) {
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})
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}
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// TestIsValidAlgorithm 测试算法验证函数。
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// TestConsistentHashSelectExcludingByKey 测试一致性哈希排除选择功能。
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func TestConsistentHashSelectExcludingByKey(t *testing.T) {
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t.Run("空排除列表", func(t *testing.T) {
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ch := NewConsistentHash(150, "ip")
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targets := []*Target{
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createHealthyTarget("http://backend1:8080", true),
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createHealthyTarget("http://backend2:8080", true),
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createHealthyTarget("http://backend3:8080", true),
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}
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ch.Rebuild(targets)
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key := "192.168.1.100"
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got := ch.SelectExcludingByKey(targets, []*Target{}, key)
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if got == nil {
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t.Fatal("SelectExcludingByKey() = nil, want non-nil")
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}
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// 验证正常选择行为
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got2 := ch.SelectExcludingByKey(targets, nil, key)
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if got2 == nil {
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t.Fatal("SelectExcludingByKey() with nil = nil, want non-nil")
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}
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if got.URL != got2.URL {
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t.Errorf("空排除和nil排除应该返回相同结果: empty=%q, nil=%q", got.URL, got2.URL)
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}
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})
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t.Run("部分排除", func(t *testing.T) {
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ch := NewConsistentHash(150, "ip")
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targets := []*Target{
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createHealthyTarget("http://backend1:8080", true),
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createHealthyTarget("http://backend2:8080", true),
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createHealthyTarget("http://backend3:8080", true),
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}
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ch.Rebuild(targets)
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// 排除第一个目标
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excluded := []*Target{targets[0]}
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key := "192.168.1.100"
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// 多次选择，验证不会选中排除的目标
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for i := 0; i < 100; i++ {
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got := ch.SelectExcludingByKey(targets, excluded, key)
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if got == nil {
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t.Fatal("SelectExcludingByKey() = nil, want non-nil")
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}
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if got.URL == targets[0].URL {
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t.Errorf("选中了被排除的目标: %q", got.URL)
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}
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}
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})
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t.Run("全部排除", func(t *testing.T) {
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ch := NewConsistentHash(150, "ip")
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targets := []*Target{
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createHealthyTarget("http://backend1:8080", true),
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createHealthyTarget("http://backend2:8080", true),
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}
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ch.Rebuild(targets)
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// 排除所有目标
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excluded := []*Target{targets[0], targets[1]}
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key := "192.168.1.100"
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got := ch.SelectExcludingByKey(targets, excluded, key)
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if got != nil {
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t.Errorf("SelectExcludingByKey() = %q, want nil (all excluded)", got.URL)
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}
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})
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t.Run("排除包含nil目标", func(t *testing.T) {
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ch := NewConsistentHash(150, "ip")
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targets := []*Target{
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createHealthyTarget("http://backend1:8080", true),
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createHealthyTarget("http://backend2:8080", true),
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}
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ch.Rebuild(targets)
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// 排除列表中包含nil
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excluded := []*Target{nil, targets[0]}
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key := "192.168.1.100"
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got := ch.SelectExcludingByKey(targets, excluded, key)
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if got == nil {
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t.Fatal("SelectExcludingByKey() = nil, want non-nil")
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}
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if got.URL == targets[0].URL {
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t.Errorf("选中了被排除的目标: %q", got.URL)
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}
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})
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t.Run("并发安全", func(t *testing.T) {
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ch := NewConsistentHash(150, "ip")
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targets := []*Target{
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createHealthyTarget("http://backend1:8080", true),
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createHealthyTarget("http://backend2:8080", true),
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createHealthyTarget("http://backend3:8080", true),
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}
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ch.Rebuild(targets)
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excluded := []*Target{targets[0]}
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key := "192.168.1.100"
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var wg sync.WaitGroup
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for i := 0; i < 100; i++ {
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wg.Add(1)
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go func() {
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defer wg.Done()
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for j := 0; j < 100; j++ {
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got := ch.SelectExcludingByKey(targets, excluded, key)
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if got != nil && got.URL == targets[0].URL {
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t.Errorf("并发时选中了被排除的目标: %q", got.URL)
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}
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}
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}()
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}
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wg.Wait()
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})
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t.Run("相同键一致性", func(t *testing.T) {
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ch := NewConsistentHash(150, "ip")
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targets := []*Target{
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createHealthyTarget("http://backend1:8080", true),
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createHealthyTarget("http://backend2:8080", true),
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createHealthyTarget("http://backend3:8080", true),
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}
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ch.Rebuild(targets)
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excluded := []*Target{targets[0]}
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key := "192.168.1.100"
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// 相同键应该始终返回相同的目标
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var firstSelection *Target
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for i := 0; i < 50; i++ {
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got := ch.SelectExcludingByKey(targets, excluded, key)
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if got == nil {
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t.Fatal("SelectExcludingByKey() = nil, want non-nil")
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}
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if firstSelection == nil {
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firstSelection = got
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} else if got.URL != firstSelection.URL {
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t.Errorf("相同键选择不同目标: first=%q, got=%q", firstSelection.URL, got.URL)
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}
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}
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})
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}
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func TestIsValidAlgorithm(t *testing.T) {
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tests := []struct {
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name string
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@ -130,9 +130,17 @@ func (c *ConsistentHash) rebuildCircle(targets []*Target) {
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continue
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}
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for i := 0; i < c.virtualNodes; i++ {
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key := fmt.Sprintf("%s#%d", target.URL, i)
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hash := c.hashKeyString(key)
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// 确保目标已预计算哈希
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if len(target.VirtualHashes) == 0 {
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target.VirtualHashes = make([]uint64, c.virtualNodes)
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for i := 0; i < c.virtualNodes; i++ {
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key := fmt.Sprintf("%s#%d", target.URL, i)
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target.VirtualHashes[i] = c.hashKeyString(key)
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}
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}
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// 使用预计算的哈希值
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for _, hash := range target.VirtualHashes {
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c.circle[hash] = target
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c.sortedHashes = append(c.sortedHashes, hash)
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}
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@ -151,6 +159,34 @@ func (c *ConsistentHash) hashKeyString(key string) uint64 {
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return h.Sum64()
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}
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// PrecomputeHashes 预计算目标的虚拟节点哈希值。
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//
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// 此方法应在目标初始化时调用，避免在 SelectExcludingByKey 中重复计算哈希值。
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// 预计算的哈希值存储在 Target.VirtualHashes 中，用于故障转移场景。
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//
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// 参数：
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// - targets: 需要预计算哈希的目标列表
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// - virtualNodes: 每个目标的虚拟节点数
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func (c *ConsistentHash) PrecomputeHashes(targets []*Target, virtualNodes int) {
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if virtualNodes <= 0 {
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virtualNodes = 150
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}
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for _, target := range targets {
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// 如果已经预计算过且数量匹配，跳过
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if len(target.VirtualHashes) == virtualNodes {
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continue
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}
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// 预计算该目标的所有虚拟节点哈希
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target.VirtualHashes = make([]uint64, virtualNodes)
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for i := 0; i < virtualNodes; i++ {
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key := fmt.Sprintf("%s#%d", target.URL, i)
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target.VirtualHashes[i] = c.hashKeyString(key)
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}
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}
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}
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// GetHashKey 返回哈希键配置。
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func (c *ConsistentHash) GetHashKey() string {
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return c.hashKey
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@ -207,6 +243,9 @@ func (c *ConsistentHash) SelectExcluding(targets []*Target, excluded []*Target)
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// 返回值：
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// - *Target: 选中的目标，如果没有可用目标则返回 nil
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func (c *ConsistentHash) SelectExcludingByKey(targets []*Target, excluded []*Target, key string) *Target {
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c.mu.RLock()
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defer c.mu.RUnlock()
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// 构建排除集合
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excludeSet := make(map[string]bool, len(excluded))
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for _, t := range excluded {
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@ -215,48 +254,46 @@ func (c *ConsistentHash) SelectExcludingByKey(targets []*Target, excluded []*Tar
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}
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}
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c.mu.RLock()
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defer c.mu.RUnlock()
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// 如果没有排除的目标，使用正常选择
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if len(excludeSet) == 0 {
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return c.SelectByKey(targets, key)
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}
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// 过滤掉被排除的目标
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filtered := make([]*Target, 0, len(targets))
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for _, t := range targets {
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if t.Healthy.Load() && !excludeSet[t.URL] {
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filtered = append(filtered, t)
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}
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}
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if len(filtered) == 0 {
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return nil
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}
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// 为过滤后的目标临时构建哈希环
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// 使用预计算的虚拟节点哈希构建哈希环
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// 避免在每次调用时重新计算哈希值
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circle := make(map[uint64]*Target)
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sortedHashes := make([]uint64, 0)
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sortedHashes := make([]uint64, 0, len(targets)*c.virtualNodes)
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for _, target := range filtered {
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for i := 0; i < c.virtualNodes; i++ {
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nodeKey := fmt.Sprintf("%s#%d", target.URL, i)
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hash := c.hashKeyString(nodeKey)
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for _, target := range targets {
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if !target.Healthy.Load() || excludeSet[target.URL] {
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continue
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}
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// 确保目标已预计算哈希
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if len(target.VirtualHashes) == 0 {
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// 回退到动态计算（不应该发生，但保持安全）
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c.mu.RUnlock()
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c.PrecomputeHashes([]*Target{target}, c.virtualNodes)
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c.mu.RLock()
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}
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// 使用预计算的哈希值
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for _, hash := range target.VirtualHashes {
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circle[hash] = target
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sortedHashes = append(sortedHashes, hash)
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}
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}
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// 排序哈希值
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sort.Slice(sortedHashes, func(i, j int) bool {
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return sortedHashes[i] < sortedHashes[j]
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})
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if len(sortedHashes) == 0 {
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return nil
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}
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// 排序哈希值（仅在需要时）
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// 使用 sort.Slice 进行排序
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sort.Slice(sortedHashes, func(i, j int) bool {
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return sortedHashes[i] < sortedHashes[j]
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})
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// 计算键的哈希值
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hash := c.hashKeyString(key)
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