Update dependencies

vendor/tailscale.com/syncs/shardedint.go

@@ -0,0 +1,69 @@
+// Copyright (c) Tailscale Inc & AUTHORS
+// SPDX-License-Identifier: BSD-3-Clause
+
+package syncs
+
+import (
+	"encoding/json"
+	"strconv"
+	"sync/atomic"
+
+	"golang.org/x/sys/cpu"
+)
+
+// ShardedInt provides a sharded atomic int64 value that optimizes high
+// frequency (Mhz range and above) writes in highly parallel workloads.
+// The zero value is not safe for use; use [NewShardedInt].
+// ShardedInt implements the expvar.Var interface.
+type ShardedInt struct {
+	sv *ShardValue[intShard]
+}
+
+// NewShardedInt returns a new [ShardedInt].
+func NewShardedInt() *ShardedInt {
+	return &ShardedInt{
+		sv: NewShardValue[intShard](),
+	}
+}
+
+// Add adds delta to the value.
+func (m *ShardedInt) Add(delta int64) {
+	m.sv.One(func(v *intShard) {
+		v.Add(delta)
+	})
+}
+
+type intShard struct {
+	atomic.Int64
+	_ cpu.CacheLinePad // avoid false sharing of neighboring shards
+}
+
+// Value returns the current value.
+func (m *ShardedInt) Value() int64 {
+	var v int64
+	for s := range m.sv.All {
+		v += s.Load()
+	}
+	return v
+}
+
+// GetDistribution returns the current value in each shard.
+// This is intended for observability/debugging only.
+func (m *ShardedInt) GetDistribution() []int64 {
+	v := make([]int64, 0, m.sv.Len())
+	for s := range m.sv.All {
+		v = append(v, s.Load())
+	}
+	return v
+}
+
+// String implements the expvar.Var interface
+func (m *ShardedInt) String() string {
+	v, _ := json.Marshal(m.Value())
+	return string(v)
+}
+
+// AppendText implements the encoding.TextAppender interface
+func (m *ShardedInt) AppendText(b []byte) ([]byte, error) {
+	return strconv.AppendInt(b, m.Value(), 10), nil
+}