Move Linux client & common packages into a public repo.

ratelimit/ratelimit.go

@@ -0,0 +1,78 @@
+// Copyright (c) 2020 Tailscale Inc & AUTHORS All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package ratelimit
+
+import (
+	"sync"
+	"time"
+)
+
+type Bucket struct {
+	mu           sync.Mutex
+	FillInterval time.Duration
+	Burst        int
+	v            int
+	quitCh       chan struct{}
+	started      bool
+	closed       bool
+}
+
+func (b *Bucket) startLocked() {
+	b.v = b.Burst
+	b.quitCh = make(chan struct{})
+	b.started = true
+
+	t := time.NewTicker(b.FillInterval)
+	go func() {
+		for {
+			select {
+			case <-b.quitCh:
+				return
+			case <-t.C:
+				b.tick()
+			}
+		}
+	}()
+}
+
+func (b *Bucket) tick() {
+	b.mu.Lock()
+	defer b.mu.Unlock()
+
+	if b.v < b.Burst {
+		b.v++
+	}
+}
+
+func (b *Bucket) Close() {
+	b.mu.Lock()
+	if !b.started {
+		b.closed = true
+		b.mu.Unlock()
+		return
+	}
+	if b.closed {
+		b.mu.Unlock()
+		return
+	}
+	b.closed = true
+	b.mu.Unlock()
+
+	b.quitCh <- struct{}{}
+}
+
+func (b *Bucket) TryGet() int {
+	b.mu.Lock()
+	defer b.mu.Unlock()
+
+	if !b.started {
+		b.startLocked()
+	}
+	if b.v > 0 {
+		b.v--
+		return b.v + 1
+	}
+	return 0
+}

ratelimit/ratelimit_test.go

@@ -0,0 +1,28 @@
+// Copyright (c) 2020 Tailscale Inc & AUTHORS All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package ratelimit
+
+import (
+	"testing"
+	"time"
+)
+
+func TestBucket(t *testing.T) {
+	b := Bucket{
+		FillInterval: time.Second,
+		Burst:        3,
+	}
+	expect := []int{3, 2, 1, 0, 0}
+	for i, want := range expect {
+		got := b.TryGet()
+		if want != got {
+			t.Errorf("#%d want=%d got=%d\n", i, want, got)
+		}
+	}
+	b.tick()
+	if want, got := 1, b.TryGet(); want != got {
+		t.Errorf("after tick: want=%d got=%d\n", want, got)
+	}
+}