Add idle package

idle/idle.go

@@ -0,0 +1,68 @@
+// Package idle helps to gracefully shutdown idle servers
+package idle
+
+import (
+	"sync/atomic"
+	"time"
+)
+
+type Idler interface {
+	Enter()
+	Exit()
+	Wait()
+	Tick()
+	Chan() <-chan struct{}
+}
+
+type idler struct {
+	lastTick atomic.Pointer[time.Time]
+	c        chan struct{}
+	active   atomic.Int64
+}
+
+func (i *idler) Enter() {
+	i.active.Add(1)
+}
+
+func (i *idler) Exit() {
+	i.Tick()
+	i.active.Add(-1)
+}
+
+func CreateIdler(timeout time.Duration) Idler {
+	i := &idler{}
+	i.c = make(chan struct{})
+	i.Tick()
+	go func() {
+		for {
+			if i.active.Load() != 0 {
+				time.Sleep(timeout)
+			} else {
+				t := *i.lastTick.Load()
+				now := time.Now()
+				dur := t.Add(timeout).Sub(now)
+				if dur == dur.Abs() {
+					time.Sleep(dur)
+				} else {
+					break
+				}
+			}
+
+		}
+		close(i.c)
+	}()
+	return i
+}
+
+func (i *idler) Tick() {
+	now := time.Now()
+	i.lastTick.Store(&now)
+}
+
+func (i *idler) Wait() {
+	<-i.c
+}
+
+func (i *idler) Chan() <-chan struct{} {
+	return i.c
+}

idle/idle_test.go

@@ -0,0 +1,11 @@
+package idle
+
+import (
+	"testing"
+	"time"
+)
+
+func TestIdlerChan(t *testing.T) {
+	i := CreateIdler(1 * time.Second)
+	<-i.Chan()
+}