add done

1 files changed, 36 insertions, 0 deletions

diff --git a/internal/done.go b/internal/done.go
new file mode 100644
index 0000000..54e5e8e
--- /dev/null
+++ b/internal/done.go
@@ -0,0 +1,36 @@
+package internal
+
+import (
+	"sync"
+)
+
+// Done is a cleanup/shutdown helper.
+type Done struct {
+	ch    chan struct{}
+	mutex sync.Mutex
+}
+
+// NewDone returns a new cleanup/shutdown helper.
+func NewDone() *Done {
+	return &Done{
+		ch: make(chan struct{}),
+	}
+}
+
+// Done returns the done channel (closed when done)
+func (d *Done) Done() <-chan struct{} {
+	return d.ch
+}
+
+// Shutdown closes the done channel. It can be called multiple times.
+func (d *Done) Shutdown() {
+	d.mutex.Lock()
+	defer d.mutex.Unlock()
+
+	select {
+	case <-d.ch:
+		return
+	default:
+		close(d.ch)
+	}
+}