Simplify node lock and various small changes

Co-authored-by: Fabian Kammel <fabian@kammel.dev>
Co-authored-by: Daniel Weiße <66256922+daniel-weisse@users.noreply.github.com>

bootstrapper/internal/clean/clean.go

@@ -0,0 +1,64 @@
+package clean
+
+import (
+	"sync"
+)
+
+type cleaner struct {
+	stoppers  []stopper
+	stopC     chan struct{}
+	startOnce sync.Once
+	wg        sync.WaitGroup
+}
+
+// New creates a new cleaner.
+func New(stoppers ...stopper) *cleaner {
+	res := &cleaner{
+		stoppers: stoppers,
+		stopC:    make(chan struct{}, 1),
+	}
+	res.wg.Add(1) // for the Start goroutine
+	return res
+}
+
+// With adds a new stopper to the cleaner.
+func (c *cleaner) With(stopper stopper) *cleaner {
+	c.stoppers = append(c.stoppers, stopper)
+	return c
+}
+
+// Start blocks until it receives a stop message, stops all services gracefully and returns.
+func (c *cleaner) Start() {
+	c.startOnce.Do(func() {
+		defer c.wg.Done()
+		// wait for the stop message
+		<-c.stopC
+
+		c.wg.Add(len(c.stoppers))
+		for _, stopItem := range c.stoppers {
+			go func(stopItem stopper) {
+				defer c.wg.Done()
+				stopItem.Stop()
+			}(stopItem)
+		}
+	})
+}
+
+// Clean initiates the cleanup but does not wait for it to complete.
+func (c *cleaner) Clean() {
+	// try to enqueue the stop message once
+	// if the channel is full, the message is dropped
+	select {
+	case c.stopC <- struct{}{}:
+	default:
+	}
+}
+
+// Done waits for the cleanup to complete.
+func (c *cleaner) Done() {
+	c.wg.Wait()
+}
+
+type stopper interface {
+	Stop()
+}