add NewCancelRunnable

Signed-off-by: Tim Ramlot <[email protected]>

Author: inteon

pkg/manager/manager.go

@@ -23,6 +23,7 @@ import (
 	"net"
 	"net/http"
 	"reflect"
+	"sync"
 	"time"
 
 	"github.com/go-logr/logr"
@@ -341,6 +342,34 @@ type LeaderElectionRunnable interface {
 	NeedLeaderElection() bool
 }
 
+// NewCancelRunnable returns a new Runnable and a function to cancel that runnable.
+func NewCancelRunnable(r Runnable) (Runnable, context.CancelFunc) {
+	mu := sync.Mutex{}
+	var cancels []func()
+	canceled := false
+
+	return RunnableFunc(func(ctx context.Context) error {
+			mu.Lock()
+			var cancel context.CancelFunc
+			ctx, cancel = context.WithCancel(ctx)
+			if canceled {
+				cancel()
+			} else {
+				cancels = append(cancels, cancel)
+			}
+			mu.Unlock()
+
+			return r.Start(ctx)
+		}), func() {
+			mu.Lock()
+			defer mu.Unlock()
+			canceled = true
+			for _, cancel := range cancels {
+				cancel()
+			}
+		}
+}
+
 // New returns a new Manager for creating Controllers.
 func New(config *rest.Config, options Options) (Manager, error) {
 	// Set default values for options fields