handle possible panic (#88)

Reviewed-on: https://gitea.com/gitea/act_runner/pulls/88
Reviewed-by: Jason Song <i@wolfogre.com>

poller/poller.go

@@ -57,6 +57,40 @@ func (p *Poller) Wait() {
 	p.routineGroup.Wait()
 }
 
+func (p *Poller) handle(ctx context.Context, l *log.Entry) {
+	defer func() {
+		if r := recover(); r != nil {
+			l.Errorf("handle task panic: %+v", r)
+		}
+	}()
+
+	for {
+		select {
+		case <-ctx.Done():
+			return
+		default:
+			task, err := p.pollTask(ctx)
+			if task == nil || err != nil {
+				if err != nil {
+					l.Errorf("can't find the task: %v", err.Error())
+				}
+				time.Sleep(5 * time.Second)
+				break
+			}
+
+			p.metric.IncBusyWorker()
+			p.routineGroup.Run(func() {
+				defer p.schedule()
+				defer p.metric.DecBusyWorker()
+				if err := p.dispatchTask(ctx, task); err != nil {
+					l.Errorf("execute task: %v", err.Error())
+				}
+			})
+			return
+		}
+	}
+}
+
 func (p *Poller) Poll(ctx context.Context) error {
 	l := log.WithField("func", "Poll")
 
@@ -70,32 +104,7 @@ func (p *Poller) Poll(ctx context.Context) error {
 		case <-ctx.Done():
 			return nil
 		}
-	LOOP:
-		for {
-			select {
-			case <-ctx.Done():
-				break LOOP
-			default:
-				task, err := p.pollTask(ctx)
-				if task == nil || err != nil {
-					if err != nil {
-						l.Errorf("can't find the task: %v", err.Error())
-					}
-					time.Sleep(5 * time.Second)
-					break
-				}
-
-				p.metric.IncBusyWorker()
-				p.routineGroup.Run(func() {
-					defer p.schedule()
-					defer p.metric.DecBusyWorker()
-					if err := p.dispatchTask(ctx, task); err != nil {
-						l.Errorf("execute task: %v", err.Error())
-					}
-				})
-				break LOOP
-			}
-		}
+		p.handle(ctx, l)
 	}
 }