feat: Support graceful job step cancellation (#69)

* for gh-act-runner
* act-cli support as well
* respecting always() and cancelled() of steps
* setup-job, bug report, gh cli and watch wait call is cancelled early

pkg/common/job_error.go

@@ -8,6 +8,10 @@ type jobErrorContextKey string
 
 const jobErrorContextKeyVal = jobErrorContextKey("job.error")
 
+type jobCancelCtx string
+
+const JobCancelCtxVal = jobCancelCtx("job.cancel")
+
 // JobError returns the job error for current context if any
 func JobError(ctx context.Context) error {
 	val := ctx.Value(jobErrorContextKeyVal)
@@ -28,3 +32,35 @@ func WithJobErrorContainer(ctx context.Context) context.Context {
 	container := map[string]error{}
 	return context.WithValue(ctx, jobErrorContextKeyVal, container)
 }
+
+func WithJobCancelContext(ctx context.Context, cancelContext context.Context) context.Context {
+	return context.WithValue(ctx, JobCancelCtxVal, cancelContext)
+}
+
+func JobCancelContext(ctx context.Context) context.Context {
+	val := ctx.Value(JobCancelCtxVal)
+	if val != nil {
+		if container, ok := val.(context.Context); ok {
+			return container
+		}
+	}
+	return nil
+}
+
+// EarlyCancelContext returns a new context based on ctx that is canceled when the first of the provided contexts is canceled.
+func EarlyCancelContext(ctx context.Context) (context.Context, context.CancelFunc) {
+	val := JobCancelContext(ctx)
+	if val != nil {
+		context, cancel := context.WithCancel(ctx)
+		go func() {
+			defer cancel()
+			select {
+			case <-context.Done():
+			case <-ctx.Done():
+			case <-val.Done():
+			}
+		}()
+		return context, cancel
+	}
+	return ctx, func() {}
+}