oversight: fix panic on restart of canceled trees

cirello-io · Jan 13, 2022 · 2e4c6e6 · 2e4c6e6
1 parent 6f2109d
commit 2e4c6e6
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Showing 2 changed files with 14 additions and 0 deletions.
diff --git a/tree.go b/tree.go
@@ -266,6 +266,11 @@ func (t *Tree) Start(rootCtx context.Context) error {
 }
 
 func (t *Tree) drain(ctx context.Context) error {
+	select {
+	case <-t.stopped:
+		return ErrTreeNotRunning
+	default:
+	}
 	close(t.stopped)
 	defer t.logger.Printf("clean up complete")
 	t.logger.Printf("context canceled (before start): %v", ctx.Err())

diff --git a/tree_test.go b/tree_test.go
@@ -1061,3 +1061,12 @@ func TestTree_shutdownOrder(t *testing.T) {
 		})
 	})
 }
+
+func TestPanicDoubleStart(t *testing.T) {
+	var tree oversight.Tree
+	oversight.NeverHalt()(&tree)
+	ctx, cancel := context.WithCancel(context.Background())
+	tree.Add(oversight.ChildProcessSpecification{Name: "child", Start: func(context.Context) error { cancel(); return nil }})
+	tree.Start(ctx)
+	tree.Start(ctx)
+}