fix close of closed channel

mafredri · mafredri · commit 45a978c0d151 · 2025-04-28T11:56:28.000Z
diff --git a/agent/agentcontainers/watcher/noop.go b/agent/agentcontainers/watcher/noop.go
@@ -12,7 +12,9 @@ func NewNoop() Watcher {
 }
 
 type noopWatcher struct {
-	closed chan struct{}
+	mu     synx.Mutex
+	closed bool
+	done   chan struct{}
 }
 
 func (*noopWatcher) Add(string) error {
@@ -27,12 +29,18 @@ func (n *noopWatcher) Next(ctx context.Context) (*fsnotify.Event, error) {
 	select {
 	case <-ctx.Done():
 		return nil, ctx.Err()
-	case <-n.closed:
+	case <-n.done:
 		return nil, xerrors.New("watcher closed")
 	}
 }
 
 func (n *noopWatcher) Close() error {
-	close(n.closed)
+	n.mu.Lock()
+	defer n.mu.Unlock()
+	if n.closed {
+		return nil
+	}
+	n.closed = true
+	close(n.done)
 	return nil
 }

Original file line number	Diff line number	Diff line change
`@@ -12,7 +12,9 @@ func NewNoop() Watcher {`
`12`	`12`	`}`
`13`	`13`
`14`	`14`	`type noopWatcher struct {`
`15`		`- closed chan struct{}`
	`15`	`+ mu synx.Mutex`
	`16`	`+ closed bool`
	`17`	`+ done chan struct{}`
`16`	`18`	`}`
`17`	`19`
`18`	`20`	`func (*noopWatcher) Add(string) error {`
`@@ -27,12 +29,18 @@ func (n noopWatcher) Next(ctx context.Context) (fsnotify.Event, error) {`
`27`	`29`	`select {`
`28`	`30`	`case <-ctx.Done():`
`29`	`31`	`return nil, ctx.Err()`
`30`		`- case <-n.closed:`
	`32`	`+ case <-n.done:`
`31`	`33`	`return nil, xerrors.New("watcher closed")`
`32`	`34`	`}`
`33`	`35`	`}`
`34`	`36`
`35`	`37`	`func (n *noopWatcher) Close() error {`
`36`		`- close(n.closed)`
	`38`	`+ n.mu.Lock()`
	`39`	`+ defer n.mu.Unlock()`
	`40`	`+ if n.closed {`
	`41`	`+ return nil`
	`42`	`+ }`
	`43`	`+ n.closed = true`
	`44`	`+ close(n.done)`
`37`	`45`	`return nil`
`38`	`46`	`}`