Fix deadlock (#11244)

This PR uses a go routine when sending would otherwise block.

core/loadpoint.go

@@ -384,8 +384,20 @@ func (lp *Loadpoint) pushEvent(event string) {
 
 // publish sends values to UI and databases
 func (lp *Loadpoint) publish(key string, val interface{}) {
-	if lp.uiChan != nil {
-		lp.uiChan <- util.Param{Key: key, Val: val}
+	// test helper
+	if lp.uiChan == nil {
+		return
+	}
+
+	p := util.Param{Key: key, Val: val}
+
+	// https://github.com/evcc-io/evcc/issues/11191 prevent deadlock
+	select {
+	case lp.uiChan <- p:
+	default:
+		go func() {
+			lp.uiChan <- p
+		}()
 	}
 }
 

core/loadpoint_test.go

@@ -526,6 +526,7 @@ func cacheExpecter(t *testing.T, lp *Loadpoint) (*util.Cache, func(key string, v
 	go cache.Run(paramC)
 
 	expect := func(key string, val interface{}) {
+		time.Sleep(100 * time.Millisecond) // wait for cache to catch up
 		p := cache.Get(key)
 		t.Logf("%s: %.f", key, p.Val) // REMOVE
 		if p.Val != val {

core/site.go

@@ -360,9 +360,15 @@ func (site *Site) publish(key string, val interface{}) {
 		val = s.String()
 	}
 
-	site.uiChan <- util.Param{
-		Key: key,
-		Val: val,
+	p := util.Param{Key: key, Val: val}
+
+	// https://github.com/evcc-io/evcc/issues/11191 prevent deadlock
+	select {
+	case site.uiChan <- p:
+	default:
+		go func() {
+			site.uiChan <- p
+		}()
 	}
 }
 

util/tee.go

@@ -20,7 +20,7 @@ type Tee struct {
 func (t *Tee) Attach() <-chan Param {
 	// TODO find better approach to prevent deadlocks
 	// this will buffer the receiver channel to prevent deadlocks when consumers use mutex-protected loadpoint api
-	out := make(chan Param, 16)
+	out := make(chan Param, 128)
 	t.add(out)
 	return out
 }