Changeset 0.23.1 (#154)

server/events/bus.go

@@ -10,9 +10,10 @@ import (
 // Handlers subscribe to patterns (exact or trailing wildcard).
 // Publishing fans out to all matching subscribers.
 type Bus struct {
-	mu   sync.RWMutex
-	subs map[string][]*subscription
-	seq  uint64 // subscription ID counter
+	mu            sync.RWMutex
+	subs          map[string][]*subscription
+	seq           uint64 // subscription ID counter
+	broadcastHook func(Event) // called after Publish for cross-pod fan-out; nil-safe
 }
 
 type subscription struct {
@@ -28,6 +29,15 @@ func NewBus() *Bus {
 	}
 }
 
+// SetBroadcastHook registers a function called after every Publish.
+// Used by the Postgres LISTEN/NOTIFY adapter to fan out across pods.
+// The hook is NOT called by publishLocal (avoids re-broadcast loops).
+func (b *Bus) SetBroadcastHook(fn func(Event)) {
+	b.mu.Lock()
+	b.broadcastHook = fn
+	b.mu.Unlock()
+}
+
 // Subscribe registers a handler for a label pattern.
 // Returns an unsubscribe function.
 //
@@ -60,7 +70,22 @@ func (b *Bus) Subscribe(pattern string, handler Handler) func() {
 // Publish dispatches an event to all matching subscribers.
 // Handlers are called synchronously in subscription order.
 // Use PublishAsync for non-blocking dispatch.
+// After local dispatch, calls the broadcastHook if set (Postgres fan-out).
 func (b *Bus) Publish(event Event) {
+	b.publishLocal(event)
+
+	b.mu.RLock()
+	hook := b.broadcastHook
+	b.mu.RUnlock()
+	if hook != nil {
+		hook(event)
+	}
+}
+
+// publishLocal dispatches to local subscribers only, without triggering
+// the broadcastHook. Used by the Postgres listener to re-publish remote
+// events without causing an infinite re-broadcast loop.
+func (b *Bus) publishLocal(event Event) {
 	b.mu.RLock()
 	var matched []Handler
 	for pattern, subs := range b.subs {
@@ -79,6 +104,7 @@ func (b *Bus) Publish(event Event) {
 
 // PublishAsync dispatches an event to all matching subscribers
 // in separate goroutines. Useful for I/O-heavy handlers.
+// Also calls the broadcastHook asynchronously if set.
 func (b *Bus) PublishAsync(event Event) {
 	b.mu.RLock()
 	var matched []Handler
@@ -89,11 +115,15 @@ func (b *Bus) PublishAsync(event Event) {
 			}
 		}
 	}
+	hook := b.broadcastHook
 	b.mu.RUnlock()
 
 	for _, h := range matched {
 		go h(event)
 	}
+	if hook != nil {
+		go hook(event)
+	}
 }
 
 // match checks if a concrete label matches a subscription pattern.