Add M0 server skeleton with SQLite store, SSE events, worktrees, and tailscale service

internal/server/hub.go

@@ -0,0 +1,53 @@
+package server
+
+import (
+	"sync"
+
+	"g.fc.run/misc/byre/internal/api"
+)
+
+type hub struct {
+	mu   sync.Mutex
+	subs map[chan api.Event]bool
+}
+
+func newHub() *hub {
+	return &hub{subs: map[chan api.Event]bool{}}
+}
+
+func (h *hub) subscribe() chan api.Event {
+	h.mu.Lock()
+	defer h.mu.Unlock()
+	ch := make(chan api.Event, 256)
+	h.subs[ch] = true
+	return ch
+}
+
+func (h *hub) unsubscribe(ch chan api.Event) {
+	h.mu.Lock()
+	defer h.mu.Unlock()
+	if !h.subs[ch] {
+		return
+	}
+	delete(h.subs, ch)
+	close(ch)
+}
+
+func (h *hub) publish(ev api.Event) {
+	h.mu.Lock()
+	defer h.mu.Unlock()
+	for ch := range h.subs {
+		select {
+		case ch <- ev:
+		default:
+			delete(h.subs, ch)
+			close(ch)
+		}
+	}
+}
+
+func (h *hub) count() int {
+	h.mu.Lock()
+	defer h.mu.Unlock()
+	return len(h.subs)
+}