refact round 2

engine/session.go

@@ -0,0 +1,43 @@
+package engine
+
+import "sync"
+
+// State holds shared server state (thread-safe)
+type State struct {
+	OnlineUsers map[string]string // addr -> username
+	Mu          sync.Mutex
+}
+
+func newState() *State {
+	return &State{
+		OnlineUsers: make(map[string]string),
+	}
+}
+
+// UserCount returns the number of online users in a thread-safe manner
+func (st *State) UserCount() int {
+	st.Mu.Lock()
+	defer st.Mu.Unlock()
+	return len(st.OnlineUsers)
+}
+
+// Snapshot returns a thread-safe copy of the online users map
+func (st *State) Snapshot() map[string]string {
+	st.Mu.Lock()
+	defer st.Mu.Unlock()
+	snap := make(map[string]string)
+	for k, v := range st.OnlineUsers {
+		snap[k] = v
+	}
+	return snap
+}
+
+// Session represents an active user connection
+type Session struct {
+	State    *State
+	Printer  *Printer
+	Username string
+	Addr     string
+	Lang     T
+	Quit     bool
+}