Naming, layout and comments: descriptive full-word names, one item per line in wrapped calls and literals, and doc comments on exported names

Short and single-letter names in application code become full words (tests
keep theirs). Wrapped calls, signatures and composite literals put one item
per line, and one-line function bodies are expanded. Exported names and
groups of constants get doc comments, and comments refer to the renamed
identifiers.

internal/websocket/hub.go

@@ -17,7 +17,7 @@ type Hub struct {
 	conf config.JSCServerWebSocket
 	log  *slog.Logger
 
-	m       sync.RWMutex
+	mu      sync.RWMutex
 	clients map[*client]struct{}
 	closed  bool
 	wg      sync.WaitGroup
@@ -82,13 +82,13 @@ func (h *Hub) Push(msgType string, payload any) {
 	}
 
 	var slow []*client
-	h.m.RLock()
+	h.mu.RLock()
 	for client := range h.clients {
 		if !client.trySend(msg) {
 			slow = append(slow, client)
 		}
 	}
-	h.m.RUnlock()
+	h.mu.RUnlock()
 
 	for _, client := range slow {
 		h.logger().Warn("dropping slow client", "client", client.id, "ip", client.ip)
@@ -98,8 +98,8 @@ func (h *Hub) Push(msgType string, payload any) {
 
 // Count returns the number of connected clients.
 func (h *Hub) Count() int {
-	h.m.RLock()
-	defer h.m.RUnlock()
+	h.mu.RLock()
+	defer h.mu.RUnlock()
 	return len(h.clients)
 }
 
@@ -108,13 +108,13 @@ func (h *Hub) Count() int {
 // closed at once and ctx's error is returned. New connections are refused
 // afterwards.
 func (h *Hub) Shutdown(ctx context.Context) error {
-	h.m.Lock()
+	h.mu.Lock()
 	h.closed = true
 	clientShutdowns := make([]*client, 0, len(h.clients))
 	for client := range h.clients {
 		clientShutdowns = append(clientShutdowns, client)
 	}
-	h.m.Unlock()
+	h.mu.Unlock()
 
 	if len(clientShutdowns) == 0 {
 		// Nothing to close. Clients that just left are only finishing their
@@ -151,7 +151,9 @@ func (h *Hub) Shutdown(ctx context.Context) error {
 }
 
 // maxMessageSize is the largest message read from a client: max_message_size,
-// or defaultMaxMessageSize if that is 0 or less.
+// or defaultMaxMessageSize if that is 0 or less. The configuration rejects -1
+// (no limit) for this setting, as a client could then exhaust the server's
+// memory; a -1 set in code also gets the default, never no limit.
 func (h *Hub) maxMessageSize() int {
 	if h.conf.MaxMessageSize <= 0 {
 		return defaultMaxMessageSize
@@ -161,21 +163,21 @@ func (h *Hub) maxMessageSize() int {
 
 // register adds a client to the hub. Hub clients receive all push messages and
 // have their lifecycles tracked by the hub.
-func (h *Hub) register(c *client) bool {
-	h.m.Lock()
-	defer h.m.Unlock()
+func (h *Hub) register(client *client) bool {
+	h.mu.Lock()
+	defer h.mu.Unlock()
 	if h.closed {
 		return false
 	}
-	h.clients[c] = struct{}{}
+	h.clients[client] = struct{}{}
 	h.wg.Add(1)
 	return true
 }
 
 // unregister removes a client from the hub.
-func (h *Hub) unregister(c *client) {
-	h.m.Lock()
-	delete(h.clients, c)
-	h.m.Unlock()
+func (h *Hub) unregister(client *client) {
+	h.mu.Lock()
+	delete(h.clients, client)
+	h.mu.Unlock()
 	h.wg.Done()
 }