fix: adding monitoring

internal/format.go

@@ -0,0 +1,16 @@
+package internal
+
+import "fmt"
+
+func FormatBytes(b uint64) string {
+	const unit = 1024
+	if b < unit {
+		return fmt.Sprintf("%d B", b)
+	}
+	div, exp := uint64(unit), 0
+	for n := b / unit; n >= unit; n /= unit {
+		div *= unit
+		exp++
+	}
+	return fmt.Sprintf("%.2f %cB", float64(b)/float64(div), "KMGTPE"[exp])
+}

internal/hub.go

@@ -1,6 +1,7 @@
 package internal
 
 import (
+	"context"
 	"fmt"
 	"log"
 	"sync"
@@ -17,6 +18,11 @@ const (
 	maxMessageSize = 512
 )
 
+const (
+	minHighWaterMarkMapRebuild = 100
+	mapRebuildThreshold        = 4
+)
+
 type Client struct {
 	ID             string
 	Conn           *websocket.Conn
@@ -36,34 +42,86 @@ func NewClient(conn *websocket.Conn, subscribedPath string) *Client {
 }
 
 type Hub struct {
-	Clients    map[*Client]bool
+	path          string
-	Broadcast  chan []byte
+	maxClients    int
-	Register   chan *Client
+	Clients       map[*Client]bool
-	Unregister chan *Client
+	Broadcast     chan []byte
+	Register      chan *Client
+	Unregister    chan *Client
+	monitor       *MemoryMonitor
+	highWaterMark int
 }
 
-func NewHub() *Hub {
+func NewHub(path string, maxClients int) *Hub {
+	log.Printf("[%s] Hub created with max clients: %d", path, maxClients)
 	return &Hub{
+		path:       path,
+		maxClients: maxClients,
+		monitor:    NewMemoryMonitor(),
 		Broadcast:  make(chan []byte, 256),
-		Register:   make(chan *Client, 10),
+		Register:   make(chan *Client, maxClients),
-		Unregister: make(chan *Client, 10),
+		Unregister: make(chan *Client, maxClients),
 		Clients:    make(map[*Client]bool),
 	}
 }
 
-func (h *Hub) Run() {
+// Run starts the hub event loop. It exits when ctx is cancelled.
+func (h *Hub) Run(ctx context.Context) {
+	monitorTicker := time.NewTicker(MonitorInterval)
 	go func() {
+		defer func() {
+			monitorTicker.Stop()
+			// On shutdown, close every client's Send channel so WritePump sends
+			// a WebSocket close frame and exits. Also expire the read deadline so
+			// blocked ReadMessage() calls in ReadPump return immediately instead
+			// of waiting up to pongWait (60 s).
+			for client := range h.Clients {
+				close(client.Send)
+				client.Conn.SetReadDeadline(time.Now())
+			}
+			log.Printf("[%s] Hub stopped\n", h.path)
+		}()
+
 		for {
 			select {
+			case <-ctx.Done():
+				log.Printf("[%s] Hub shutting down\n", h.path)
+				return
+
 			case client := <-h.Register:
+				if len(h.Clients) >= h.maxClients {
+					close(client.Send)
+					client.Conn.Close()
+					log.Printf("[%s] Rejected client %s (max %d reached)\n", h.path, client.ID, h.maxClients)
+					break
+				}
 				h.Clients[client] = true
-				log.Printf("Client registered %s\n", client.ID)
+				if len(h.Clients) > h.highWaterMark {
+					h.highWaterMark = len(h.Clients)
+				}
+				log.Printf("[%s] Client registered %s\n", h.path, client.ID)
+
 			case client := <-h.Unregister:
 				if _, ok := h.Clients[client]; ok {
 					delete(h.Clients, client)
 					close(client.Send)
+
+					// Rebuild the map when the live set has dropped to less than
+					// 1/mapRebuildThreshold of the peak, so the old backing buckets
+					// are released to the GC.
+					if h.highWaterMark >= minHighWaterMarkMapRebuild &&
+						len(h.Clients) < h.highWaterMark/mapRebuildThreshold {
+						rebuilt := make(map[*Client]bool, len(h.Clients))
+						for c := range h.Clients {
+							rebuilt[c] = true
+						}
+						h.Clients = rebuilt
+						h.highWaterMark = len(h.Clients)
+						log.Printf("[%s] Clients map rebuilt: %d active clients\n", h.path, len(h.Clients))
+					}
+					log.Printf("[%s] Client Unregistered %s\n", h.path, client.ID)
 				}
-				log.Printf("Client Unregistered %s\n", client.ID)
+
 			case message := <-h.Broadcast:
 				for client := range h.Clients {
 					select {
@@ -71,9 +129,18 @@ func (h *Hub) Run() {
 					default:
 						close(client.Send)
 						delete(h.Clients, client)
-						log.Printf("Client %s removed (slow/disconnected)", client.ID)
+						log.Printf("[%s] Client %s removed (slow/disconnected)\n", h.path, client.ID)
 					}
 				}
+
+			case <-monitorTicker.C:
+				current, peak := h.monitor.Snapshot()
+				clientLength := len(h.Clients)
+				if clientLength > 0 {
+					log.Printf("[%s] connected clients: %d | heap alloc: %s | peak heap alloc: %s",
+						h.path, clientLength, FormatBytes(current), FormatBytes(peak),
+					)
+				}
 			}
 		}
 	}()
@@ -82,7 +149,10 @@ func (h *Hub) Run() {
 func WritePump(c *Client, h *Hub) {
 	pingTicker := time.NewTicker(pingPeriod)
 	defer func() {
-		h.Unregister <- c
+		select {
+		case h.Unregister <- c:
+		default:
+		}
 		pingTicker.Stop()
 		c.Conn.Close()
 	}()
@@ -103,7 +173,7 @@ func WritePump(c *Client, h *Hub) {
 			}
 			w.Write(message)
 
-			// Queue queued messages in the same buffer (optional optimization)
+			// Flush any messages that queued up while we were writing.
 			n := len(c.Send)
 			for i := 0; i < n; i++ {
 				w.Write(<-c.Send)
@@ -120,13 +190,15 @@ func WritePump(c *Client, h *Hub) {
 				return
 			}
 		}
-
 	}
 }
 
 func ReadPump(c *Client, h *Hub) {
 	defer func() {
-		h.Unregister <- c
+		select {
+		case h.Unregister <- c:
+		default:
+		}
 		c.Conn.Close()
 	}()
 

internal/memory_monitor.go

@@ -0,0 +1,60 @@
+package internal
+
+import (
+	"context"
+	"log"
+	"runtime"
+	"sync/atomic"
+	"time"
+)
+
+const MonitorInterval = 30 * time.Second
+
+type MemoryMonitor struct {
+	peakAlloc atomic.Uint64
+}
+
+func NewMemoryMonitor() *MemoryMonitor {
+	return &MemoryMonitor{}
+}
+
+// Snapshot reads current heap allocation, updates the peak, and returns both.
+func (m *MemoryMonitor) Snapshot() (currentAlloc, peakAlloc uint64) {
+	var ms runtime.MemStats
+	runtime.ReadMemStats(&ms)
+	currentAlloc = ms.HeapAlloc
+	for {
+		peak := m.peakAlloc.Load()
+		if currentAlloc <= peak {
+			return currentAlloc, peak
+		}
+		if m.peakAlloc.CompareAndSwap(peak, currentAlloc) {
+			return currentAlloc, currentAlloc
+		}
+	}
+}
+
+// Run starts a periodic monitor loop that calls logFn with each snapshot.
+// It blocks until ctx is cancelled.
+func (m *MemoryMonitor) Run(ctx context.Context, logFn func(currentAlloc, peakAlloc uint64)) {
+	ticker := time.NewTicker(MonitorInterval)
+	defer ticker.Stop()
+
+	for {
+		select {
+		case <-ctx.Done():
+			return
+		case <-ticker.C:
+			current, peak := m.Snapshot()
+			logFn(current, peak)
+		}
+	}
+}
+
+// DefaultLogFn returns a log function with the given prefix.
+func DefaultLogFn(prefix string) func(currentAlloc, peakAlloc uint64) {
+	return func(currentAlloc, peakAlloc uint64) {
+		log.Printf("[%s] heap alloc: %s | peak heap alloc: %s",
+			prefix, FormatBytes(currentAlloc), FormatBytes(peakAlloc))
+	}
+}

v1/client/client.go

@@ -7,9 +7,10 @@ import (
 	"net/http"
 	"net/url"
 	"strings"
+	"sync"
 	"time"
 
-	custom_rwmutex "git.neurocipta.com/rogerferdinan/custom-rwmutex"
+	customrwmutex "git.neurocipta.com/rogerferdinan/custom-rwmutex"
 	safemap "git.neurocipta.com/rogerferdinan/safe-map"
 	"git.neurocipta.com/rogerferdinan/safe-web-socket/internal"
 	"github.com/gorilla/websocket"
@@ -131,15 +132,17 @@ func (b *SafeWebsocketClientBuilder) Build(ctx context.Context) (*SafeWebsocketC
 		path:        b.path,
 		rawQuery:    b.rawQuery,
 		dataChannel: make(chan []byte, *b.channelSize),
-		mu:          custom_rwmutex.NewCustomRwMutex(),
+		mu:          customrwmutex.NewCustomRwMutex(),
 		ctx:         ctx,
 		reconnectCh: make(chan struct{}, 1),
 		isConnected: false,
 		doneMap:     safemap.NewSafeMap[string, chan struct{}](),
 		writeChan:   make(chan Message, *b.writeChannelSize),
+		monitor:     internal.NewMemoryMonitor(),
 	}
 
 	go wsClient.reconnectHandler()
+	go wsClient.monitor.Run(ctx, internal.DefaultLogFn("client-monitor"))
 
 	if err := wsClient.connect(); err != nil {
 		return nil, fmt.Errorf("failed to establish initial connection: %v", err)
@@ -158,11 +161,12 @@ type SafeWebsocketClient struct {
 	path     *string
 	rawQuery *string
 
-	mu          *custom_rwmutex.CustomRwMutex
+	mu              *customrwmutex.CustomRwMutex
-	conn        *websocket.Conn
+	conn            *websocket.Conn
-	ctx         context.Context
+	ctx             context.Context
-	cancelFuncs []context.CancelFunc
+	cancelFuncs     []context.CancelFunc
-	dataChannel chan []byte
+	dataChannel     chan []byte
+	dataChannelOnce sync.Once
 
 	reconnectCh    chan struct{}
 	reconnectChans []chan struct{}
@@ -170,8 +174,10 @@ type SafeWebsocketClient struct {
 	doneMap        *safemap.SafeMap[string, chan struct{}]
 
 	writeChan chan Message
+	monitor   *internal.MemoryMonitor
 }
 
+
 func (wsClient *SafeWebsocketClient) connect() error {
 	var scheme string
 	if wsClient.useTLS {
@@ -190,7 +196,7 @@ func (wsClient *SafeWebsocketClient) connect() error {
 		newURL.RawQuery = *wsClient.rawQuery
 	}
 
-	header := make(http.Header)
+	header := make(http.Header, 0)
 	if wsClient.headers != nil {
 		for k, v := range *wsClient.headers {
 			header.Set(k, v)
@@ -226,9 +232,13 @@ func (wsClient *SafeWebsocketClient) connect() error {
 			return err
 		}
 
-		wsClient.writeChan <- Message{
+		select {
+		case wsClient.writeChan <- Message{
 			MessageType: MessageTypePong,
 			Data:        []byte(pingData),
+		}:
+		default:
+			log.Println("writeChan full, dropping pong")
 		}
 		return nil
 	})
@@ -291,14 +301,10 @@ func (wsClient *SafeWebsocketClient) reconnectHandler() {
 				for _, reconnectCh := range wsClient.reconnectChans {
 					select {
 					case reconnectCh <- struct{}{}:
-					default: // prevent blocking if chan is full
+					default:
 					}
 				}
-				if len(wsClient.reconnectChans) > 1 {
+				wsClient.reconnectChans = nil
-					wsClient.reconnectChans = wsClient.reconnectChans[1:]
-				} else {
-					wsClient.reconnectChans = nil
-				}
 			}
 		case <-wsClient.ctx.Done():
 			log.Println("reconnect handler stopped due to client shutdown")
@@ -334,8 +340,11 @@ func (wsClient *SafeWebsocketClient) writePump(ctx context.Context, c *websocket
 }
 
 func (wsClient *SafeWebsocketClient) readPump(ctx context.Context, c *websocket.Conn) {
+	canceled := false
 	defer func() {
-		wsClient.triggerReconnect()
+		if !canceled {
+			wsClient.triggerReconnect()
+		}
 		c.Close()
 	}()
 
@@ -343,6 +352,7 @@ func (wsClient *SafeWebsocketClient) readPump(ctx context.Context, c *websocket.
 		select {
 		case <-ctx.Done():
 			log.Println("Reader canceled by context")
+			canceled = true
 			return
 		default:
 			// Set read deadline
@@ -363,6 +373,7 @@ func (wsClient *SafeWebsocketClient) readPump(ctx context.Context, c *websocket.
 			select {
 			case wsClient.dataChannel <- data:
 			case <-ctx.Done():
+				canceled = true
 				return
 			default:
 				if wsClient.isDrop {
@@ -383,9 +394,14 @@ func (wsClient *SafeWebsocketClient) startPingTicker(ctx context.Context) {
 			log.Println("ping ticker canceled by context")
 			return
 		case <-ticker.C:
-			wsClient.writeChan <- Message{
+			select {
+			case wsClient.writeChan <- Message{
 				MessageType: websocket.PingMessage,
 				Data:        []byte{},
+			}:
+			case <-ctx.Done():
+				log.Println("ping ticker canceled by context")
+				return
 			}
 		}
 	}
@@ -413,7 +429,9 @@ func (wsClient *SafeWebsocketClient) DataChannel() <-chan []byte {
 }
 
 func (wsClient *SafeWebsocketClient) CloseDataChannel() {
-	close(wsClient.dataChannel)
+	wsClient.dataChannelOnce.Do(func() {
+		close(wsClient.dataChannel)
+	})
 }
 
 func (wsClient *SafeWebsocketClient) Write(data []byte) error {
@@ -425,7 +443,7 @@ func (wsClient *SafeWebsocketClient) Write(data []byte) error {
 }
 
 func (wsClient *SafeWebsocketClient) Close() error {
-	wsClient.mu.ReadHandler(func() error {
+	wsClient.mu.WriteHandler(func() error {
 		if wsClient.cancelFuncs != nil {
 			for _, cancel := range wsClient.cancelFuncs {
 				cancel()
@@ -443,7 +461,10 @@ func (wsClient *SafeWebsocketClient) Close() error {
 		wsClient.conn.Close()
 	}
 	wsClient.isConnected = false
-	close(wsClient.dataChannel)
+
+	wsClient.dataChannelOnce.Do(func() {
+		close(wsClient.dataChannel)
+	})
 
 	return nil
 }

v1/examples/server/main.go

@@ -1,8 +1,12 @@
 package main
 
 import (
+	"context"
 	"encoding/json"
 	"log"
+	"os"
+	"os/signal"
+	"syscall"
 	"time"
 
 	"git.neurocipta.com/rogerferdinan/safe-web-socket/v1/server"
@@ -14,34 +18,66 @@ type ExampleData struct {
 }
 
 func main() {
+	ctx, cancel := context.WithCancel(context.Background())
+	defer cancel()
+
+	sigChan := make(chan os.Signal, 1)
+	signal.Notify(sigChan, syscall.SIGINT, syscall.SIGTERM)
+	go func() {
+		<-sigChan
+		log.Println("Received shutdown signal")
+		cancel()
+	}()
+
 	s, err := server.NewSafeWebsocketServerBuilder().
 		BaseHost("localhost").
 		BasePort(8080).
 		ApiKey("abcd").
-		HandleFuncWebsocket("/ws/test/", "data_1", func(c chan []byte) {
+		Context(ctx).
+		HandleFuncWebsocket("/ws/test/", "data_1", 5_000, func(ctx context.Context, c chan []byte) {
 			ticker := time.NewTicker(100 * time.Millisecond)
-			for range ticker.C {
+			defer ticker.Stop()
-				jsonBytes, err := json.Marshal(ExampleData{
+			for {
-					Time: time.Now(),
+				select {
-					Data: "data_1",
+				case <-ctx.Done():
-				})
+					return
-				if err != nil {
+				case <-ticker.C:
-					continue
+					jsonBytes, err := json.Marshal(ExampleData{
+						Time: time.Now(),
+						Data: "data_1",
+					})
+					if err != nil {
+						continue
+					}
+					select {
+					case c <- jsonBytes:
+					case <-ctx.Done():
+						return
+					}
 				}
-				c <- jsonBytes
 			}
 		}).
-		HandleFuncWebsocket("/ws/test/", "data_2", func(c chan []byte) {
+		HandleFuncWebsocket("/ws/test/", "data_2", 5_000, func(ctx context.Context, c chan []byte) {
 			ticker := time.NewTicker(100 * time.Millisecond)
-			for range ticker.C {
+			defer ticker.Stop()
-				jsonBytes, err := json.Marshal(ExampleData{
+			for {
-					Time: time.Now(),
+				select {
-					Data: "data_2",
+				case <-ctx.Done():
-				})
+					return
-				if err != nil {
+				case <-ticker.C:
-					continue
+					jsonBytes, err := json.Marshal(ExampleData{
+						Time: time.Now(),
+						Data: "data_2",
+					})
+					if err != nil {
+						continue
+					}
+					select {
+					case c <- jsonBytes:
+					case <-ctx.Done():
+						return
+					}
 				}
-				c <- jsonBytes
 			}
 		}).
 		Build()

v1/server/server.go

@@ -1,12 +1,14 @@
 package server
 
 import (
+	"context"
 	"crypto/subtle"
 	"fmt"
 	"log"
 	"net/http"
 	"strings"
 	"syscall"
+	"time"
 
 	"git.neurocipta.com/rogerferdinan/safe-web-socket/internal"
 	"github.com/gorilla/websocket"
@@ -29,6 +31,7 @@ type SafeWebsocketServerBuilder struct {
 	apiKey   *string             `nil_checker:"required"`
 	upgrader *websocket.Upgrader `nil_checker:"required"`
 	mux      *http.ServeMux      `nil_checker:"required"`
+	ctx      context.Context
 }
 
 func NewSafeWebsocketServerBuilder() *SafeWebsocketServerBuilder {
@@ -41,6 +44,7 @@ func NewSafeWebsocketServerBuilder() *SafeWebsocketServerBuilder {
 			},
 		},
 		mux: http.NewServeMux(),
+		ctx: context.Background(),
 	}
 }
 
@@ -59,14 +63,26 @@ func (b *SafeWebsocketServerBuilder) ApiKey(apiKey string) *SafeWebsocketServerB
 	return b
 }
 
+// Context sets the lifecycle context for all hub and writeFunc goroutines.
+// When ctx is cancelled, hubs stop dispatching and all active connections
+// are unblocked so their goroutines can exit cleanly.
+// Call this before HandleFuncWebsocket. Defaults to context.Background().
+func (b *SafeWebsocketServerBuilder) Context(ctx context.Context) *SafeWebsocketServerBuilder {
+	b.ctx = ctx
+	return b
+}
+
 func (b *SafeWebsocketServerBuilder) HandleFunc(pattern string, fn func(http.ResponseWriter, *http.Request)) *SafeWebsocketServerBuilder {
 	b.mux.HandleFunc(pattern, fn)
 	return b
 }
 
-func (b *SafeWebsocketServerBuilder) HandleFuncWebsocket(pattern string, subscribedPath string, writeFunc func(chan []byte)) *SafeWebsocketServerBuilder {
+// HandleFuncWebsocket registers a WebSocket endpoint.
-	h := internal.NewHub()
+func (b *SafeWebsocketServerBuilder) HandleFuncWebsocket(pattern string, subscribedPath string, maxClients int, writeFunc func(ctx context.Context, writeChannel chan []byte)) *SafeWebsocketServerBuilder {
-	h.Run()
+	h := internal.NewHub(pattern+subscribedPath, maxClients)
+	h.Run(b.ctx)
+
+	go writeFunc(b.ctx, h.Broadcast)
 
 	b.mux.HandleFunc(pattern+subscribedPath, func(w http.ResponseWriter, r *http.Request) {
 		conn, err := b.upgrader.Upgrade(w, r, nil)
@@ -85,7 +101,6 @@ func (b *SafeWebsocketServerBuilder) HandleFuncWebsocket(pattern string, subscri
 
 		go internal.WritePump(c, h)
 		go internal.ReadPump(c, h)
-		go writeFunc(h.Broadcast)
 	})
 	return b
 }
@@ -100,6 +115,7 @@ func (b *SafeWebsocketServerBuilder) Build() (*SafeWebsocketServer, error) {
 		mux:    b.mux,
 		url:    fmt.Sprintf("%s:%d", *b.baseHost, *b.basePort),
 		apiKey: *b.apiKey,
+		ctx:    b.ctx,
 	}
 	return &safeServer, nil
 }
@@ -108,6 +124,7 @@ type SafeWebsocketServer struct {
 	mux    *http.ServeMux
 	url    string
 	apiKey string
+	ctx    context.Context
 }
 
 func (s *SafeWebsocketServer) AuthMiddleware(next http.Handler) http.Handler {
@@ -128,9 +145,30 @@ func (s *SafeWebsocketServer) AuthMiddleware(next http.Handler) http.Handler {
 }
 
 func (s *SafeWebsocketServer) ListenAndServe() error {
-	log.Printf("HTTP serve on %s\n", s.url)
+	srv := &http.Server{
-	if err := http.ListenAndServe(s.url, s.AuthMiddleware(s.mux)); err != nil {
+		Addr:    s.url,
-		return fmt.Errorf("failed to serve websocket: %w", err)
+		Handler: s.AuthMiddleware(s.mux),
+	}
+
+	errCh := make(chan error, 1)
+	go func() {
+		log.Printf("HTTP serve on %s\n", s.url)
+		if err := srv.ListenAndServe(); err != nil && err != http.ErrServerClosed {
+			errCh <- fmt.Errorf("failed to serve websocket: %w", err)
+		}
+		close(errCh)
+	}()
+
+	select {
+	case err := <-errCh:
+		return err
+	case <-s.ctx.Done():
+		log.Println("Server shutting down...")
+		shutdownCtx, cancel := context.WithTimeout(context.Background(), 5*time.Second)
+		defer cancel()
+		if err := srv.Shutdown(shutdownCtx); err != nil {
+			return fmt.Errorf("server shutdown: %w", err)
+		}
+		return <-errCh
 	}
-	return nil
 }