"Implement connection limit for WebSocket connections"

channel/channel.go

@@ -67,6 +67,11 @@ func (c *Channel) wsConnectionHandler() http.Handler {
 	return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
 		ctx := r.Context()
 
+		if !c.connRegistry.CanAccept() {
+			http.Error(w, "Connection limit reached", http.StatusServiceUnavailable)
+			return
+		}
+
 		ws, err := websocket.Accept(w, r, &websocket.AcceptOptions{
 			OriginPatterns: c.config.originPatterns,
 		})
@@ -75,8 +80,9 @@ func (c *Channel) wsConnectionHandler() http.Handler {
 			return
 		}
 
-		conn := c.connRegistry.AddConnection(ctx, ws, c.disptacher.Dispatch)
-		conn.HandleRequests()
+		if conn := c.connRegistry.AddConnection(ctx, ws, c.disptacher.Dispatch); conn != nil {
+			conn.HandleRequests()
+		}
 	})
 }
 

channel/channel_test.go

@@ -3,6 +3,7 @@ package channel
 import (
 	"context"
 	"net/http"
+	"net/http/httptest"
 	"testing"
 
 	"github.com/ksysoev/wasabi/mocks"
@@ -146,3 +147,60 @@ func TestChannel_Shutdown(t *testing.T) {
 		t.Errorf("Unexpected error: %v", err)
 	}
 }
+func TestChannel_wsConnectionHandler_CannotAcceptNewConnection(t *testing.T) {
+	path := "/test/path"
+	dispatcher := mocks.NewMockDispatcher(t)
+	connRegistry := mocks.NewMockConnectionRegistry(t)
+	connRegistry.EXPECT().CanAccept().Return(false)
+
+	channel := NewChannel(path, dispatcher, connRegistry)
+
+	// Create a mock request
+	mockRequest := httptest.NewRequest(http.MethodGet, "http://example.com", http.NoBody)
+
+	// Create a mock response writer
+	mockResponseWriter := httptest.NewRecorder()
+
+	// Call the wsConnectionHandler method
+	handler := channel.wsConnectionHandler()
+
+	// Serve the mock request
+	handler.ServeHTTP(mockResponseWriter, mockRequest)
+
+	res := mockResponseWriter.Result()
+
+	defer res.Body.Close()
+
+	if res.StatusCode != http.StatusServiceUnavailable {
+		t.Errorf("Unexpected status code: got %d, expected %d", res.StatusCode, http.StatusServiceUnavailable)
+	}
+}
+
+func TestChannel_wsConnectionHandler_CanAcceptNewConnection(t *testing.T) {
+	path := "/test/path"
+	dispatcher := mocks.NewMockDispatcher(t)
+	connRegistry := mocks.NewMockConnectionRegistry(t)
+	connRegistry.EXPECT().CanAccept().Return(true)
+
+	channel := NewChannel(path, dispatcher, connRegistry)
+
+	// Create a mock request
+	mockRequest := httptest.NewRequest(http.MethodGet, "http://example.com", http.NoBody)
+
+	// Create a mock response writer
+	mockResponseWriter := httptest.NewRecorder()
+
+	// Call the wsConnectionHandler method
+	handler := channel.wsConnectionHandler()
+
+	// Serve the mock request
+	handler.ServeHTTP(mockResponseWriter, mockRequest)
+
+	res := mockResponseWriter.Result()
+
+	defer res.Body.Close()
+
+	if res.StatusCode != http.StatusUpgradeRequired {
+		t.Errorf("Unexpected status code: got %d, expected %d", res.StatusCode, http.StatusUpgradeRequired)
+	}
+}

channel/connection_registry.go

@@ -2,6 +2,7 @@ package channel
 
 import (
 	"context"
+	"fmt"
 	"sync"
 	"time"
 
@@ -13,6 +14,7 @@ const (
 	concurencyLimitPerConnection = 25
 	frameSizeLimitInBytes        = 32768
 	inActivityTimeout            = 0 * time.Second
+	connectionLimt               = -1
 )
 
 type ConnectionHook func(wasabi.Connection)
@@ -25,6 +27,7 @@ type ConnectionRegistry struct {
 	onConnect         ConnectionHook
 	onDisconnect      ConnectionHook
 	concurrencyLimit  uint
+	connectionLimit   int
 	frameSizeLimit    int64
 	inActivityTimeout time.Duration
 	mu                sync.RWMutex
@@ -42,6 +45,7 @@ func NewConnectionRegistry(opts ...ConnectionRegistryOption) *ConnectionRegistry
 		bufferPool:       newBufferPool(),
 		frameSizeLimit:   frameSizeLimitInBytes,
 		isClosed:         false,
+		connectionLimit:  connectionLimt,
 	}
 
 	for _, opt := range opts {
@@ -62,6 +66,11 @@ func (r *ConnectionRegistry) AddConnection(
 	r.mu.Lock()
 	defer r.mu.Unlock()
 
+	if r.connectionLimit > 0 && len(r.connections) >= r.connectionLimit {
+		ws.Close(websocket.StatusTryAgainLater, "Connection limit reached")
+		return nil
+	}
+
 	if r.isClosed {
 		return nil
 	}
@@ -78,6 +87,23 @@ func (r *ConnectionRegistry) AddConnection(
 	return conn
 }
 
+// CanAccept checks if the connection registry can accept new connections.
+// It returns true if the registry can accept new connections, and false otherwise.
+func (r *ConnectionRegistry) CanAccept() bool {
+	fmt.Println("Connection limit", r.connectionLimit)
+
+	if r.connectionLimit <= 0 {
+		return true
+	}
+
+	r.mu.RLock()
+	defer r.mu.RUnlock()
+
+	fmt.Println("Connections", len(r.connections))
+
+	return len(r.connections) < r.connectionLimit
+}
+
 // GetConnection returns connection by id
 func (r *ConnectionRegistry) GetConnection(id string) wasabi.Connection {
 	r.mu.RLock()
@@ -189,3 +215,13 @@ func WithOnDisconnectHook(cb ConnectionHook) ConnectionRegistryOption {
 		r.onDisconnect = cb
 	}
 }
+
+// WithConnectionLimit sets the maximum number of connections that can be accepted by the ConnectionRegistry.
+// The default connection limit is -1, which means there is no limit on the number of connections.
+// If the connection limit is set to a positive integer, the ConnectionRegistry will not accept new connections
+// once the number of active connections reaches the specified limit.
+func WithConnectionLimit(limit int) ConnectionRegistryOption {
+	return func(r *ConnectionRegistry) {
+		r.connectionLimit = limit
+	}
+}

channel/connection_registry_test.go

@@ -273,3 +273,95 @@ func TestConnectionRegistry_WithOnDisconnectHook(t *testing.T) {
 		t.Error("Expected onDisconnect hook to be executed")
 	}
 }
+
+func TestConnectionRegistry_WithConnectionLimit(t *testing.T) {
+	registry := NewConnectionRegistry()
+
+	if registry.connectionLimit != -1 {
+		t.Errorf("Unexpected connection limit: got %d, expected %d", registry.connectionLimit, -1)
+	}
+
+	registry = NewConnectionRegistry(WithConnectionLimit(10))
+
+	if registry.connectionLimit != 10 {
+		t.Errorf("Unexpected connection limit: got %d, expected %d", registry.connectionLimit, 10)
+	}
+}
+
+func TestConnectionRegistry_AddConnection_ConnectionLimitReached(t *testing.T) {
+	registry := NewConnectionRegistry(WithConnectionLimit(2))
+	conn1 := mocks.NewMockConnection(t)
+	conn2 := mocks.NewMockConnection(t)
+	conn3 := mocks.NewMockConnection(t)
+
+	conn1.EXPECT().ID().Return("conn1")
+	conn2.EXPECT().ID().Return("conn2")
+	conn3.EXPECT().ID().Return("conn3")
+
+	registry.connections[conn1.ID()] = conn1
+	registry.connections[conn2.ID()] = conn2
+
+	ctx := context.Background()
+	cb := func(wasabi.Connection, wasabi.MessageType, []byte) {}
+
+	server := httptest.NewServer(wsHandlerEcho)
+	defer server.Close()
+	url := "ws://" + server.Listener.Addr().String()
+
+	ws, resp, err := websocket.Dial(context.Background(), url, nil)
+	if err != nil {
+		t.Errorf("Unexpected error dialing websocket: %v", err)
+	}
+
+	if resp.Body != nil {
+		resp.Body.Close()
+	}
+
+	conn := registry.AddConnection(ctx, ws, cb)
+
+	if conn != nil {
+		t.Error("Expected connection to be nil")
+	}
+
+	if _, ok := registry.connections[conn3.ID()]; ok {
+		t.Error("Expected connection to not be added to the registry")
+	}
+}
+
+func TestConnectionRegistry_CanAccept_ConnectionLimitNotSet(t *testing.T) {
+	registry := NewConnectionRegistry()
+
+	if !registry.CanAccept() {
+		t.Error("Expected CanAccept to return true when connection limit is not set")
+	}
+
+	conn := mocks.NewMockConnection(t)
+	conn.EXPECT().ID().Return("conn1")
+
+	registry.connections[conn.ID()] = conn
+
+	if !registry.CanAccept() {
+		t.Error("Expected CanAccept to return true when connection limit is not set")
+	}
+}
+
+func TestConnectionRegistry_CanAccept_ConnectionLimitReached(t *testing.T) {
+	registry := NewConnectionRegistry(WithConnectionLimit(2))
+
+	conn1 := mocks.NewMockConnection(t)
+	conn1.EXPECT().ID().Return("conn1")
+
+	registry.connections[conn1.ID()] = conn1
+
+	if !registry.CanAccept() {
+		t.Error("Expected CanAccept to return true when connection limit is reached")
+	}
+
+	conn2 := mocks.NewMockConnection(t)
+	conn2.EXPECT().ID().Return("conn2")
+	registry.connections[conn2.ID()] = conn2
+
+	if registry.CanAccept() {
+		t.Error("Expected CanAccept to return false when connection limit is reached")
+	}
+}

interfaces.go

@@ -59,4 +59,5 @@ type ConnectionRegistry interface {
 	) Connection
 	GetConnection(id string) Connection
 	Close(ctx ...context.Context) error
+	CanAccept() bool
 }