/
hub.go
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/
hub.go
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package websockethub
import (
"context"
"errors"
"net/http"
"go.uber.org/atomic"
"nhooyr.io/websocket"
"github.com/iotaledger/hive.go/core/generics/event"
"github.com/iotaledger/hive.go/core/logger"
)
var (
ErrWebsocketServerUnavailable = errors.New("websocket server unavailable")
ErrClientDisconnected = errors.New("client was disconnected")
)
type ClientConnectionEvent struct {
ID ClientID
}
// Events contains all the events that are triggered by the websocket hub.
type Events struct {
// A ClientConnected event is triggered, when a new client has connected to the websocket hub.
ClientConnected *event.Event[*ClientConnectionEvent]
// A ClientDisconnected event is triggered, when a client has disconnected from the websocket hub.
ClientDisconnected *event.Event[*ClientConnectionEvent]
}
func newEvents() *Events {
return &Events{
ClientConnected: event.New[*ClientConnectionEvent](),
ClientDisconnected: event.New[*ClientConnectionEvent](),
}
}
// Hub maintains the set of active clients and broadcasts messages to the clients.
type Hub struct {
// used Logger instance.
logger *logger.Logger
// the accept options of the websocket per client.
acceptOptions *websocket.AcceptOptions
// registered clients.
clients map[*Client]struct{}
// maximum size of queued messages that should be sent to the peer.
clientSendChannelSize int
// inbound messages from the clients.
broadcast chan *message
// register requests from the clients.
register chan *Client
// unregister requests from clients.
unregister chan *Client
// context of the websocket hub
ctx context.Context
// indicates that the websocket hub was shut down
shutdownFlag *atomic.Bool
// indicates the max amount of bytes that will be read from a client, i.e. the max message size
clientReadLimit int64
// lastClientID holds the ClientID of the last connected client
lastClientID *atomic.Uint32
// events of the websocket hub
events *Events
}
// message is a message that is sent to the broadcast channel.
type message struct {
data interface{}
dontDrop bool
}
func NewHub(logger *logger.Logger, acceptOptions *websocket.AcceptOptions, broadcastQueueSize int, clientSendChannelSize int, clientReadLimit int64) *Hub {
return &Hub{
logger: logger,
acceptOptions: acceptOptions,
clientSendChannelSize: clientSendChannelSize,
clients: make(map[*Client]struct{}),
broadcast: make(chan *message, broadcastQueueSize),
register: make(chan *Client, 1),
unregister: make(chan *Client, 1),
ctx: nil,
shutdownFlag: atomic.NewBool(true),
clientReadLimit: clientReadLimit,
lastClientID: atomic.NewUint32(0),
events: newEvents(),
}
}
// Events returns all the events that are triggered by the websocket hub.
func (h *Hub) Events() *Events {
return h.events
}
// BroadcastMsg sends a message to all clients.
func (h *Hub) BroadcastMsg(ctx context.Context, data interface{}, dontDrop ...bool) error {
if h.shutdownFlag.Load() {
// hub was already shut down or was not started yet
return ErrWebsocketServerUnavailable
}
notDrop := false
if len(dontDrop) > 0 {
notDrop = dontDrop[0]
}
msg := &message{data: data, dontDrop: notDrop}
if notDrop {
select {
case <-ctx.Done():
return ctx.Err()
case <-h.ctx.Done():
return ErrWebsocketServerUnavailable
case h.broadcast <- msg:
return nil
}
}
select {
case <-ctx.Done():
return ctx.Err()
case <-h.ctx.Done():
return ErrWebsocketServerUnavailable
case h.broadcast <- msg:
return nil
default:
return nil
}
}
func (h *Hub) removeClient(client *Client) {
delete(h.clients, client)
close(client.ExitSignal)
// wait until writePump and readPump finished
client.shutdownWaitGroup.Wait()
// drain the send channel
drainLoop:
for {
select {
case <-client.sendChan:
default:
break drainLoop
}
}
if client.onDisconnect != nil {
client.onDisconnect(client)
}
h.events.ClientDisconnected.Trigger(&ClientConnectionEvent{ID: client.id})
// We do not call "close(client.sendChan)" because we have multiple senders.
//
// As written at https://go101.org/article/channel-closing.html
// A channel will be eventually garbage collected if no goroutines reference it any more,
// whether it is closed or not.
// So the gracefulness of closing a channel here is not to close the channel.
}
// Returns the number of websocket clients.
func (h *Hub) Clients() int {
return len(h.clients)
}
// Run starts the hub.
func (h *Hub) Run(ctx context.Context) {
// set the hub context so it can be used by the clients
h.ctx = ctx
// set the hub as running
h.shutdownFlag.Store(false)
for {
select {
case <-ctx.Done():
h.shutdownFlag.Store(true)
for client := range h.clients {
h.removeClient(client)
}
return
case client := <-h.register:
// register client
h.clients[client] = struct{}{}
client.shutdownWaitGroup.Add(3)
//nolint:contextcheck // client context is already based on the hub ctx
go client.writePump()
// first start the read pump to read pong answers from keepAlive
client.startWaitGroup.Add(1)
go client.readPump()
client.startWaitGroup.Wait()
// wait until keepAlive started, before calling onConnect
client.startWaitGroup.Add(1)
//nolint:contextcheck // client context is already based on the hub ctx
go client.keepAlive()
client.startWaitGroup.Wait()
if client.onConnect != nil {
client.onConnect(client)
}
h.events.ClientConnected.Trigger(&ClientConnectionEvent{ID: client.id})
case client := <-h.unregister:
if _, ok := h.clients[client]; ok {
h.removeClient(client)
h.logger.Infof("Removed websocket client")
}
case message := <-h.broadcast:
if message.dontDrop {
for client := range h.clients {
if client.FilterCallback != nil {
if !client.FilterCallback(client, message.data) {
// do not broadcast the message to this client
continue
}
}
select {
case <-ctx.Done():
case <-client.ExitSignal:
case <-client.sendChanClosed:
case client.sendChan <- message.data:
}
}
continue
}
for client := range h.clients {
if client.FilterCallback != nil {
if !client.FilterCallback(client, message.data) {
// do not broadcast the message to this client
continue
}
}
select {
case <-ctx.Done():
case <-client.ExitSignal:
case <-client.sendChanClosed:
case client.sendChan <- message.data:
default:
}
}
}
}
}
// ServeWebsocket handles websocket requests from the peer.
// onCreate gets called when the client is created.
// onConnect gets called when the client was registered.
func (h *Hub) ServeWebsocket(
w http.ResponseWriter,
r *http.Request,
onCreate func(client *Client),
onConnect func(client *Client),
onDisconnect func(client *Client)) error {
if h.shutdownFlag.Load() {
// hub was already shut down or was not started yet
return ErrWebsocketServerUnavailable
}
defer func() {
if r := recover(); r != nil {
h.logger.Errorf("recovered from ServeWebsocket func: %s", r)
}
}()
conn, err := websocket.Accept(w, r, h.acceptOptions)
if err != nil {
h.logger.Warn(err.Error())
return err
}
client := NewClient(h, conn, onConnect, onDisconnect)
if onCreate != nil {
onCreate(client)
}
return h.Register(client)
}
func (h *Hub) Stopped() bool {
return h.shutdownFlag.Load()
}
func (h *Hub) Register(client *Client) error {
select {
case <-h.ctx.Done():
return ErrWebsocketServerUnavailable
case h.register <- client:
return nil
}
}
func (h *Hub) Unregister(client *Client) error {
select {
case <-h.ctx.Done():
return ErrWebsocketServerUnavailable
case h.unregister <- client:
return nil
}
}