package server import ( "time" "github.com/drone/drone/common" "github.com/drone/drone/eventbus" log "github.com/Sirupsen/logrus" "github.com/gin-gonic/gin" "github.com/gorilla/websocket" ) const ( // Time allowed to write the message to the client. writeWait = 10 * time.Second // Time allowed to read the next pong message from the client. pongWait = 60 * time.Second // Send pings to client with this period. Must be less than pongWait. pingPeriod = (pongWait * 9) / 10 ) var upgrader = websocket.Upgrader{ ReadBufferSize: 1024, WriteBufferSize: 1024, } // GetEvents will upgrade the connection to a Websocket and will stream // event updates to the browser. func GetEvents(c *gin.Context) { bus := ToBus(c) user := ToUser(c) remote := ToRemote(c) // TODO (bradrydzewski) revisit this approach at some point. // // instead of constantly checking for remote permissions, we will // cache them for the lifecycle of this websocket. The pro here is // that we are making way less external calls (good). The con is that // if a ton of developers conntect to websockets for long periods of // time with heavy build traffic (not super likely, but possible) this // caching strategy could take up a lot of memory. perms_ := map[string]*common.Perm{} // upgrade the websocket ws, err := upgrader.Upgrade(c.Writer, c.Request, nil) if err != nil { c.Fail(400, err) return } ticker := time.NewTicker(pingPeriod) eventc := make(chan *eventbus.Event, 1) bus.Subscribe(eventc) defer func() { bus.Unsubscribe(eventc) ticker.Stop() ws.Close() close(eventc) }() go func() { for { select { case event := <-eventc: if event == nil { return // why would this ever happen? } perm, ok := perms_[event.Repo.FullName] if !ok { perm = perms(remote, user, event.Repo) perms_[event.Repo.FullName] = perm } if perm != nil && perm.Pull { err := ws.WriteJSON(event) if err != nil { log.Errorln(err, event) } } case <-ticker.C: ws.SetWriteDeadline(time.Now().Add(writeWait)) err := ws.WriteMessage(websocket.PingMessage, []byte{}) if err != nil { ws.Close() log.Debugf("closed websocket") return } } } }() readWebsocket(ws) log.Debugf("closed websocket") } // readWebsocket will block while reading the websocket data func readWebsocket(ws *websocket.Conn) { defer ws.Close() ws.SetReadLimit(512) ws.SetReadDeadline(time.Now().Add(pongWait)) ws.SetPongHandler(func(string) error { ws.SetReadDeadline(time.Now().Add(pongWait)) return nil }) for { _, _, err := ws.ReadMessage() if err != nil { break } } }