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2.8 kB · 120 lines
Go
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import ( "context" "encoding/json" "net/http" "strconv" "time"
"github.com/gorilla/websocket" "tangled.org/core/log")
var upgrader = websocket.Upgrader{ ReadBufferSize: 1024, WriteBufferSize: 1024,}
func (h *Knot) Events(w http.ResponseWriter, r *http.Request) { l := log.SubLogger(h.l, "eventstream") l.Debug("received new connection")
conn, err := upgrader.Upgrade(w, r, nil) if err != nil { l.Error("websocket upgrade failed", "err", err) w.WriteHeader(http.StatusInternalServerError) return } defer conn.Close() l.Debug("upgraded http to wss")
ch := h.n.Subscribe() defer h.n.Unsubscribe(ch)
ctx, cancel := context.WithCancel(r.Context()) defer cancel() go func() { for { if _, _, err := conn.NextReader(); err != nil { l.Error("failed to read", "err", err) cancel() return } } }()
defaultCursor := time.Now().UnixNano() cursorStr := r.URL.Query().Get("cursor") cursor, err := strconv.ParseInt(cursorStr, 10, 64) if err != nil { l.Error("empty or invalid cursor", "invalidCursor", cursorStr, "default", defaultCursor) } if cursor == 0 { cursor = defaultCursor }
// complete backfill first before going to live data l.Debug("going through backfill", "cursor", cursor) if err := h.streamOps(conn, &cursor); err != nil { l.Error("failed to backfill", "err", err) return }
for { // wait for new data or timeout select { case <-ctx.Done(): l.Debug("stopping stream: client closed connection") return case <-ch: // we have been notified of new data l.Debug("going through live data", "cursor", cursor) if err := h.streamOps(conn, &cursor); err != nil { l.Error("failed to stream", "err", err) return } case <-time.After(30 * time.Second): // send a keep-alive if err = conn.WriteControl(websocket.PingMessage, []byte{}, time.Now().Add(time.Second)); err != nil { l.Error("failed to write control", "err", err) } } }}
func (h *Knot) streamOps(conn *websocket.Conn, cursor *int64) error { events, err := h.db.GetEvents(*cursor) if err != nil { h.l.Error("failed to fetch events from db", "err", err, "cursor", cursor) return err }
for _, event := range events { // first extract the inner json into a map var eventJson map[string]any err := json.Unmarshal([]byte(event.EventJson), &eventJson) if err != nil { h.l.Error("failed to unmarshal event", "err", err) return err }
jsonMsg, err := json.Marshal(map[string]any{ "rkey": event.Rkey, "nsid": event.Nsid, "event": eventJson, }) if err != nil { h.l.Error("failed to marshal record", "err", err) return err }
if err := conn.WriteMessage(websocket.TextMessage, jsonMsg); err != nil { h.l.Debug("err", "err", err) return err } *cursor = event.Created }
return nil}