tangled.org
oppi.li
+93
knotserver/events.go
+93
knotserver/events.go
···
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package knotserver
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import (
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"context"
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"net/http"
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"time"
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"github.com/gorilla/websocket"
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)
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var upgrader = websocket.Upgrader{
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ReadBufferSize: 1024,
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WriteBufferSize: 1024,
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}
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func (h *Handle) OpLog(w http.ResponseWriter, r *http.Request) {
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l := h.l.With("handler", "OpLog")
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l.Info("received new connection")
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conn, err := upgrader.Upgrade(w, r, nil)
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if err != nil {
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l.Error("websocket upgrade failed", "err", err)
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w.WriteHeader(http.StatusInternalServerError)
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return
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}
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defer conn.Close()
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l.Info("upgraded http to wss")
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ch := h.n.Subscribe()
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defer h.n.Unsubscribe(ch)
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ctx, cancel := context.WithCancel(r.Context())
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defer cancel()
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go func() {
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for {
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if _, _, err := conn.NextReader(); err != nil {
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l.Error("failed to read", "err", err)
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cancel()
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return
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}
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}
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}()
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cursor := ""
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// complete backfill first before going to live data
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l.Info("going through backfill", "cursor", cursor)
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if err := h.streamOps(conn, &cursor); err != nil {
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l.Error("failed to backfill", "err", err)
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return
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}
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for {
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// wait for new data or timeout
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select {
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case <-ctx.Done():
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l.Info("stopping stream: client closed connection")
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return
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case <-ch:
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// we have been notified of new data
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l.Info("going through live data", "cursor", cursor)
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if err := h.streamOps(conn, &cursor); err != nil {
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l.Error("failed to stream", "err", err)
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return
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}
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case <-time.After(30 * time.Second):
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// send a keep-alive
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l.Info("sent keepalive")
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if err = conn.WriteControl(websocket.PingMessage, []byte{}, time.Now().Add(time.Second)); err != nil {
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l.Error("failed to write control", "err", err)
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}
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}
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}
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}
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func (h *Handle) streamOps(conn *websocket.Conn, cursor *string) error {
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ops, err := h.db.GetOps(*cursor)
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if err != nil {
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h.l.Debug("err", "err", err)
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return err
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}
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h.l.Debug("ops", "ops", ops)
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for _, op := range ops {
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if err := conn.WriteJSON(op); err != nil {
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h.l.Debug("err", "err", err)
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return err
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}
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*cursor = op.Tid
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}
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return nil
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}