listmonk/cmd/events.go

47 lines
1 KiB
Go

package main
import (
"encoding/json"
"fmt"
"log"
"time"
"github.com/labstack/echo/v4"
)
// EventStream serves an endpoint that never closes and pushes a
// live event stream (text/event-stream) such as a error messages.
func (a *App) EventStream(c echo.Context) error {
hdr := c.Response().Header()
hdr.Set(echo.HeaderContentType, "text/event-stream")
hdr.Set(echo.HeaderCacheControl, "no-store")
hdr.Set(echo.HeaderConnection, "keep-alive")
// Subscribe to the event stream with a random ID.
id := fmt.Sprintf("api:%v", time.Now().UnixNano())
sub, err := a.events.Subscribe(id)
if err != nil {
log.Fatalf("error subscribing to events: %v", err)
}
ctx := c.Request().Context()
for {
select {
case e := <-sub:
b, err := json.Marshal(e)
if err != nil {
a.log.Printf("error marshalling event: %v", err)
continue
}
c.Response().Write([]byte(fmt.Sprintf("retry: 3000\ndata: %s\n\n", b)))
c.Response().Flush()
case <-ctx.Done():
// On HTTP connection close, unsubscribe.
a.events.Unsubscribe(id)
return nil
}
}
}