Redmage/server/routes/events/event_simple.go

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package events
import (
"encoding/json"
"fmt"
"net/http"
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"strings"
"github.com/tigorlazuardi/redmage/pkg/log"
)
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// SimpleEvents is a simple event stream for the purpose of
// notification that something did happen. Not what the content of the event is.
//
// Useful for simple notification whose client just need to know that something
// happened and do something that does not require the content of the event,
// like refreshing the list by calling another http request.
func (handler *Handler) SimpleEvents(rw http.ResponseWriter, r *http.Request) {
ctx, span := tracer.Start(r.Context(), "*Routes.SimpleDownloadEvent")
defer span.End()
flush, ok := rw.(http.Flusher)
if !ok {
rw.WriteHeader(http.StatusInternalServerError)
_ = json.NewEncoder(rw).Encode(map[string]string{"error": "response writer does not support streaming"})
return
}
var filters []string
if q := r.URL.Query().Get("filter"); q != "" {
filters = strings.Split(q, ",")
}
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log.New(ctx).Info("new simple event stream connection", "user_agent", r.UserAgent())
rw.Header().Set("Content-Type", "text/event-stream")
rw.Header().Set("Cache-Control", "no-cache")
rw.Header().Set("Connection", "keep-alive")
rw.WriteHeader(200)
flush.Flush()
ev, close := handler.Subscribe()
defer close()
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loop:
for {
select {
case <-r.Context().Done():
log.New(ctx).Info("simple event stream connection closed", "user_agent", r.UserAgent())
return
case event := <-ev:
msg := event.Event()
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for _, filter := range filters {
if filter != msg {
continue loop
}
}
if _, err := fmt.Fprintf(rw, "event: %s\ndata: %s\n\n", msg, msg); err != nil {
return
}
flush.Flush()
}
}
}