84 lines
1.7 KiB
Go
84 lines
1.7 KiB
Go
package main
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import (
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"fmt"
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"net/http"
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"time"
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"github.com/labstack/echo/v4"
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)
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func (a *App) handleEvents(c echo.Context) error {
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res := c.Response()
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req := c.Request()
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res.Header().Set(echo.HeaderContentType, "text/event-stream")
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res.Header().Set("Cache-Control", "no-cache, no-transform")
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res.Header().Set("Connection", "keep-alive")
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res.Header().Set("X-Accel-Buffering", "no")
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res.WriteHeader(http.StatusOK)
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flusher, ok := res.Writer.(http.Flusher)
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if !ok {
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return writeError(c, http.StatusInternalServerError, "streaming not supported")
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}
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if _, err := fmt.Fprintf(res, "event: ready\ndata: {\"ts\":\"%s\"}\n\n", time.Now().UTC().Format(time.RFC3339)); err != nil {
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return nil
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}
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flusher.Flush()
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id, events := a.events.Subscribe()
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defer a.events.Unsubscribe(id)
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keepAlive := time.NewTicker(20 * time.Second)
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defer keepAlive.Stop()
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for {
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select {
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case <-req.Context().Done():
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return nil
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case <-events:
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if _, err := fmt.Fprintf(res, "event: state\ndata: {\"ts\":\"%s\"}\n\n", time.Now().UTC().Format(time.RFC3339)); err != nil {
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return nil
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}
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flusher.Flush()
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case t := <-keepAlive.C:
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if _, err := fmt.Fprintf(res, ": ping %d\n\n", t.Unix()); err != nil {
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return nil
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}
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flusher.Flush()
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}
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}
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}
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func (h *EventHub) Subscribe() (int, <-chan struct{}) {
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h.mu.Lock()
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defer h.mu.Unlock()
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h.nextID++
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id := h.nextID
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ch := make(chan struct{}, 1)
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h.subscribers[id] = ch
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return id, ch
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}
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func (h *EventHub) Unsubscribe(id int) {
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h.mu.Lock()
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defer h.mu.Unlock()
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if ch, ok := h.subscribers[id]; ok {
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delete(h.subscribers, id)
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close(ch)
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}
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}
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func (h *EventHub) Broadcast() {
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h.mu.RLock()
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defer h.mu.RUnlock()
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for _, ch := range h.subscribers {
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select {
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case ch <- struct{}{}:
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default:
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}
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}
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}
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