func (g *ChanGroup) Sample(ctx slog.Context) {
	ctx.Add("source", g.Name)
	for i := 0; i < numSeries; i++ {
		// TODO: If we set the ChanGroup.Name to be the hostname, this might need to change.
		ctx.Sample(fmt.Sprintf("points.%s.pending", seriesNames[i]), len(g.points[i]))
	}
}

func (p *RiemannPoster) deliver(event *raidman.Event) {
	ctx := slog.Context{}
	defer func() { LogWithContext(ctx) }()

	start := time.Now()

	log.Printf("sending %#v\n", *event)

	err := p.riemann.Send(event)

	if err != nil {
		log.Println(ctx, "delivery error, trying to reconnect:", err)
		new_riemann, err := raidman.Dial("tcp", p.riemannAddress)
		if err == nil {
			log.Println("reconnected!")
			p.riemann = new_riemann
		} else {
			log.Println("reconnection failed:", err)
		}
	}

	ctx.MeasureSince("riemann_poster.time", start)
}

func main() {
	ctx := slog.Context{}
	ctx.Add("fixture", true)
	fmt.Println(ctx)
}

// "Parse tree" from hell
func serveDrain(w http.ResponseWriter, r *http.Request) {

	ctx := slog.Context{}
	defer func() { LogWithContext(ctx) }()
	w.Header().Set("Content-Length", "0")

	if r.Method != "POST" {
		w.WriteHeader(http.StatusMethodNotAllowed)
		ctx.Count("errors.drain.wrong.method", 1)
		return
	}

	id := r.Header.Get("Logplex-Drain-Token")

	if id == "" {
		if err := checkAuth(r); err != nil {
			w.WriteHeader(http.StatusForbidden)
			ctx.Count("errors.auth.failure", 1)
			return
		}
	}

	ctx.Count("batch", 1)

	parseStart := time.Now()
	lp := lpx.NewReader(bufio.NewReader(r.Body))

	for lp.Next() {
		ctx.Count("lines.total", 1)
		header := lp.Header()

		// If the syslog App Name Header field containts what looks like a log token,
		// let's assume it's an override of the id and we're getting the data from the magic
		// channel
		if bytes.HasPrefix(header.Name, TokenPrefix) {
			id = string(header.Name)
		}

		// If we still don't have an id, throw an error and try the next line
		if id == "" {
			ctx.Count("errors.token.missing", 1)
			continue
		}

		chanGroup := hashRing.Get(id)

		msg := lp.Bytes()
		switch {
		case bytes.Equal(header.Name, Heroku), bytes.HasPrefix(header.Name, TokenPrefix):
			t, e := time.Parse("2006-01-02T15:04:05.000000+00:00", string(lp.Header().Time))
			if e != nil {
				log.Printf("Error Parsing Time(%s): %q\n", string(lp.Header().Time), e)
				continue
			}
			timestamp := t.UnixNano() / int64(time.Microsecond)

			pid := string(header.Procid)
			switch pid {
			case "router":

				switch {
				// router logs with a H error code in them
				case bytes.Contains(msg, keyCodeH):
					ctx.Count("lines.router.error", 1)
					re := routerError{}
					err := logfmt.Unmarshal(msg, &re)
					if err != nil {
						log.Printf("logfmt unmarshal error: %s\n", err)
						continue
					}
					chanGroup.points[EventsRouter] <- []interface{}{timestamp, id, re.Code}

				// likely a standard router log
				default:
					ctx.Count("lines.router", 1)
					rm := routerMsg{}
					err := logfmt.Unmarshal(msg, &rm)
					if err != nil {
						log.Printf("logfmt unmarshal error: %s\n", err)
						continue
					}
					chanGroup.points[Router] <- []interface{}{timestamp, id, rm.Status, rm.Service}
				}

				// Non router logs, so either dynos, runtime, etc
			default:
				switch {
				// Dyno error messages
				case bytes.HasPrefix(msg, dynoErrorSentinel):
					ctx.Count("lines.dyno.error", 1)
					de, err := parseBytesToDynoError(msg)
					if err != nil {
						log.Printf("Unable to parse dyno error message: %q\n", err)
					}

					what := string(lp.Header().Procid)
					chanGroup.points[EventsDyno] <- []interface{}{
						timestamp,
						id,
//.........这里部分代码省略.........

func LogWithContext(ctx slog.Context) {
	ctx.Add("app", "lumbermill")
	log.Println(ctx)
}