func()

in transport/http.go [453:509]

• 51 lines of code
• 11 McCabe index (conditional complexity)

func (t *HTTPTransport) WatchConfig(ctx context.Context, args apmconfig.WatchParams) <-chan apmconfig.Change {
	changes := make(chan apmconfig.Change)
	go func() {
		defer close(changes)

		var etag string
		var out chan apmconfig.Change
		var change apmconfig.Change
		timer := time.NewTimer(0)
		for {
			select {
			case <-ctx.Done():
				return
			case out <- change:
				out = nil
				change = apmconfig.Change{}
				continue
			case <-timer.C:
			}

			urlIndex := atomic.LoadInt32(&t.urlIndex)
			query := make(url.Values)
			query.Set("service.name", args.Service.Name)
			if args.Service.Environment != "" {
				query.Set("service.environment", args.Service.Environment)
			}
			url := *t.configURLs[urlIndex]
			url.RawQuery = query.Encode()

			req := t.newRequest("GET", &url)
			req.Header = t.configHeaders
			if etag != "" {
				req.Header = copyHeaders(req.Header)
				req.Header.Set("If-None-Match", strconv.QuoteToASCII(etag))
			}

			req = requestWithContext(ctx, req)
			resp := t.configRequest(req)
			var send bool
			if resp.err != nil {
				// The request will have failed if the context has been
				// cancelled. No need to send a a change in this case.
				send = ctx.Err() == nil
			}
			if !send && resp.attrs != nil {
				etag = resp.etag
				send = true
			}
			if send {
				change = apmconfig.Change{Err: resp.err, Attrs: resp.attrs}
				out = changes
			}
			timer.Reset(resp.maxAge)
		}
	}()
	return changes
}