Method doPrefetch

plugin/cache/handler.go:115–127

(ctx context.Context, cw *ResponseWriter, i *item, now time.Time)

}

func (c *Cache) doPrefetch(ctx context.Context, cw *ResponseWriter, i *item, now time.Time) {
	// Use a fresh metadata map to avoid concurrent writes to the original request's metadata.
	ctx = metadata.ContextWithMetadata(ctx)
	cachePrefetches.WithLabelValues(cw.server, c.zonesMetricLabel, c.viewMetricLabel).Inc()
	c.doRefresh(ctx, cw.state, cw)

	// When prefetching we loose the item i, and with it the frequency
	// that we've gathered sofar. See we copy the frequencies info back
	// into the new item that was stored in the cache.
	if i1 := c.exists(cw.state.Name(), cw.state.QType(), cw.do, cw.cd); i1 != nil {
		i1.Reset(now, i.Hits())
	}
}

func (c *Cache) doRefresh(ctx context.Context, state request.Request, cw dns.ResponseWriter) (int, error) {
	return plugin.NextOrFailure(c.Name(), c.Next, ctx, cw, state.Req)