f9bdd382dd
* - ensure plugins that use prometheus.MustRegister, re-register after reload - removing once.Do on the startup function was simplest way to do it. * - fix underscored names (advice of bot) * - tune existing UT for reload, and add a test verifying failing reload does not prevent correct registering for metrics * - ensure different ports for tests that can run in same time ..
127 lines
3.5 KiB
Go
127 lines
3.5 KiB
Go
package cache
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import (
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"context"
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"math"
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"time"
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"github.com/coredns/coredns/plugin"
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"github.com/coredns/coredns/plugin/metrics"
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"github.com/coredns/coredns/request"
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"github.com/miekg/dns"
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"github.com/prometheus/client_golang/prometheus"
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)
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// ServeDNS implements the plugin.Handler interface.
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func (c *Cache) ServeDNS(ctx context.Context, w dns.ResponseWriter, r *dns.Msg) (int, error) {
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state := request.Request{W: w, Req: r}
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zone := plugin.Zones(c.Zones).Matches(state.Name())
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if zone == "" {
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return plugin.NextOrFailure(c.Name(), c.Next, ctx, w, r)
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}
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now := c.now().UTC()
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server := metrics.WithServer(ctx)
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i, found := c.get(now, state, server)
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if i != nil && found {
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resp := i.toMsg(r, now)
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w.WriteMsg(resp)
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if c.prefetch > 0 {
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ttl := i.ttl(now)
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i.Freq.Update(c.duration, now)
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threshold := int(math.Ceil(float64(c.percentage) / 100 * float64(i.origTTL)))
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if i.Freq.Hits() >= c.prefetch && ttl <= threshold {
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cw := newPrefetchResponseWriter(server, state, c)
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go func(w dns.ResponseWriter) {
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cachePrefetches.WithLabelValues(server).Inc()
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plugin.NextOrFailure(c.Name(), c.Next, ctx, w, r)
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// When prefetching we loose the item i, and with it the frequency
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// that we've gathered sofar. See we copy the frequencies info back
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// into the new item that was stored in the cache.
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if i1 := c.exists(state); i1 != nil {
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i1.Freq.Reset(now, i.Freq.Hits())
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}
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}(cw)
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}
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}
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return dns.RcodeSuccess, nil
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}
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crr := &ResponseWriter{ResponseWriter: w, Cache: c, state: state, server: server}
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return plugin.NextOrFailure(c.Name(), c.Next, ctx, crr, r)
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}
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// Name implements the Handler interface.
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func (c *Cache) Name() string { return "cache" }
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func (c *Cache) get(now time.Time, state request.Request, server string) (*item, bool) {
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k := hash(state.Name(), state.QType(), state.Do())
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if i, ok := c.ncache.Get(k); ok && i.(*item).ttl(now) > 0 {
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cacheHits.WithLabelValues(server, Denial).Inc()
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return i.(*item), true
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}
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if i, ok := c.pcache.Get(k); ok && i.(*item).ttl(now) > 0 {
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cacheHits.WithLabelValues(server, Success).Inc()
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return i.(*item), true
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}
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cacheMisses.WithLabelValues(server).Inc()
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return nil, false
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}
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func (c *Cache) exists(state request.Request) *item {
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k := hash(state.Name(), state.QType(), state.Do())
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if i, ok := c.ncache.Get(k); ok {
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return i.(*item)
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}
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if i, ok := c.pcache.Get(k); ok {
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return i.(*item)
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}
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return nil
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}
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var (
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cacheSize = prometheus.NewGaugeVec(prometheus.GaugeOpts{
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Namespace: plugin.Namespace,
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Subsystem: "cache",
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Name: "size",
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Help: "The number of elements in the cache.",
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}, []string{"server", "type"})
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cacheHits = prometheus.NewCounterVec(prometheus.CounterOpts{
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Namespace: plugin.Namespace,
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Subsystem: "cache",
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Name: "hits_total",
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Help: "The count of cache hits.",
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}, []string{"server", "type"})
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cacheMisses = prometheus.NewCounterVec(prometheus.CounterOpts{
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Namespace: plugin.Namespace,
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Subsystem: "cache",
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Name: "misses_total",
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Help: "The count of cache misses.",
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}, []string{"server"})
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cachePrefetches = prometheus.NewCounterVec(prometheus.CounterOpts{
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Namespace: plugin.Namespace,
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Subsystem: "cache",
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Name: "prefetch_total",
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Help: "The number of time the cache has prefetched a cached item.",
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}, []string{"server"})
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cacheDrops = prometheus.NewCounterVec(prometheus.CounterOpts{
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Namespace: plugin.Namespace,
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Subsystem: "cache",
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Name: "drops_total",
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Help: "The number responses that are not cached, because the reply is malformed.",
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}, []string{"server"})
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)
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