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package cache
import (
"time"
"github.com/miekg/coredns/middleware"
"github.com/miekg/coredns/request"
"github.com/miekg/dns"
"github.com/prometheus/client_golang/prometheus"
"golang.org/x/net/context"
)
// ServeDNS implements the middleware.Handler interface.
func (c *Cache) ServeDNS(ctx context.Context, w dns.ResponseWriter, r *dns.Msg) (int, error) {
state := request.Request{W: w, Req: r}
qname := state.Name()
qtype := state.QType()
zone := middleware.Zones(c.Zones).Matches(qname)
if zone == "" {
return c.Next.ServeDNS(ctx, w, r)
}
do := state.Do() // might need more from OPT record? Like the actual bufsize?
if i, ok, expired := c.get(qname, qtype, do); ok && !expired {
resp := i.toMsg(r)
state.SizeAndDo(resp)
w.WriteMsg(resp)
return dns.RcodeSuccess, nil
}
crr := &ResponseWriter{w, c}
return c.Next.ServeDNS(ctx, crr, r)
}
// Name implements the Handler interface.
func (c *Cache) Name() string { return "cache" }
func (c *Cache) get(qname string, qtype uint16, do bool) (*item, bool, bool) {
k := rawKey(qname, qtype, do)
if i, ok := c.ncache.Get(k); ok {
return i.(*item), ok, i.(*item).expired(time.Now())
}
if i, ok := c.pcache.Get(k); ok {
return i.(*item), ok, i.(*item).expired(time.Now())
}
return nil, false, false
}
var (
cacheSize = prometheus.NewGaugeVec(prometheus.GaugeOpts{
Namespace: middleware.Namespace,
Subsystem: subsystem,
Name: "size",
Help: "The number of elements in the cache.",
}, []string{"type"})
cacheCapacity = prometheus.NewGaugeVec(prometheus.GaugeOpts{
Namespace: middleware.Namespace,
Subsystem: subsystem,
Name: "capacity",
Help: "The cache's capacity.",
}, []string{"type"})
)
const subsystem = "cache"
func init() {
prometheus.MustRegister(cacheSize)
prometheus.MustRegister(cacheCapacity)
}
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