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middleware/cache: split cache in positive and negative and use lru (#298)

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Make the cache memory bounded, by using a LRU cache. Also split the
cache in a positive and negative one - each with its own controls.

Extend the cache stanza to allow for this:

    cache {
       positive limit [ttl]
       negative limit [ttl]
    }

is now possible. This also add a cache_test.go in the toplevel test/
directory that exercises the caching path.

Fixes #260
This commit is contained in:
Miek Gieben 2016-10-02 08:31:44 +01:00 • committed by GitHub
parent 9b6b8d2762
commit e54c232c8c
16 changed files with 413 additions and 190 deletions
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30
middleware/cache/handler.go vendored
View file

@ -1,6 +1,8 @@
package cache
import (
"time"
"github.com/miekg/coredns/middleware"
"github.com/miekg/coredns/request"
@ -10,7 +12,7 @@ import (
)
// ServeDNS implements the middleware.Handler interface.
func (c Cache) ServeDNS(ctx context.Context, w dns.ResponseWriter, r *dns.Msg) (int, error) {
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()
@ -20,34 +22,36 @@ func (c Cache) ServeDNS(ctx context.Context, w dns.ResponseWriter, r *dns.Msg) (
return c.Next.ServeDNS(ctx, w, r)
}
do := state.Do() // might need more from OPT record?
do := state.Do() // might need more from OPT record? Like the actual bufsize?
if i, ok, expired := c.get(qname, qtype, do); ok && !expired {
if i, ok := c.get(qname, qtype, do); ok {
resp := i.toMsg(r)
state.SizeAndDo(resp)
w.WriteMsg(resp)
cacheHitCount.WithLabelValues(zone).Inc()
return dns.RcodeSuccess, nil
}
cacheMissCount.WithLabelValues(zone).Inc()
crr := NewCachingResponseWriter(w, c.cache, c.cap)
crr := &ResponseWriter{w, c}
return c.Next.ServeDNS(ctx, crr, r)
}
func (c Cache) get(qname string, qtype uint16, do bool) (*item, bool) {
nxdomain := nameErrorKey(qname, do)
if i, ok := c.cache.Get(nxdomain); ok {
return i.(*item), true
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())
}
// TODO(miek): delegation was added double check
successOrNoData := successKey(qname, qtype, do)
if i, ok := c.cache.Get(successOrNoData); ok {
return i.(*item), true
if i, ok := c.pcache.Get(k); ok {
return i.(*item), ok, i.(*item).expired(time.Now())
}
return nil, false
return nil, false, false
}
var (