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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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55
middleware/cache/item.go vendored
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@@ -1,9 +1,9 @@
package cache
import (
"strconv"
"time"
"github.com/miekg/coredns/middleware/pkg/response"
"github.com/miekg/dns"
)
@@ -44,7 +44,7 @@ func newItem(m *dns.Msg, d time.Duration) *item {
return i
}
// toMsg turns i into a message, it tailers to reply to m.
// toMsg turns i into a message, it tailers the reply to m.
func (i *item) toMsg(m *dns.Msg) *dns.Msg {
m1 := new(dns.Msg)
m1.SetReply(m)
@@ -58,44 +58,51 @@ func (i *item) toMsg(m *dns.Msg) *dns.Msg {
m1.Extra = i.Extra
ttl := int(i.origTTL) - int(time.Now().UTC().Sub(i.stored).Seconds())
if ttl < baseTTL {
ttl = baseTTL
if ttl < int(minTTL.Seconds()) {
ttl = int(minTTL.Seconds())
}
setCap(m1, uint32(ttl))
setMsgTTL(m1, uint32(ttl))
return m1
}
// setCap sets the ttl on all RRs in all sections.
func setCap(m *dns.Msg, ttl uint32) {
func (i *item) expired(now time.Time) bool {
ttl := int(i.origTTL) - int(now.UTC().Sub(i.stored).Seconds())
return ttl < 0
}
// setMsgTTL sets the ttl on all RRs in all sections.
func setMsgTTL(m *dns.Msg, ttl uint32) {
for _, r := range m.Answer {
r.Header().Ttl = uint32(ttl)
r.Header().Ttl = ttl
}
for _, r := range m.Ns {
r.Header().Ttl = uint32(ttl)
r.Header().Ttl = ttl
}
for _, r := range m.Extra {
if r.Header().Rrtype == dns.TypeOPT {
continue
}
r.Header().Ttl = uint32(ttl)
r.Header().Ttl = ttl
}
}
// nodataKey returns a caching key for NODATA responses.
func noDataKey(qname string, qtype uint16, do bool) string {
if do {
return "1" + qname + ".." + strconv.Itoa(int(qtype))
func minMsgTTL(m *dns.Msg, mt response.Type) time.Duration {
if mt != response.Success && mt != response.NameError && mt != response.NoData {
return 0
}
return "0" + qname + ".." + strconv.Itoa(int(qtype))
}
// nameErrorKey returns a caching key for NXDOMAIN responses.
func nameErrorKey(qname string, do bool) string {
if do {
return "1" + qname
minTTL := maxTTL
for _, r := range append(m.Answer, m.Ns...) {
switch mt {
case response.NameError, response.NoData:
if r.Header().Rrtype == dns.TypeSOA {
return time.Duration(r.(*dns.SOA).Minttl) * time.Second
}
case response.Success, response.Delegation:
if r.Header().Ttl < uint32(minTTL.Seconds()) {
minTTL = time.Duration(r.Header().Ttl) * time.Second
}
}
}
return "0" + qname
return minTTL
}
// successKey returns a caching key for successfull answers.
func successKey(qname string, qtype uint16, do bool) string { return noDataKey(qname, qtype, do) }