TrueCloudLab/coredns
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cache: some optimizations (#2247)

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Remove some optimization and lowercasing of the qname (in the end
miekg/dns should provide a fast and OK function for it).

* remove the make([]byte, 2) allocation in the key()
* use already lowercased qname in hash key calculation.

% benchcmp old.txt new.txt
benchmark                    old ns/op     new ns/op     delta
BenchmarkCacheResponse-4     9599          8735          -9.00%

Signed-off-by: Miek Gieben <miek@miek.nl>
This commit is contained in:
Miek Gieben 2018-10-29 15:13:39 +00:00 • committed by Yong Tang
parent 29f4205364
commit e6d02a3fd2
2 changed files with 10 additions and 21 deletions
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26
plugin/cache/cache.go vendored
View file

@ -2,7 +2,6 @@
package cache package cache
import ( import (
"encoding/binary"
"hash/fnv" "hash/fnv"
"net" "net"
"time" "time"
@ -61,10 +60,10 @@ func New() *Cache {
} }
} }
// Return key under which we store the item, -1 will be returned if we don't store the // key returns key under which we store the item, -1 will be returned if we don't store the message.
// message.
// Currently we do not cache Truncated, errors zone transfers or dynamic update messages. // Currently we do not cache Truncated, errors zone transfers or dynamic update messages.
func key(m *dns.Msg, t response.Type, do bool) (bool, uint64) { // qname holds the already lowercased qname.
func key(qname string, m *dns.Msg, t response.Type, do bool) (bool, uint64) {
// We don't store truncated responses. // We don't store truncated responses.
if m.Truncated { if m.Truncated {
return false, 0 return false, 0
@ -74,7 +73,7 @@ func key(m *dns.Msg, t response.Type, do bool) (bool, uint64) {
return false, 0 return false, 0
} }
return true, hash(m.Question[0].Name, m.Question[0].Qtype, do) return true, hash(qname, m.Question[0].Qtype, do)
} }
var one = []byte("1") var one = []byte("1")
@ -89,18 +88,9 @@ func hash(qname string, qtype uint16, do bool) uint64 {
h.Write(zero) h.Write(zero)
} }
b := make([]byte, 2) h.Write([]byte{byte(qtype >> 8)})
binary.BigEndian.PutUint16(b, qtype) h.Write([]byte{byte(qtype)})
h.Write(b) h.Write([]byte(qname))
for i := range qname {
c := qname[i]
if c >= 'A' && c <= 'Z' {
c += 'a' - 'A'
}
h.Write([]byte{c})
}
return h.Sum64() return h.Sum64()
} }
@ -167,7 +157,7 @@ func (w *ResponseWriter) WriteMsg(res *dns.Msg) error {
} }
// key returns empty string for anything we don't want to cache. // key returns empty string for anything we don't want to cache.
hasKey, key := key(res, mt, do) hasKey, key := key(w.state.Name(), res, mt, do)
msgTTL := dnsutil.MinimalTTL(res, mt) msgTTL := dnsutil.MinimalTTL(res, mt)
var duration time.Duration var duration time.Duration

5
plugin/cache/cache_test.go vendored
View file

@ -167,7 +167,7 @@ func TestCache(t *testing.T) {
state := request.Request{W: nil, Req: m} state := request.Request{W: nil, Req: m}
mt, _ := response.Typify(m, utc) mt, _ := response.Typify(m, utc)
valid, k := key(m, mt, state.Do()) valid, k := key(state.Name(), m, mt, state.Do())
if valid { if valid {
crr.set(m, k, mt, c.pttl) crr.set(m, k, mt, c.pttl)
@ -241,8 +241,7 @@ func BenchmarkCacheResponse(b *testing.B) {
for i := 0; i < b.N; i++ { for i := 0; i < b.N; i++ {
req := reqs[j] req := reqs[j]
c.ServeDNS(ctx, &test.ResponseWriter{}, req) c.ServeDNS(ctx, &test.ResponseWriter{}, req)
j++ j = (j + 1) % 5
j = j % 5
} }
} }