TrueCloudLab/coredns
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plugin/cache: unroll minTTL loop (#1773)

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This allocates memory because of the append, just unroll the loop.
Also add benchmark.

Before:
goos: linux
goarch: amd64
pkg: github.com/coredns/coredns/plugin/cache
BenchmarkCacheResponse-4   	  100000	     11910 ns/op
BenchmarkMinMsgTTL-4       	 1000000	      1494 ns/op
PASS

After:
goos: linux
goarch: amd64
pkg: github.com/coredns/coredns/plugin/cache
BenchmarkCacheResponse-4   	  100000	     12016 ns/op
BenchmarkMinMsgTTL-4       	 2000000	       668 ns/op
PASS
This commit is contained in:
Miek Gieben 2018-05-08 18:36:29 +01:00 • committed by GitHub
parent 565e416407
commit 68b45f5377
No known key found for this signature in database
GPG key ID: 4AEE18F83AFDEB23
2 changed files with 57 additions and 2 deletions
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29
plugin/cache/item.go vendored
View file

@ -99,7 +99,32 @@ func minMsgTTL(m *dns.Msg, mt response.Type) time.Duration {
}
minTTL := maxTTL
for _, r := range append(append(m.Answer, m.Ns...), m.Extra...) {
for _, r := range m.Answer {
switch mt {
case response.NameError, response.NoData:
if r.Header().Rrtype == dns.TypeSOA {
minTTL = time.Duration(r.(*dns.SOA).Minttl) * time.Second
}
case response.NoError, response.Delegation:
if r.Header().Ttl < uint32(minTTL.Seconds()) {
minTTL = time.Duration(r.Header().Ttl) * time.Second
}
}
}
for _, r := range m.Ns {
switch mt {
case response.NameError, response.NoData:
if r.Header().Rrtype == dns.TypeSOA {
minTTL = time.Duration(r.(*dns.SOA).Minttl) * time.Second
}
case response.NoError, response.Delegation:
if r.Header().Ttl < uint32(minTTL.Seconds()) {
minTTL = time.Duration(r.Header().Ttl) * time.Second
}
}
}
for _, r := range m.Extra {
if r.Header().Rrtype == dns.TypeOPT {
// OPT records use TTL field for extended rcode and flags
continue
@ -107,7 +132,7 @@ func minMsgTTL(m *dns.Msg, mt response.Type) time.Duration {
switch mt {
case response.NameError, response.NoData:
if r.Header().Rrtype == dns.TypeSOA {
return time.Duration(r.(*dns.SOA).Minttl) * time.Second
minTTL = time.Duration(r.(*dns.SOA).Minttl) * time.Second
}
case response.NoError, response.Delegation:
if r.Header().Ttl < uint32(minTTL.Seconds()) {

30
plugin/cache/minttl_test.go vendored
View file

@ -40,3 +40,33 @@ func TestMinMsgTTL(t *testing.T) {
t.Fatalf("Expected minttl duration to be %d, got %d", 3600, dur)
}
}
func BenchmarkMinMsgTTL(b *testing.B) {
m := new(dns.Msg)
m.SetQuestion("example.org.", dns.TypeA)
m.Ns = []dns.RR{
test.A("a.example.org. 1800 IN A 127.0.0.53"),
test.A("b.example.org. 1900 IN A 127.0.0.53"),
test.A("c.example.org. 1600 IN A 127.0.0.53"),
test.A("d.example.org. 1100 IN A 127.0.0.53"),
test.A("e.example.org. 1000 IN A 127.0.0.53"),
}
m.Extra = []dns.RR{
test.A("a.example.org. 1800 IN A 127.0.0.53"),
test.A("b.example.org. 1600 IN A 127.0.0.53"),
test.A("c.example.org. 1400 IN A 127.0.0.53"),
test.A("d.example.org. 1200 IN A 127.0.0.53"),
test.A("e.example.org. 1100 IN A 127.0.0.53"),
}
utc := time.Now().UTC()
mt, _ := response.Typify(m, utc)
b.ResetTimer()
for i := 0; i < b.N; i++ {
dur := minMsgTTL(m, mt)
if dur != 1000*time.Second {
b.Fatalf("Wrong minMsgTTL %d, expected %d", dur, 1000*time.Second)
}
}
}