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Add MINTTL parameter to cache configuration. (#2055)

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* Add success min TTL parameter to cache.

* Add MINTTL to README.

* Update README.

* Add MINTTL to negative cache.

* Remove unnecessary variable name.

* Address review comments.

* Configure cache in TestCacheZeroTTL to have 0 min ttl.
This commit is contained in:
Aaron Riekenberg 2018-09-03 14:26:02 -05:00 • committed by Tobias Schmidt
parent 4c6c9d4b27
commit b42eae7a04
5 changed files with 111 additions and 31 deletions
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41
plugin/cache/cache.go vendored
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@ -22,13 +22,15 @@ type Cache struct {
Next plugin.Handler
Zones []string
ncache *cache.Cache
ncap int
nttl time.Duration
ncache *cache.Cache
ncap int
nttl time.Duration
minnttl time.Duration
pcache *cache.Cache
pcap int
pttl time.Duration
pcache *cache.Cache
pcap int
pttl time.Duration
minpttl time.Duration
// Prefetch.
prefetch int
@ -47,9 +49,11 @@ func New() *Cache {
pcap: defaultCap,
pcache: cache.New(defaultCap),
pttl: maxTTL,
minpttl: minTTL,
ncap: defaultCap,
ncache: cache.New(defaultCap),
nttl: maxNTTL,
minnttl: minNTTL,
prefetch: 0,
duration: 1 * time.Minute,
percentage: 10,
@ -100,6 +104,17 @@ func hash(qname string, qtype uint16, do bool) uint64 {
return h.Sum64()
}
func computeTTL(msgTTL, minTTL, maxTTL time.Duration) time.Duration {
ttl := msgTTL
if ttl < minTTL {
ttl = minTTL
}
if ttl > maxTTL {
ttl = maxTTL
}
return ttl
}
// ResponseWriter is a response writer that caches the reply message.
type ResponseWriter struct {
dns.ResponseWriter
@ -154,14 +169,12 @@ func (w *ResponseWriter) WriteMsg(res *dns.Msg) error {
// key returns empty string for anything we don't want to cache.
hasKey, key := key(res, mt, do)
duration := w.pttl
if mt == response.NameError || mt == response.NoData {
duration = w.nttl
}
msgTTL := dnsutil.MinimalTTL(res, mt)
if msgTTL < duration {
duration = msgTTL
var duration time.Duration
if mt == response.NameError || mt == response.NoData {
duration = computeTTL(msgTTL, w.minnttl, w.nttl)
} else {
duration = computeTTL(msgTTL, w.minpttl, w.pttl)
}
if hasKey && duration > 0 {
@ -226,7 +239,9 @@ func (w *ResponseWriter) Write(buf []byte) (int, error) {
const (
maxTTL = dnsutil.MaximumDefaulTTL
minTTL = dnsutil.MinimalDefaultTTL
maxNTTL = dnsutil.MaximumDefaulTTL / 2
minNTTL = dnsutil.MinimalDefaultTTL
defaultCap = 10000 // default capacity of the cache.