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package cache
import (
"sync"
"time"
"linum/internal/dns"
)
type Entry struct {
Msg *dns.Msg
Expires time.Time
}
func (e *Entry) expired() bool {
return time.Now().After(e.Expires)
}
type Cache struct {
mu sync.RWMutex
data map[string]*Entry
}
func New() *Cache {
return &Cache{
data: make(map[string]*Entry),
}
}
func makeKey(qname dns.Name, qtype, qclass uint16) string {
return qname.String() + ":" + itoa(qtype) + ":" + itoa(qclass)
}
func itoa(v uint16) string {
if v == 0 {
return "0"
}
var buf [5]byte
i := len(buf)
for v > 0 {
i--
buf[i] = byte(v%10) + '0'
v /= 10
}
return string(buf[i:])
}
func (c *Cache) Get(qname dns.Name, qtype, qclass uint16) (*dns.Msg, bool) {
key := makeKey(qname, qtype, qclass)
c.mu.RLock()
e, ok := c.data[key]
c.mu.RUnlock()
if !ok || e.expired() {
return nil, false
}
return e.Msg, true
}
func (c *Cache) Set(qname dns.Name, qtype, qclass uint16, msg *dns.Msg, ttl uint32) {
if ttl == 0 {
return
}
if ttl > 3600 {
ttl = 3600
}
key := makeKey(qname, qtype, qclass)
c.mu.Lock()
c.data[key] = &Entry{
Msg: msg,
Expires: time.Now().Add(time.Duration(ttl) * time.Second),
}
c.mu.Unlock()
}
func (c *Cache) Len() int {
c.mu.RLock()
defer c.mu.RUnlock()
return len(c.data)
}
|
