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|
package firewall
import (
"sync/atomic"
"time"
"github.com/sirupsen/logrus"
)
// ConntrackCache is used as a local routine cache to know if a given flow
// has been seen in the conntrack table.
type ConntrackCache map[Packet]struct{}
type ConntrackCacheTicker struct {
cacheV uint64
cacheTick uint64
cache ConntrackCache
}
func NewConntrackCacheTicker(d time.Duration) *ConntrackCacheTicker {
if d == 0 {
return nil
}
c := &ConntrackCacheTicker{
cache: ConntrackCache{},
}
go c.tick(d)
return c
}
func (c *ConntrackCacheTicker) tick(d time.Duration) {
for {
time.Sleep(d)
atomic.AddUint64(&c.cacheTick, 1)
}
}
// Get checks if the cache ticker has moved to the next version before returning
// the map. If it has moved, we reset the map.
func (c *ConntrackCacheTicker) Get(l *logrus.Logger) ConntrackCache {
if c == nil {
return nil
}
if tick := atomic.LoadUint64(&c.cacheTick); tick != c.cacheV {
c.cacheV = tick
if ll := len(c.cache); ll > 0 {
if l.Level == logrus.DebugLevel {
l.WithField("len", ll).Debug("resetting conntrack cache")
}
c.cache = make(ConntrackCache, ll)
}
}
return c.cache
}
|
