78 lines
1.7 KiB
Go
78 lines
1.7 KiB
Go
package session
|
|
|
|
import (
|
|
"errors"
|
|
"sync"
|
|
)
|
|
|
|
const (
|
|
unlimitedActiveSessions = 0
|
|
)
|
|
|
|
var (
|
|
ErrTooManyActiveSessions = errors.New("too many active sessions")
|
|
)
|
|
|
|
type Limiter interface {
|
|
// Acquire tries to acquire a free slot for a session, if the value of sessions is already above
|
|
// the maximum it returns ErrTooManyActiveSessions.
|
|
Acquire(sessionType string) error
|
|
// Release releases a slot for a session.
|
|
Release()
|
|
// SetLimit allows to hot swap the limit value of the limiter.
|
|
SetLimit(uint64)
|
|
}
|
|
|
|
type sessionLimiter struct {
|
|
limiterLock sync.Mutex
|
|
activeSessionsCounter uint64
|
|
maxActiveSessions uint64
|
|
unlimited bool
|
|
}
|
|
|
|
func NewLimiter(maxActiveSessions uint64) Limiter {
|
|
sessionLimiter := &sessionLimiter{
|
|
maxActiveSessions: maxActiveSessions,
|
|
unlimited: isUnlimited(maxActiveSessions),
|
|
}
|
|
|
|
return sessionLimiter
|
|
}
|
|
|
|
func (s *sessionLimiter) Acquire(sessionType string) error {
|
|
s.limiterLock.Lock()
|
|
defer s.limiterLock.Unlock()
|
|
|
|
if !s.unlimited && s.activeSessionsCounter >= s.maxActiveSessions {
|
|
sessionRegistrationsDropped.WithLabelValues(sessionType).Inc()
|
|
return ErrTooManyActiveSessions
|
|
}
|
|
|
|
s.activeSessionsCounter++
|
|
return nil
|
|
}
|
|
|
|
func (s *sessionLimiter) Release() {
|
|
s.limiterLock.Lock()
|
|
defer s.limiterLock.Unlock()
|
|
|
|
if s.activeSessionsCounter <= 0 {
|
|
return
|
|
}
|
|
|
|
s.activeSessionsCounter--
|
|
}
|
|
|
|
func (s *sessionLimiter) SetLimit(newMaxActiveSessions uint64) {
|
|
s.limiterLock.Lock()
|
|
defer s.limiterLock.Unlock()
|
|
|
|
s.maxActiveSessions = newMaxActiveSessions
|
|
s.unlimited = isUnlimited(newMaxActiveSessions)
|
|
}
|
|
|
|
// isUnlimited checks if the value received matches the configuration for the unlimited session limiter.
|
|
func isUnlimited(value uint64) bool {
|
|
return value == unlimitedActiveSessions
|
|
}
|