package consul import ( "fmt" "time" "github.com/armon/go-metrics" "github.com/hashicorp/consul/consul/structs" ) // initializeSessionTimers is used when a leader is newly elected to create // a new map to track session expiration and to reset all the timers from // the previously known set of timers. func (s *Server) initializeSessionTimers() error { // Scan all sessions and reset their timer state := s.fsm.State() _, sessions, err := state.SessionList() if err != nil { return err } for _, session := range sessions { if err := s.resetSessionTimer(session.ID, session); err != nil { return err } } return nil } // resetSessionTimer is used to renew the TTL of a session. // This can be used for new sessions and existing ones. A session // will be faulted in if not given. func (s *Server) resetSessionTimer(id string, session *structs.Session) error { // Fault the session in if not given if session == nil { state := s.fsm.State() _, s, err := state.SessionGet(id) if err != nil { return err } if s == nil { return fmt.Errorf("Session '%s' not found", id) } session = s } // Bail if the session has no TTL, fast-path some common inputs switch session.TTL { case "", "0", "0s", "0m", "0h": return nil } // Parse the TTL, and skip if zero time ttl, err := time.ParseDuration(session.TTL) if err != nil { return fmt.Errorf("Invalid Session TTL '%s': %v", session.TTL, err) } if ttl == 0 { return nil } // Reset the session timer s.sessionTimersLock.Lock() defer s.sessionTimersLock.Unlock() s.resetSessionTimerLocked(id, ttl) return nil } // resetSessionTimerLocked is used to reset a session timer // assuming the sessionTimerLock is already held func (s *Server) resetSessionTimerLocked(id string, ttl time.Duration) { // Ensure a timer map exists if s.sessionTimers == nil { s.sessionTimers = make(map[string]*time.Timer) } // Adjust the given TTL by the TTL multiplier. This is done // to give a client a grace period and to compensate for network // and processing delays. The contract is that a session is not expired // before the TTL, but there is no explicit promise about the upper // bound so this is allowable. ttl = ttl * structs.SessionTTLMultiplier // Renew the session timer if it exists if timer, ok := s.sessionTimers[id]; ok { timer.Reset(ttl) return } // Create a new timer to track expiration of thi ssession timer := time.AfterFunc(ttl, func() { s.invalidateSession(id) }) s.sessionTimers[id] = timer } // invalidateSession is invoked when a session TTL is reached and we // need to invalidate the session. func (s *Server) invalidateSession(id string) { defer metrics.MeasureSince([]string{"consul", "session_ttl", "invalidate"}, time.Now()) // Clear the session timer s.sessionTimersLock.Lock() delete(s.sessionTimers, id) s.sessionTimersLock.Unlock() // Create a session destroy request args := structs.SessionRequest{ Datacenter: s.config.Datacenter, Op: structs.SessionDestroy, Session: structs.Session{ ID: id, }, } s.logger.Printf("[DEBUG] consul.state: Session %s TTL expired", id) // Apply the update to destroy the session if _, err := s.raftApply(structs.SessionRequestType, args); err != nil { s.logger.Printf("[ERR] consul.session: Invalidation failed: %v", err) } } // clearSessionTimer is used to clear the session time for // a single session. This is used when a session is destroyed // explicitly and no longer needed. func (s *Server) clearSessionTimer(id string) error { s.sessionTimersLock.Lock() defer s.sessionTimersLock.Unlock() if timer, ok := s.sessionTimers[id]; ok { timer.Stop() delete(s.sessionTimers, id) } return nil } // clearAllSessionTimers is used when a leader is stepping // down and we no longer need to track any session timers. func (s *Server) clearAllSessionTimers() error { s.sessionTimersLock.Lock() defer s.sessionTimersLock.Unlock() for _, t := range s.sessionTimers { t.Stop() } s.sessionTimers = nil return nil } // sessionStats is a long running routine used to capture // the number of active sessions being tracked func (s *Server) sessionStats() { for { select { case <-time.After(5 * time.Second): s.sessionTimersLock.Lock() num := len(s.sessionTimers) s.sessionTimersLock.Unlock() metrics.SetGauge([]string{"consul", "session_ttl", "active"}, float32(num)) case <-s.shutdownCh: return } } }