142 lines
3.9 KiB
Go
142 lines
3.9 KiB
Go
package consul
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import (
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"fmt"
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"time"
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"github.com/armon/go-metrics"
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"github.com/hashicorp/consul/agent/structs"
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)
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const (
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// maxInvalidateAttempts limits how many invalidate attempts are made
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maxInvalidateAttempts = 6
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// invalidateRetryBase is a baseline retry time
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invalidateRetryBase = 10 * time.Second
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)
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// initializeSessionTimers is used when a leader is newly elected to create
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// a new map to track session expiration and to reset all the timers from
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// the previously known set of timers.
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func (s *Server) initializeSessionTimers() error {
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// Scan all sessions and reset their timer
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state := s.fsm.State()
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_, sessions, err := state.SessionList(nil)
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if err != nil {
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return err
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}
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for _, session := range sessions {
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if err := s.resetSessionTimer(session.ID, session); err != nil {
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return err
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}
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}
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return nil
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}
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// resetSessionTimer is used to renew the TTL of a session.
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// This can be used for new sessions and existing ones. A session
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// will be faulted in if not given.
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func (s *Server) resetSessionTimer(id string, session *structs.Session) error {
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// Fault the session in if not given
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if session == nil {
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state := s.fsm.State()
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_, s, err := state.SessionGet(nil, id)
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if err != nil {
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return err
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}
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if s == nil {
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return fmt.Errorf("Session '%s' not found", id)
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}
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session = s
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}
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// Bail if the session has no TTL, fast-path some common inputs
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switch session.TTL {
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case "", "0", "0s", "0m", "0h":
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return nil
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}
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// Parse the TTL, and skip if zero time
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ttl, err := time.ParseDuration(session.TTL)
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if err != nil {
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return fmt.Errorf("Invalid Session TTL '%s': %v", session.TTL, err)
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}
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if ttl == 0 {
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return nil
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}
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s.createSessionTimer(session.ID, ttl)
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return nil
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}
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func (s *Server) createSessionTimer(id string, ttl time.Duration) {
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// Reset the session timer
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// Adjust the given TTL by the TTL multiplier. This is done
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// to give a client a grace period and to compensate for network
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// and processing delays. The contract is that a session is not expired
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// before the TTL, but there is no explicit promise about the upper
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// bound so this is allowable.
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ttl = ttl * structs.SessionTTLMultiplier
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s.sessionTimers.ResetOrCreate(id, ttl, func() { s.invalidateSession(id) })
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}
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// invalidateSession is invoked when a session TTL is reached and we
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// need to invalidate the session.
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func (s *Server) invalidateSession(id string) {
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defer metrics.MeasureSince([]string{"session_ttl", "invalidate"}, time.Now())
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// Clear the session timer
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s.sessionTimers.Del(id)
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// Create a session destroy request
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args := structs.SessionRequest{
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Datacenter: s.config.Datacenter,
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Op: structs.SessionDestroy,
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Session: structs.Session{
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ID: id,
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},
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}
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// Retry with exponential backoff to invalidate the session
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for attempt := uint(0); attempt < maxInvalidateAttempts; attempt++ {
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_, err := s.raftApply(structs.SessionRequestType, args)
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if err == nil {
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s.logger.Printf("[DEBUG] consul.state: Session %s TTL expired", id)
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return
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}
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s.logger.Printf("[ERR] consul.session: Invalidation failed: %v", err)
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time.Sleep((1 << attempt) * invalidateRetryBase)
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}
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s.logger.Printf("[ERR] consul.session: maximum revoke attempts reached for session: %s", id)
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}
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// clearSessionTimer is used to clear the session time for
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// a single session. This is used when a session is destroyed
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// explicitly and no longer needed.
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func (s *Server) clearSessionTimer(id string) error {
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s.sessionTimers.Stop(id)
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return nil
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}
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// clearAllSessionTimers is used when a leader is stepping
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// down and we no longer need to track any session timers.
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func (s *Server) clearAllSessionTimers() {
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s.sessionTimers.StopAll()
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}
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// sessionStats is a long running routine used to capture
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// the number of active sessions being tracked
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func (s *Server) sessionStats() {
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for {
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select {
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case <-time.After(5 * time.Second):
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metrics.SetGauge([]string{"session_ttl", "active"}, float32(s.sessionTimers.Len()))
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case <-s.shutdownCh:
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return
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}
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}
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}
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