Solved 5-session-cleaner

5-session-cleaner/main.go

@@ -20,17 +20,22 @@ package main
 import (
 	"errors"
 	"log"
+	"sync"
+	"time"
 )
 
 // SessionManager keeps track of all sessions from creation, updating
 // to destroying.
 type SessionManager struct {
 	sessions map[string]Session
+	rwmu     sync.RWMutex
 }
 
 // Session stores the session's data
 type Session struct {
-	Data map[string]interface{}
+	Data  map[string]interface{}
+	timer *time.Timer
+	mu    sync.Mutex
 }
 
 // NewSessionManager creates a new sessionManager
@@ -42,6 +47,12 @@ func NewSessionManager() *SessionManager {
 	return m
 }
 
+func (m *SessionManager) CleanSession(sessionID string) {
+	m.rwmu.Lock()
+	delete(m.sessions, sessionID)
+	m.rwmu.Unlock()
+}
+
 // CreateSession creates a new session and returns the sessionID
 func (m *SessionManager) CreateSession() (string, error) {
 	sessionID, err := MakeSessionID()
@@ -49,9 +60,14 @@ func (m *SessionManager) CreateSession() (string, error) {
 		return "", err
 	}
 
+	m.rwmu.Lock()
 	m.sessions[sessionID] = Session{
 		Data: make(map[string]interface{}),
+		timer: time.AfterFunc(5*time.Second, func() {
+			m.CleanSession(sessionID)
+		}),
 	}
+	m.rwmu.Unlock()
 
 	return sessionID, nil
 }
@@ -63,7 +79,9 @@ var ErrSessionNotFound = errors.New("SessionID does not exists")
 // GetSessionData returns data related to session if sessionID is
 // found, errors otherwise
 func (m *SessionManager) GetSessionData(sessionID string) (map[string]interface{}, error) {
+	m.rwmu.RLock()
 	session, ok := m.sessions[sessionID]
+	m.rwmu.RUnlock()
 	if !ok {
 		return nil, ErrSessionNotFound
 	}
@@ -72,15 +90,22 @@ func (m *SessionManager) GetSessionData(sessionID string) (map[string]interface{
 
 // UpdateSessionData overwrites the old session data with the new one
 func (m *SessionManager) UpdateSessionData(sessionID string, data map[string]interface{}) error {
-	_, ok := m.sessions[sessionID]
+	m.rwmu.RLock()
+	s, ok := m.sessions[sessionID]
+	m.rwmu.RUnlock()
+
 	if !ok {
 		return ErrSessionNotFound
 	}
 
-	// Hint: you should renew expiry of the session here
+	// Lock the session data to handle concurrent access to the same session
-	m.sessions[sessionID] = Session{
+	s.mu.Lock()
-		Data: data,
+	s.Data = data
+	if !s.timer.Stop() {
+		<-s.timer.C
 	}
+	s.timer.Reset(5 * time.Second)
+	s.mu.Unlock()
 
 	return nil
 }