Remove expired sessions from server memory

auth.go

@@ -1,6 +1,7 @@
 package main
 
 import (
+	"container/heap"
 	"crypto/rand"
 	"encoding/base64"
 	"errors"
@@ -10,13 +11,68 @@ import (
 )
 
 type SessionData struct {
+	sid      string
 	username string
+	priority time.Time
+	index    int
+}
+
+type SessionQueue []*SessionData
+
+func (pq SessionQueue) Len() int {
+	return len(pq)
+}
+
+func (pq SessionQueue) Less(i, j int) bool {
+	return pq[i].priority.Before(pq[j].priority)
+}
+
+func (pq SessionQueue) Swap(i, j int) {
+	pq[i], pq[j] = pq[j], pq[i]
+	pq[i].index = i
+	pq[j].index = j
+}
+
+func (pq *SessionQueue) Push(x interface{}) {
+	n := len(*pq)
+	item := x.(*SessionData)
+	item.index = n
+	*pq = append(*pq, item)
+}
+
+func (pq *SessionQueue) Pop() interface{} {
+	old := *pq
+	n := len(old)
+	item := old[n-1]
+	item.index = -1 // for safety
+	*pq = old[0 : n-1]
+	return item
 }
 
 var (
-	sessions = make(map[string]*SessionData)
+	sessions     = make(map[string]*SessionData)
+	sessionQueue = make(SessionQueue, 0)
 )
 
+func sessionExpirer() {
+	for {
+		for len(sessionQueue) > 0 && time.Now().After(sessionQueue[0].priority) {
+			session := heap.Pop(&sessionQueue).(*SessionData)
+			delete(sessions, session.sid)
+		}
+		time.Sleep(time.Second * 5)
+	}
+}
+
+func init() {
+	go sessionExpirer()
+}
+
+func addSession(data *SessionData) {
+	sessions[data.sid] = data
+	heap.Push(&sessionQueue, data)
+}
+
 func userOk(username, password string) bool {
 	return (username == "Lamperi" && password == "paskaa")
 }
@@ -32,20 +88,21 @@ func tryLogin(username, password string, longerTime bool) (http.Cookie, error) {
 		return http.Cookie{}, err
 	}
 
-	sessions[sid] = &SessionData{username}
-
-	hours := time.Duration(1)
+	duration := time.Hour * 1
 	if longerTime {
-		hours = time.Duration(336)
+		duration = time.Hour * 24 * 14
 	}
 
 	loginCookie := http.Cookie{
 		Name:     "id",
 		Value:    sid,
-		MaxAge:   int((time.Hour * hours).Seconds()),
+		MaxAge:   int(duration.Seconds()),
 		HttpOnly: true,
 	}
 
+	expiration := time.Now().Add(duration)
+	addSession(&SessionData{sid, username, expiration, 0})
+
 	return loginCookie, nil
 }