// Notification raised before ADAL accesses the cache.
        // This is your chance to update the in-memory copy from the DB, if the in-memory version is stale
        void BeforeAccessNotification(TokenCacheNotificationArgs args)
        {
            if (Cache == null)
            {
                // first time access
                Cache = db.UserTokenCacheList.FirstOrDefault(c => c.webUserUniqueId == userId);
            }
            else
            {
                // retrieve last write from the DB
                var status = from e in db.UserTokenCacheList
                             where (e.webUserUniqueId == userId)
                             select new
                             {
                                 LastWrite = e.LastWrite
                             };

                // if the in-memory copy is older than the persistent copy
                if (status.First().LastWrite > Cache.LastWrite)
                {
                    // read from from storage, update in-memory copy
                    Cache = db.UserTokenCacheList.FirstOrDefault(c => c.webUserUniqueId == userId);
                }
            }
            this.Deserialize((Cache == null) ? null : MachineKey.Unprotect(Cache.cacheBits, "ADALCache"));
        }
 public ADALTokenCache(string signedInUserId)
 {
     // associate the cache to the current user of the web app
     userId = signedInUserId;
     this.AfterAccess = AfterAccessNotification;
     this.BeforeAccess = BeforeAccessNotification;
     this.BeforeWrite = BeforeWriteNotification;
     // look up the entry in the database
     Cache = db.UserTokenCacheList.FirstOrDefault(c => c.webUserUniqueId == userId);
     // place the entry in memory
     this.Deserialize((Cache == null) ? null : MachineKey.Unprotect(Cache.cacheBits, "ADALCache"));
 }
 // Notification raised after ADAL accessed the cache.
 // If the HasStateChanged flag is set, ADAL changed the content of the cache
 void AfterAccessNotification(TokenCacheNotificationArgs args)
 {
     // if state changed
     if (this.HasStateChanged)
     {
         Cache = new UserTokenCache
         {
             webUserUniqueId = userId,
             cacheBits = MachineKey.Protect(this.Serialize(), "ADALCache"),
             LastWrite = DateTime.Now
         };
         // update the DB and the lastwrite 
         db.Entry(Cache).State = Cache.UserTokenCacheId == 0 ? EntityState.Added : EntityState.Modified;
         db.SaveChanges();
         this.HasStateChanged = false;
     }
 }