/// <summary> /// Reads a stored session /// </summary> /// <param name="Key">Session Key</param> /// <param name="Reader">Method to call to complete read</param> /// <param name="StateObject">State object</param> /// <param name="isExporting">Indicates if the session is to be exported</param> /// <returns>Result of read action</returns> private SessionActionResult Read(string Key, SessionReadHandler Reader, object StateObject, bool isExporting) { if (Key == null) { throw new ArgumentNullException("Key"); } bool tryAgain; bool sessionIslocked = false; Diags.ResetDeadLockCounter(); //Reset Dead lock counter do { tryAgain = false; AcquireReadLock(); ISessionObject entry; try { dict.TryGetValue(Key, out entry); } finally { ReleaseReadLock(); } if (entry == null) { //Session not found Diags.LogSessionNotFound(Key); return(SessionActionResult.NotFound); } else { //Session Found if (entry.CompareExchangeIsInUse(true, false) == false) { //The InUse flag has been set and now this thread has exclusive access to this session object try { //Set IsExporting flag for this entry if item is to be exported if (isExporting) { entry.IsExporting = true; } //Call Reader Delegate if (Reader != null) { Reader(entry, StateObject); } if (isExporting) { Diags.LogSessionExporting(Key, entry); } else { Diags.LogSessionRead(Key, entry); } sessionIslocked = entry.IsLocked; } finally { if (!isExporting) //Remove inUse property if not exporting { entry.CompareExchangeIsInUse(false, true); } } } else { //Nope, it's still there so check if it's been exported and try again if (entry.IsExporting) { //This session is already been exported so leave Diags.ResetDeadLockCounter(); return(SessionActionResult.Exporting); } Thread.Sleep(1); //pause for 1 ms tryAgain = true; } Diags.DetectDeadLock(Key, DeadLockIterationCount); //Signal a deadlock after 2000 iterations } } while (tryAgain); Diags.ResetDeadLockCounter(); //Signal deadlock was freed if (sessionIslocked && !isExporting) { Diags.LogSessionIsLocked(Key); return(SessionActionResult.Locked); } else { return(SessionActionResult.OK); } }