| private LogSessionDeleted ( string key ) : void | ||
| key | string | |
| return | void | |
/// <summary>
/// Ends an external session export
/// </summary>
/// <param name="Key">Session key</param>
/// <param name="RemoveSession">True to remove session from dictionary</param>
public void EndExport(string Key, bool RemoveSession)
{
//This method resets the inuse property if the isExporting property is true
if (Key == null)
{
throw new ArgumentNullException("Key");
}
AcquireReadLock();
ISessionObject entry;
try
{
dict.TryGetValue(Key, out entry);
}
finally
{
ReleaseReadLock();
}
if (entry == null)
{
//Session not found -- it's okay, don't freak out, session may have expired.
return;
}
else
{
//Session Found
if (entry.IsInUse)
{
//The InUse flag, now check the isExporting flag
if (!entry.IsExporting)
{
Exception ex = new InvalidOperationException("EndExport must be called after a call to BeginExport");
Diags.LogApplicationError("EndExport must be called after a call to BeginExport -- Entry is InUse but IsExporting is false", ex);
throw ex;
}
try
{
//Delete session
if (RemoveSession)
{
AcquireWriteLock();
try
{
if (dict.Remove(Key))
{
expiryList.Remove(Key);
Diags.LogSessionDeleted(Key);
}
}
finally
{
ReleaseWriteLock();
}
}
}
finally
{
entry.IsExporting = false;
Diags.LogSessionExported(Key);
entry.CompareExchangeIsInUse(false, true);
}
}
else
{
Exception ex = new InvalidOperationException("EndExport must be called after a call to BeginExport");
Diags.LogApplicationError("EndExport must be called after a call to BeginExport -- Entry is not in use", ex);
throw ex;
}
}
}
/// <summary>
/// Removes a session from the dictionary
/// </summary>
/// <param name="Key">Session Key</param>
/// <param name="LockCookie">Lock Cookie</param>
/// <param name="IsExpiring">Indicates that the item is being removed because it's expiring</param>
/// <param name="ExpiryDate">The Item expiry date (for comparison)</param>
/// <param name="LockedSessionInfo">Locked session information if session is locked</param>
/// <returns>Result of Action</returns>
private SessionActionResult Remove(string Key, uint LockCookie, bool IsExpiring, DateTime ExpiryDate, out SessionResponseInfo LockedSessionInfo)
{
if (Key == null)
{
throw new ArgumentNullException("Key");
}
LockedSessionInfo = null;
bool tryAgain;
Diags.ResetDeadLockCounter();
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)
{
try
{
//The InUse flag is set and so this code section has exclusive access to this session object
AcquireWriteLock();
try
{
//Check again to be sure, now that the write-lock has been obtained
ISessionObject oldEntry = entry;
if (!dict.TryGetValue(Key, out entry))
{
//ooops -- another thread deleted the session from the dictionary while this thread
//was either trying to do the compareExchange (or if buggy, while obtaining the write-lock)
//so try again
oldEntry.CompareExchangeIsInUse(false, true); //unlock the previously locked item
tryAgain = true;
continue;
}
if (IsExpiring)
{
DateTime timeStamp;
if (expiryList.TryGetTimeStamp(Key, out timeStamp))
{
if (timeStamp != ExpiryDate)
{
//The expiration date on this session was updated, so leave
return(SessionActionResult.OK);
}
}
}
if (!IsExpiring && entry.IsLocked) //Locked items DO expire. if not expiring, LockCookie has to match session's
{
if (!entry.UnLock(LockCookie))
{
//Lockcookie did not match
LockedSessionInfo = (SessionResponseInfo)entry.CreateResponseInfo();
Diags.LogSessionIsLocked(Key);
return(SessionActionResult.Locked);
}
}
if (dict.Remove(Key))
{
expiryList.Remove(Key);
if (IsExpiring)
{
Diags.LogSessionExpired(Key);
}
else
{
Diags.LogSessionDeleted(Key);
}
}
else
{
//This should never happen
Diags.Fail("ASSERTION Failed -- Session dictionary was unable to remove key\r\n");
}
}
finally
{
ReleaseWriteLock();
}
}
finally
{
if (entry != null)
{
entry.CompareExchangeIsInUse(false, true);
}
}
}
else
{
//Is this entry being exported?
if (entry.IsExporting)
{
//This session is already been exported so leave
Diags.ResetDeadLockCounter();
return(SessionActionResult.Exporting);
}
//Another thread is using this session and will be done soon so try again
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
return(SessionActionResult.OK);
}