/// <summary>
/// Sends data via the socket asynchronously
/// </summary>
/// <param name="Message">Data to transmit</param>
public void Send(ResponseData Message)
{
IBuffer sendBuffer = null;
//TODO: ENHANCEMENT: Log consecutive bad request response types and use that information to disconnect socket after 3
try
{
lock (syncSocket)
{
if (sentMsgs.Count > 1)
{
sentMsgs.Dequeue();
}
sentMsgs.Enqueue(Message);
//Log error if .Data is null -- this will help raise a flag if the message is being resent after .ClearData was called
Diags.Assert(Message.Data != null, "ASSERTION FAILED: Message Data is null", new System.Diagnostics.StackTrace().ToString());
sendBuffer = bufferPool.GetBuffer(Message.Data.LongLength);
sendBuffer.CopyFrom(Message.Data);
socket.BeginSend(sendBuffer.GetSegments(), SocketFlags.None, CompleteSend, sendBuffer);
Message.ClearData(); //free some memory
}
}
catch (Exception ex)
{
Diags.LogSocketException(ex);
if (sendBuffer != null)
{
sendBuffer.Dispose();
sendBuffer = null;
}
}
}
/// <summary>
/// Completes an asynchronous send
/// </summary>
/// <param name="ar">AsyncResul obtained from BeginSend</param>
private void CompleteSend(IAsyncResult ar)
{
// Complete asynchronous send
IBuffer sendBuffer = (IBuffer)ar.AsyncState;
try
{
if (!socket.Connected)
{
return;
}
lock (syncSocket)
{
socket.EndSend(ar);
}
sendBuffer.Dispose();
sendBuffer = null;
}
catch (Exception ex)
{
Diags.LogSocketException(ex);
if (sendBuffer != null)
{
sendBuffer.Dispose();
sendBuffer = null;
}
}
}
/// <summary>
/// Closes the socket gracefully
/// </summary>
public void Close()
{
//TODO: ENHANCEMENT: Seems like the graceful shutdown process in this method is not working well
//Is it because of the 1 ms timeout?
//I see a lot more stale Peer connections than stale web server connections, so it looks like
//Thw web server connections are closing better than the peer connections. Investigate this.
try
{
lock (syncSocket)
{
if (socket.Connected)
{
socket.Shutdown(SocketShutdown.Both);
}
isClosing = true;
socket.Close(1);
}
if (recvBuffer != null)
{
recvBuffer.Dispose();
}
}
catch (Exception ex)
{
Diags.LogSocketException(ex);
}
}
/// <summary>
/// Begins an asynchronous receive
/// </summary>
/// <param name="Buffer">Buffer to store received data</param>
/// <param name="ReadCallBack">Method to call on receiving data</param>
/// <param name="StateObject">State object to be passed to ReadCallBack</param>
/// <returns>AsyncResult for the asynchronous operation</returns>
public IAsyncResult BeginReceive(int BufferLength, AsyncCallback ReadCallBack, object StateObject)
{
try
{
if (recvBuffer == null || recvBuffer.IsDisposed)
{
recvBuffer = bufferPool.GetBuffer(BufferLength);
}
else if (recvBuffer.Size < BufferLength)
{
recvBuffer.Dispose();
recvBuffer = bufferPool.GetBuffer(BufferLength);
}
lock (syncSocket)
{
return(socket.BeginReceive(recvBuffer.GetSegments(), SocketFlags.None, ReadCallBack, StateObject));
}
}
catch (Exception ex)
{
Diags.LogSocketException(ex);
return(null);
}
}
/// <summary>
/// Ends an asynchronous Receive
/// </summary>
/// <param name="ar">AsyncResult obtained from BeginReive</param>
/// <param name="Error">Indicates an error occured while receiving data</param>
/// <returns>Received Data</returns>
public byte[] EndReceive(IAsyncResult ar, out bool Error)
{
Error = false;
int bytesRead = 0;
try
{
lock (syncSocket)
{
bytesRead = socket.EndReceive(ar);
}
}
catch (ObjectDisposedException ex)
{
if (!isClosing)
{
Diags.LogSocketException(ex);
}
Error = true;
}
catch (Exception ex)
{
Diags.LogSocketException(ex);
Error = true;
}
byte[] readData;
if (Error || bytesRead < 0)
{
readData = new byte[0];
}
else
{
readData = new byte[bytesRead];
}
if (recvBuffer != null && !recvBuffer.IsDisposed)
{
if (!Error && bytesRead > 0)
{
recvBuffer.CopyTo(readData, 0, bytesRead);
}
//Dispose buffer if it's greater than a specified threshold
if (recvBuffer.Size > BufferRenewalSizeThreshold)
{
recvBuffer.Dispose();
}
}
return(readData);
}
/// <summary>
/// Ends an asynchronous Connect
/// </summary>
/// <param name="ar">AsyncResult obtained from BeginConnect</param>
public void EndConnect(IAsyncResult ar)
{
try
{
lock (syncSocket)
{
isOutbound = true;
socket.EndConnect(ar);
}
}
catch (Exception ex)
{
Diags.LogSocketException(ex);
}
}
/// <summary>
/// Begins an asynchronous Connect
/// </summary>
/// <param name="Host">Host to connect to</param>
/// <param name="Port">Port number to connect to</param>
/// <param name="ConnectCallBack">Callback to call on connecting</param>
/// <param name="StateObject">State object to pass to ConnectCallback</param>
/// <returns>AsyncResult for the asynchronous operation</returns>
public IAsyncResult BeginConnect(string Host, int Port, AsyncCallback ConnectCallBack, object StateObject)
{
try
{
lock (syncSocket)
{
return(socket.BeginConnect(Host, Port, ConnectCallBack, StateObject));
}
}
catch (Exception ex)
{
Diags.LogSocketException(ex);
return(null);
}
}
/// <summary>
/// Listens on a specified port on the machine
/// </summary>
/// <param name="Port">Port number</param>
/// <param name="AcceptCallback">Callback for accepting new connections</param>
/// <returns>.NET Socket if successful, Null if not</returns>
public static Socket Listen(int Port, AsyncCallback AcceptCallback)
{
Socket listener;
// Start Listening on Web Server Socket
IPEndPoint wsEndPoint = new IPEndPoint(IPAddress.Any, Port);
listener = new Socket(AddressFamily.InterNetwork, SocketType.Stream, ProtocolType.Tcp);
try
{
listener.Bind(wsEndPoint);
listener.Listen(MaxConnections);
listener.BeginAccept(AcceptCallback, listener);
}
catch (Exception ex)
{
Diags.LogSocketException(ex);
return(null);
}
return(listener);
}
/// <summary>
/// Terminates a connection
/// </summary>
public void Abort()
{
try
{
lock (syncSocket)
{
if (socket.Connected)
{
socket.Shutdown(SocketShutdown.Send);
}
isClosing = true;
socket.Close();
}
if (recvBuffer != null)
{
recvBuffer.Dispose();
}
}
catch (Exception ex)
{
Diags.LogSocketException(ex);
}
}
/// <summary>
/// Updates or inserts a session in the dictionary
/// </summary>
/// <param name="Key">Session Key</param>
/// <param name="Session">Session object</param>
/// <param name="InsertOnly">Indicates that session should only be inserted if it does not already exist</param>
/// <param name="UpdateIfNotFound">Indicates whether session should be updated if the session was not found. If set to flase, this gives the caller a chance to query the network before trying again </param>
/// <param name="LockedSessionInfo">Locked session information if session is locked</param>
/// <returns>Result of Action</returns>
private SessionActionResult UpSert(string Key, ISessionObject Session, bool InsertOnly, bool UpdateIfNotFound, out SessionResponseInfo LockedSessionInfo)
{
// Look for the session using a reader lock.
// If session is not found, switch to a writer lock and insert item.
// If session is found:
// Perform an atomic compare exchange on the variable 'InUse'
// If session is in Use, try Upsert again from the start.
// If session is not in Use, Perform UpSert and reset InUse
// Also update Sorted session list
if (Key == null)
{
throw new ArgumentNullException("Key");
}
if (Session == null)
{
throw new ArgumentNullException("Session");
}
LockedSessionInfo = null;
bool tryAgain;
Diags.ResetDeadLockCounter();
do
{
tryAgain = false;
AcquireReadLock();
ISessionObject entry;
try
{
dict.TryGetValue(Key, out entry);
}
finally
{
ReleaseReadLock();
}
if (entry == null)
{
if (!UpdateIfNotFound)
{
return(SessionActionResult.NotFound);
}
//Session not found -- insert brand new session object
AcquireWriteLock();
try
{
//Check again to be sure now that the write-lock has been obtained
dict.TryGetValue(Key, out entry);
if (entry != null)
{
//ooops -- another thread inserted a seesion with this key while this thread was trying to obtain the write-lock
//so try again
tryAgain = true;
continue;
}
Session.LockCookie = 1; //For some reason Lockcookie starts counting from 2 -- so set it to 1 now so that it increments to 2 when sought
dict[Key] = Session;
expiryList.Add(DateTime.UtcNow.Add(new TimeSpan(0, Session.TimeOut, 0)), Key, Key);
Diags.LogNewSession(Key, Session);
}
finally
{
ReleaseWriteLock();
}
}
else
{
//Session Found
if (InsertOnly)
{
Diags.LogSessionAlreadyExists(Key);
return(SessionActionResult.AlreadyExists); //Do not perform an update if InsertOnly is requested
}
//There is no need to acquire a write lock here since the dictionary is not been modified.
//Only the dictionary entry itself is been updated and such updates are guaranteed to be atomic
//if the atomic InUse property is set.
if (entry.CompareExchangeIsInUse(true, false) == false)
{
//the InUse flag is set, so this code section has exclusive access to this session object
try
{
if (entry.IsLocked)
{
if (!entry.UnLock(Session.LockCookie))
{
//Lockcookie did not match
LockedSessionInfo = (SessionResponseInfo)entry.CreateResponseInfo();
Diags.LogSessionIsLocked(Key);
return(SessionActionResult.Locked);
}
}
Session.LockCookie = entry.LockCookie; //Overwrite the incoming session's lock-cookie with the internal one's so as not to let external input change the lockcookie
Session.ExtraFlags = -1; //disable extra flags since an update is being performed
entry.CopyFrom(Session); //Copy all information from Session to entry
expiryList.Add(DateTime.UtcNow.Add(new TimeSpan(0, Session.TimeOut, 0)), Key, Key); //reset expiry timeout
Diags.LogUpdatedSession(Key, Session);
}
finally
{
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);
}
/// <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>
/// 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);
}
}
/// <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);
}
