// the thread function
// (static to reduce state for maximum reliability)
static void ThreadFunction(TcpClient client, string ip, int port, SafeQueue <Message> messageQueue)
{
// absolutely must wrap with try/catch, otherwise thread
// exceptions are silent
try
{
// connect (blocking)
// (NoDelay disables nagle algorithm. lowers CPU% and latency)
client.NoDelay = true;
client.Connect(ip, port);
// run the receive loop
ReceiveLoop(0, client, messageQueue);
}
catch (SocketException exception)
{
// this happens if (for example) the ip address is correct
// but there is no server running on that ip/port
Logger.Log("Client: failed to connect to ip=" + ip + " port=" + port + " reason=" + exception);
// add 'Disconnected' event to message queue so that the caller
// knows that the Connect failed. otherwise they will never know
messageQueue.Enqueue(new Message(0, EventType.Disconnected, null, 0));
}
catch (Exception exception)
{
// something went wrong. probably important.
Logger.LogError("Client Exception: " + exception);
}
// if we got here then we are done. ReceiveLoop cleans up already,
// but we may never get there if connect fails. so let's clean up
// here too.
client.Close();
}
protected static void SendLoop(int connectionId, TcpClient client, SafeQueue <byte[]> sendQueue,
ManualResetEvent sendPending)
{
NetworkStream stream = client.GetStream();
try
{
while (client.Connected)
{
sendPending.Reset();
byte[][] messages;
if (sendQueue.TryDequeueAll(out messages))
{
if (!SendMessagesBlocking(stream, messages))
{
return;
}
}
sendPending.WaitOne();
}
}
catch (ThreadAbortException) { }
catch (ThreadInterruptedException) { }
catch (Exception exception)
{
Logger.Log("SendLoop Exception: connectionId=" + connectionId + " reason: " + exception);
}
}
// thread send function
// note: we really do need one per connection, so that if one connection
// blocks, the rest will still continue to get sends
protected static void SendLoop(int connectionId, TcpClient client, SafeQueue <byte[]> sendQueue, ManualResetEvent sendPending)
{
// get NetworkStream from client
NetworkStream stream = client.GetStream();
try
{
// (Yurgis) while (client.Connected) // try this. client will get closed eventually.
while (true)
{
// reset ManualResetEvent before we do anything else. this
// way there is no race condition. if Send() is called again
// while in here then it will be properly detected next time
// -> otherwise Send might be called right after dequeue but
// before .Reset, which would completely ignore it until
// the next Send call.
sendPending.Reset(); // WaitOne() blocks until .Set() again
// dequeue all
// SafeQueue.TryDequeueAll is twice as fast as
// ConcurrentQueue, see SafeQueue.cs!
byte[][] messages;
if (sendQueue.TryDequeueAll(out messages))
{
// send message (blocking) or stop if stream is closed
if (!SendMessagesBlocking(stream, messages))
{
// (Yurgis)
if (stream.CanWrite == false)
{
Logger.LogWarning("SendLoop(): EXIT because....");
return;
}
}
}
// don't choke up the CPU: wait until queue not empty anymore
sendPending.WaitOne();
}
}
catch (ThreadAbortException)
{
// happens on stop. don't log anything.
Logger.LogWarning($"SendLoop() Conn #{connectionId}: ThreadAbortException");
}
catch (ThreadInterruptedException)
{
// happens if receive thread interrupts send thread.
Logger.LogWarning($"SendLoop() Conn #{connectionId}: ThreadInterruptedException");
}
catch (Exception exception)
{
// something went wrong. the thread was interrupted or the
// connection closed or we closed our own connection or ...
// -> either way we should stop gracefully
Logger.Log("SendLoop Exception: connectionId=" + connectionId + " reason: " + exception);
}
}
// thread send function
// note: we really do need one per connection, so that if one connection
// blocks, the rest will still continue to get sends
protected static void SendLoop(int connectionId, TcpClient client, SafeQueue <byte[]> sendQueue, ManualResetEvent sendPending)
{
// get NetworkStream from client
NetworkStream stream = client.GetStream();
try {
// try this. client will get closed eventually.
while (client.Connected)
{
// reset ManualResetEvent before we do anything else. this
// way there is no race condition. if Send() is called again
// while in here then it will be properly detected next time
// -> otherwise Send might be called right after dequeue but
// before .Reset, which would completely ignore it until
// the next Send call.
// WaitOne() blocks until .Set() again
sendPending.Reset();
// dequeue all
// SafeQueue.TryDequeueAll is twice as fast as
// ConcurrentQueue, see SafeQueue.cs!
byte[][] messages;
if (sendQueue.TryDequeueAll(out messages))
{
// send message (blocking) or stop if stream is closed
if (!SendMessagesBlocking(stream, messages))
{
// break instead of return so stream close still happens!
break;
}
}
// don't choke up the CPU: wait until queue not empty anymore
sendPending.WaitOne();
}
} catch (ThreadAbortException) {
// happens on stop. don't log anything.
} catch (ThreadInterruptedException) {
// happens if receive thread interrupts send thread.
} catch (Exception exception) {
// something went wrong. the thread was interrupted or the
// connection closed or we closed our own connection or ...
// -> either way we should stop gracefully
Logger.Log("SendLoop Exception: connectionId=" + connectionId + " reason: " + exception);
} finally {
// clean up no matter what
// we might get SocketExceptions when sending if the 'host has
// failed to respond' - in which case we should close the connection
// which causes the ReceiveLoop to end and fire the Disconnected
// message. otherwise the connection would stay alive forever even
// though we can't send anymore.
stream.Close();
client.Close();
}
}
// the thread function
void ReceiveThreadFunction(string ip, int port)
{
// absolutely must wrap with try/catch, otherwise thread
// exceptions are silent
try
{
// connect (blocking)
client.Connect(ip, port);
_Connecting = false;
// create send queue for this client
SafeQueue <byte[]> sendQueue = new SafeQueue <byte[]>();
sendQueues.Add(0, sendQueue);
// start send thread only after connected
sendThread = new Thread(() => { SendLoop(0, client, sendQueue); });
sendThread.IsBackground = true;
sendThread.Start();
// run the receive loop
ReceiveLoop(0, client, receiveQueue);
}
catch (SocketException exception)
{
// this happens if (for example) the ip address is correct
// but there is no server running on that ip/port
Logger.Log("Client Recv: failed to connect to ip=" + ip + " port=" + port + " reason=" + exception);
// add 'Disconnected' event to message queue so that the caller
// knows that the Connect failed. otherwise they will never know
receiveQueue.Enqueue(new Message(0, EventType.Disconnected, null));
}
catch (Exception exception)
{
// something went wrong. probably important.
Logger.LogError("Client Recv Exception: " + exception);
}
// try interrupting send thread after receive thread
// ends, just to be sure
if (sendThread != null)
{
sendThread.Interrupt();
}
// Connect might have failed. thread might have been closed.
// let's reset connecting state no matter what.
_Connecting = false;
// if we got here then we are done. ReceiveLoop cleans up already,
// but we may never get there if connect fails. so let's clean up
// here too.
client.Close();
}
// thread send function
// note: we really do need one per connection, so that if one connection
// blocks, the rest will still continue to get sends
protected static void SendLoop(int connectionId, TcpClient client, SafeQueue <byte[]> sendQueue)
{
// get NetworkStream from client
NetworkStream stream = client.GetStream();
try
{
while (client.Connected) // try this. client will get closed eventually.
{
// dequeue all
byte[][] messages;
if (sendQueue.TryDequeueAll(out messages))
{
// send message (blocking) or stop if stream is closed
if (!SendMessagesBlocking(stream, messages))
{
return;
}
}
// don't choke up the CPU: wait until queue not empty anymore
sendQueue.notEmpty.WaitOne();
}
}
catch (ThreadAbortException)
{
// happens on stop. don't log anything.
}
catch (Exception exception)
{
// something went wrong. the thread was interrupted or the
// connection closed or we closed our own connection or ...
// -> either way we should stop gracefully
Logger.Log("SendLoop Exception: connectionId=" + connectionId + " reason: " + exception);
}
}
// thread receive function is the same for client and server's clients
// (static to reduce state for maximum reliability)
protected static void ReceiveLoop(int connectionId, TcpClient client, SafeQueue <Message> messageQueue)
{
// get NetworkStream from client
NetworkStream stream = client.GetStream();
// keep track of last message queue warning
DateTime messageQueueLastWarning = DateTime.Now;
// absolutely must wrap with try/catch, otherwise thread exceptions
// are silent
try
{
// add connected event to queue with ip address as data in case
// it's needed
messageQueue.Enqueue(new Message(connectionId, EventType.Connected, null, 0));
// let's talk about reading data.
// -> normally we would read as much as possible and then
// extract as many <size,content>,<size,content> messages
// as we received this time. this is really complicated
// and expensive to do though
// -> instead we use a trick:
// Read(2) -> size
// Read(size) -> content
// repeat
// Read is blocking, but it doesn't matter since the
// best thing to do until the full message arrives,
// is to wait.
// => this is the most elegant AND fast solution.
// + no resizing
// + no extra allocations, just one for the content
// + no crazy extraction logic
while (true)
{
byte[] content = ByteArrayPool.Take();
// read the next message (blocking) or stop if stream closed
if (!ReadMessageBlocking(stream, content, out int size))
{
break;
}
// queue it
messageQueue.Enqueue(new Message(connectionId, EventType.Data, content, size));
// it is now up to the developer to Dispose the message to return the
// buffer to the pool.
// and show a warning if the queue gets too big
// -> we don't want to show a warning every single time,
// because then a lot of processing power gets wasted on
// logging, which will make the queue pile up even more.
// -> instead we show it every 10s, so that the system can
// use most it's processing power to hopefully process it.
if (messageQueue.Count > MessageQueueSizeWarning)
{
TimeSpan elapsed = DateTime.Now - messageQueueLastWarning;
if (elapsed.TotalSeconds > 10)
{
Logger.LogWarning("ReceiveLoop: messageQueue is getting big(" + messageQueue.Count + "), try calling GetNextMessage more often. You can call it more than once per frame!");
messageQueueLastWarning = DateTime.Now;
}
}
}
}
catch (Exception exception)
{
// something went wrong. the thread was interrupted or the
// connection closed or we closed our own connection or ...
// -> either way we should stop gracefully
Logger.Log("ReceiveLoop: finished receive function for connectionId=" + connectionId + " reason: " + exception);
}
// if we got here then either the client while loop ended, or an
// exception happened. disconnect
messageQueue.Enqueue(new Message(connectionId, EventType.Disconnected, null, 0));
// clean up no matter what
stream.Close();
client.Close();
}
// the listener thread's listen function
// note: no maxConnections parameter. high level API should handle that.
// (Transport can't send a 'too full' message anyway)
void Listen(int port)
{
// absolutely must wrap with try/catch, otherwise thread
// exceptions are silent
try
{
// start listener
listener = new TcpListener(new IPEndPoint(IPAddress.Any, port));
listener.Server.NoDelay = NoDelay;
listener.Server.SendTimeout = SendTimeout;
listener.Start();
Logger.Log("Server: listening port=" + port);
// keep accepting new clients
while (true)
{
// wait and accept new client
// note: 'using' sucks here because it will try to
// dispose after thread was started but we still need it
// in the thread
TcpClient client = listener.AcceptTcpClient();
// generate the next connection id (thread safely)
int connectionId = NextConnectionId();
// spawn a send thread for each client
Thread sendThread = new Thread(() =>
{
// wrap in try-catch, otherwise Thread exceptions
// are silent
try
{
// create send queue immediately
SafeQueue <byte[]> sendQueue = new SafeQueue <byte[]>();
sendQueues[connectionId] = sendQueue;
// run the send loop
SendLoop(connectionId, client, sendQueue);
// remove queue from queues afterwards
sendQueues.TryRemove(connectionId, out SafeQueue <byte[]> _);
}
catch (ThreadAbortException)
{
// happens on stop. don't log anything.
// (we catch it in SendLoop too, but it still gets
// through to here when aborting. don't show an
// error.)
}
catch (Exception exception)
{
Logger.LogError("Server send thread exception: " + exception);
}
});
sendThread.IsBackground = true;
sendThread.Start();
// spawn a receive thread for each client
Thread receiveThread = new Thread(() =>
{
// wrap in try-catch, otherwise Thread exceptions
// are silent
try
{
// add to dict immediately
clients[connectionId] = client;
// run the receive loop
ReceiveLoop(connectionId, client, receiveQueue);
// remove client from clients dict afterwards
clients.TryRemove(connectionId, out TcpClient _);
}
catch (Exception exception)
{
Logger.LogError("Server client thread exception: " + exception);
}
});
receiveThread.IsBackground = true;
receiveThread.Start();
}
}
catch (ThreadAbortException exception)
{
// UnityEditor causes AbortException if thread is still
// running when we press Play again next time. that's okay.
Logger.Log("Server thread aborted. That's okay. " + exception);
}
catch (SocketException exception)
{
// calling StopServer will interrupt this thread with a
// 'SocketException: interrupted'. that's okay.
Logger.Log("Server Thread stopped. That's okay. " + exception);
}
catch (Exception exception)
{
// something went wrong. probably important.
Logger.LogError("Server Exception: " + exception);
}
}