// start listening for new connections in a background thread and spawn
// a new thread for each one.
public bool Start(int port)
{
// not if already started
if (Active)
{
return(false);
}
// create receive pipe with max message size for pooling
// => create new pipes every time!
// if an old receive thread is still finishing up, it might still
// be using the old pipes. we don't want to risk any old data for
// our new start here.
receivePipe = new MagnificentReceivePipe(MaxMessageSize);
// start the listener thread
// (on low priority. if main thread is too busy then there is not
// much value in accepting even more clients)
Log.Info("Server: Start port=" + port);
listenerThread = new Thread(() => { Listen(port); });
listenerThread.IsBackground = true;
listenerThread.Priority = ThreadPriority.BelowNormal;
listenerThread.Start();
return(true);
}
public ConnectionState(TcpClient client, int MaxMessageSize)
{
this.client = client;
// create send pipe with max message size for pooling
receivePipe = new MagnificentReceivePipe(MaxMessageSize);
sendPipe = new MagnificentSendPipe(MaxMessageSize);
}
// thread receive function is the same for client and server's clients
public static void ReceiveLoop(int connectionId, TcpClient client, int MaxMessageSize, MagnificentReceivePipe receivePipe, int queueLimit)
{
// get NetworkStream from client
NetworkStream stream = client.GetStream();
// every receive loop needs it's own receive buffer of
// HeaderSize + MaxMessageSize
// to avoid runtime allocations.
//
// IMPORTANT: DO NOT make this a member, otherwise every connection
// on the server would use the same buffer simulatenously
byte[] receiveBuffer = new byte[4 + MaxMessageSize];
// avoid header[4] allocations
//
// IMPORTANT: DO NOT make this a member, otherwise every connection
// on the server would use the same buffer simulatenously
byte[] headerBuffer = new byte[4];
// absolutely must wrap with try/catch, otherwise thread exceptions
// are silent
try
{
// set connected event in pipe
receivePipe.SetConnected();
// 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)
{
// read the next message (blocking) or stop if stream closed
if (!ReadMessageBlocking(stream, MaxMessageSize, headerBuffer, receiveBuffer, out int size))
{
// break instead of return so stream close still happens!
break;
}
// create arraysegment for the read message
ArraySegment <byte> message = new ArraySegment <byte>(receiveBuffer, 0, size);
// send to main thread via pipe
// -> it'll copy the message internally so we can reuse the
// receive buffer for next read!
receivePipe.Enqueue(message);
// disconnect if receive pipe gets too big.
// -> avoids ever growing queue memory if network is slower
// than input
// -> disconnecting is great for load balancing. better to
// disconnect one connection than risking every
// connection / the whole server
if (receivePipe.Count >= queueLimit)
{
// log the reason
Log.Warning($"receivePipe reached limit of {queueLimit}. This can happen if network messages come in way faster than we manage to process them. Disconnecting this connection for load balancing.");
// clear queue so the final disconnect message will be
// processed immediately. no need to process thousands
// of pending messages before disconnecting.
// it would just delay it for quite some time.
receivePipe.Clear();
// just break. the finally{} will close everything.
break;
}
}
}
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
Log.Info("ReceiveLoop: finished receive function for connectionId=" + connectionId + " reason: " + exception);
}
finally
{
// clean up no matter what
stream.Close();
client.Close();
// set 'Disconnected' event in pipe after disconnecting properly
// -> always AFTER closing the streams to avoid a race condition
// where Disconnected -> Reconnect wouldn't work because
// Connected is still true for a short moment before the stream
// would be closed.
receivePipe.SetDisconnected();
}
}
// constructor always creates new TcpClient for client connection!
public ClientConnectionState(int MaxMessageSize) : base(new TcpClient(), MaxMessageSize)
{
// create receive pipe with max message size for pooling
receivePipe = new MagnificentReceivePipe(MaxMessageSize);
}
public int Tick(int processLimit, Func <bool> checkEnabled = null)
{
int remaining = 0;
// for each connection
// checks enabled in case a Mirror scene message arrived
foreach (KeyValuePair <int, ConnectionState> kvp in clients)
{
MagnificentReceivePipe receivePipe = kvp.Value.receivePipe;
// need a processLimit copy just for this connection so that
// we can count the Connected message as a processed one.
// => otherwise decreasing the limit in Connected event would
// decrease the limit for everyone!
int connectionProcessLimit = processLimit;
// always process connect FIRST before anything else
if (connectionProcessLimit > 0)
{
if (receivePipe.CheckConnected())
{
OnConnected?.Invoke(kvp.Key);
// it counts as a processed message
--connectionProcessLimit;
}
}
// process up to 'processLimit' messages for this connection
// checks enabled in case a Mirror scene message arrived
for (int i = 0; i < connectionProcessLimit; ++i)
{
// check enabled in case a Mirror scene message arrived
if (checkEnabled != null && !checkEnabled())
{
break;
}
// peek first. allows us to process the first queued entry while
// still keeping the pooled byte[] alive by not removing anything.
if (receivePipe.TryPeek(out ArraySegment <byte> message))
{
OnData?.Invoke(kvp.Key, message);
// IMPORTANT: now dequeue and return it to pool AFTER we are
// done processing the event.
receivePipe.TryDequeue();
}
// AFTER PROCESSING, add remaining ones to our counter
remaining += receivePipe.Count;
}
// always process disconnect AFTER anything else
// (should never process data messages after disconnect message)
if (connectionProcessLimit > 0)
{
if (receivePipe.CheckDisconnected())
{
OnDisconnected?.Invoke(kvp.Key);
connectionsToRemove.Add(kvp.Key);
}
}
}
// remove all disconnected connections now that we processed the
// final disconnect message.
foreach (int connectionId in connectionsToRemove)
{
clients.TryRemove(connectionId, out ConnectionState _);
}
connectionsToRemove.Clear();
return(remaining);
}
