public static async Task<WebSocketMessage> ReadMessageAsync(WebSocket webSocket, MemoryPool _memoryPool, int bufferSize, int? maxMessageSize, CancellationToken disconnectToken)
{
WebSocketMessage message;
// Read the first time with an empty array
// Holds hear untill first message comes through. Because its empty, it will go onto the next
// TryGetMessage when the data comes through.
var receiveResult = await webSocket.ReceiveAsync(_emptyArraySegment, disconnectToken).PreserveCultureNotContext();
if (TryGetMessage(receiveResult, null, out message))
{
return message;
}
var arraySegment = _memoryPool.AllocSegment(bufferSize);
// Now read with the real buffer
// We now know there is content, so we we allocate memory. Additionally this is setup in hopes
// that the first message we read will only take one read.
receiveResult = await webSocket.ReceiveAsync(arraySegment, disconnectToken).PreserveCultureNotContext();
if (TryGetMessage(receiveResult, arraySegment.Array, out message))
{
return message;
}
// Lastly read the rest of the message if needed
// For multi-fragment messages, we need to coalesce and use a buffer that can grow in size
// as more of the message comes in.
var bytebuffer = new ByteBuffer(maxMessageSize);
bytebuffer.Append(BufferSliceToByteArray(arraySegment.Array, receiveResult.Count));
var originalMessageType = receiveResult.MessageType;
while (true)
{
// loop until an error occurs or we see EOF
receiveResult = await webSocket.ReceiveAsync(arraySegment, disconnectToken).PreserveCultureNotContext();
if (receiveResult.MessageType == WebSocketMessageType.Close)
{
return WebSocketMessage.CloseMessage;
}
if (receiveResult.MessageType != originalMessageType)
{
throw new InvalidOperationException("Incorrect message type");
}
bytebuffer.Append(BufferSliceToByteArray(arraySegment.Array, receiveResult.Count));
if (receiveResult.EndOfMessage)
{
switch (receiveResult.MessageType)
{
case WebSocketMessageType.Binary:
return new WebSocketMessage(bytebuffer.GetByteArray(), WebSocketMessageType.Binary);
case WebSocketMessageType.Text:
return new WebSocketMessage(bytebuffer.GetString(), WebSocketMessageType.Text);
default:
throw new InvalidOperationException("Unknown message type");
}
}
}
}
