对Socket beginreceive的异步接收回调函数有点疑问

[ArcRain]

请问下，关于那个socket的异步接收回调，为什么当bytesRead < StateObject.BufferSize的时候，只运行一次？
分值不多，还望高手慷慨赐教，谢！


private static void ReceiveCallback( IAsyncResult ar ) {
try {
// Retrieve the state object and the client socket
// from the asynchronous state object.
StateObject state = (StateObject) ar.AsyncState;
Socket client = state.workSocket;

// Read data from the remote device.
int bytesRead = client.EndReceive(ar);

if (bytesRead > 0) {
// There might be more data, so store the data received so far.
state.sb.Append(Encoding.ASCII.GetString(state.buffer,0,bytesRead));

// Get the rest of the data. bytesRead < StateObject.BufferSize的时候这句就没运行过，然后就无法继续了，因为receiveDone.Set();无法执行
client.BeginReceive(state.buffer,0,StateObject.BufferSize,0,
new AsyncCallback(ReceiveCallback), state);
}
else {
// All the data has arrived; put it in response.
if (state.sb.Length > 1) {
response = state.sb.ToString();
}
// Signal that all bytes have been received.
receiveDone.Set();
}
} catch (Exception e) {
Console.WriteLine(e.ToString());
}
}

[love_your_eyes]

学习中~~~