Difference between Recv/send blocking and non-blocking in socket

==> Recv/sendAll parameters are specifiedLength

==>
Blocking typeSend:Copy to the sending buffer. If the buffer zone is full, wait until data of the specified length is sent to the buffer zone.

==>
Non-blockingSend:Keep copying. If the buffer is full, return immediately without waiting.

==>
Blocking typeRecv:Until data of the specified length is received.

==>
Non-blockingRecv:Return immediately, no matter whether there is data in the buffer or whether the data is enough to specify the length, return immediately