Read from socket: Is it guaranteed to at least get x bytes?

Question

I have a rare bug that seems to occur reading a socket.

It seems, that during reading of data sometimes I get only 1-3 bytes of a data package that is bigger than th

Answer 1

Use recv_into(...) method from the socket module.

Robert S. Barnes written the example in C.

But you can use Python 2.x with standard python-libraries:

def readReliably(s,n):
    buf = bytearray(n)
    view = memoryview(buf)
    sz = s.recv_into(view,n)
    return sz,buf

while True:
  sk,skfrom = s.accept()
  sz,buf = io.readReliably(sk,4)
  a = struct.unpack("4B",buf)
  print repr(a)
  ...

Notice, that sz returned by readReliably() function may be greater than n.