1[/ 2 / Copyright (c) 2003-2021 Christopher M. Kohlhoff (chris at kohlhoff dot com) 3 / 4 / Distributed under the Boost Software License, Version 1.0. (See accompanying 5 / file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt) 6 /] 7 8[section:synchronous_socket_operations Requirements on synchronous socket operations] 9 10In this section, ['synchronous socket operations] are those member functions 11specified as two overloads, with and without an argument of type `error_code&`: 12 13 ``[*['R f]]``(``['[*A1]]`` a1, ``['[*A2]]`` a2, ..., ``['[*AN]]`` aN); 14 ``[*['R f]]``(``['[*A1]]`` a1, ``['[*A2]]`` a2, ..., ``['[*AN]]`` aN, error_code& ec); 15 16For an object `s`, the conditions under which its synchronous socket operations 17may block the calling thread (C++Std [defns.block]) are determined as follows. 18 19If: 20 21[mdash] `s.non_blocking() == true`, 22 23[mdash] the synchronous socket operation is specified in terms of a __POSIX__ 24function other than `__poll__`, 25 26[mdash] that __POSIX__ function lists `EWOULDBLOCK` or `EAGAIN` 27in its failure conditions, and 28 29[mdash] the effects of the operation cannot be established immediately 30 31then the synchronous socket operation shall not block the calling thread. 32[inline_note And the effects of the operation are not established.] 33 34Otherwise, the synchronous socket operation shall block the calling thread 35until the effects are established. 36 37[endsect] 38