so is it safe to resume execution state in CompletionHandler in diffrent thread from when execution state was saved ? And what will happen if io_service completes before saving contex (look code below)?
s_.async_read_some(
boost::asio::buffer( buffer_ + pb_size, bf_size - pb_size),
boost::bind(& coro_t::operator(),& coro_, _1, _2));// Q: what will happen if handler completes here, before contex switch
ca_();