Future<std::shared_ptr<SocketImpl>> PollSocketImpl::accept()
{
// Need to hold a copy of `this` so that the underlying socket
// doesn't end up getting reused before we return from the call to
// `io::poll` and end up accepting a socket incorrectly.
auto self = shared(this);
Try<Address> address = network::address(get());
if (address.isError()) {
return Failure("Failed to get address: " + address.error());
}
int family = 0;
if (address->family() == Address::Family::INET4) {
family = AF_INET;
} else if (address->family() == Address::Family::INET6) {
family = AF_INET6;
} else {
return Failure("Unsupported address family. Windows only supports IP.");
}
Try<int_fd> accept_socket_ = net::socket(family, SOCK_STREAM, 0);
if (accept_socket_.isError()) {
return Failure(accept_socket_.error());
}
int_fd accept_socket = accept_socket_.get();
return windows::accept(self->get(), accept_socket)
.onAny([accept_socket](const Future<Nothing> future) {
if (!future.isReady()) {
os::close(accept_socket);
}
})
.then([self, accept_socket]() -> Future<std::shared_ptr<SocketImpl>> {
SOCKET listen = self->get();
// Inherit from the listening socket.
int res = ::setsockopt(
accept_socket,
SOL_SOCKET,
SO_UPDATE_ACCEPT_CONTEXT,
reinterpret_cast<char*>(&listen),
sizeof(listen));
if (res != 0) {
const WindowsError error;
os::close(accept_socket);
return Failure("Failed to set accepted socket: " + error.message);
}
// Disable Nagle algorithm, since we care about latency more than
// throughput. See https://en.wikipedia.org/wiki/Nagle%27s_algorithm
// for more info.
const int on = 1;
res = ::setsockopt(
accept_socket,
SOL_TCP,
TCP_NODELAY,
reinterpret_cast<const char*>(&on),
sizeof(on));
if (res != 0) {
const WindowsError error;
os::close(accept_socket);
return Failure(
"Failed to turn off the Nagle algorithm: " + error.message);
}
Try<Nothing> error = io::prepare_async(accept_socket);
if (error.isError()) {
os::close(accept_socket);
return Failure(
"Failed to set socket for asynchronous IO: " + error.error());
}
Try<std::shared_ptr<SocketImpl>> impl = create(accept_socket);
if (impl.isError()) {
os::close(accept_socket);
return Failure("Failed to create socket: " + impl.error());
}
return impl.get();
});
}
