Wednesday, July 29, 2009

Wife says: "I can't believe it works"

Just a teaser:

int main()
{
try
{
using asio::ip::tcp;
using namespace boost::lambda;

asio::io_service io_service;
tcp::acceptor acceptor(io_service,
tcp::endpoint(tcp::v4(), 54321));

const int max_clients = 100;
coroutine coro[max_clients];
std::auto_ptr<tcp::socket> socket[max_clients];
asio::error_code ec[max_clients];
std::size_t length[max_clients];
boost::array<char, 1024> data[max_clients];

// Kick off all the coroutines.
int n = -1;
for (int i = 0; i < max_clients; ++i)
{
socket[i].reset(new tcp::socket(io_service));
io_service.post(
unlambda((
var(n) = i
)));
}

for (; io_service.run_one() > 0; n = -1)
{
if (n != -1)
{
reenter (coro[n])
{
entry:
for (;;)
{
// Wait for a client to connect.
yield acceptor.async_accept(
*socket[n],
unlambda((
var(n) = n,
var(ec[n]) = _1
)));

// Echo at will.
while (!ec[n])
{
yield socket[n]->async_read_some(
asio::buffer(data[n]),
unlambda((
var(n) = n,
var(ec[n]) = _1,
var(length[n]) = _2
)));

if (!ec[n])
{
yield asio::async_write(
*socket[n],
asio::buffer(data[n], length[n]),
unlambda((
var(n) = n,
var(ec[n]) = _1
)));
}
}

// Clean up before accepting next client.
socket[n]->close();
}
}
}
}
}
catch (std::exception& e)
{
std::cerr << "Exception: " << e.what() << "\n";
}
}

One function. One fully asynchronous server. Bog standard C++.

4 comments:

macbirdie said...

Cute!

Thanks for boost::asio by the way!

Brendan Miller said...

yield in c++?

wait, what compiler is this using?

chris said...

Tested with: g++ 3.4.5, 4.1, 4.3 and 4.4; MSVC 8.0 and 9.0.

Obviously there's a little bit of something not shown in the snippet :)

Anonymous said...

I envy the fact that your wife understands enough about what you do to not understand how that works :~(