boost::asio::async_resolve Problem - sockets

Question

I'm in the process of constructing a Socket class that uses boost::asio. To start with, I made a connect method that took a host and a port and resolved it to an IP address. This worked well, so I decided to look in to async_resolve. However, my callback always gets an error code of 995 (using the same destination host/port as when it worked synchronously).
code:
Function that starts the resolution:
// resolve a host asynchronously
template<typename ResolveHandler>
void resolveHost(const String& _host, Port _port, ResolveHandler _handler) const
{
boost::asio::ip::tcp::endpoint ret;
boost::asio::ip::tcp::resolver::query query(_host, boost::lexical_cast<std::string>(_port));
boost::asio::ip::tcp::resolver r(m_IOService);
r.async_resolve(query, _handler);
}; // eo resolveHost
Code that calls this function:
void Socket::connect(const String& _host, Port _port)
{
// Anon function for resolution of the host-name and asynchronous calling of the above
auto anonResolve = [this](const boost::system::error_code& _errorCode,
boost::asio::ip::tcp::resolver_iterator _epIt)
{
// raise event
onResolve.raise(SocketResolveEventArgs(*this, !_errorCode ? (*_epIt).host_name() : String(""), _errorCode));
// perform connect, calling back to anonymous function
if(!_errorCode)
connect(*_epIt);
};
// Resolve the host calling back to anonymous function
Root::instance().resolveHost(_host, _port, anonResolve);
}; // eo connect
The message() function of the error_code is:
The I/O operation has been aborted because of either a thread exit or an application request
And my main.cpp looks like this:
int _tmain(int argc, _TCHAR* argv[])
{
morse::Root root;
TextSocket s;
s.connect("somehost.com", 1234);
while(true)
{
root.performIO(); // calls io_service::run_one()
}
return 0;
}
Thanks in advance!

Answer 1

Your resolver object is going out of scope, move it to a member of the Socket class and make resolveHost a method rather than free function.
This happens because boost::asio::ip::tcp::resolver is a typedef of a basic_resolver, which inherits from basic_io_object. When the resolver goes out of scope, ~basic_io_object() destroys the underlying resolver service before your handler can be posted.
Regardless of whether the asynchronous
operation completes immediately or
not, the handler will not be invoked
from within this function. Invocation
of the handler will be performed in a
manner equivalent to using
boost::asio::io_service::post().