Re: [Boost-users] [asio] http-server example

From: Daniel Albuschat (d.albuschat_at_[hidden])
Date: 2007-06-13 09:46:25

2007/6/13, Christopher Kohlhoff <chris_at_[hidden]>:

Thanks for your reply, Christopher!

> Daniel Albuschat wrote:
> > I experience crashes for certain types of replies.
>
> The "crash" you see is asio's buffer debug checking in action. For
> whatever reason, it thinks one of the strings referred to in a buffer is
> no longer valid.

I'm pretty sure it actually *is* invalid.

> What is different about those "certain types of replies"?

I could not trace that down. I've rewritten that part to be synchronous, so
I do not have the lifetime-problem.
There's a reply::to_string() function now:

std::string reply::to_string() const
{
   std::stringstream ss;
   ss << status_strings::to_string(status);
   for (std::size_t i = 0; i < headers.size(); ++i)
   {
      const header& h = headers[i];
      ss << h.name << misc_strings::name_value_separator << h.value <<
misc_strings::crlf;
   }
   ss << misc_strings::crlf;
   ss << content;
   return ss.str();
}

And I've changed the write-part of connection::handle_read as follows:

         request_handler_.handle_request(request_, reply_);
         std::string s = reply_.to_string();
         boost::asio::write(socket_,boost::asio::buffer(s.data(),s.size()));
         connection_manager_.stop(shared_from_this());

It's not the optimal solution, but it's safe.

> > IMHO the whole content needs to be COPIED to new buffers and then,
> > after the async_write finished, deleted.
> >
> > Am I missing something? Was the author of this example not aware of
> > the const_buffer's ownership policy (i.e. it is *not* owner of the
> > data)?
>
> I pretty sure I was aware ;) However that's not to say there are no bugs
> in the HTTP server or buffer debug checking.

As the reply is local to the connection, this should indeed work.
I don't know where the problem lies exactly, probably it is a bug introduced
by me at a different code-location.

The server runs stable now, and I'll leave it at that.

Since you seem to be the auther of the example:
BIG THANKS to you, it really saved me MUCH time and I have a very very
neat solution to connect my PHP script with the program-logic/database now.

Regards,
   Daniel Albuschat

-- 
eat(this); // delicious suicide