std.socket - problems closing socket

[Regan Heath]

On Mon, 03 Oct 2011 17:33:57 +0100, simendsjo <simendsjo at gmail.com> wrote:
> Yes. I've coded the client as follows:
> 1) start listening socket
> 2) wait for incoming connections or incoming data
> 3) receive(). If a socket returns 0 or -1, close it and process next  
> with data
> 4) read fastcgi request from server
> 5) write fastcgi response
> 6) write fastcgi EndRequest (the server should now end the request)
> 7) if the application should close the request, send shutdown(send)
> 8) accept incoming connection
> 9) back to 2)
>
> FastCGI connections works in one of two ways: the server is responsible  
> for closing the connections (supports mulitplexing) or the application  
> should close the connection after a request has been sent.
> For the latter I send SocketShutdown.SEND after writing EndRequest in  
> step 6), but it doesn't really matter as nginx doesn't support  
> multiplexing. It closes the connection after each request anyway. I see  
> the same result no matter what option I use.

Ok, so your "client" (that you have coded) is also the "application" you  
refer to in the bit about FastCGI above?  Or are there 2 components here,  
and are both written in D?

Does the fastcgi "EndRequest" close the socket/connection?  If so, doing a  
socket.Shutdown /after/ this is not going to work as the socket has  
already been closed (which implicitly does a shutdown(BOTH)).  In that  
case, try doing the shutdown /before/ the EndRequest, and make sure you  
also read any/all data remaining on the socket before doing the  
EndRequest/close.

The key question seems to be, at which point does nginx close the  
connection?  and therefore, is there any unread data on the socket (at  
either end) when it does.  If, for example, it flushes the response to the  
other end, but does not wait for it to be read, and closes the socket, you  
will get CONNRESET/ABORTED errors on the other end.

> I'm running the exact same request and writing the exact same response  
> for all queries, so there shouldn't be any unknown fields.

I didn't mean unknown "field" I mean extra data of any kind, but I suspect  
you're using an API to form the requests etc so this is probably not the  
case.

> I also only get an error on <1/5 of the requests, and even when the  
> error occurs, the response has been written completely to the browser.

Ahh, ok, I believe the problem is simply the timing of the  
'close/EndRequest'.  Sometimes it happens /before/ the data has been  
completely read (1/5), other times after (4/5).

R