Re: Adaptor modification - WOResponse streaming failure detection

Hi,

Ben Scarola wrote:
> Can someone validate my findings on this? The stock WO Apache adaptor 
> does not detect a broken pipe on the client side while streaming a 
> response. This means that the WOResponse will always read its entire 
> source InputStream and in turn dump all the content to the adaptor, 
> even if the pipe from Apache to the client is broken.


Interesting! Did you report this problem to Apple 
(https://bugreport.apple.com/)?

Maybe it would be nice to add this patch the Wonder 
(http://wonder.sourceforge.net/) enhanced HTTP adaptors as well?


> I've traced this behavior to a loop inside SendResponse() in 
> mod_WebObjects.c (line 465) and added the lines below (indicated with 
> ---->). By inspecting Apache's "conn_rec" you can detect an aborted 
> connection and break out of the loop. This cause the WOResponse to 
> immediately stop reading data from its InputStream, and also cause a 
> broken pipe in the WOWorkerThread.
>
> Now when WOResponse calls InputStream.close(), read() will return >= 0 
> if the InputStream was not fully processed, allowing the application 
> to detect a failed transmission. Does anyone see adverse side effects 
> of this modification? If a client disconnects from Apache is there any 
> chance that the pipe can be re-established?? Is there a reason for WO 
> to keep dumping data on the adaptor?
>
>    if ( (!r->header_only) && (resp->content_valid) ) {
>       while (resp->content_read < resp->content_length)
>       {
>          ap_soft_timeout("sending WebObjects response", r);
>          ap_rwrite(resp->content, resp->content_valid, r);
>          ap_kill_timeout(r);
> ---->	if (r->connection->aborted) {
> ---->		break;
> ---->	}
>     	 resp_getResponseContent(resp, 1);
>       }
>       ap_soft_timeout("sending WebObjects response", r);
>       ap_rwrite(resp->content, resp->content_valid, r);
>       ap_kill_timeout(r);
>    }


Kind regards,

--
Francis Labrie
Saint-Bruno-de-Montarville, Québec, Canada