What can cause throughput to become really slow when an ISAPI filter implements SF_NOTIFY_SEND_RAW_D

Posted by Gerald on Stack Overflow See other posts from Stack Overflow or by Gerald
Published on 2009-11-17T06:58:25Z Indexed on 2010/04/13 5:02 UTC
Read the original article Hit count: 520

Filed under:

c++

|

isapi

I have an ISAPI filter for IIS6 that I've been developing for a while, but I just noticed something disturbing. Anytime I have the filter installed and I download a file, the file download becomes really slow. From a remote machine I'm getting ~120kb per second without the filter installed, and ~45kb per second with the filter installed.

This seems to be related to the SF_NOTIFY_SEND_RAW_DATA callback. Whenever I register for this callback, I get the slow downloads, when I don't register for it, everything is fine.

Even if I make my HttpFilterProc function just return immediately, like this:

DWORD WINAPI HttpFilterProc( PHTTP_FILTER_CONTEXT pfc, 
   DWORD notificationType,
   LPVOID pvNotification )
{   
    return SF_STATUS_REQ_NEXT_NOTIFICATION;
}

I've also tried returning SF_STATUS_REQ_HANDLED_NOTIFICATION with the same result.

Is it possible that I have some build setting on my DLL that is causing a slow execution of the callback function, or is this just the way it's going to be with ISAPI?

© Stack Overflow or respective owner

Related posts about c++

Which C++ book shold I get between "C++ Primer" vs "C++ Primer Plus"

as seen on Stack Overflow - Search for 'Stack Overflow'
I want to learn C++ by using Vim and MinGW as compiler. I'm interesting at "C++ Primer (4th Edition)" and "C++ Primer Plus (5th Edition)" but I don't know how about it different. It has no book store that I can review those books, so I want to know, what is the different between those book and which… >>> More
C++ : C++ Primer (Stanley Lipmann) or The C++ programming language (special edition)

as seen on Stack Overflow - Search for 'Stack Overflow'
I have a Computer Science degree (long2 time ago) .. I do know Java OOP but i am now trying to pick up C++. I do have C and of course data structure using C or pascal. I have started reading Bjarne Stroustrup book (The C++ Programming Language - Special Edition) but find it extremely difficult esp… >>> More
I need help on my C++ assignment using MS Visual C++

as seen on Stack Overflow - Search for 'Stack Overflow'
Ok, so I don't want you to do my homework for me, but I'm a little lost with this final assignment and need all the help I can get. Learning about programming is tough enough, but doing it online is next to impossible for me... Now, to get to the program, I am going to paste what I have so far. This… >>> More
Managed c++ std::string not accessible in unmanaged c++

as seen on Stack Overflow - Search for 'Stack Overflow'
In unmanaged c++ dll i have a function which takes constant std::string as argument Prototype : void read ( const std::string &imageSpec_ ) I call this function from managed c++ dll by passing a std::string. When i debug the unmanaged c++ code the parameter imageSpec_ shows the value correctly… >>> More
The Definitive C++ Book Guide and List

as seen on Stack Overflow - Search for 'Stack Overflow'
After more than a few questions about deciding on C++ books I thought we could make a better community wiki version. Providing QUALITY books and an approximate skill level. Maybe we can add a short blurb/description about each book that you have personally read / benefited from. Feel free to debate… >>> More

Related posts about isapi

Fake ISAPI Handler to serve static files with extention that are rewritted by url rewriter

as seen on Developer IT - Search for 'Developer IT'
Introduction I often map html extention to the asp.net dll in order to use url rewritter with .html extentions. Recently, in the new version of www.nouvelair.ca, we renamed all urls to end with .html. This works great, but failed when we used FCK Editor. Static html files would not get serve because… >>> More
Helicon ISAPI Rewrite Proxy 500 Internal Server Error

as seen on Server Fault - Search for 'Server Fault'
Hi, I have a website running at www.domain.com. The client now wants the website to appear to be running under www.otherdomain.com/whatson/brand/ Since the website is umbraco it won't run under a subfolder. I wanted to use ISAPI rewrite to proxy requests to www.domain.com using the following rule… >>> More
How to enable .NET Extensibility, ASP.NET, ISAPI Extensions, and ISAPI Filters on Windows Small Buis

as seen on Stack Overflow - Search for 'Stack Overflow'
Today wanting to deploy an asp.net mvc application I had to enable .NET Extensibility, ASP.NET, ISAPI Extensions, and ISAPI Filters on Win Small Buisness Server 2008 I was surprised 1h and I could not find how to do it. This was the hint but ... still nothing. http://blogs.dovetailsoftware.com/blogs/kmiller/archive/2008/10/07/deploying-an-asp-net-mvc-web-application-to-iis7… >>> More
Setting custom header values in an IIS ISAPI filter

as seen on Stack Overflow - Search for 'Stack Overflow'
I have an ISAPI filter that I am using to do URL rewriting for my CMS. I am processing SF_NOTIFY_PREPROC_HEADERS notifications, and trying to do this: DWORD ProcessHeader(HTTP_FILTER_CONTEXT *con, HTTP_FILTER_PREPROC_HEADERS *head) { head->SetHeader(con, "test1", "aaa"); con->AddResponseHeaders(con… >>> More
Faulting DLL (ISAPI Filter)...

as seen on Stack Overflow - Search for 'Stack Overflow'
I wrote this ISAPI filter to rewrite the URL because we had some sites that moved locations... Basically the filter looks at the referrer, and if it's the local server, it looks at the requested URL and compared it to the full referrer. If the first path is identical, nothing is done, however if… >>> More