Ted's Mozilla Blog

Some time ago, Lukas Blakk implemented support for a source server on our Windows builds as a class project in Dave Humphrey‘s class at Seneca College. Of course, soon after that we switched our main VCS from CVS to Mercurial, which broke all of her hard work. Thankfully, we got another one of Dave’s students, Jesse Valianes, to fix things to make it work with Mercurial. We landed his patch, but as it turns out we never enabled a setting on our build machines to make it actually work. However, when we finally tried to do so, I found out that another patch we had landed in the interim had broken things. I finally landed a fix for that, and we flipped it back on, and so today’s trunk build is source-enabled again.

If you have no idea what any of this means, it means you can download a Windows nightly build, attach a debugger, have it download the debug symbols automatically from our symbol server, and the debugger will download the matching source for you automatically.

I hope to get this backported to our 1.9.2 and 1.9.1 branches ASAP, so that our 3.5.x and 3.6 release builds will be similarly debuggable.

Some time ago, we set up a symbol server for our Windows builds. This was sort of an afterthought, it just happened to be really easy to do in our new crash reporting architecture. It turns out that this is incredibly useful for people. This shouldn’t be surprising, given how difficult it is to build your own Firefox. Some time after we set this up, I found out that Microsoft’s debuggers also supported something called a source server (Note: this page did not contain this much information when this project started). This sounded interesting, but it wasn’t something I had time to work on, so I added some information to Seneca’s wiki, hoping an interested student would pick it up as a class project.

To say that I got more than I hoped for would be an understatement. Lukas Blakk took the project and ran with it, producing a working prototype and fleshing it out to the point where it now works perfectly on current nightly builds. She’s done an incredible job working with a practically undocumented feature of Microsoft’s debugging tools and having the perseverance to stick it out. As a result, you can now debug nightly Windows builds with full source available. We’ve got a handy MDC document available to tell you how. You’ll need a nightly from today (April 15th) or newer, and this will be available in the Firefox 3.0 release builds. Happy debugging!