Yep, this post is totally not Mozilla related so I’ll keep it short, but a lot of people in Mozilla do take great photos and maybe they are stuck in my position: No actual GPS device and an compulsion to try to correctly GPS tag their vast collection. I put it off for a long while but finally this weekend wrote a Lightroom plugin to help ease a lot of the manual labour. Go check it out if you’re interested. It’s even on github!
- Sent out schedule for the Add-ons SDK work week
- Worked on job descriptions for new hires
- Assigning owners to goals
- Finalized the Add-ons SDK goals for Q1
- Add-ons SDK work week planning
- Finalized the new Toolkit module peer structure
- Working on testing the new hotfix feature
- Building test hotfix add-ons to ship out to beta users
- Post to the newsgroup about the Toolkit module peer changes
- Find owners for all the Add-ons SDK goals
- Write up the draft schedule for the Add-ons SDK work week
About three and a half years ago (I recall it happening at the 2008 summit in Whistler), Rob Strong handed ownership of the add-ons manager over to me. I had already been very involved in working on the module so I was really excited to have something to call my own and be responsible for. It’s been a great few years with many fun bugs and new features culminating with the complete redesign that we did for Firefox 4 and the third party blocking features in Firefox 8, but times have changed. I now have more responsibilities on my plate (like managing the awesome Add-ons SDK engineers) and to be honest I think it’s probably a bad idea to have such a fundamental feature of Firefox to be under the control of just one person for so long. So I’m delighted to say that Blair McBride has agreed to take over as module owner.
Blair has been integral to the add-ons manager work since Firefox 4 where he wrote all the UI parts of the redesign from scratch. Most recently he knocked it out of the park with the default to compatible feature that is in beta builds now. That was a large hairy project involving multiple teams that Blair basically ran as the lead engineer with no real help from me. Since then he’s proven to be keen on moving the add-ons manager forwards in ways that I wish I still had the time for so I’m sure that I’m leaving the module in safe hands. I still really care about the add-ons manager so I know I’ll continue to be active in reviews, bug reports and discussions (hopefully Blair won’t have to tell me to shut up too many times ) but I look forward to seeing where Blair takes things now.
I recently switched to a Windows laptop and have been going through the usual teething pains related. One thing that confused me though was that when I was running xpcshell tests on my new machine they would frequently fail with access denied errors. I’ve seen this sort of thing before so I know some service was monitoring files and opening them after they had changed, when this happens they can’t be deleted or edited until the service closes them again and often tests open, close and delete files so fast that there isn’t time for that to happen.
It took me a little while to remember that I can just use Process Monitor to track down the offending service. Just fire it up, set a filter to only include results to a particular directory (the temp directory in this case) and go create a file there and see what shows up. I was quite surprised to see Crashplan, the backup software I (and probably many people in Mozilla) use. Surprised because Crashplan isn’t set to backup my temp directory and really I shudder to think what the performance cost is of something continually accessing every file that changes in the temp directory.
Turns out you can turn it off though. Hidden in the depths of Crashplan’s advanced backup settings is an option to disable real-time filesystem watching. From what I can see online the downside to this is that files will only be backed up once a day, but that’s a pretty fine tradeoff to having functioning xpcshell tests for me. There is also an option to put crashplan to sleep for an hour or so, that seems to work too but I don’t know exactly what that does.
It confuses me a little why Crashplan monitors files it never intends to backup (even when the backup server isn’t connected and backups aren’t in progress) and it is quite a lot of file accesses it does too. Seems likely to be a bug to me but at least I can workaround it for now.
The extension I’ve been working on in my spare time for the past couple of weeks is now available as a first (hopefully not too buggy) release. It lets you open WebApps in Thunderbird, properly handling loading new links into Firefox and making all features like spellchecking work in Thunderbird (most other extensions I found didn’t do this). You can read more about the actual extension at its homepage.
Mostly I’ve been really encouraged during the development of this at just how far our platform has come for developing restartless add-ons. When we first made it possible in Firefox 4 there was a whole list of things that were quite difficult to do but we’ve come a long way since then. While there are still things that are difficult there are lots of things that are now pretty straightforward. My add-on loads simple XUL overlays, style overlays, installs JS XPCOM components with category manager registration, all similar to older add-ons. In fact I’m struggling to think of things that it is still hard to do though I’m sure other more prolific developers will have plenty of comments on that!
The other thing I’ve been doing with this extension is experimenting with git and GitHub. I think it’s been an interesting experience, there are continual arguments over which is better between git and mercurial with many pros and cons listed. I think most of these were done some time ago before mercurial and git really matured because from what I’ve seen there is really little difference between the two. They have slightly different default branching styles, but both can do the same kind of branching that the other can if you want and there are a few other minor differences but nothing that would really make me all that bothered over deciding which to use. I think the only place where git has a bonus is with GitHub, and really as far as I can see there isn’t a reason why someone couldn’t develop a similar site backed by mercurial repositories, it’s just that no-one really has.
GitHub is pretty nice with built-in basic issue tracking and documentation though it still has some frustrating issues. It seems odd for example that you can’t fork your own project, only someone else’s, but that’s only a minor niggle really. As project hosting goes I can’t say I’ve come across anything better that I can remember.
Perhaps the most common way of making changes to Firefox with an extension has always been using the overlay. For a window’s UI you can make changes to the underlying XUL document, add script elements to be executed in the context of the normal window’s code and add new stylesheets to the window to change how the UI looks.
Restartless add-ons change this around completely, the normal overlay and style-overlay mechanisms just aren’t available to restartless add-ons and this is likely to remain true for a while, these methods don’t clean up after themselves when the add-on is uninstalled.
This can make things hard, particularly for porting older add-ons to become restartless. I was in this situation earlier this weekend. I was working on porting David Ascher‘s WebTabs for Thunderbird to be restartless. I could have just moved all the script code over to bootstrap.js but in many ways it is nice to keep the code that works on the main UI separate to the code that runs for the preferences UI etc. Plus I like to play around with new ways of doing things so I developed a JS module I’m calling the
OverlayManager watches for new windows being opened and for every new window it can run JS script and apply CSS stylesheets to the window in a way that is easy to undo if the add-on is disabled at runtime. Although it can’t do any XUL modifications right now (I didn’t need any for this particular extension) it would be pretty easy to extend this to support a minimum about of XUL overlays.
Stylesheets are loaded by adding a HTML style tag to the XUL document, so they can be removed easily when the add-on is disabled. Scripts are handled in a way that may even be better than normal overlays. In the old system extension scripts all run in the same context as the window they overlay giving rise to the possibility of conflicts. Restartless add-ons shouldn’t do this since it makes removing the script code again much more troublesome. The
OverlayManager handles it by creating a sandbox to run the script in. The sandbox’s prototype is set to the window the script is being run for meaning the script sees all the functions and objects of the window directly in its own scope but as long as it doesn’t modify any of the objects in the main window’s code all we have to do is throw away the sandbox to get rid of its JS.
There are a few things different of course. The script shouldn’t use load and unload event handlers for the window as it may get loaded well after the window does or unloaded well before. Instead the
OverlayManager looks for an
OverlayListener object in the script and calls
unload methods on it, these are called either with the window’s real
unload events or while the window is open normally. You also can’t reference code in the script from JS string blocks, so if you set
onclick="myfunc()" on a XUL element it wouldn’t work because that would run in the main window scope which can’t see the sandbox code at that point. This tends to be pretty simple to get around by using
addEventListener for all your events though.
You can see the existing state of the code on github and an example of the structure you’d pass to
OverlayManager.addOverlays is in the bootstrap script for the same project. It is appropriately licensed so go nuts!
Update: I changed the stylesheets to use XML processing instructions to be more like they work currently and just for fun I implemented the very basics of document overlaying, almost totally untested though so YMMV.
- Finish the add-on hotfix work
- Various HR stuff
- Start planning Jetpack work week
- 7.0.1 Post Mortem
- Hotfix planning work
- Understanding the new mobile architecture
- Problems with third party add-ons in Firefox 8
- Default to compatible planning
- Final draft of Q4 goals
- Update module description for the Jetpack module
- Fix third-party add-on detection problems