fishsoup

OK, time to make good on my promise to write about Splinter some more and show it off. The basic idea of Splinter (hinted at in my last post) is that instead of doing patch review as a completely new system and building all the infrastructure from scratch, it should be possible to do the kind of interactive patch review featured by systems like Review Board or Rietveld directly on patches attached to Bugzilla.

When you visit Splinter’s display of patch attachment, you see a standard two-column patch display like:

Any coments that people have previously made will show up inline. If you have comments to make yourself, you can double-click on a line and an editor will open where you can type the new comment:

I put up a (read-only) demo instance of Splinter where you can try this out live.

When you publish your review, it will be published as a comment in Bugzilla that looks (in part) something like:

::: js/ui/lookingGlass.js
@@ -355,3 +355,3 @@
             inspector.connect('closed', Lang.bind(this, function() {
                 this.actor.show();
-                global.stage.set_key_focus(this._entry);
+                Main.acquireKeyboardFocusStack(this._entry);

I'm not sure why we are setting the keyboard focus (either way) when the
inspector is closed, but using a stack-based acquire() seems
definitely wrong.

The idea of the format is to be readable if someone is just reading the comments in the review or in emails from Bugzilla, while still being parseable by Splinter for inline display.

A neat feature of Splinter is it uses the new DOM Storage mechanism to save in-progress reviews. You can leave the page for a review and come back to it any time and your review will be as you left it. (This requires a brand new browser, like Firefox 3.5.)

Using it yourself

Assuming that there’s interest, I’d like to make this available on bugzilla.gnome.org. The first step would be just having it there behind the scenes if you know the URL. The second step would be to write a small Bugzilla extension to link to add links to Splinter from review comments and from the attachments section.

But you don’t need to wait for this. If the above is something that you want now, then you can clone it from git://git.fishsoup.net/splinter (browse, README). In the proxy/ subdirectory, there’s a README file that describes how to run a local proxy server pointed to a Bugzilla instance. It’s really easy. Then connect to:

http://127.0.0.1:23080/index.html

in your web browser. Some aspects are a bit obscure as of yet; for example if posting a review hits “a mid-air conflict” then it will fail and you need to reload the page (safe because of the use of DOM Storage!) and try again. But it’s definitely usable.

Behind the scenes

The most interesting thing about Splinter is that the server referred to above is just a proxy server. The only reason that it is there at all is to safely get around cross-site-scripting restrictions; there’s no server side component at all. Instead, the Javascript code of Splinter uses the existing exposed web interfaces of Bugzilla (and your existing Bugzilla login credentials) to get information about the bug and post reviews back. Everything – parsing the patch files, building the display – is done in Javascript in your web browser.

One of the main reasons for doing it this way was language choice. I’m doing a lot of Javascript coding for gnome-shell, so its very much at my fingertips. And there was going to be Javascript and DOM manipulation in any case – I wanted a modern interactive interface for editing reviews. If I was going to write a server side component, I’d need to do it in Perl to integrate nicely with the Bugzilla environment, but my Perl is distinctly rusty. Everything in Javascript side-stepped that issue.

The Javascript approach also is easy for development – you don’t need a test Bugzilla instance to work on, you can just hack on the Javascript and HTML files, and use the proxy server to run your changes against a public Bugzilla instance.

The Javascript code uses JQuery extensively. It’s my second project using it, and I’m liking it a lot. In some ways, it’s really a meta-language on top of Javascript, but it gives a lot of power compactly and readably. (Readably if you don’t get too clever with it.) The source code also contains a SpiderMonkey-based test harness so that I could write tests for the non-interactive parts like parsing patches and run ‘make check’.

Future

Splinter is never going to be as nice for the single task of patch review as Review Board. But there’s quite a bit of low-hanging fruit to make it better. In addition to the small Bugzilla extension mentioned above, other things I’m thinking of include: better control of how much context is shown with a comment. A collapsed view of a review that just shows the review and the sections being commented on. A threaded display of the attachments of a bug showing their relationship to each other and the reviews on each version. The ability to add extra context around a particular section of a patch.