Okay, enough about the hurricane– let’s talk shop.
Last week, I was having some problems with keyboard input and random freezes during certain interactions. A little tracing found that a global timer was being instantiated and would greedily respawn itself during a single cycle of the browser’s message loop.
Me, in my brilliance (or rather, my unwillingness to spawn a separate thread), decided to kill the global timer every time we cycled through the message loop. This solved all of the hangs but it still didn’t fix keyboard input and caused some secondary problems (like utter failure of all Javascript timers).
It was then I realized that I couldn’t implement this thing correctly without dipping my toes into the deep, dark depths of multi-threaded programming. I needed to encapsulate the core and components of Awesomium within a separate thread, run a dedicated message loop within said thread, and handle inter-thread communication and synchronization.
It took me five days of banzai, headache-inducing coding to implement but I’m proud to declare that Awesomium is multi-threaded (and stable!). It was one of the most complex tasks I’ve ever achieved as a programmer but it’s so cool seeing both of my laptop’s cores work at the same time.
Despite the multi-threading, I still wasn’t able to get keyboard input working. I finally went code diving (about 2 hours of tracing) and realized that the problem was linked with some assertions about the unicode text encoding: as I had suspected earlier, ICU wasn’t being initialized correctly. Upon inspection of the ICU initialization source, it had seemed to be attempting to load a DLL that it had assumed would be in the working directory. I located the ICU DLL, copied it to my working directory and voila– keyboard input worked and the runtime text encoding assertions disappeared. Unfortunately, this means that my previous statement about the total dependency size was incorrect: the ICU DLL is about 8 MB and the Awesomium DLL (release) is about 7 MB, so together, that’s a total dependency size of about 15 MB. It’s not too bad I suppose– people who need the absolute tiniest dependency size can always gzip the DLL’s and load them at runtime.
But hooray! Almost everything critical now works and is pretty stable. Popup-widgets (such as drop-down combo-boxes) are now supported by compositing them with the main web-view texture. Event listeners are also implemented– you can currently receive notifications for the beginnings of navigations, title receptions, and finishing of loads. Dirty-rectangle optimization and querying for ‘dirty’ render state is implemented. The only other ‘big’ point left on my to-do list is support for Javascript evaluation/callbacks. Getting that working seems to be a little more tricky than I thought and so I may put it off for later.
Oh and yes, in true ninja style, I’ve written this latest post using Awesomium.
