[Sugar-devel] MANIFEST experiments

[Bert Freudenberg]

On 14.10.2009, at 13:44, Daniel Drake wrote:

> Today I ran a quick experiment on OLPC OS v8.2.1, based on the
> question: what are the activity MANIFEST files used for?
>
> I see sugar frequently complaining about MANIFEST inconsistencies in
> the logs, but I don't recall seeing it act on these inconsistencies in
> any way. I noticed that it even logs such inconsistencies during
> startup, meaning that it must be checking every file in every activity
> during a regular boot...
>
> So, I reflashed 2 XOs, booted for the first time, entered a name. On
> one, I modified sugar.bundle.ActivityBundle.read_manifest() to be a
> no-op, then turned it off. On the other, I just turned it off.
>
> Then I powered both on at the same time and started a stopwatch. I
> measured how long it takes for the XOs to reach the stage of boot
> where the XO stick figure and the activity icons are visible.
>
> The one with the modification reached this point *55* seconds faster
> than the other one! It basically zeroes the time where you can see the
> XO stick figure on screen but the activity icons on the home view have
> yet to appear.
>
> This was using OLE Nepal's customized build which includes a big
> activity with many manifest errors, so the difference might be less
> elsewhere.
>
> Tomeu points out that this behaviour has been improved in more recent
> sugar versions to the point where manifest checking probably is not
> happening in the startup path, but personally I question why we are
> even checking at all. Perhaps we should rip out all that code and
> leave MANIFESTs purely as a tool for developers to specify which files
> get included in a bundle or something like that.

I did indeed think that's the entire purpose of it.

- Bert -