The patch did not improve performance. I'd like to think that the increased
control over when inline scripts are executed makes the patch worthwhile
regardless, but that is post hoc justification and possibly a bit of personal
ego. Krinkle agrees that we may use some of the ideas in this patch in the
future but he thinks we're better off not heading down this path before we
have a better sense of where we're going, and I trust his judgment.
This reverts commit e86e5f8460.
Change-Id: I151f74a41dd664b5a0aa5cfd99fcc95e2686a1e6
The current ordering of scripts and stylesheets in <head> causes all major
browsers to serialize and defer requests that could be performed in parallel.
The problem is that external stylesheets are loaded before inline scripts. As
Steven Souders explains, "all major browsers preserve the order of CSS and
JavaScript. The stylesheet has to be fully downloaded, parsed, and applied
before the inline script is executed. And the inline script must be executed
before the remaining resources can be downloaded. Therefore, resources that
follow a stylesheet and inline script are blocked from downloading."[1]
In other words: the browser could start loading body images, but it refuses to
do that until it has executed inline scripts in head. And it refuses to execute
those scripts until the external CSS is downloaded, parsed and applied. You can
see the effect of this in this image, showing the request waterfall for
[[en:Gothic Alphabet]]: [2]. Notice how no images were requested before the
browser had finished processing the three load.php requests at the top.
To fix this, we want to move the inline scripts above the external CSS. This is
a little bit tricky, because the inline scripts depend on mw.loader, which is
loaded via an external script. If we move the external script so that it too is
above the external stylesheet, we force the browser to serialize requests,
because the browser will not retrieve the external CSS until it has retrieved
and executed the external JS code. So what we want is to move the inline
scripts above the external stylesheet, but keep the external script (which the
inline scripts depend on) below the external stylesheet.
We can do this by wrapping the inline script code in a closure (which binds
'mw') and enqueuing the closure in a global array which will be processed by
the startup module at just the right time.
Net result: external CSS and JS is retrieved in parallel, retrieval of images
(and other external assets) is unblocked, but the order in which code is
evaluated remains the same.
[1]: <http://www.stevesouders.com/blog/2009/05/06/positioning-inline-scripts/>
[2]: <http://people.wikimedia.org/~ori/enwiki-waterfall.png> (excerpted from
<http://www.webpagetest.org/result/150316_0C_7MB/1/details/>.
Change-Id: I98d383a6299ffbd10210431544a505338ca8643f
These functions actually does not return anything, so the @return is
wrong here. '@return void' is ignored.
Change-Id: I11495ee05b943c16c1c4715d617c8b50de22276c
Strings like "5.6.99-hhvm" are not version numbers but merely
a way for HHVM to pass version checks. They should not be
displayed in the UI.
This affects Special:Version, the API (action=query&meta=siteinfo),
the installer welcome page, and the debug toolbar.
Follows-up d09ab9001f.
Change-Id: Ia99dca64779e9c4eaddf5f0e0101674d029b8d55
