Currently VarCache prefs are setup in two parts:
- The vanilla pref part, installed via a data file such as all.js, or via an
API call.
- The VarCache variable part, setup by an Add*VarCache() call.
Both parts are needed for the pref to actually operate as a proper VarCache
pref. (There are various prefs for which we do one but not the other unless a
certain condition is met.)
This patch introduces a new way of doing things. There is a new file,
modules/libpref/init/StaticPrefList.h, which defines prefs like this:
> VARCACHE_PREF(
> "layout.accessiblecaret.width",
> layout_accessiblecaret_width,
> float, 34.0
> )
This replaces both the existing parts.
The preprocessor is used to generate multiple things from this single
definition:
- A global variable (the VarCache itself).
- A getter for that global variable.
- A call to an init function that unconditionally installs the pref in the
prefs hash table at startup.
C++ files can include the new StaticPrefs.h file to access the getter.
Rust code cannot use the getter, but can access the global variable directly
via structs.rs. This is similar to how things currently work for Rust code.
Non-VarCache prefs can also be declared in StaticPrefList.h, using PREF instead
of the VARCACHE_PREF.
The new approach has the following advantages.
+ It eliminates the duplication (in all.js and the Add*VarCache() call) of the
pref name and default value, preventing potential mismatches. (This is a real
problem in practice!)
+ There is now a single initialization point for these VarCache prefs.
+ This avoids need to find a place to insert the Add*VarCache() calls, which
are currently spread all over the place.
+ It also eliminates the common pattern whereby these calls are wrapped in a
execute-once block protected by a static boolean (see bug 1346224).
+ It's no longer possible to have a VarCache pref for which only one of the
pieces has been setup.
+ It encapsulates the VarCache global variable, so there is no need to declare
it separately.
+ VarCache reads are done via a getter (e.g. StaticPrefs::foo_bar_baz())
instead of a raw global variable read.
+ This makes it clearer that you're reading a pref value, and easier to
search for uses.
+ This prevents accidental writes to the global variable.
+ This prevents accidental mistyping of the pref name.
+ This provides a single chokepoint in the code for such accesses, which make
adding checking and instrumentation feasible.
+ It subsumes MediaPrefs, and will allow that class to be removed. (gfxPrefs is
a harder lift, unfortunately.)
+ Once all VarCache prefs are migrated to the new approach, the VarCache
mechanism will be better encapsulated, with fewer details publicly visible.
+ (Future work) This will allow the pref names to be stored statically, saving
memory in every process.
The main downside of the new approach is that all of these prefs are in a
single header that is included in quite a few places, so any changes to this
header will cause a fair amount of recompilation.
Another minor downside is that all VarCache prefs are defined and visible from
start-up. For test-only prefs like network.predictor.doing-tests, having them
show in about:config isn't particularly useful.
The patch also moves three network VarCache prefs to the new mechanism as a
basic demonstration. (And note the inconsistencies in the multiple initial
values that were provided for
network.auth.subresource-img-cross-origin-http-auth-allow!) There will be
numerous follow-up bugs to convert the remaining VarCache prefs.
MozReview-Commit-ID: 9ABNpOR16uW
* * *
[mq]: fixup
MozReview-Commit-ID: 6ToT9dQjIAq
- The first two SYNTAX HINTS are wrong, and citing the syntax is more useful
than specifying a single example of what isn't allowed.
- The sentence about #ifdefs is wrong. (#ifdefs appear all throughout, and
prefs are only specified once.)
- I chose a better example file.
MozReview-Commit-ID: JyYFyutqrFD
Previously we had disabled them in content pages on Nightly and Early Beta,
now we're ready to let this ride the trains in 61.
We're going to land this ahead of Bug 1446470 which is specifically about
url-prefix().
MozReview-Commit-ID: AGDHt1snyjU
For confirming to UI Events spec, we should dispatch "keydown" event and
"keyup" event even during in composition.
This patch makes only Nightly and early Beta start to dispatch those events
during a composition.
MozReview-Commit-ID: 8md7NtSdurJ
This pref was introduced in case we encountered compatibility issues from
changing the return value of Animation.playState (bug 1412765). Now that the
change to Animation.playState has shipped to release channel without any known
problems we should drop this pref.
MozReview-Commit-ID: CwMWRRtIf6u
The compartment-per-addon code was added so that we could segregate at least
some of the code from system-privileged add-ons into tagged compartments, even
when it ran in browser windows. That allowed us to apply certain special
behavior to them, such as enabling e10s shims, and to track some performance
characteristics.
The only remaining chrome-privileged add-ons now are system add-ons controlled
by us, and the shim system and per-compartment performance metrics are gone,
it no longer serves a purpose.
MozReview-Commit-ID: Ap186bWAaqP
We no longer support legacy extensions with e10s shims, and the only remaining
uses that matter are in-tree test harnesses, which have been fixed. This flag
no longer serves a purpose.
MozReview-Commit-ID: EdCNqF4MttN
uim is an old IM which uses key snooper to listen to key events rather than
via filter key event API which should be called by applications. It's still
used by Debian 9.x, so, we still need to support this.
Unfortunately, we cannot detect if uim actually uses key snooper because it's
switch by build option of uim. Currently, Debian builds uim as using key
snooper. So, we should assume uim uses key snooper always. On the other
hand, somebody *might* use uim built as not using key snooper, so, let's
decide if uim uses key snooper with new pref,
"intl.ime.hack.uim.using_key_snooper", but its default should be true.
Note that ibus and Fcitx also have the mode to use key snooper (perhaps for
backward compatibility with uim). However, it's not enabled in default
settings and even if it's enabled, Firefox is in whitelist in the default
settings of them for stop using key snooper. Therefore, we don't need to
support key snooper mode for them unless we'll get some requests to
support their key snooping mode.
MozReview-Commit-ID: 6fTsfKrHzvo
- gfxVRExternal Enables other processes to present
real or simulated VR hardware to Firefox.
- This functionality is disabled by default, under
dom.vr.external.enabled.
- VRDisplayInfo, VRControllerInfo, and associated
structs have been restructured to ensure internal
state is not exposed via shmem interface.
- Some refactoring to convert structs to
POD types, enabling them to be located
in shmem and be memcpy'd.
- Work needed before unpreffing marked
with "TODO" comments.
MozReview-Commit-ID: FbsusbxuoQ8
