On 07/10/2017 01:29 PM, Nicholas Nethercote wrote:
Hi,
Firefox now has multiple Rust components, and it's on track to get a bunch
more. See https://wiki.mozilla.org/Oxidation for details.
I think this is an excellent trend, and I've been thinking about how to
accelerate it. Here's a provocative goal worth considering: "when writing a
new compiled-code component, or majorly rewriting an existing one, Rust
should be considered / preferred / mandated."
What are the obstacles? Here are some that I've heard.
- Lack of Rust expertise for both writing and reviewing code. We have some
pockets of expertise, but these need to be expanded greatly. I've heard
that there has been some Rust training in the Paris and Toronto offices.
Would training in other offices (esp. MV and SF, given their size) be a
good idea? What about remoties?
- ARM/Android is not yet a Tier-1 platform for Rust. See
https://forge.rust-lang.org/platform-support.html and
https://internals.rust-lang.org/t/arm-android-to-tier-1/5227 for some
details.
- Interop with existing components can be difficult. IPDL codegen rust
bindings could be a big help.
- Compile times are high, especially for optimized builds.
Anything else?
How is the performance when crossing Rust <-> C++ boundary? We need to make
everything faster, not slower.
If I understood emilio's explanation on IRC correctly having the performance of
an inlined (C++) function requires
handwritten rust bindings to access member variables of some C++ object.
That doesn't sound too good - hard to maintain and possibly easy to forget to
optimize.
I don't claim to understand anything about the current setup, but
has anyone written down what would be needed to have fast and easy to maintain Rust
<-> C++ boundary in
such way that also memory handling is easy to manage (aka, how to deal with
CC/GC).
I think it would be better to sort out this kind of low level issues rather
soon before we have too much
Rust code in tree, or perhaps we won't see much Rust usage before those issues
are sorted out.
(I'm looking this all from DOM point of view, where pretty much all the objects need to be cycle collectable JS holders, but perhaps Rust would fit
better in code outside DOM)
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