This PR changes the following:
- Modifies `EphemeronBox` to be more akin to `GcBox`, with its own header, roots and markers. This also makes it more similar to [Racket's](https://docs.racket-lang.org/reference/ephemerons.html) implementation.
- Removes `EPHEMERON_QUEUE`.
- Ephemerons are now tracked on a special `weak_start` linked list, instead of `strong_start` which is where all other GC boxes live.
- Documents all unsafe blocks.
- Documents our current garbage collection algorithm. I hope this'll clarify a bit what exactly are we doing on every garbage collection.
- Renames/removes some functions.
This PR is a complete redesign of our current native functions and closures API.
I was a bit dissatisfied with our previous design (even though I created it 😆), because it had a lot of superfluous traits, a forced usage of `Gc<GcCell<T>>` and an overly restrictive `NativeObject` bound. This redesign, on the other hand, simplifies a lot our public API, with a simple `NativeCallable` struct that has several constructors for each type of required native function.
This new design doesn't require wrapping every capture type with `Gc<GcCell<T>>`, relaxes the trait requirement to `Trace + 'static` for captures, can be reused in both `JsObject` functions and (soonish) host defined functions, and is (in my opinion) a bit cleaner than the previous iteration. It also offers an `unsafe` API as an escape hatch for users that want to pass non-Copy closures which don't capture traceable types.
Would ask for bikeshedding about the names though, because I don't know if `NativeCallable` is the most precise name for this. Same about the constructor names; I added the `from` prefix to all of them because it's the "standard" practice, but seeing the API doesn't have any other method aside from `call`, it may be better to just remove the prefix altogether.
Let me know what you think :)
Per the [Standard Library development guide](https://std-dev-guide.rust-lang.org/code-considerations/performance/inline.html):
> You can add `#[inline]`:
>
> - To public, small, non-generic functions.
>
> You shouldn't need `#[inline]`:
> - On methods that have any generics in scope.
> - On methods on traits that don't have a default implementation.
>
> `#[inline]` can always be introduced later, so if you're in doubt they can just be removed.
This PR follows this guideline to reduce the number of `#[inline]` annotations in our code, removing the annotation in:
- Non-public functions
- Generic functions
- Medium and big functions.
Hopefully this shouldn't impact our perf at all, but let's wait to see the benchmark results.
This Pull Request restructures the lint deny/warn/allow lists in almost all crates. `boa_engine` will be done in a follow up PR as the changes there are pretty extensive.
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Not sure if anyone else may be working on something more substantial/in-depth, but I thought I'd post this. 😄
The basic rundown is that this is more of an untested (and in some ways naïve) draft than anything else. It builds rather heavily on `rust-gc`, and tries to keep plenty of the core aspects so as to not break anything too much, and also to minimize overarching changes were it to actually be merged at some point.
This implementation does add ~~a generational divide (although a little unoptimized) to the heap,~~ a GcAlloc/Collector struct with methods, and an ephemeron implementation that allows for the WeakPair and WeakGc pointers.
José Julián Espina
raskad
Kevin