* Find roots when running GC
Attempt to address the issue #2773.
The existing implementation had an expensive overhead of managing root
counts, especially for mutable borrow of GcRefCell.
Instead of managing the root counts, this change counts the number of
Gc/WeakGc handles located in Gc heap objects and total number of them.
Then, we can find whether there is a root by comparing those numbers.
* Fix clippy errors
* Keep reference counts in Box
* Addressing comment
* Fix clippy errors
* Fix typo
* non_root_count includes mark bit
* give a space
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.
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.
Kevin
Choongwoo Han
José Julián Espina
raskad
Kevin