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feat(tvix/eval): Forbid Hash{Map,Set}, use Fx instead

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Per https://nnethercote.github.io/perf-book/hashing.html, we have
basically no reason to use the default hasher over a faster,
non-DoS-resistant hasher. This gives a nice perf boost basically for
free:

hello outpath           time:   [704.76 ms 714.91 ms 725.63 ms]
                        change: [-7.2391% -6.1018% -4.9189%] (p = 0.00 < 0.05)
                        Performance has improved.

Change-Id: If5587f444ed3af69f8af4eead6af3ea303b4ae68
Reviewed-on: https://cl.tvl.fyi/c/depot/+/12046
Tested-by: BuildkiteCI
Reviewed-by: flokli <flokli@flokli.de>
Reviewed-by: Ilan Joselevich <personal@ilanjoselevich.com>
Autosubmit: aspen <root@gws.fyi>
This commit is contained in:
Aspen Smith 2024-07-28 12:11:41 -04:00 • committed by clbot
parent 1d7ba89c19
commit b8f92a6d53
17 changed files with 116 additions and 46 deletions
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4
tvix/eval/src/value/thunk.rs
View file

@ -18,9 +18,9 @@
//! object, but when forcing a thunk, the runtime *must* mutate the
//! memoisable slot.
use rustc_hash::FxHashSet;
use std::{
cell::{Ref, RefCell, RefMut},
collections::HashSet,
fmt::Debug,
rc::Rc,
};
@ -413,7 +413,7 @@ impl TotalDisplay for Thunk {
/// The inner `HashSet` is not available on the outside, as it would be
/// potentially unsafe to interact with the pointers in the set.
#[derive(Default)]
pub struct ThunkSet(HashSet<*const ThunkRepr>);
pub struct ThunkSet(FxHashSet<*const ThunkRepr>);
impl ThunkSet {
/// Check whether the given thunk has already been seen. Will mark the thunk