binius_maybe_rayon/
lib.rs

1// Copyright 2025 Irreducible Inc.
2// The code is initially based on `maybe-rayon` crate, https://github.com/shssoichiro/maybe-rayon
3
4//! This crate provides a subset of the `rayon` API to allow conditional
5//! compilation without `rayon`.
6//! This is useful for profiling single-threaded code, as it simplifies call stacks significantly.
7//! The initial code was taken from the `maybe-rayon` crate, but many changes were made to
8//! support the usage of `ParallelIterator` and `IndexedParallelIterator` methods, which have different
9//! signatures from `std::iter::Iterator`. Some of these changes may be potentially backward-incompatible,
10//! and given the absence of tests in the original crate, it is very unlikely that it is possible to
11//! commit the changes back to the original crate.
12
13cfg_if::cfg_if! {
14	if #[cfg(any(not(feature = "rayon"), all(target_arch="wasm32", not(target_feature = "atomics"))))] {
15		use std::marker::PhantomData;
16
17		pub mod iter;
18		pub mod slice;
19
20		pub mod prelude {
21			pub use super::{iter::*, slice::*};
22		}
23
24		#[derive(Default)]
25		pub struct ThreadPoolBuilder();
26		impl ThreadPoolBuilder {
27			#[inline(always)]
28			pub const fn new() -> Self {
29				Self()
30			}
31
32			#[inline(always)]
33			pub const fn build(self) -> Result<ThreadPool, ::core::convert::Infallible> {
34				Ok(ThreadPool())
35			}
36
37			#[inline(always)]
38			pub const fn num_threads(self, _num_threads: usize) -> Self {
39				Self()
40			}
41		}
42
43		#[derive(Debug)]
44		pub struct ThreadPool();
45		impl ThreadPool {
46			#[inline(always)]
47			pub fn install<OP, R>(&self, op: OP) -> R
48			where
49				OP: FnOnce() -> R + Send,
50				R: Send,
51			{
52				op()
53			}
54		}
55
56		#[derive(Debug, Default)]
57		pub struct ThreadPoolBuildError;
58		impl std::fmt::Display for ThreadPoolBuildError {
59			fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
60				write!(f, "ThreadPoolBuildError")
61			}
62		}
63		impl std::error::Error for ThreadPoolBuildError {
64			fn description(&self) -> &str {
65				"Error building thread pool"
66			}
67		}
68
69		#[inline(always)]
70		pub const fn current_num_threads() -> usize {
71			1
72		}
73
74		#[inline(always)]
75		pub fn join<A, B, RA, RB>(oper_a: A, oper_b: B) -> (RA, RB)
76		where
77			A: FnOnce() -> RA + Send,
78			B: FnOnce() -> RB + Send,
79			RA: Send,
80			RB: Send,
81		{
82			(oper_a(), oper_b())
83		}
84
85		pub struct Scope<'scope> {
86			#[allow(clippy::type_complexity)]
87			marker: PhantomData<Box<dyn FnOnce(&Scope<'scope>) + Send + Sync + 'scope>>,
88		}
89
90		impl<'scope> Scope<'scope> {
91			#[inline(always)]
92			pub fn spawn<BODY>(&self, body: BODY)
93			where
94				BODY: FnOnce(&Self) + Send + 'scope,
95			{
96				body(self)
97			}
98		}
99
100		#[inline(always)]
101		pub fn scope<'scope, OP, R>(op: OP) -> R
102		where
103			OP: for<'s> FnOnce(&'s Scope<'scope>) -> R + 'scope + Send,
104			R: Send,
105		{
106			op(&Scope {
107				marker: PhantomData,
108			})
109		}
110	} else {
111		pub use rayon::*;
112	}
113}
binius_maybe_rayon/lib.rs

binius_maybe_rayon/
lib.rs
