How to use dynamic struct reference within multithread process in Rust?

Question

I am trying to simulate and transform data with multithreading, while leaving to user what kind of transformation to use, as long as it implements my Transformation trait.

I understand broadly why complier doesn't like to use raw Transformation in .map() method, but I wanted to know the best way to approach this problem in Rust.

I am using rayon here but any other suggestion will be also appreciated.

use rayon::prelude::*;

pub trait Transformation {
    fn result(&self, input: &f64) -> f64; 
}
pub struct Division { 
    pub by: f64 
}
impl Transformation for Division {
    fn result(&self, input: &f64) -> f64 {
        input / self.by
    }
}

fn simulate_and_transform(paths_num: &usize, trans: &dyn Transformation) -> Vec<f64> {
    (0..*paths_num)
        .into_par_iter()
        .map(|_| trans.result(&rand::random::<f64>()))
        .collect()
}

fn main() {
    let div = Division {by: 2.0};
    let paths = 100;
    let sims = simulate_and_transform(&paths, &div);
    println!("Samples: {}, {}, {}", sims[3], sims[56], sims[99]);
}

score 0 · Accepted Answer · answered Oct 08 '22 at 22:31

There is only a simple problem here: you haven't required that the Transformation is safe to use from multiple threads. That is expressed using the Sync trait. You can either require it for all implementors of the trait:

pub trait Transformation: Sync {

or you can require it when it's used:

fn simulate_and_transform(paths_num: &usize, trans: &(dyn Transformation + Sync)) -> Vec<f64> {

Either of these changes will allow your program to compile.

How to use dynamic struct reference within multithread process in Rust?

1 Answers1