rarity 0.3.0

Library of useful functions.
Documentation 
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59

use std::sync::{Arc, Mutex};
use std::thread::Builder;

pub fn multithread<F, I, O>(tasks: Vec<I>, num_threads: Option<usize>, task_fn: F) -> Vec<O>
where
	F: Fn(usize, I) -> Option<O> + Send + Clone + 'static,
	I: Send + 'static,
	O: Send + 'static,
{
	let num_tasks = tasks.len();
	let wrapped_tasks = Arc::new(Mutex::new(tasks.into_iter().enumerate()));
	let num_threads = num_threads.unwrap_or_else(num_cpus::get);
	let mut join_handles = Vec::with_capacity(num_threads);

	for thread_num in 0..num_threads {
		let wrapped_tasks = Arc::clone(&wrapped_tasks);
		let task_fn = task_fn.clone();

		let builder = Builder::new().name(format!("pdtthread::multithread thread {thread_num}"));

		let join_handle = builder
			.spawn(move || {
				let mut results = vec![];

				loop {
					let mut unlocked_wrapped_tasks = wrapped_tasks.lock().unwrap();
					let task = unlocked_wrapped_tasks.next();

					// unlock as quickly as possible,
					// let other threads get at the data
					drop(unlocked_wrapped_tasks);

					match task {
						Some((i, task)) => {
							if let Some(res) = task_fn(thread_num, task) {
								results.push((i, res));
							}
						}
						None => break,
					}
				}

				results
			})
			.unwrap();

		join_handles.push(join_handle);
	}

	let mut thread_results = Vec::with_capacity(num_tasks);

	for thread in join_handles.into_iter() {
		let res = thread.join().unwrap();
		res.into_iter().for_each(|e| thread_results.push(e));
	}

	thread_results.sort_unstable_by_key(|e| e.0);
	thread_results.into_iter().map(|e| e.1).collect()
}