ractor/factory/
hash.rs

1// Copyright (c) Sean Lawlor
2//
3// This source code is licensed under both the MIT license found in the
4// LICENSE-MIT file in the root directory of this source tree.
5
6//! Factory's defaulting routing hash mechanism. Hashes a [super::JobKey] to a finite
7//! space
8
9use std::collections::hash_map::DefaultHasher;
10use std::hash::Hash;
11use std::hash::Hasher;
12
13/// Hash a key into a finite space
14pub fn hash_with_max<TKey>(key: &TKey, excluded_max: usize) -> usize
15where
16    TKey: Hash,
17{
18    let mut dh = DefaultHasher::new();
19    key.hash(&mut dh);
20    let bounded_hash = dh.finish() % (excluded_max as u64);
21    bounded_hash as usize
22}
23
24#[cfg(test)]
25mod tests {
26
27    use super::*;
28
29    #[derive(Hash)]
30    struct TestHashable(u128);
31
32    #[test]
33    fn test_bounded_hashing() {
34        let test_values = [
35            TestHashable(0),
36            TestHashable(10),
37            TestHashable(23),
38            TestHashable(128),
39            TestHashable(u64::MAX as u128),
40        ];
41
42        let test_results = [0usize, 2, 1, 0, 0];
43
44        for (test_value, test_result) in test_values.iter().zip(test_results) {
45            let hashed = hash_with_max(test_value, 3);
46            assert_eq!(test_result, hashed);
47        }
48    }
49}
ractor/factory/hash.rs

ractor/factory/
hash.rs
