rquest_util/emulation/
rand.rs

1use super::Emulation;
2use std::cell::Cell;
3use std::collections::hash_map::RandomState;
4use std::hash::{BuildHasher, Hasher};
5use std::num::Wrapping;
6use strum::VariantArray;
7
8// from: https://github.com/seanmonstar/reqwest/blob/44ac897f1ab35ba24a195927043d185d5cbb6912/src/util.rs#L27
9fn fast_random() -> u64 {
10    thread_local! {
11        static RNG: Cell<Wrapping<u64>> = Cell::new(Wrapping(seed()));
12    }
13
14    #[inline]
15    fn seed() -> u64 {
16        let seed = RandomState::new();
17
18        let mut out = 0;
19        let mut cnt = 0;
20        while out == 0 {
21            cnt += 1;
22            let mut hasher = seed.build_hasher();
23            hasher.write_usize(cnt);
24            out = hasher.finish();
25        }
26        out
27    }
28
29    RNG.with(|rng| {
30        let mut n = rng.get();
31        debug_assert_ne!(n.0, 0);
32        n ^= n >> 12;
33        n ^= n << 25;
34        n ^= n >> 27;
35        rng.set(n);
36        n.0.wrapping_mul(0x2545_f491_4f6c_dd1d)
37    })
38}
39
40impl Emulation {
41    #[inline]
42    pub fn random() -> Emulation {
43        let variants = Emulation::VARIANTS;
44        let index = fast_random() as usize % variants.len();
45        variants[index]
46    }
47}
48
49#[cfg(test)]
50mod tests {
51    use super::*;
52    use std::sync::{Arc, Mutex};
53    use std::thread;
54
55    #[test]
56    fn test_concurrent_get_random_emulation() {
57        const THREAD_COUNT: usize = 10;
58        const ITERATIONS: usize = 100;
59
60        let results = Arc::new(Mutex::new(Vec::new()));
61
62        let mut handles = vec![];
63
64        for _ in 0..THREAD_COUNT {
65            let results = Arc::clone(&results);
66            let handle = thread::spawn(move || {
67                for _ in 0..ITERATIONS {
68                    let emulation = Emulation::random();
69                    let mut results = results.lock().unwrap();
70                    results.push(emulation);
71                }
72            });
73            handles.push(handle);
74        }
75
76        for handle in handles {
77            handle.join().unwrap();
78        }
79
80        let results = results.lock().unwrap();
81        println!("Total results: {}", results.len());
82        for emulation in results.iter() {
83            println!("{:?}", emulation);
84        }
85    }
86}
rquest_util/emulation/rand.rs

rquest_util/emulation/
rand.rs
