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    /// Returns a random variant of the `Emulation` enum.
42    ///
43    /// This method uses a fast random number generator to select a random variant
44    /// from the `Emulation::VARIANTS` array. The random number generator is based
45    /// on the XOR-Shift algorithm, which is efficient and suitable for use in
46    /// multi-threaded environments.
47    ///
48    /// # Examples
49    ///
50    /// ```
51    /// use rquest_util::Emulation;
52    ///
53    /// let random_emulation = Emulation::random();
54    /// println!("{:?}", random_emulation);
55    /// ```
56    ///
57    /// # Panics
58    ///
59    /// This method will panic if the `Emulation::VARIANTS` array is empty.
60    #[inline]
61    pub fn random() -> Emulation {
62        let variants = Emulation::VARIANTS;
63        let index = fast_random() as usize % variants.len();
64        variants[index]
65    }
66}
67
68#[cfg(test)]
69mod tests {
70    use super::*;
71    use std::sync::{Arc, Mutex};
72    use std::thread;
73
74    #[test]
75    fn test_concurrent_get_random_emulation() {
76        const THREAD_COUNT: usize = 10;
77        const ITERATIONS: usize = 100;
78
79        let results = Arc::new(Mutex::new(Vec::new()));
80
81        let mut handles = vec![];
82
83        for _ in 0..THREAD_COUNT {
84            let results = Arc::clone(&results);
85            let handle = thread::spawn(move || {
86                for _ in 0..ITERATIONS {
87                    let emulation = Emulation::random();
88                    let mut results = results.lock().unwrap();
89                    results.push(emulation);
90                }
91            });
92            handles.push(handle);
93        }
94
95        for handle in handles {
96            handle.join().unwrap();
97        }
98
99        let results = results.lock().unwrap();
100        println!("Total results: {}", results.len());
101        for emulation in results.iter() {
102            println!("{:?}", emulation);
103        }
104    }
105}
rquest_util/emulation/rand.rs

rquest_util/emulation/
rand.rs
