Fairly large update before release 4.1, cleaning up docs and some minor additions.

1 files changed, 82 insertions, 0 deletions

diff --git a/misc/benchmarks/various/rust_hashmap.rs b/misc/benchmarks/various/rust_hashmap.rs
new file mode 100644
index 00000000..5394a7c3
--- /dev/null
+++ b/misc/benchmarks/various/rust_hashmap.rs
@@ -0,0 +1,82 @@
+use std::{
+    hash::{BuildHasherDefault, Hasher},
+    io::Read,
+    time::Instant,
+};
+
+struct MyHasher {
+    seed: u64,
+}
+
+impl Default for MyHasher {
+    fn default() -> Self {
+        Self { seed: 0xb5ad4eceda1ce2a9_u64 }
+    }
+}
+
+impl Hasher for MyHasher {
+    fn write(&mut self, bytes: &[u8]) {
+        use std::convert::TryInto;
+        self.seed = u64::from_ne_bytes(bytes.try_into().unwrap()).wrapping_mul(0xc6a4a7935bd1e99d);
+    }
+
+    #[inline]
+    fn write_u64(&mut self, i: u64) {
+        self.seed = i.wrapping_mul(0xc6a4a7935bd1e99d);
+    }
+
+    #[inline]
+    fn finish(&self) -> u64 {
+        self.seed
+    }
+}
+
+type MyBuildHasher = BuildHasherDefault<MyHasher>;
+
+fn romu_trio(s: &mut [u64]) -> u64 {
+    let xp = s[0];
+    let yp = s[1];
+    let zp = s[2];
+    s[0] = 15241094284759029579_u64.wrapping_mul(zp);
+    s[1] = yp.wrapping_sub(xp);
+    s[1] = s[1].rotate_left(12);
+    s[2] = zp.wrapping_sub(yp);
+    s[2] = s[2].rotate_left(44);
+    return xp;
+}
+
+fn main() {
+    let n = 50_000_000;
+    let mask = (1 << 25) - 1;
+
+    let mut m = std::collections::HashMap::<u64, u64, MyBuildHasher>::default();
+    m.reserve(n);
+
+    let mut rng: [u64; 3] = [1872361123, 123879177, 87739234];
+    println!("Rust HashMap  n = {}, mask = {:#x}", n, mask);
+    let now = Instant::now();
+    for _i in 0..n {
+        let key: u64 = romu_trio(&mut rng) & mask;
+        *m.entry(key).or_insert(0) += 1;
+    }
+    println!("insert  : {}ms  \tsize : {}", now.elapsed().as_millis(), m.len());
+    let now = Instant::now();
+    let mut sum = 0;
+    for i in 0..mask + 1 { if m.contains_key(&i) { sum += 1; }}
+    println!("lookup  : {}ms  \tsum  : {}", now.elapsed().as_millis(), sum);
+
+    let now = Instant::now();
+    let mut sum = 0;
+    for (_, value) in &m { sum += value; }
+    println!("iterate : {}ms  \tsum  : {}", now.elapsed().as_millis(), sum);
+
+    let mut rng: [u64; 3] = [1872361123, 123879177, 87739234];
+    let now = Instant::now();
+    for _ in 0..n {
+        let key: u64 = romu_trio(&mut rng) & mask;
+        m.remove(&key);
+    }
+    println!("remove  : {}ms  \tsize : {}", now.elapsed().as_millis(), m.len());
+    println!("press a key:");
+    std::io::stdin().bytes().next();
+}
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