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+// This benchmark suite contains some benchmarks along a set of dimensions:
+// Hasher: std default (SipHash) and crate default (AHash).
+// Int key distribution: low bit heavy, top bit heavy, and random.
+// Task: basic functionality: insert, insert_erase, lookup, lookup_fail, iter
+#![feature(test)]
+
+extern crate test;
+
+use test::{black_box, Bencher};
+
+use hashbrown::hash_map::DefaultHashBuilder;
+use hashbrown::{HashMap, HashSet};
+use std::{
+ collections::hash_map::RandomState,
+ sync::atomic::{self, AtomicUsize},
+};
+
+const SIZE: usize = 1000;
+
+// The default hashmap when using this crate directly.
+type AHashMap<K, V> = HashMap<K, V, DefaultHashBuilder>;
+// This uses the hashmap from this crate with the default hasher of the stdlib.
+type StdHashMap<K, V> = HashMap<K, V, RandomState>;
+
+// A random key iterator.
+#[derive(Clone, Copy)]
+struct RandomKeys {
+ state: usize,
+}
+
+impl RandomKeys {
+ fn new() -> Self {
+ RandomKeys { state: 0 }
+ }
+}
+
+impl Iterator for RandomKeys {
+ type Item = usize;
+ fn next(&mut self) -> Option<usize> {
+ // Add 1 then multiply by some 32 bit prime.
+ self.state = self.state.wrapping_add(1).wrapping_mul(3_787_392_781);
+ Some(self.state)
+ }
+}
+
+// Just an arbitrary side effect to make the maps not shortcircuit to the non-dropping path
+// when dropping maps/entries (most real world usages likely have drop in the key or value)
+lazy_static::lazy_static! {
+ static ref SIDE_EFFECT: AtomicUsize = AtomicUsize::new(0);
+}
+
+#[derive(Clone)]
+struct DropType(usize);
+impl Drop for DropType {
+ fn drop(&mut self) {
+ SIDE_EFFECT.fetch_add(self.0, atomic::Ordering::SeqCst);
+ }
+}
+
+macro_rules! bench_suite {
+ ($bench_macro:ident, $bench_ahash_serial:ident, $bench_std_serial:ident,
+ $bench_ahash_highbits:ident, $bench_std_highbits:ident,
+ $bench_ahash_random:ident, $bench_std_random:ident) => {
+ $bench_macro!($bench_ahash_serial, AHashMap, 0..);
+ $bench_macro!($bench_std_serial, StdHashMap, 0..);
+ $bench_macro!(
+ $bench_ahash_highbits,
+ AHashMap,
+ (0..).map(usize::swap_bytes)
+ );
+ $bench_macro!(
+ $bench_std_highbits,
+ StdHashMap,
+ (0..).map(usize::swap_bytes)
+ );
+ $bench_macro!($bench_ahash_random, AHashMap, RandomKeys::new());
+ $bench_macro!($bench_std_random, StdHashMap, RandomKeys::new());
+ };
+}
+
+macro_rules! bench_insert {
+ ($name:ident, $maptype:ident, $keydist:expr) => {
+ #[bench]
+ fn $name(b: &mut Bencher) {
+ let mut m = $maptype::with_capacity_and_hasher(SIZE, Default::default());
+ b.iter(|| {
+ m.clear();
+ for i in ($keydist).take(SIZE) {
+ m.insert(i, (DropType(i), [i; 20]));
+ }
+ black_box(&mut m);
+ });
+ eprintln!("{}", SIDE_EFFECT.load(atomic::Ordering::SeqCst));
+ }
+ };
+}
+
+bench_suite!(
+ bench_insert,
+ insert_ahash_serial,
+ insert_std_serial,
+ insert_ahash_highbits,
+ insert_std_highbits,
+ insert_ahash_random,
+ insert_std_random
+);
+
+macro_rules! bench_grow_insert {
+ ($name:ident, $maptype:ident, $keydist:expr) => {
+ #[bench]
+ fn $name(b: &mut Bencher) {
+ b.iter(|| {
+ let mut m = $maptype::default();
+ for i in ($keydist).take(SIZE) {
+ m.insert(i, DropType(i));
+ }
+ black_box(&mut m);
+ })
+ }
+ };
+}
+
+bench_suite!(
+ bench_grow_insert,
+ grow_insert_ahash_serial,
+ grow_insert_std_serial,
+ grow_insert_ahash_highbits,
+ grow_insert_std_highbits,
+ grow_insert_ahash_random,
+ grow_insert_std_random
+);
+
+macro_rules! bench_insert_erase {
+ ($name:ident, $maptype:ident, $keydist:expr) => {
+ #[bench]
+ fn $name(b: &mut Bencher) {
+ let mut base = $maptype::default();
+ for i in ($keydist).take(SIZE) {
+ base.insert(i, DropType(i));
+ }
+ let skip = $keydist.skip(SIZE);
+ b.iter(|| {
+ let mut m = base.clone();
+ let mut add_iter = skip.clone();
+ let mut remove_iter = $keydist;
+ // While keeping the size constant,
+ // replace the first keydist with the second.
+ for (add, remove) in (&mut add_iter).zip(&mut remove_iter).take(SIZE) {
+ m.insert(add, DropType(add));
+ black_box(m.remove(&remove));
+ }
+ black_box(m);
+ });
+ eprintln!("{}", SIDE_EFFECT.load(atomic::Ordering::SeqCst));
+ }
+ };
+}
+
+bench_suite!(
+ bench_insert_erase,
+ insert_erase_ahash_serial,
+ insert_erase_std_serial,
+ insert_erase_ahash_highbits,
+ insert_erase_std_highbits,
+ insert_erase_ahash_random,
+ insert_erase_std_random
+);
+
+macro_rules! bench_lookup {
+ ($name:ident, $maptype:ident, $keydist:expr) => {
+ #[bench]
+ fn $name(b: &mut Bencher) {
+ let mut m = $maptype::default();
+ for i in $keydist.take(SIZE) {
+ m.insert(i, DropType(i));
+ }
+
+ b.iter(|| {
+ for i in $keydist.take(SIZE) {
+ black_box(m.get(&i));
+ }
+ });
+ eprintln!("{}", SIDE_EFFECT.load(atomic::Ordering::SeqCst));
+ }
+ };
+}
+
+bench_suite!(
+ bench_lookup,
+ lookup_ahash_serial,
+ lookup_std_serial,
+ lookup_ahash_highbits,
+ lookup_std_highbits,
+ lookup_ahash_random,
+ lookup_std_random
+);
+
+macro_rules! bench_lookup_fail {
+ ($name:ident, $maptype:ident, $keydist:expr) => {
+ #[bench]
+ fn $name(b: &mut Bencher) {
+ let mut m = $maptype::default();
+ let mut iter = $keydist;
+ for i in (&mut iter).take(SIZE) {
+ m.insert(i, DropType(i));
+ }
+
+ b.iter(|| {
+ for i in (&mut iter).take(SIZE) {
+ black_box(m.get(&i));
+ }
+ })
+ }
+ };
+}
+
+bench_suite!(
+ bench_lookup_fail,
+ lookup_fail_ahash_serial,
+ lookup_fail_std_serial,
+ lookup_fail_ahash_highbits,
+ lookup_fail_std_highbits,
+ lookup_fail_ahash_random,
+ lookup_fail_std_random
+);
+
+macro_rules! bench_iter {
+ ($name:ident, $maptype:ident, $keydist:expr) => {
+ #[bench]
+ fn $name(b: &mut Bencher) {
+ let mut m = $maptype::default();
+ for i in ($keydist).take(SIZE) {
+ m.insert(i, DropType(i));
+ }
+
+ b.iter(|| {
+ for i in &m {
+ black_box(i);
+ }
+ })
+ }
+ };
+}
+
+bench_suite!(
+ bench_iter,
+ iter_ahash_serial,
+ iter_std_serial,
+ iter_ahash_highbits,
+ iter_std_highbits,
+ iter_ahash_random,
+ iter_std_random
+);
+
+#[bench]
+fn clone_small(b: &mut Bencher) {
+ let mut m = HashMap::new();
+ for i in 0..10 {
+ m.insert(i, DropType(i));
+ }
+
+ b.iter(|| {
+ black_box(m.clone());
+ })
+}
+
+#[bench]
+fn clone_from_small(b: &mut Bencher) {
+ let mut m = HashMap::new();
+ let mut m2 = HashMap::new();
+ for i in 0..10 {
+ m.insert(i, DropType(i));
+ }
+
+ b.iter(|| {
+ m2.clone_from(&m);
+ black_box(&mut m2);
+ })
+}
+
+#[bench]
+fn clone_large(b: &mut Bencher) {
+ let mut m = HashMap::new();
+ for i in 0..1000 {
+ m.insert(i, DropType(i));
+ }
+
+ b.iter(|| {
+ black_box(m.clone());
+ })
+}
+
+#[bench]
+fn clone_from_large(b: &mut Bencher) {
+ let mut m = HashMap::new();
+ let mut m2 = HashMap::new();
+ for i in 0..1000 {
+ m.insert(i, DropType(i));
+ }
+
+ b.iter(|| {
+ m2.clone_from(&m);
+ black_box(&mut m2);
+ })
+}
+
+#[bench]
+fn rehash_in_place(b: &mut Bencher) {
+ b.iter(|| {
+ let mut set = HashSet::new();
+
+ // Each loop triggers one rehash
+ for _ in 0..10 {
+ for i in 0..223 {
+ set.insert(i);
+ }
+
+ assert_eq!(
+ set.capacity(),
+ 224,
+ "The set must be at or close to capacity to trigger a re hashing"
+ );
+
+ for i in 100..1400 {
+ set.remove(&(i - 100));
+ set.insert(i);
+ }
+ set.clear();
+ }
+ });
+}