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https://github.com/rust-lang/rust.git
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270 lines
6.4 KiB
Rust
270 lines
6.4 KiB
Rust
use core::iter::Iterator;
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use std::{
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collections::{vec_deque, VecDeque},
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mem,
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};
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use test::{black_box, Bencher};
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#[bench]
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fn bench_new(b: &mut Bencher) {
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b.iter(|| {
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let ring: VecDeque<i32> = VecDeque::new();
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black_box(ring);
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})
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}
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#[bench]
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fn bench_grow_1025(b: &mut Bencher) {
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b.iter(|| {
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let mut deq = VecDeque::new();
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for i in 0..1025 {
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deq.push_front(i);
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}
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black_box(deq);
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})
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}
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#[bench]
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fn bench_iter_1000(b: &mut Bencher) {
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let ring: VecDeque<_> = (0..1000).collect();
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b.iter(|| {
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let mut sum = 0;
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for &i in &ring {
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sum += i;
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}
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black_box(sum);
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})
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}
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#[bench]
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fn bench_mut_iter_1000(b: &mut Bencher) {
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let mut ring: VecDeque<_> = (0..1000).collect();
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b.iter(|| {
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let mut sum = 0;
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for i in &mut ring {
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sum += *i;
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}
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black_box(sum);
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})
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}
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#[bench]
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fn bench_try_fold(b: &mut Bencher) {
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let ring: VecDeque<_> = (0..1000).collect();
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b.iter(|| black_box(ring.iter().try_fold(0, |a, b| Some(a + b))))
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}
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/// does the memory bookkeeping to reuse the buffer of the Vec between iterations.
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/// `setup` must not modify its argument's length or capacity. `g` must not move out of its argument.
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fn into_iter_helper<
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T: Copy,
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F: FnOnce(&mut VecDeque<T>),
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G: FnOnce(&mut vec_deque::IntoIter<T>),
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>(
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v: &mut Vec<T>,
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setup: F,
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g: G,
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) {
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let ptr = v.as_mut_ptr();
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let len = v.len();
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// ensure that the vec is full, to make sure that any wrapping from the deque doesn't
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// access uninitialized memory.
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assert_eq!(v.len(), v.capacity());
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let mut deque = VecDeque::from(mem::take(v));
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setup(&mut deque);
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let mut it = deque.into_iter();
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g(&mut it);
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mem::forget(it);
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// SAFETY: the provided functions are not allowed to modify the allocation, so the buffer is still alive.
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// len and capacity are accurate due to the above assertion.
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// All the elements in the buffer are still valid, because of `T: Copy` which implies `T: !Drop`.
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mem::forget(mem::replace(v, unsafe { Vec::from_raw_parts(ptr, len, len) }));
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}
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#[bench]
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fn bench_into_iter(b: &mut Bencher) {
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let len = 1024;
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// we reuse this allocation for every run
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let mut vec: Vec<usize> = (0..len).collect();
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vec.shrink_to_fit();
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b.iter(|| {
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let mut sum = 0;
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into_iter_helper(
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&mut vec,
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|_| {},
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|it| {
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for i in it {
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sum += i;
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}
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},
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);
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black_box(sum);
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let mut sum = 0;
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// rotating a full deque doesn't move any memory.
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into_iter_helper(
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&mut vec,
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|d| d.rotate_left(len / 2),
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|it| {
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for i in it {
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sum += i;
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}
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},
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);
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black_box(sum);
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});
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}
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#[bench]
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fn bench_into_iter_fold(b: &mut Bencher) {
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let len = 1024;
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// because `fold` takes ownership of the iterator,
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// we can't prevent it from dropping the memory,
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// so we have to bite the bullet and reallocate
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// for every iteration.
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b.iter(|| {
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let deque: VecDeque<usize> = (0..len).collect();
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assert_eq!(deque.len(), deque.capacity());
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let sum = deque.into_iter().fold(0, |a, b| a + b);
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black_box(sum);
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// rotating a full deque doesn't move any memory.
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let mut deque: VecDeque<usize> = (0..len).collect();
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assert_eq!(deque.len(), deque.capacity());
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deque.rotate_left(len / 2);
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let sum = deque.into_iter().fold(0, |a, b| a + b);
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black_box(sum);
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});
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}
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#[bench]
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fn bench_into_iter_try_fold(b: &mut Bencher) {
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let len = 1024;
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// we reuse this allocation for every run
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let mut vec: Vec<usize> = (0..len).collect();
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vec.shrink_to_fit();
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// Iterator::any uses Iterator::try_fold under the hood
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b.iter(|| {
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let mut b = false;
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into_iter_helper(&mut vec, |_| {}, |it| b = it.any(|i| i == len - 1));
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black_box(b);
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into_iter_helper(&mut vec, |d| d.rotate_left(len / 2), |it| b = it.any(|i| i == len - 1));
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black_box(b);
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});
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}
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#[bench]
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fn bench_into_iter_next_chunk(b: &mut Bencher) {
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let len = 1024;
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// we reuse this allocation for every run
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let mut vec: Vec<usize> = (0..len).collect();
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vec.shrink_to_fit();
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b.iter(|| {
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let mut buf = [0; 64];
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into_iter_helper(
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&mut vec,
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|_| {},
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|it| {
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while let Ok(a) = it.next_chunk() {
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buf = a;
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}
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},
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);
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black_box(buf);
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into_iter_helper(
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&mut vec,
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|d| d.rotate_left(len / 2),
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|it| {
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while let Ok(a) = it.next_chunk() {
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buf = a;
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}
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},
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);
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black_box(buf);
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});
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}
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#[bench]
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fn bench_from_array_1000(b: &mut Bencher) {
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const N: usize = 1000;
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let mut array: [usize; N] = [0; N];
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for i in 0..N {
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array[i] = i;
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}
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b.iter(|| {
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let deq: VecDeque<_> = array.into();
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black_box(deq);
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})
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}
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#[bench]
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fn bench_extend_bytes(b: &mut Bencher) {
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let mut ring: VecDeque<u8> = VecDeque::with_capacity(1000);
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let input: &[u8] = &[128; 512];
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b.iter(|| {
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ring.clear();
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ring.extend(black_box(input));
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});
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}
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#[bench]
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fn bench_extend_vec(b: &mut Bencher) {
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let mut ring: VecDeque<u8> = VecDeque::with_capacity(1000);
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let input = vec![128; 512];
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b.iter(|| {
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ring.clear();
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let input = input.clone();
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ring.extend(black_box(input));
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});
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}
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#[bench]
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fn bench_extend_trustedlen(b: &mut Bencher) {
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let mut ring: VecDeque<u16> = VecDeque::with_capacity(1000);
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b.iter(|| {
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ring.clear();
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ring.extend(black_box(0..512));
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});
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}
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#[bench]
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fn bench_extend_chained_trustedlen(b: &mut Bencher) {
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let mut ring: VecDeque<u16> = VecDeque::with_capacity(1000);
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b.iter(|| {
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ring.clear();
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ring.extend(black_box((0..256).chain(768..1024)));
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});
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}
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#[bench]
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fn bench_extend_chained_bytes(b: &mut Bencher) {
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let mut ring: VecDeque<u16> = VecDeque::with_capacity(1000);
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let input1: &[u16] = &[128; 256];
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let input2: &[u16] = &[255; 256];
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b.iter(|| {
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ring.clear();
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ring.extend(black_box(input1.iter().chain(input2.iter())));
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});
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}
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