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another hash

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This commit is contained in:
Paul Masurel
2017-05-30 15:36:48 +09:00
parent 568d149db8
commit 4a805733db
5 changed files with 128 additions and 54 deletions
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47
src/datastruct/stacker/hashmap.rs
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@@ -1,15 +1,14 @@
use std::iter;
use super::heap::{Heap, HeapAllocable, BytesRef};
use murmurhash64::murmur_hash64a;
/// dbj2 hash function
fn djb2(key: &[u8]) -> u64 {
let mut state: u64 = 5381;
for &b in key {
state = (state << 5).wrapping_add(state).wrapping_add(b as u64);
}
state
const SEED: u64 = 2915580697u64;
fn hash(key: &[u8]) -> u64 {
murmur_hash64a(key, SEED)
}
impl Default for BytesRef {
fn default() -> BytesRef {
BytesRef {
@@ -99,7 +98,7 @@ impl<'a> HashMap<'a> {
}
pub fn is_saturated(&self) -> bool {
self.table.len() < self.occupied.len() * 5
self.table.len() < self.occupied.len() * 3
}
#[inline(never)]
@@ -137,7 +136,7 @@ impl<'a> HashMap<'a> {
pub fn get_or_create<S: AsRef<[u8]>, V: HeapAllocable>(&mut self, key: S) -> &mut V {
let key_bytes: &[u8] = key.as_ref();
let hash = djb2(key.as_ref());
let hash = hash(key.as_ref());
let masked_hash = self.mask_hash(hash);
let mut probe = self.probe(hash);
loop {
@@ -163,7 +162,6 @@ mod tests {
use super::*;
use super::super::heap::{Heap, HeapAllocable};
use super::djb2;
use test::Bencher;
use std::collections::hash_map::DefaultHasher;
use std::hash::Hasher;
@@ -218,20 +216,21 @@ mod tests {
assert!(iter_values.next().is_none());
}
#[bench]
fn bench_djb2(bench: &mut Bencher) {
let v = String::from("abwer");
bench.iter(|| djb2(v.as_bytes()));
}
// #[bench]
// fn bench_djb2(bench: &mut Bencher) {
// let v = String::from("abwer");
// bench.iter(|| djb2(v.as_bytes()));
// }
// #[bench]
// fn bench_siphasher(bench: &mut Bencher) {
// let v = String::from("abwer");
// bench.iter(|| {
// let mut h = DefaultHasher::new();
// h.write(v.as_bytes());
// h.finish()
// });
// }
#[bench]
fn bench_siphasher(bench: &mut Bencher) {
let v = String::from("abwer");
bench.iter(|| {
let mut h = DefaultHasher::new();
h.write(v.as_bytes());
h.finish()
});
}
}