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hashmap: change hash-function to wyhash and add benchmarks

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ka-weihe
2020-01-29 04:06:05 +01:00
committed by GitHub
parent 5c29e7b257
commit a14a5fbf95
2 changed files with 120 additions and 26 deletions
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34
vlib/builtin/hashmap/hashmap.v
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@ -3,6 +3,8 @@
// that can be found in the LICENSE file.
module hashmap
import hash.wyhash
const (
initial_size = 2 << 4
initial_cap = initial_size - 1
@ -10,23 +12,6 @@ const (
load_factor = 0.8
)
// hash-function should not be in this file
const (
fnv64_prime = 1099511628211
fnv64_offset_basis = 14695981039346656037
fnv32_offset_basis = u32(2166136261)
fnv32_prime = u32(16777619)
)
[inline]
fn fnv1a64(data string) u64 {
mut hash := fnv64_offset_basis
for i := 0; i < data.len; i++ {
hash = (hash ^ u64(data[i])) * fnv64_prime
}
return hash
}
pub struct Hashmap {
mut:
info &u16
@ -54,14 +39,11 @@ pub fn new_hashmap() Hashmap {
}
pub fn (h mut Hashmap) set(key string, value int) {
// The load factor is 0.5.
// It will be adjustable in the future and with
// a higher default settings to lower memory usage.
// load_factor can be adjusted.
if (f32(h.size) / f32(h.cap)) > h.load_factor {
h.rehash()
}
// Hash-function will be swapped for wyhash
hash := fnv1a64(key)
hash := wyhash.wyhash_c(key.str, u64(key.len), 0)
mut info := u16((hash >> 56) | probe_offset)
mut index := hash & h.cap
// While probe count is less
@ -115,7 +97,7 @@ fn (h mut Hashmap) rehash() {
for i in 0 .. (old_cap + 1) {
if h.info[i] != 0 {
mut kv := h.key_values[i]
hash := fnv1a64(kv.key)
hash := wyhash.wyhash_c(kv.key.str, u64(kv.key.len), 0)
mut info := u16((hash >> 56) | probe_offset)
mut index := hash & h.cap
// While probe count is less
@ -154,7 +136,7 @@ fn (h mut Hashmap) rehash() {
}
pub fn (h mut Hashmap) delete(key string) {
hash := fnv1a64(key)
hash := wyhash.wyhash_c(key.str, u64(key.len), 0)
mut index := hash & h.cap
mut info := u16((hash >> 56) | probe_offset)
for info < h.info[index] {
@ -184,7 +166,7 @@ pub fn (h mut Hashmap) delete(key string) {
}
pub fn (h Hashmap) get(key string) int {
hash := fnv1a64(key)
hash := wyhash.wyhash_c(key.str, u64(key.len), 0)
mut index := hash & h.cap
mut info := u16((hash >> 56) | probe_offset)
for info < h.info[index] {
@ -202,7 +184,7 @@ pub fn (h Hashmap) get(key string) int {
}
pub fn (h Hashmap) exists(key string) bool {
hash := fnv1a64(key)
hash := wyhash.wyhash_c(key.str, u64(key.len), 0)
mut index := hash & h.cap
mut info := u16((hash >> 56) | probe_offset)
for info < h.info[index] {