1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
|
/* This Source Code Form is subject to the terms of the Mozilla Public
* License, v. 2.0. If a copy of the MPL was not distributed with this
* file, You can obtain one at http://mozilla.org/MPL/2.0/. */
//! Two simple cache data structures.
use rand;
use rand::Rng;
use std::hash::{Hash, Hasher, SipHasher};
use std::slice::{Iter, IterMut};
pub struct LRUCache<K, V> {
entries: Vec<(K, V)>,
cache_size: usize,
}
impl<K: PartialEq, V: Clone> LRUCache<K, V> {
pub fn new(size: usize) -> LRUCache<K, V> {
LRUCache {
entries: vec![],
cache_size: size,
}
}
#[inline]
pub fn touch(&mut self, pos: usize) -> &V {
let last_index = self.entries.len() - 1;
if pos != last_index {
let entry = self.entries.remove(pos);
self.entries.push(entry);
}
&self.entries[last_index].1
}
pub fn iter(&self) -> Iter<(K, V)> {
self.entries.iter()
}
pub fn iter_mut(&mut self) -> IterMut<(K, V)> {
self.entries.iter_mut()
}
pub fn insert(&mut self, key: K, val: V) {
if self.entries.len() == self.cache_size {
self.entries.remove(0);
}
self.entries.push((key, val));
}
pub fn find(&mut self, key: &K) -> Option<V> {
match self.entries.iter().position(|&(ref k, _)| key == k) {
Some(pos) => Some(self.touch(pos).clone()),
None => None,
}
}
pub fn find_or_create<F>(&mut self, key: K, mut blk: F) -> V where F: FnMut() -> V {
match self.entries.iter().position(|&(ref k, _)| *k == key) {
Some(pos) => self.touch(pos).clone(),
None => {
let val = blk();
self.insert(key, val.clone());
val
}
}
}
pub fn evict_all(&mut self) {
self.entries.clear();
}
}
pub struct SimpleHashCache<K, V> {
entries: Vec<Option<(K, V)>>,
k0: u64,
k1: u64,
}
impl<K: Clone + Eq + Hash, V: Clone> SimpleHashCache<K, V> {
pub fn new(cache_size: usize) -> SimpleHashCache<K, V> {
let mut r = rand::thread_rng();
SimpleHashCache {
entries: vec![None; cache_size],
k0: r.gen(),
k1: r.gen(),
}
}
#[inline]
fn to_bucket(&self, h: usize) -> usize {
h % self.entries.len()
}
#[inline]
fn bucket_for_key<Q: Hash>(&self, key: &Q) -> usize {
let mut hasher = SipHasher::new_with_keys(self.k0, self.k1);
key.hash(&mut hasher);
self.to_bucket(hasher.finish() as usize)
}
pub fn insert(&mut self, key: K, value: V) {
let bucket_index = self.bucket_for_key(&key);
self.entries[bucket_index] = Some((key, value));
}
pub fn find<Q>(&self, key: &Q) -> Option<V> where Q: PartialEq<K> + Hash + Eq {
let bucket_index = self.bucket_for_key(key);
match self.entries[bucket_index] {
Some((ref existing_key, ref value)) if key == existing_key => Some((*value).clone()),
_ => None,
}
}
pub fn find_or_create<F>(&mut self, key: K, mut blk: F) -> V where F: FnMut() -> V {
if let Some(value) = self.find(&key) {
return value;
}
let value = blk();
self.insert(key, value.clone());
value
}
pub fn evict_all(&mut self) {
for slot in &mut self.entries {
*slot = None
}
}
}
|
