зеркало из https://github.com/mozilla/gecko-dev.git
243 строки
6.7 KiB
Rust
243 строки
6.7 KiB
Rust
/* This Source Code Form is subject to the terms of the Mozilla Public
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* License, v. 2.0. If a copy of the MPL was not distributed with this
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* file, You can obtain one at http://mozilla.org/MPL/2.0/. */
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use std::collections::HashMap;
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use std::collections::hash_map::{Occupied, Vacant};
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use rand::Rng;
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use std::hash::{Hash, sip};
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use std::rand::task_rng;
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use std::slice::Items;
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#[cfg(test)]
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use std::cell::Cell;
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pub trait Cache<K: PartialEq, V: Clone> {
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fn insert(&mut self, key: K, value: V);
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fn find(&mut self, key: &K) -> Option<V>;
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fn find_or_create(&mut self, key: &K, blk: |&K| -> V) -> V;
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fn evict_all(&mut self);
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}
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pub struct HashCache<K, V> {
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entries: HashMap<K, V>,
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}
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impl<K: Clone + PartialEq + Eq + Hash, V: Clone> HashCache<K,V> {
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pub fn new() -> HashCache<K, V> {
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HashCache {
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entries: HashMap::new(),
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}
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}
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}
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impl<K: Clone + PartialEq + Eq + Hash, V: Clone> Cache<K,V> for HashCache<K,V> {
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fn insert(&mut self, key: K, value: V) {
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self.entries.insert(key, value);
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}
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fn find(&mut self, key: &K) -> Option<V> {
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match self.entries.get(key) {
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Some(v) => Some(v.clone()),
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None => None,
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}
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}
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fn find_or_create(&mut self, key: &K, blk: |&K| -> V) -> V {
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match self.entries.entry(key.clone()) {
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Occupied(occupied) => {
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(*occupied.get()).clone()
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}
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Vacant(vacant) => {
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(*vacant.set(blk(key))).clone()
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}
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}
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}
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fn evict_all(&mut self) {
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self.entries.clear();
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}
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}
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impl<K,V> HashCache<K,V> where K: Clone + PartialEq + Eq + Hash, V: Clone {
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pub fn find_equiv<'a,Sized? Q>(&'a self, key: &Q) -> Option<&'a V> where Q: Hash + Equiv<K> {
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self.entries.find_equiv(key)
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}
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}
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#[test]
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fn test_hashcache() {
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let mut cache: HashCache<uint, Cell<&str>> = HashCache::new();
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let one = Cell::new("one");
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let two = Cell::new("two");
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cache.insert(1, one);
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assert!(cache.find(&1).is_some());
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assert!(cache.find(&2).is_none());
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cache.find_or_create(&2, |_v| { two });
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assert!(cache.find(&1).is_some());
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assert!(cache.find(&2).is_some());
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}
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pub struct LRUCache<K, V> {
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entries: Vec<(K, V)>,
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cache_size: uint,
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}
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impl<K: Clone + PartialEq, V: Clone> LRUCache<K,V> {
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pub fn new(size: uint) -> LRUCache<K, V> {
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LRUCache {
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entries: vec!(),
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cache_size: size,
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}
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}
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#[inline]
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pub fn touch(&mut self, pos: uint) -> V {
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let last_index = self.entries.len() - 1;
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if pos != last_index {
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let entry = self.entries.remove(pos);
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self.entries.push(entry.unwrap());
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}
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self.entries[last_index].ref1().clone()
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}
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pub fn iter<'a>(&'a self) -> Items<'a,(K,V)> {
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self.entries.iter()
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}
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}
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impl<K: Clone + PartialEq, V: Clone> Cache<K,V> for LRUCache<K,V> {
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fn insert(&mut self, key: K, val: V) {
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if self.entries.len() == self.cache_size {
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self.entries.remove(0);
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}
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self.entries.push((key, val));
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}
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fn find(&mut self, key: &K) -> Option<V> {
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match self.entries.iter().position(|&(ref k, _)| *k == *key) {
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Some(pos) => Some(self.touch(pos)),
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None => None,
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}
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}
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fn find_or_create(&mut self, key: &K, blk: |&K| -> V) -> V {
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match self.entries.iter().position(|&(ref k, _)| *k == *key) {
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Some(pos) => self.touch(pos),
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None => {
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let val = blk(key);
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self.insert(key.clone(), val.clone());
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val
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}
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}
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}
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fn evict_all(&mut self) {
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self.entries.clear();
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}
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}
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pub struct SimpleHashCache<K,V> {
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entries: Vec<Option<(K,V)>>,
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k0: u64,
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k1: u64,
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}
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impl<K:Clone+PartialEq+Hash,V:Clone> SimpleHashCache<K,V> {
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pub fn new(cache_size: uint) -> SimpleHashCache<K,V> {
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let mut r = task_rng();
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SimpleHashCache {
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entries: Vec::from_elem(cache_size, None),
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k0: r.gen(),
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k1: r.gen(),
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}
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}
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#[inline]
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fn to_bucket(&self, h: uint) -> uint {
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h % self.entries.len()
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}
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#[inline]
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fn bucket_for_key<Q:Hash>(&self, key: &Q) -> uint {
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self.to_bucket(sip::hash_with_keys(self.k0, self.k1, key) as uint)
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}
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#[inline]
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pub fn find_equiv<'a,Q:Hash+Equiv<K>>(&'a self, key: &Q) -> Option<&'a V> {
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let bucket_index = self.bucket_for_key(key);
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match self.entries[bucket_index] {
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Some((ref existing_key, ref value)) if key.equiv(existing_key) => Some(value),
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_ => None,
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}
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}
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}
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impl<K:Clone+PartialEq+Hash,V:Clone> Cache<K,V> for SimpleHashCache<K,V> {
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fn insert(&mut self, key: K, value: V) {
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let bucket_index = self.bucket_for_key(&key);
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self.entries[bucket_index] = Some((key, value));
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}
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fn find(&mut self, key: &K) -> Option<V> {
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let bucket_index = self.bucket_for_key(key);
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match self.entries[bucket_index] {
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Some((ref existing_key, ref value)) if existing_key == key => Some((*value).clone()),
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_ => None,
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}
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}
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fn find_or_create(&mut self, key: &K, blk: |&K| -> V) -> V {
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match self.find(key) {
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Some(value) => return value,
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None => {}
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}
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let value = blk(key);
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self.insert((*key).clone(), value.clone());
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value
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}
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fn evict_all(&mut self) {
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for slot in self.entries.iter_mut() {
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*slot = None
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}
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}
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}
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#[test]
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fn test_lru_cache() {
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let one = Cell::new("one");
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let two = Cell::new("two");
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let three = Cell::new("three");
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let four = Cell::new("four");
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// Test normal insertion.
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let mut cache: LRUCache<uint,Cell<&str>> = LRUCache::new(2); // (_, _) (cache is empty)
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cache.insert(1, one); // (1, _)
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cache.insert(2, two); // (1, 2)
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cache.insert(3, three); // (2, 3)
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assert!(cache.find(&1).is_none()); // (2, 3) (no change)
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assert!(cache.find(&3).is_some()); // (2, 3)
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assert!(cache.find(&2).is_some()); // (3, 2)
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// Test that LRU works (this insertion should replace 3, not 2).
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cache.insert(4, four); // (2, 4)
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assert!(cache.find(&1).is_none()); // (2, 4) (no change)
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assert!(cache.find(&2).is_some()); // (4, 2)
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assert!(cache.find(&3).is_none()); // (4, 2) (no change)
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assert!(cache.find(&4).is_some()); // (2, 4) (no change)
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// Test find_or_create.
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cache.find_or_create(&1, |_| { one }); // (4, 1)
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assert!(cache.find(&1).is_some()); // (4, 1) (no change)
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assert!(cache.find(&2).is_none()); // (4, 1) (no change)
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assert!(cache.find(&3).is_none()); // (4, 1) (no change)
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assert!(cache.find(&4).is_some()); // (1, 4)
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}
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