mirror of https://github.com/dswd/zvault
54 lines
1.3 KiB
Rust
54 lines
1.3 KiB
Rust
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use std::hash::Hash;
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use std::collections::HashMap;
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pub struct LruCache<K, V> {
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items: HashMap<K, (V, u64)>,
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min_size: usize,
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max_size: usize,
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next: u64
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}
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impl<K: Eq+Hash, V> LruCache<K, V> {
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#[inline]
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pub fn new(min_size: usize, max_size: usize) -> Self {
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LruCache {
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items: HashMap::default(),
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min_size: min_size,
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max_size: max_size,
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next: 0
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}
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}
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#[inline]
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pub fn put(&mut self, key: K, value: V) {
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self.items.insert(key, (value, self.next));
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self.next += 1;
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if self.items.len() > self.max_size {
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self.shrink()
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}
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}
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#[inline]
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pub fn get(&mut self, key: &K) -> Option<&V> {
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if let Some(&mut (ref item, ref mut n)) = self.items.get_mut(key) {
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*n = self.next;
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self.next += 1;
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Some(item)
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} else {
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None
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}
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}
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#[inline]
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fn shrink(&mut self) {
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let mut tags: Vec<u64> = self.items.values().map(|&(_, n)| n).collect();
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tags.sort();
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let min = tags[tags.len()-self.min_size];
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let mut new = HashMap::with_capacity(self.min_size);
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new.extend(self.items.drain().filter(|&(_,(_, n))| n>=min));
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self.items = new;
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}
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}
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