add test

async-fat32/src/cache.rs

@@ -55,13 +55,31 @@ pub struct LFUCache<K: Eq + PartialEq + Copy, V, const N: usize> {
     time: usize
 }
 
+impl<K: Eq + PartialEq + Copy, V, const N: usize> LFUCache<K, V, N> {
+    fn init(data: [Node<K, V>; N]) -> Self {
+        Self {
+            data,
+            size: N,
+            time: 0
+        }
+    }
+    // todo: 用 `maybuninit`
+    fn empty(data: [Node<K, V>; N]) -> Self {
+        Self {
+            data,
+            size: 0,
+            time: 0
+        }
+    }
+}
+
 impl<K: Eq + PartialEq + Copy, V, const N: usize> Cache for LFUCache<K, V, N> {
     type Key = K;
     type Value = V;
     fn get(&mut self, key: &Self::Key) -> Option<&Self::Value> {
         self.time += 1;
         let time = self.time;
-        self.data.iter_mut().find(|i| i.key == *key).map(|node| {
+        self.data[0..self.size].iter_mut().find(|i| i.key == *key).map(|node| {
             // 更新结点时间和访问次数
             node.time = time;
             node.cnt += 1;
@@ -83,7 +101,7 @@ impl<K: Eq + PartialEq + Copy, V, const N: usize> Cache for LFUCache<K, V, N> {
                 self.data[self.size].cnt = 1;
                 self.data[self.size].time = self.time;
                 self.size += 1;
-            } else {
+            } else { // 缓存已满
                 // 顺序排序
                 self.data[0..self.size].sort_by(|a, b| a.cmp(b));
                 // 淘汰第一项
@@ -94,9 +112,30 @@ impl<K: Eq + PartialEq + Copy, V, const N: usize> Cache for LFUCache<K, V, N> {
                 }
                 node.key = *key;
                 node.value = value;
-                node.cnt = 0;
+                node.cnt = 1;
                 node.time = self.time;
             }
         }
     }
 }
+
+
+#[test]
+fn lfu_cache_test() {
+    let nodes = [Node::new(0, 0); 2];
+    let mut lfu_cache = LFUCache::empty(nodes);
+    
+    assert!(lfu_cache.get(&0).is_none());
+    assert!(lfu_cache.get(&1).is_none());
+    assert!(lfu_cache.get(&2).is_none());
+    lfu_cache.put(&1, 1, |_ , _| {});
+    lfu_cache.put(&2, 2, |_ , _| {});
+    assert_eq!(lfu_cache.get(&1).map(|v| *v), Some(1));
+    lfu_cache.put(&3, 3, |_ , _| {});
+    assert_eq!(lfu_cache.get(&2), None);
+    assert_eq!(lfu_cache.get(&3).map(|v| *v), Some(3));
+    lfu_cache.put(&4, 4, |_ , _| {});
+    assert_eq!(lfu_cache.get(&1), None);
+    assert_eq!(lfu_cache.get(&3).map(|v| *v), Some(3));
+    assert_eq!(lfu_cache.get(&4).map(|v| *v), Some(4));
+}