fix tlfu small size (#11)

src/core.rs

@@ -298,6 +298,8 @@ impl LruCore {
 
 #[cfg(test)]
 mod tests {
+    use crate::core::TlfuCore;
+
     use super::LruCore;
 
     #[test]
@@ -310,4 +312,15 @@ mod tests {
         assert_eq!("cdefg", lru.policy.link.display(false, &lru.metadata));
         assert_eq!(5, lru.metadata.len());
     }
+
+    #[test]
+    fn test_tlfu_core_size_small() {
+        for size in [1, 2, 3] {
+            let mut tlfu = TlfuCore::new(size);
+            for s in ["a", "b", "c", "d", "e", "f", "g", "g", "g"] {
+                tlfu.set(s, 0);
+            }
+            assert_eq!(size, tlfu.metadata.len());
+        }
+    }
 }

src/lru.rs

@@ -54,6 +54,9 @@ impl Slru {
     }
 
     pub fn insert(&mut self, index: u32, metadata: &mut MetaData) -> Option<u32> {
+        if self.maxsize == 0 {
+            return Some(index);
+        }
         if self.protected.len + self.probation.len >= self.maxsize as u32 {
             if let Some(evicted) = self.probation.pop_tail(metadata) {
                 self.probation.insert_front(index, metadata);
@@ -67,6 +70,9 @@ impl Slru {
     }
 
     pub fn victim(&mut self, metadata: &mut MetaData) -> Option<u32> {
+        if self.maxsize == 0 {
+            return None;
+        }
         if self.probation.len + self.protected.len < self.maxsize as u32 {
             return None;
         }