Added Cache::remove_if

This method removes the entry from cache for a given key only if a
provided predicate returns true for the entry's value.

Author: xonatius

src/shard.rs

@@ -604,6 +604,19 @@ impl<
         self.remove_internal(hash, idx)
     }
 
+    pub fn remove_if<Q, F>(&mut self, hash: u64, key: &Q, f: F) -> Option<(Key, Val)>
+    where
+        Q: Hash + Equivalent<Key> + ?Sized,
+        F: FnOnce(&Val) -> bool,
+    {
+        let (idx, resident) = self.search_resident(hash, key)?;
+        if f(&resident.value) {
+            self.remove_internal(hash, idx)
+        } else {
+            None
+        }
+    }
+
     pub fn remove_token(&mut self, token: Token) -> Option<(Key, Val)> {
         let Some((Entry::Resident(resident), _)) = self.entries.get(token) else {
             return None;

src/sync.rs

@@ -274,6 +274,19 @@ impl<
         shard.write().remove(hash, key)
     }
 
+    /// Remove an item from the cache whose key is `key` if `f(&value)` returns `true` for that entry.
+    /// Compared to peek and remove, this method guarantees that no new value was inserted in-between.
+    ///
+    /// Returns the removed entry, if any.
+    pub fn remove_if<Q, F>(&self, key: &Q, f: F) -> Option<(Key, Val)>
+    where
+        Q: Hash + Equivalent<Key> + ?Sized,
+        F: FnOnce(&Val) -> bool,
+    {
+        let (shard, hash) = self.shard_for(key).unwrap();
+        shard.write().remove_if(hash, key, f)
+    }
+
     /// Inserts an item in the cache, but _only_ if an entry with key `key` already exists.
     /// If `soft` is set, the replace operation won't affect the "hotness" of the entry,
     /// even if the value is replaced.
@@ -756,4 +769,28 @@ mod tests {
         assert!(cache.len() <= 180);
         assert!(cache.weight() <= 200);
     }
+
+    #[test]
+    fn test_remove_if() {
+        let cache = Cache::new(100);
+
+        // Insert test data
+        cache.insert(1, 10);
+        cache.insert(2, 20);
+        cache.insert(3, 30);
+
+        // Test removing with predicate that returns true
+        let removed = cache.remove_if(&2, |v| *v == 20);
+        assert_eq!(removed, Some((2, 20)));
+        assert_eq!(cache.get(&2), None);
+
+        // Test removing with predicate that returns false
+        let not_removed = cache.remove_if(&3, |v| *v == 999);
+        assert_eq!(not_removed, None);
+        assert_eq!(cache.get(&3), Some(30));
+
+        // Test removing non-existent key
+        let not_found = cache.remove_if(&999, |_| true);
+        assert_eq!(not_found, None);
+    }
 }

src/unsync.rs

@@ -194,6 +194,18 @@ impl<Key: Eq + Hash, Val, We: Weighter<Key, Val>, B: BuildHasher, L: Lifecycle<K
         self.shard.remove(self.shard.hash(key), key)
     }
 
+    /// Remove an item from the cache whose key is `key` if `f(&value)` returns `true` for that entry.
+    /// Compared to peek and remove, this method is more efficient as it requires only 1 lookup.
+    ///
+    /// Returns the removed entry, if any.
+    pub fn remove_if<Q, F>(&mut self, key: &Q, f: F) -> Option<(Key, Val)>
+    where
+        Q: Hash + Equivalent<Key> + ?Sized,
+        F: FnOnce(&Val) -> bool,
+    {
+        self.shard.remove_if(self.shard.hash(key), key, f)
+    }
+
     /// Replaces an item in the cache, but only if it already exists.
     /// If `soft` is set, the replace operation won't affect the "hotness" of the key,
     /// even if the value is replaced.
@@ -635,4 +647,30 @@ mod tests {
         }
         cache.validate(false);
     }
+
+    #[test]
+    fn test_remove_if() {
+        let mut cache = Cache::new(100);
+
+        // Insert test data
+        cache.insert(1, 10);
+        cache.insert(2, 20);
+        cache.insert(3, 30);
+
+        // Test removing with predicate that returns true
+        let removed = cache.remove_if(&2, |v| *v == 20);
+        assert_eq!(removed, Some((2, 20)));
+        assert_eq!(cache.get(&2), None);
+
+        // Test removing with predicate that returns false
+        let not_removed = cache.remove_if(&3, |v| *v == 999);
+        assert_eq!(not_removed, None);
+        assert_eq!(cache.get(&3), Some(&30));
+
+        // Test removing non-existent key
+        let not_found = cache.remove_if(&999, |_| true);
+        assert_eq!(not_found, None);
+
+        cache.validate(false);
+    }
 }