sine_cache 0.2.0

//! Traits and structs used in eviction_policies modules.

/// A trait defining the eviction policy for a cache.
///
/// This trait, `EvictionPolicy<K>`, establishes a contract for different eviction
/// strategies a cache can employ. It outlines the functions an eviction policy
/// must implement.
pub trait EvictionPolicy<K> {
    /// Called when a value is retrieved from the cache using the given key.
    ///
    /// This function is triggered on a cache get operation with the provided `key`.
    /// The specific behavior of this function might vary depending on the
    /// eviction policy implementation.
    fn on_get(&mut self, key: &K);

    /// Called when a new value is inserted into the cache using the given key.
    ///
    /// This function is called whenever a new key-value pair is inserted into
    /// the cache. The eviction policy can leverage this function to update its
    /// internal state or perform actions based on the set operation. The specific
    /// behavior might vary depending on the eviction policy.
    fn on_set(&mut self, key: K);

    /// Attempts to evict a key-value pair from the cache according to the eviction policy.
    ///
    /// This function is responsible for selecting a key-value pair to evict from
    /// the cache based on the implemented eviction policy. It returns
    /// `Some(key)` if an eviction occurs, containing the evicted key. If no
    /// eviction is necessary, it returns `None`.
    fn evict(&mut self) -> Option<K>;

    /// Removes the entry with the given key from the cache.
    ///
    /// This function explicitly removes the key-value entry associated with the
    /// provided `key` from the cache. The behavior upon encountering a missing
    /// key might vary based on the cache implementation (e.g., return an error
    /// or a boolean indicating success).
    fn remove(&mut self, key: K);
}