crates/iceberg/src/cache.rs

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//! Cache management for Iceberg.

use std::sync::Arc;

use crate::spec::{Manifest, ManifestList};

/// A trait for caching in-memory objects of given type.
///
/// # Notes
///
/// ObjectCache will store deeply nested objects, such as `Manifest`,
/// which contains `Schema`. Please ensure that the cache stores the
/// object in memory as-is, without attempting to serialize it, as
/// serialization could be extremely expensive.
pub trait ObjectCache<K, V>: Send + Sync {
    /// Gets an object from the cache by its key.
    fn get(&self, key: &K) -> Option<V>;
    /// Sets an object in the cache with the given key and value.
    fn set(&self, key: K, value: V);
}

/// A trait for caching different in-memory objects used by iceberg.
///
/// # Notes
///
/// ObjectCache will store deeply nested objects, such as `Manifest`,
/// which contains `Schema`. Please ensure that the cache stores the
/// object in memory as-is, without attempting to serialize it, as
/// serialization could be extremely expensive.
pub trait ObjectCacheProvide: Send + Sync {
    /// Gets a cache for manifests.
    fn manifest_cache(&self) -> &dyn ObjectCache<String, Arc<Manifest>>;
    /// Gets a cache for manifest lists.
    fn manifest_list_cache(&self) -> &dyn ObjectCache<String, Arc<ManifestList>>;
}

/// CacheProvider is a type alias for a thread-safe reference-counted pointer to a CacheProvide trait object.
pub type ObjectCacheProvider = Arc<dyn ObjectCacheProvide>;

#[cfg(test)]
mod tests {
    use super::*;

    struct _TestDynCompatibleForObjectCache(Arc<dyn ObjectCache<String, Arc<Manifest>>>);
    struct _TestDynCompatibleForObjectCacheProvider(ObjectCacheProvider);
}