Struct MemoryBudgetCache 

pub struct MemoryBudgetCache { /* private fields */ }

Memory budget cache with LRU eviction

Tracks loaded partitions and their memory footprint, evicting least-recently-used partitions when the memory budget is exceeded.

Thread-safe: All methods take &self and use interior mutability via parking_lot::Mutex for concurrent access.

Implementations

impl MemoryBudgetCache

pub fn new(max_memory_bytes: usize) -> Self

Create a new cache with the given memory budget

pub fn with_default_budget() -> Self

Create a cache with default memory budget (512 MB)

pub fn with_min_partitions(self, min: usize) -> Self

Set the minimum number of partitions to keep

pub fn max_memory_bytes(&self) -> usize

Get the memory budget in bytes

pub fn current_memory_bytes(&self) -> usize

Get current memory usage in bytes

pub fn memory_usage_ratio(&self) -> f64

Get memory usage as a percentage (0.0 - 1.0)

pub fn partition_count(&self) -> usize

Get the number of partitions currently tracked

pub fn metrics(&self) -> CacheMetrics

Get a snapshot of cache metrics

pub fn reset_metrics(&self)

Reset cache metrics

pub fn contains(&self, partition_id: &str) -> bool

Check if a partition is in the cache

pub fn touch(&self, partition_id: &str) -> bool

Mark a partition as accessed (updates LRU order)

Returns true if the partition was found, false otherwise.

pub fn record_loaded(&self, partition_id: String, stats: PartitionStats)

Record that a partition has been loaded

Adds the partition to the cache and updates memory tracking.

pub fn get_stats(&self, partition_id: &str) -> Option<PartitionStats>

Get stats for a partition (if tracked)

Returns a clone of the stats to avoid holding the lock.

pub fn remove(&self, partition_id: &str) -> Option<PartitionStats>

Remove a partition from the cache

Returns the stats if the partition was tracked, None otherwise.

pub fn is_over_budget(&self) -> bool

Check if memory budget is exceeded

pub fn get_eviction_candidates(&self) -> Vec<String>

Get partition IDs that should be evicted to make room

Returns partition IDs in LRU order (least recently used first). Respects min_partitions to avoid thrashing.

pub fn memory_needed_for(&self, additional_bytes: usize) -> usize

Get the amount of memory needed to be freed to accommodate a new load

pub fn get_eviction_candidates_for(&self, needed_bytes: usize) -> Vec<String>

Get partitions to evict to make room for a specific amount of memory

Returns partition IDs in LRU order.

pub fn clear(&self)

Clear all tracked partitions

Trait Implementations

impl Default for MemoryBudgetCache

fn default() -> Self

Returns the “default value” for a type.