Struct BlockCacheManager 

pub struct BlockCacheManager {
    pub config: BcmCacheConfig,
    pub hot: HashMap<String, BcmCachedBlock>,
    pub warm: HashMap<String, BcmCachedBlock>,
    pub cold: HashMap<String, BcmCachedBlock>,
    /* private fields */
}

A multi-tier, policy-driven block cache.

Blocks are stored across three tiers (Cold → Warm → Hot) and migrate upward based on access frequency thresholds and downward via explicit demote calls or administrator policy.

Fields

config: BcmCacheConfig

Cache configuration.

hot: HashMap<String, BcmCachedBlock>

warm: HashMap<String, BcmCachedBlock>

cold: HashMap<String, BcmCachedBlock>

Implementations

impl BlockCacheManager

pub fn new(config: BcmCacheConfig) -> Self

Create a new BlockCacheManager with the given configuration.

pub fn insert(&mut self, cid: String, data: Vec<u8>, now: u64) -> bool

Insert a block into the Cold tier.

Returns false if the CID is already present in any tier. If the Cold tier is full, attempts eviction before inserting.

pub fn get(&mut self, cid: &str, now: u64) -> Option<&[u8]>

Return a reference to the block data, or None if not present.

Updates access_count and last_accessed, then checks whether the block should be promoted to a higher tier.

pub fn pin(&mut self, cid: &str) -> bool

Mark a block as pinned so it cannot be evicted. Returns false if not found.

pub fn unpin(&mut self, cid: &str) -> bool

Remove the pin from a block, allowing it to be evicted again. Returns false if not found.

pub fn evict_to_fit( &mut self, tier: CacheTier, needed_bytes: u64, now: u64, ) -> u64

Evict unpinned blocks from tier until at least needed_bytes have been freed.

Returns the total number of bytes actually freed. Pinned blocks are never evicted; if only pinned blocks remain, eviction stops early.

pub fn promote(&mut self, cid: &str, now: u64)

Check whether the block identified by cid should be promoted to a higher tier based on its current access_count, and move it if so.

Promotion chain:

• Cold → Warm if access_count >= warm_threshold
• Warm → Hot if access_count >= hot_threshold

pub fn demote(&mut self, cid: &str, now: u64)

Move a block one tier down. Has no effect if the block is in Cold tier or not found.

pub fn total_hot_bytes(&self) -> u64

Total bytes used by the Hot tier.

pub fn total_warm_bytes(&self) -> u64

Total bytes used by the Warm tier.

pub fn total_cold_bytes(&self) -> u64

Total bytes used by the Cold tier.

pub fn total_bytes(&self) -> u64

Total bytes across all tiers.

pub fn len(&self) -> usize

Total number of blocks across all tiers.

pub fn is_empty(&self) -> bool

true if no blocks are currently cached.

pub fn remove(&mut self, cid: &str) -> bool

Remove a block from the cache, regardless of tier.

Returns false if the block is pinned or not found.

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

Return true if the CID is cached in any tier.

pub fn tier_of(&self, cid: &str) -> Option<CacheTier>

Return which tier the block lives in, or None if not cached.

pub fn stats(&self) -> BcmCacheStats

Snapshot of current cache statistics.

Trait Implementations

impl Debug for BlockCacheManager

fn fmt(&self, f: &mut Formatter<'_>) -> Result

Formats the value using the given formatter.