Struct BlockAccessOptimizer 

pub struct BlockAccessOptimizer {
    pub config: OptimizerConfig,
    pub recent_window: VecDeque<AccessEvent>,
    pub patterns: HashMap<String, AccessPattern>,
    pub co_access: HashMap<String, HashMap<String, CoAccessPair>>,
    pub total_events: u64,
    pub cache_hit_count: u64,
}

Access-pattern optimizer that learns block co-access patterns, predicts future accesses, and generates prefetch recommendations.

Fields

config: OptimizerConfig

Configuration parameters.

recent_window: VecDeque<AccessEvent>

Sliding window of recent access events (bounded by config.window_size).

patterns: HashMap<String, AccessPattern>

Per-block access statistics.

co_access: HashMap<String, HashMap<String, CoAccessPair>>

Co-access statistics: co_access[cid_a][cid_b].

total_events: u64

Total number of events ever recorded.

cache_hit_count: u64

Number of events that were cache hits.

Implementations

impl BlockAccessOptimizer

pub fn new(config: OptimizerConfig) -> Self

Create a new optimizer with the given configuration.

pub fn with_defaults() -> Self

Create a new optimizer with default configuration.

pub fn record_access(&mut self, event: AccessEvent)

Record a block access event.

This method:

1. Updates the sliding window (evicting the oldest event if necessary).
2. Updates the per-block AccessPattern using EWMA smoothing (α = 0.3).
3. Records co-access pairs with the last 5 events in the window.

pub fn recommend_prefetch(&self, trigger_cid: &str) -> PrefetchRecommendation

Generate a prefetch recommendation for a given trigger CID.

Returns a PrefetchRecommendation even when no candidates meet the threshold (in that case prefetch_cids will be empty and confidence = 0).

pub fn predict_next_access(&self, cid: &str) -> Option<u64>

Predict the next access timestamp (ms) for the given CID.

pub fn hot_blocks(&self, k: usize) -> Vec<&AccessPattern>

Return the top-k hottest blocks by total access count.

pub fn top_co_access_pairs(&self, k: usize) -> Vec<&CoAccessPair>

Return the top-k co-access pairs by co-access count across all CIDs.

pub fn apply_decay(&mut self)

Apply exponential decay to all co-access counts.

Counts are multiplied by pattern_decay_factor and rounded. Pairs whose count drops below 1 are removed.

pub fn cache_hit_rate(&self) -> f64

Overall cache-hit rate across all recorded events.

pub fn optimizer_stats(&self) -> OptimizerStats

Return a snapshot of high-level optimizer statistics.