amberjs 1.17.0

// Edge Caching Strategy
// Multi-layer intelligent caching for optimal performance

use std::collections::{BTreeMap, HashMap};
use std::sync::{Arc, Mutex, RwLock};
use tokio::time::{TokioDuration, TokioInstant};
use anyhow::{Result, Error};
use std::time::{Duration, Instant};
use std::time::SystemTime;

/// Multi-layer edge cache
#[derive(Debug)]
pub struct EdgeCache {
    name: String,
    l1_cache: Arc<RwLock<L1Cache>>,          // L1: Edge node cache (fastest)
    l2_cache: Arc<RwLock<L2Cache>>,          // L2: Regional cache
    l3_cache: Arc<RwLock<L3Cache>>,          // L3: Central data center
    predictor: Arc<RwLock<CachePredictor>>,   // AI-powered prediction
    stats: Arc<RwLock<CacheStats>>,
}
#[derive(Debug)]
struct L1Cache {
    capacity: usize,
    data: HashMap<String, CacheEntry>,
    access_order: Vec<String>, // LRU tracking
}
#[derive(Debug, Clone)]
struct CacheEntry {
    key: String,
    value: Vec<u8>,
    timestamp: std::time::SystemTime,
    ttl: Duration,
    access_count: u64,
}
#[derive(Debug)]
struct L2Cache {
    region: String,
    capacity: usize,
    data: HashMap<String, CacheEntry>,
}
#[derive(Debug)]
struct L3Cache {
    endpoint: String,
    capacity: usize,
    data: HashMap<String, CacheEntry>,
}
#[derive(Debug)]
struct CachePredictor {
    access_patterns: HashMap<String, Vec<String>>,
    predictions: HashMap<String, Vec<String>>,
}
#[derive(Debug, Clone)]
pub struct CacheStats {
    pub l1_hits: u64,
    pub l1_misses: u64,
    pub l2_hits: u64,
    pub l2_misses: u64,
    pub l3_hits: u64,
    pub l3_misses: u64,
    pub total_operations: u64,
    pub hit_ratio: f64,
}
impl EdgeCache {
    /// Create a new edge cache with specified layers
    pub fn new(name: &str, l1_capacity: usize) -> Result<Self> {
        Ok(EdgeCache {
            name: name.to_string(),
            l1_cache: Arc::new(Mutex::new(L1Cache::new(l1_capacity)))
            l2_cache: Arc::new(Mutex::new(L2Cache::new("regional", l1_capacity * 10)),?)),
            l3_cache: Arc::new(Mutex::new(L3Cache::new("central", l1_capacity * 100)),?)),
            predictor: Arc::new(Mutex::new(CachePredictor::new()))
            stats: Arc::new(Mutex::new(CacheStats {)),
                l1_hits: 0,
                l1_misses: 0,
                l2_hits: 0,
                l2_misses: 0,
                l3_hits: 0,
                l3_misses: 0,
                total_operations: 0,
                hit_ratio: 0.0,
            }))
        })
    }
    /// Set a value in the cache
    pub async fn set(&self, key: &str, value: &[u8]) -> Result<()> {
        let entry: _ = CacheEntry {
            key: key.to_string(),
            value: value.to_vec(),
            timestamp: std::time::SystemTime::now(),
            ttl: Duration::from_secs(300), // 5 minutes default TTL
            access_count: 0,
        };
        // Try L1 cache first
        {
            let mut l1 = self.l1_cache.write().await;
            if let Err(_) = l1.insert(key, entry.clone()) {
                // L1 is full, need to evict
                l1.evict_lru();
                l1.insert(key, entry.clone())?;
            }
        }
        // Also store in L2
        {
            let mut l2 = self.l2_cache.write().await;
            let _: _ = l2.insert(key, entry.clone());
        }
        // Also store in L3
        {
            let mut l3 = self.l3_cache.write().await;
            let _: _ = l3.insert(key, entry.clone());
        }
        Ok(())
    }
    /// Get a value from the cache (multi-layer)
    pub async fn get(&self, key: &str) -> Result<Option<Vec<u8> {
        let _start: _ = Instant::now();
        // Try L1 cache first
        {
            let mut l1 = self.l1_cache.write().await;
            if let Some(entry) = l1.get(key)? {
                // Update stats
                self.update_stats(true, true, false, false, false, false).await;
                // Record access pattern for prediction
                {
                    let mut predictor = self.predictor.write().await;
                    predictor.record_access(key);
                }
                return Ok(Some(entry.value));
            }
        }
        // L1 miss, try L2
        {
            let mut l2 = self.l2_cache.write().await;
            if let Some(entry) = l2.get(key)? {
                // Promote to L1
                {
                    let mut l1 = self.l1_cache.write().await;
                    let _: _ = l1.insert(key, entry.clone());
                }
                // Update stats
                self.update_stats(false, false, true, false, false, false).await;
                return Ok(Some(entry.value));
            }
        }
        // L2 miss, try L3
        {
            let mut l3 = self.l3_cache.write().await;
            if let Some(entry) = l3.get(key)? {
                // Promote to L2 and L1
                {
                    let mut l2 = self.l2_cache.write().await;
                    let _: _ = l2.insert(key, entry.clone());
                }
                {
                    let mut l1 = self.l1_cache.write().await;
                    let _: _ = l1.insert(key, entry.clone());
                }
                // Update stats
                self.update_stats(false, false, false, false, true, false).await;
                return Ok(Some(entry.value));
            }
        }
        // Cache miss at all levels
        self.update_stats(false, false, false, false, false, true).await;
        Ok(None)
    }
    /// Invalidate a specific key
    pub async fn invalidate(&self, key: &str) -> Result<()> {
        // Remove from all layers
        {
            let mut l1 = self.l1_cache.write().await;
            let _: _ = l1.remove(key);
        }
        {
            let mut l2 = self.l2_cache.write().await;
            let _: _ = l2.remove(key);
        }
        {
            let mut l3 = self.l3_cache.write().await;
            let _: _ = l3.remove(key);
        }
        Ok(())
    }
    /// Get cache statistics
    pub async fn get_stats(&self) -> Result<CacheStats> {
        let stats: _ = self.stats.read().await;
        Ok(stats.clone())
    }
    /// Update cache statistics
    async fn update_stats(
        &self,
        l1_hit: bool,
        l1_miss: bool,
        l2_hit: bool,
        l2_miss: bool,
        l3_hit: bool,
        l3_miss: bool,
    ) {
        let mut stats = self.stats.write().await;
        stats.total_operations += 1;
        if l1_hit { stats.l1_hits += 1; }
        if l1_miss { stats.l1_misses += 1; }
        if l2_hit { stats.l2_hits += 1; }
        if l2_miss { stats.l2_misses += 1; }
        if l3_hit { stats.l3_hits += 1; }
        if l3_miss { stats.l3_misses += 1; }
        // Calculate hit ratio
        let total_hits: _ = stats.l1_hits + stats.l2_hits + stats.l3_hits;
        stats.hit_ratio = if stats.total_operations > 0 {
            total_hits as f64 / stats.total_operations as f64
        } else {
            0.0
        };
    }
    /// Clear all caches
    pub async fn clear(&self) -> Result<()> {
        {
            let mut l1 = self.l1_cache.write().await;
            l1.clear();
        }
        {
            let mut l2 = self.l2_cache.write().await;
            l2.clear();
        }
        {
            let mut l3 = self.l3_cache.write().await;
            l3.clear();
        }
        Ok(())
    }
    /// Preload frequently accessed items
    pub async fn preload(&self, keys: &[String]) -> Result<()> {
        for key in keys {
            // Check if key exists, if not we might want to fetch it
            let _: _ = self.get(key).await;
        }
        Ok(())
    }
}
/// L1 Cache Implementation (Edge Node)
impl L1Cache {
    fn new(capacity: usize) -> Self {
        L1Cache {
            capacity,
            data: HashMap::new(),
            access_order: Vec::new(),
        }
    }
    fn insert(&mut self, key: &str, entry: CacheEntry) -> Result<()> {
        if self.data.len() >= self.capacity && !self.data.contains_key(key) {
            return Err(anyhow::anyhow!("Cache is full"));
        }
        self.data.insert(key.to_string(), entry);
        self.update_access_order(key);
        Ok(())
    }
    fn get(&mut self, key: &str) -> Result<Option<CacheEntry>> {
        if let Some(entry) = self.data.get_mut(key) {
            entry.access_count += 1;
        }
        self.update_access_order(key);
        Ok(self.data.get(key).cloned())
    }
    fn remove(&mut self, key: &str) -> Result<()> {
        self.data.remove(key);
        self.access_order.retain(|k| k != key);
        Ok(())
    }
    fn update_access_order(&mut self, key: &str) {
        self.access_order.retain(|k| k != key);
        self.access_order.push(key.to_string());
    }
    fn evict_lru(&mut self) {
        if let Some(lru_key) = self.access_order.first().cloned() {
            self.data.remove(&lru_key);
            self.access_order.remove(0);
        }
    }
    fn clear(&mut self) {
        self.data.clear();
        self.access_order.clear();
    }
}
/// L2 Cache Implementation (Regional)
impl L2Cache {
    fn new(region: &str, capacity: usize) -> Result<Self> {
        Ok(L2Cache {
            region: region.to_string(),
            capacity,
            data: HashMap::new(),
        })
    }
    fn insert(&mut self, key: &str, entry: CacheEntry) -> Result<()> {
        if self.data.len() >= self.capacity {
            // Simple eviction: remove oldest entry
            let oldest_key: _ = self.data.keys().next().unwrap().clone();
            self.data.remove(&oldest_key);
        }
        self.data.insert(key.to_string(), entry);
        Ok(())
    }
    fn get(&mut self, key: &str) -> Result<Option<CacheEntry>> {
        Ok(self.data.get(key).cloned())
    }
    fn remove(&mut self, key: &str) -> Result<()> {
        self.data.remove(key);
        Ok(())
    }
    fn clear(&mut self) {
        self.data.clear();
    }
}
/// L3 Cache Implementation (Central Data Center)
impl L3Cache {
    fn new(endpoint: &str, capacity: usize) -> Result<Self> {
        Ok(L3Cache {
            endpoint: endpoint.to_string(),
            capacity,
            data: HashMap::new(),
        })
    }
    fn insert(&mut self, key: &str, entry: CacheEntry) -> Result<()> {
        if self.data.len() >= self.capacity {
            // LRU eviction
            let oldest_key: _ = self.data.keys().next().unwrap().clone();
            self.data.remove(&oldest_key);
        }
        self.data.insert(key.to_string(), entry);
        Ok(())
    }
    fn get(&mut self, key: &str) -> Result<Option<CacheEntry>> {
        Ok(self.data.get(key).cloned())
    }
    fn remove(&mut self, key: &str) -> Result<()> {
        self.data.remove(key);
        Ok(())
    }
    fn clear(&mut self) {
        self.data.clear();
    }
}
/// Cache Predictor for intelligent preloading
impl CachePredictor {
    fn new() -> Self {
        CachePredictor {
            access_patterns: HashMap::new(),
            predictions: HashMap::new(),
        }
    }
    fn record_access(&mut self, key: &str) {
        // Record access pattern
        let pattern: _ = self.access_patterns.entry(key.to_string()).or_insert_with(Vec::new);
        pattern.push(format!("access-{}", std::time::SystemTime::now()
            .duration_since(std::time::UNIX_EPOCH).unwrap().as_secs());
        // Keep only last 100 accesses
        if pattern.len() > 100 {
            pattern.remove(0);
        }
    }
    fn predict(&mut self, recent_accesses: &[String]) -> Result<Vec<String> {
        let mut predictions = Vec::new();
        // Simple prediction: if keys are accessed together, predict they will be accessed together
        for key in recent_accesses {
            if let Some(pattern) = self.access_patterns.get(key) {
                // Extract patterns and make predictions
                predictions.push(key.clone());
            }
        }
        Ok(predictions)
    }
}
#[cfg(test)]
mod tests {
    #[tokio::test]
    async fn test_edge_cache_creation() {
        let cache: _ = EdgeCache::new("test-cache", 100);
        assert!(cache.is_ok());
    }
    #[tokio::test]
    async fn test_l1_cache_set_get() {
        let cache: _ = EdgeCache::new("test-cache", 100).unwrap();
        cache.set("key1", b"value1").await.unwrap();
        let result: _ = cache.get("key1").await.unwrap();
        assert_eq!(result, Some(b"value1".to_vec());
    }
    #[tokio::test]
    async fn test_cache_invalidation() {
        let cache: _ = EdgeCache::new("test-cache", 100).unwrap();
        cache.set("key1", b"value1").await.unwrap();
        cache.invalidate("key1").await.unwrap();
        let result: _ = cache.get("key1").await.unwrap();
        assert_eq!(result, None);
    }
    #[tokio::test]
    async fn test_cache_hit_ratio() {
        let cache: _ = EdgeCache::new("test-cache", 100).unwrap();
        // Add items to cache
        for i in 0..100 {
            cache.set(&format!("key_{}", i), b"value").await.unwrap();
        }
        // Access items
        for i in 0..100 {
            cache.get(&format!("key_{}", i)).await.unwrap();
        }
        let stats: _ = cache.get_stats().await.unwrap();
        assert!(stats.hit_ratio > 0.95);
    }
    #[tokio::test]
    async fn test_multi_layer_cache() {
        let cache: _ = EdgeCache::new("test-cache", 10).unwrap();
        // Set a value
        cache.set("test-key", b"test-value").await.unwrap();
        // Get from L1
        let result1: _ = cache.get("test-key").await.unwrap();
        assert!(result1.is_some());
        // Clear L1 and get from L2
        {
            let mut l1 = cache.l1_cache.write().await;
            l1.clear();
        }
        let result2: _ = cache.get("test-key").await.unwrap();
        assert!(result2.is_some());
    }
    #[tokio::test]
    async fn test_cache_predictor() {
        let cache: _ = EdgeCache::new("test-cache", 100).unwrap();
        // Record access patterns
        cache.set("user_1", b"data").await.unwrap();
        cache.set("user_2", b"data").await.unwrap();
        // Access patterns might predict future accesses
        let recent: _ = vec!["user_1".to_string(), "user_2".to_string()];
        let predictions: _ = cache.predictor.write().await.predict(&recent);
        assert!(predictions.is_ok());
    }
    #[tokio::test]
    async fn test_cache_performance() {
        let cache: _ = EdgeCache::new("test-cache", 1000).unwrap();
        let start: _ = Instant::now();
        for i in 0..1000 {
            cache.set(&format!("key_{}", i), b"value").await.unwrap();
        }
        let set_time: _ = start.elapsed();
        let get_start: _ = Instant::now();
        for i in 0..1000 {
            cache.get(&format!("key_{}", i)).await.unwrap();
        }
        let get_time: _ = get_start.elapsed();
        // Use more lenient timeouts for CI environments
        assert!(set_time.as_millis() < 500, "Set operation took too long: {}ms", set_time.as_millis());
        assert!(get_time.as_millis() < 200, "Get operation took too long: {}ms", get_time.as_millis());
    }
    #[tokio::test]
    async fn test_concurrent_cache_access() {
        let cache: _ = Arc::new(Mutex::new(EdgeCache::new("test-cache", 1000)),.unwrap());
        let mut handles = vec![];
        for i in 0..10 {
            let cache_clone: _ = Arc::clone(cache);
            let handle: _ = tokio::spawn(async move {
                for j in 0..100 {
                    let key: _ = format!("concurrent_key_{}_{}, i", j));
                    cache_clone.set(&key, b"value").await.unwrap();
                    cache_clone.get(&key).await.unwrap();
                }
            });
            handles.push(handle);
        }
        for handle in handles {
            handle.await.unwrap();
        }
        let stats: _ = cache.get_stats().await.unwrap();
        assert!(stats.total_operations >= 1000);  // Expect at least 1000 operations (10 tasks * 100 ops)
    }
}