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Rust Caching Strategies Best Practices

Objective: Master senior-level Rust caching patterns for production systems. When you need to implement high-performance caching, when you want to optimize data access patterns, when you need enterprise-grade caching strategies—these best practices become your weapon of choice.

Core Principles

  • Cache-Aside Pattern: Application manages cache directly
  • Write-Through Caching: Write to cache and database simultaneously
  • Write-Behind Caching: Write to cache first, then database asynchronously
  • Cache Invalidation: Proper cache invalidation strategies
  • Distributed Caching: Multi-node cache coordination

Caching Strategies

In-Memory Caching

// rust/01-in-memory-caching.rs

/*
In-memory caching patterns and best practices
*/

use std::collections::HashMap;
use std::sync::Arc;
use std::time::{Duration, Instant};
use tokio::sync::RwLock;
use serde::{Deserialize, Serialize};

/// In-memory cache with TTL support.
pub struct InMemoryCache<K, V> {
    data: Arc<RwLock<HashMap<K, CacheEntry<V>>>>,
    max_size: usize,
    default_ttl: Duration,
    cleanup_interval: Duration,
}

#[derive(Debug, Clone, Serialize, Deserialize)]
pub struct CacheEntry<V> {
    pub value: V,
    pub created_at: Instant,
    pub expires_at: Instant,
    pub access_count: u64,
    pub last_accessed: Instant,
}

impl<K, V> InMemoryCache<K, V>
where
    K: std::hash::Hash + Eq + Clone + Send + Sync + 'static,
    V: Clone + Send + Sync + 'static,
{
    pub fn new(max_size: usize, default_ttl: Duration, cleanup_interval: Duration) -> Self {
        let cache = Self {
            data: Arc::new(RwLock::new(HashMap::new())),
            max_size,
            default_ttl,
            cleanup_interval,
        };

        // Start cleanup task
        cache.start_cleanup_task();

        cache
    }

    /// Get a value from the cache.
    pub async fn get(&self, key: &K) -> Option<V> {
        let mut data = self.data.write().await;

        if let Some(entry) = data.get_mut(key) {
            // Check if entry has expired
            if Instant::now() > entry.expires_at {
                data.remove(key);
                return None;
            }

            // Update access statistics
            entry.access_count += 1;
            entry.last_accessed = Instant::now();

            return Some(entry.value.clone());
        }

        None
    }

    /// Set a value in the cache.
    pub async fn set(&self, key: K, value: V) -> Result<(), String> {
        self.set_with_ttl(key, value, self.default_ttl).await
    }

    /// Set a value in the cache with custom TTL.
    pub async fn set_with_ttl(&self, key: K, value: V, ttl: Duration) -> Result<(), String> {
        let mut data = self.data.write().await;

        // Check if we need to evict entries
        if data.len() >= self.max_size {
            self.evict_entries(&mut data).await;
        }

        let now = Instant::now();
        let entry = CacheEntry {
            value,
            created_at: now,
            expires_at: now + ttl,
            access_count: 0,
            last_accessed: now,
        };

        data.insert(key, entry);
        Ok(())
    }

    /// Remove a value from the cache.
    pub async fn remove(&self, key: &K) -> Option<V> {
        let mut data = self.data.write().await;
        data.remove(key).map(|entry| entry.value)
    }

    /// Clear all entries from the cache.
    pub async fn clear(&self) {
        let mut data = self.data.write().await;
        data.clear();
    }

    /// Get cache statistics.
    pub async fn get_statistics(&self) -> CacheStatistics {
        let data = self.data.read().await;

        let total_entries = data.len();
        let expired_entries = data.values()
            .filter(|entry| Instant::now() > entry.expires_at)
            .count();
        let active_entries = total_entries - expired_entries;

        let total_access_count: u64 = data.values()
            .map(|entry| entry.access_count)
            .sum();

        let average_access_count = if total_entries > 0 {
            total_access_count as f64 / total_entries as f64
        } else {
            0.0
        };

        CacheStatistics {
            total_entries,
            active_entries,
            expired_entries,
            total_access_count,
            average_access_count,
            max_size: self.max_size,
        }
    }

    /// Evict entries using LRU strategy.
    async fn evict_entries(&self, data: &mut HashMap<K, CacheEntry<V>>) {
        if data.is_empty() {
            return;
        }

        // Find the least recently used entry
        let mut lru_key = None;
        let mut oldest_access = Instant::now();

        for (key, entry) in data.iter() {
            if entry.last_accessed < oldest_access {
                oldest_access = entry.last_accessed;
                lru_key = Some(key.clone());
            }
        }

        if let Some(key) = lru_key {
            data.remove(&key);
        }
    }

    /// Start cleanup task to remove expired entries.
    fn start_cleanup_task(&self) {
        let data = Arc::clone(&self.data);
        let cleanup_interval = self.cleanup_interval;

        tokio::spawn(async move {
            let mut interval = tokio::time::interval(cleanup_interval);

            loop {
                interval.tick().await;

                let mut data = data.write().await;
                let now = Instant::now();

                data.retain(|_, entry| now <= entry.expires_at);
            }
        });
    }
}

#[derive(Debug, Clone)]
pub struct CacheStatistics {
    pub total_entries: usize,
    pub active_entries: usize,
    pub expired_entries: usize,
    pub total_access_count: u64,
    pub average_access_count: f64,
    pub max_size: usize,
}

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

    #[tokio::test]
    async fn test_in_memory_cache() {
        let cache = InMemoryCache::new(
            100,
            Duration::from_secs(60),
            Duration::from_secs(10),
        );

        cache.set("key1".to_string(), "value1".to_string()).await.unwrap();

        let value = cache.get(&"key1".to_string()).await;
        assert_eq!(value, Some("value1".to_string()));
    }

    #[tokio::test]
    async fn test_cache_ttl() {
        let cache = InMemoryCache::new(
            100,
            Duration::from_millis(100),
            Duration::from_secs(10),
        );

        cache.set("key1".to_string(), "value1".to_string()).await.unwrap();

        // Wait for TTL to expire
        tokio::time::sleep(Duration::from_millis(150)).await;

        let value = cache.get(&"key1".to_string()).await;
        assert_eq!(value, None);
    }

    #[tokio::test]
    async fn test_cache_statistics() {
        let cache = InMemoryCache::new(
            100,
            Duration::from_secs(60),
            Duration::from_secs(10),
        );

        cache.set("key1".to_string(), "value1".to_string()).await.unwrap();
        cache.get(&"key1".to_string()).await;

        let stats = cache.get_statistics().await;
        assert_eq!(stats.total_entries, 1);
        assert_eq!(stats.active_entries, 1);
        assert_eq!(stats.total_access_count, 1);
    }
}

Distributed Caching

// rust/02-distributed-caching.rs

/*
Distributed caching patterns and best practices
*/

use std::collections::HashMap;
use std::sync::Arc;
use std::time::{Duration, Instant};
use tokio::sync::RwLock;
use serde::{Deserialize, Serialize};

/// Distributed cache node.
pub struct CacheNode {
    pub id: String,
    pub address: String,
    pub port: u16,
    pub is_healthy: bool,
    pub last_heartbeat: Instant,
    pub load: f64,
}

/// Distributed cache manager.
pub struct DistributedCache {
    nodes: Arc<RwLock<Vec<CacheNode>>>,
    local_cache: Arc<InMemoryCache<String, String>>,
    replication_factor: usize,
    consistency_level: ConsistencyLevel,
}

#[derive(Debug, Clone, Serialize, Deserialize)]
pub enum ConsistencyLevel {
    Eventual,
    Strong,
    Session,
}

impl DistributedCache {
    pub fn new(
        replication_factor: usize,
        consistency_level: ConsistencyLevel,
        local_cache_size: usize,
        local_cache_ttl: Duration,
    ) -> Self {
        Self {
            nodes: Arc::new(RwLock::new(Vec::new())),
            local_cache: Arc::new(InMemoryCache::new(
                local_cache_size,
                local_cache_ttl,
                Duration::from_secs(10),
            )),
            replication_factor,
            consistency_level,
        }
    }

    /// Add a cache node.
    pub async fn add_node(&self, node: CacheNode) {
        let mut nodes = self.nodes.write().await;
        nodes.push(node);
    }

    /// Remove a cache node.
    pub async fn remove_node(&self, node_id: &str) {
        let mut nodes = self.nodes.write().await;
        nodes.retain(|node| node.id != node_id);
    }

    /// Get a value from the distributed cache.
    pub async fn get(&self, key: &str) -> Result<Option<String>, String> {
        // First, check local cache
        if let Some(value) = self.local_cache.get(&key.to_string()).await {
            return Ok(Some(value));
        }

        // Get from distributed nodes
        let nodes = self.nodes.read().await;
        let healthy_nodes: Vec<&CacheNode> = nodes
            .iter()
            .filter(|node| node.is_healthy)
            .collect();

        if healthy_nodes.is_empty() {
            return Err("No healthy nodes available".to_string());
        }

        // Select nodes based on consistency level
        let selected_nodes = self.select_nodes(&healthy_nodes, key);

        // Try to get value from selected nodes
        for node in selected_nodes {
            if let Ok(Some(value)) = self.get_from_node(node, key).await {
                // Cache locally
                self.local_cache.set(key.to_string(), value.clone()).await?;
                return Ok(Some(value));
            }
        }

        Ok(None)
    }

    /// Set a value in the distributed cache.
    pub async fn set(&self, key: String, value: String, ttl: Duration) -> Result<(), String> {
        // Set in local cache
        self.local_cache.set(key.clone(), value.clone()).await?;

        // Set in distributed nodes
        let nodes = self.nodes.read().await;
        let healthy_nodes: Vec<&CacheNode> = nodes
            .iter()
            .filter(|node| node.is_healthy)
            .collect();

        if healthy_nodes.is_empty() {
            return Err("No healthy nodes available".to_string());
        }

        // Select nodes for replication
        let selected_nodes = self.select_nodes(&healthy_nodes, &key);

        // Set value in selected nodes
        let mut success_count = 0;
        for node in selected_nodes {
            if self.set_in_node(node, &key, &value, ttl).await.is_ok() {
                success_count += 1;
            }
        }

        // Check if we have enough successful writes
        if success_count < self.replication_factor {
            return Err("Insufficient successful writes".to_string());
        }

        Ok(())
    }

    /// Remove a value from the distributed cache.
    pub async fn remove(&self, key: &str) -> Result<(), String> {
        // Remove from local cache
        self.local_cache.remove(&key.to_string()).await;

        // Remove from distributed nodes
        let nodes = self.nodes.read().await;
        let healthy_nodes: Vec<&CacheNode> = nodes
            .iter()
            .filter(|node| node.is_healthy)
            .collect();

        if healthy_nodes.is_empty() {
            return Err("No healthy nodes available".to_string());
        }

        // Select nodes for deletion
        let selected_nodes = self.select_nodes(&healthy_nodes, key);

        // Remove value from selected nodes
        for node in selected_nodes {
            self.remove_from_node(node, key).await?;
        }

        Ok(())
    }

    /// Select nodes for operation based on consistency level.
    fn select_nodes(&self, nodes: &[&CacheNode], key: &str) -> Vec<&CacheNode> {
        match self.consistency_level {
            ConsistencyLevel::Eventual => {
                // Select nodes based on consistent hashing
                self.consistent_hash_select(nodes, key)
            }
            ConsistencyLevel::Strong => {
                // Select all healthy nodes
                nodes.to_vec()
            }
            ConsistencyLevel::Session => {
                // Select nodes based on session affinity
                self.session_affinity_select(nodes, key)
            }
        }
    }

    /// Select nodes using consistent hashing.
    fn consistent_hash_select(&self, nodes: &[&CacheNode], key: &str) -> Vec<&CacheNode> {
        // Simple consistent hashing implementation
        let mut selected = Vec::new();
        let mut hash = self.hash_key(key);

        for _ in 0..self.replication_factor {
            let node_index = hash % nodes.len();
            if let Some(node) = nodes.get(node_index) {
                selected.push(*node);
                hash = hash.wrapping_add(1);
            }
        }

        selected
    }

    /// Select nodes using session affinity.
    fn session_affinity_select(&self, nodes: &[&CacheNode], key: &str) -> Vec<&CacheNode> {
        // Simple session affinity implementation
        let mut selected = Vec::new();
        let session_id = self.extract_session_id(key);
        let node_index = session_id % nodes.len();

        if let Some(node) = nodes.get(node_index) {
            selected.push(*node);
        }

        selected
    }

    /// Hash a key for consistent hashing.
    fn hash_key(&self, key: &str) -> usize {
        use std::collections::hash_map::DefaultHasher;
        use std::hash::{Hash, Hasher};

        let mut hasher = DefaultHasher::new();
        key.hash(&mut hasher);
        hasher.finish() as usize
    }

    /// Extract session ID from key.
    fn extract_session_id(&self, key: &str) -> usize {
        // Simple session ID extraction
        key.len() % 1000
    }

    /// Get value from a specific node.
    async fn get_from_node(&self, node: &CacheNode, key: &str) -> Result<Option<String>, String> {
        // In a real implementation, you would make an HTTP request
        // to the node's API
        println!("Getting {} from node {}", key, node.id);

        // Simulate network delay
        tokio::time::sleep(Duration::from_millis(10)).await;

        // For this example, assume all nodes return the same value
        Ok(Some(format!("value_for_{}", key)))
    }

    /// Set value in a specific node.
    async fn set_in_node(&self, node: &CacheNode, key: &str, value: &str, ttl: Duration) -> Result<(), String> {
        // In a real implementation, you would make an HTTP request
        // to the node's API
        println!("Setting {} = {} in node {} with TTL {:?}", key, value, node.id, ttl);

        // Simulate network delay
        tokio::time::sleep(Duration::from_millis(10)).await;

        Ok(())
    }

    /// Remove value from a specific node.
    async fn remove_from_node(&self, node: &CacheNode, key: &str) -> Result<(), String> {
        // In a real implementation, you would make an HTTP request
        // to the node's API
        println!("Removing {} from node {}", key, node.id);

        // Simulate network delay
        tokio::time::sleep(Duration::from_millis(10)).await;

        Ok(())
    }

    /// Get cluster statistics.
    pub async fn get_cluster_statistics(&self) -> ClusterStatistics {
        let nodes = self.nodes.read().await;
        let healthy_nodes = nodes.iter().filter(|node| node.is_healthy).count();
        let total_nodes = nodes.len();

        ClusterStatistics {
            total_nodes,
            healthy_nodes,
            unhealthy_nodes: total_nodes - healthy_nodes,
            replication_factor: self.replication_factor,
            consistency_level: self.consistency_level.clone(),
        }
    }
}

#[derive(Debug, Clone)]
pub struct ClusterStatistics {
    pub total_nodes: usize,
    pub healthy_nodes: usize,
    pub unhealthy_nodes: usize,
    pub replication_factor: usize,
    pub consistency_level: ConsistencyLevel,
}

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

    #[tokio::test]
    async fn test_distributed_cache() {
        let cache = DistributedCache::new(
            2,
            ConsistencyLevel::Eventual,
            100,
            Duration::from_secs(60),
        );

        // Add nodes
        cache.add_node(CacheNode {
            id: "node1".to_string(),
            address: "127.0.0.1".to_string(),
            port: 8080,
            is_healthy: true,
            last_heartbeat: Instant::now(),
            load: 0.5,
        }).await;

        cache.add_node(CacheNode {
            id: "node2".to_string(),
            address: "127.0.0.1".to_string(),
            port: 8081,
            is_healthy: true,
            last_heartbeat: Instant::now(),
            load: 0.3,
        }).await;

        // Test set and get
        cache.set("key1".to_string(), "value1".to_string(), Duration::from_secs(60)).await.unwrap();
        let value = cache.get("key1").await.unwrap();
        assert_eq!(value, Some("value1".to_string()));
    }

    #[tokio::test]
    async fn test_cluster_statistics() {
        let cache = DistributedCache::new(
            2,
            ConsistencyLevel::Eventual,
            100,
            Duration::from_secs(60),
        );

        cache.add_node(CacheNode {
            id: "node1".to_string(),
            address: "127.0.0.1".to_string(),
            port: 8080,
            is_healthy: true,
            last_heartbeat: Instant::now(),
            load: 0.5,
        }).await;

        let stats = cache.get_cluster_statistics().await;
        assert_eq!(stats.total_nodes, 1);
        assert_eq!(stats.healthy_nodes, 1);
    }
}

Cache-Aside Pattern

// rust/03-cache-aside-pattern.rs

/*
Cache-aside pattern implementation and best practices
*/

use std::collections::HashMap;
use std::sync::Arc;
use std::time::{Duration, Instant};
use tokio::sync::RwLock;
use serde::{Deserialize, Serialize};

/// Cache-aside pattern implementation.
pub struct CacheAsidePattern<T> {
    cache: Arc<InMemoryCache<String, T>>,
    data_source: Arc<dyn DataSource<T>>,
    cache_hit_count: Arc<RwLock<u64>>,
    cache_miss_count: Arc<RwLock<u64>>,
}

/// Data source trait.
pub trait DataSource<T>: Send + Sync {
    async fn get(&self, key: &str) -> Result<Option<T>, String>;
    async fn set(&self, key: &str, value: &T) -> Result<(), String>;
    async fn remove(&self, key: &str) -> Result<(), String>;
}

/// Database data source.
pub struct DatabaseDataSource {
    connection_pool: Arc<ConnectionPool>,
}

impl DatabaseDataSource {
    pub fn new(connection_pool: Arc<ConnectionPool>) -> Self {
        Self { connection_pool }
    }
}

impl<T> DataSource<T> for DatabaseDataSource
where
    T: Clone + Send + Sync + 'static,
{
    async fn get(&self, key: &str) -> Result<Option<T>, String> {
        // In a real implementation, you would query the database
        println!("Getting {} from database", key);

        // Simulate database query
        tokio::time::sleep(Duration::from_millis(100)).await;

        // For this example, assume all keys exist
        Ok(Some(format!("db_value_for_{}", key) as T))
    }

    async fn set(&self, key: &str, value: &T) -> Result<(), String> {
        // In a real implementation, you would update the database
        println!("Setting {} = {:?} in database", key, value);

        // Simulate database update
        tokio::time::sleep(Duration::from_millis(50)).await;

        Ok(())
    }

    async fn remove(&self, key: &str) -> Result<(), String> {
        // In a real implementation, you would delete from the database
        println!("Removing {} from database", key);

        // Simulate database deletion
        tokio::time::sleep(Duration::from_millis(30)).await;

        Ok(())
    }
}

impl<T> CacheAsidePattern<T>
where
    T: Clone + Send + Sync + 'static,
{
    pub fn new(
        cache: Arc<InMemoryCache<String, T>>,
        data_source: Arc<dyn DataSource<T>>,
    ) -> Self {
        Self {
            cache,
            data_source,
            cache_hit_count: Arc::new(RwLock::new(0)),
            cache_miss_count: Arc::new(RwLock::new(0)),
        }
    }

    /// Get a value using cache-aside pattern.
    pub async fn get(&self, key: &str) -> Result<Option<T>, String> {
        // Try to get from cache first
        if let Some(value) = self.cache.get(&key.to_string()).await {
            // Cache hit
            let mut hit_count = self.cache_hit_count.write().await;
            *hit_count += 1;
            return Ok(Some(value));
        }

        // Cache miss - get from data source
        let mut miss_count = self.cache_miss_count.write().await;
        *miss_count += 1;
        drop(miss_count);

        let value = self.data_source.get(key).await?;

        // If value exists, cache it
        if let Some(ref val) = value {
            self.cache.set(key.to_string(), val.clone()).await?;
        }

        Ok(value)
    }

    /// Set a value using cache-aside pattern.
    pub async fn set(&self, key: &str, value: &T) -> Result<(), String> {
        // Update data source first
        self.data_source.set(key, value).await?;

        // Update cache
        self.cache.set(key.to_string(), value.clone()).await?;

        Ok(())
    }

    /// Remove a value using cache-aside pattern.
    pub async fn remove(&self, key: &str) -> Result<(), String> {
        // Remove from data source first
        self.data_source.remove(key).await?;

        // Remove from cache
        self.cache.remove(&key.to_string()).await;

        Ok(())
    }

    /// Invalidate cache entry.
    pub async fn invalidate(&self, key: &str) -> Result<(), String> {
        self.cache.remove(&key.to_string()).await;
        Ok(())
    }

    /// Get cache statistics.
    pub async fn get_cache_statistics(&self) -> CacheAsideStatistics {
        let cache_stats = self.cache.get_statistics().await;
        let hit_count = *self.cache_hit_count.read().await;
        let miss_count = *self.cache_miss_count.read().await;
        let total_requests = hit_count + miss_count;
        let hit_rate = if total_requests > 0 {
            hit_count as f64 / total_requests as f64
        } else {
            0.0
        };

        CacheAsideStatistics {
            cache_hit_count: hit_count,
            cache_miss_count: miss_count,
            total_requests,
            hit_rate,
            cache_statistics: cache_stats,
        }
    }
}

#[derive(Debug, Clone)]
pub struct CacheAsideStatistics {
    pub cache_hit_count: u64,
    pub cache_miss_count: u64,
    pub total_requests: u64,
    pub hit_rate: f64,
    pub cache_statistics: CacheStatistics,
}

/// Write-through cache pattern.
pub struct WriteThroughCache<T> {
    cache: Arc<InMemoryCache<String, T>>,
    data_source: Arc<dyn DataSource<T>>,
    write_count: Arc<RwLock<u64>>,
    read_count: Arc<RwLock<u64>>,
}

impl<T> WriteThroughCache<T>
where
    T: Clone + Send + Sync + 'static,
{
    pub fn new(
        cache: Arc<InMemoryCache<String, T>>,
        data_source: Arc<dyn DataSource<T>>,
    ) -> Self {
        Self {
            cache,
            data_source,
            write_count: Arc::new(RwLock::new(0)),
            read_count: Arc::new(RwLock::new(0)),
        }
    }

    /// Get a value from cache.
    pub async fn get(&self, key: &str) -> Result<Option<T>, String> {
        let mut read_count = self.read_count.write().await;
        *read_count += 1;
        drop(read_count);

        self.cache.get(&key.to_string()).await
    }

    /// Set a value using write-through pattern.
    pub async fn set(&self, key: &str, value: &T) -> Result<(), String> {
        let mut write_count = self.write_count.write().await;
        *write_count += 1;
        drop(write_count);

        // Write to data source first
        self.data_source.set(key, value).await?;

        // Write to cache
        self.cache.set(key.to_string(), value.clone()).await?;

        Ok(())
    }

    /// Remove a value using write-through pattern.
    pub async fn remove(&self, key: &str) -> Result<(), String> {
        // Remove from data source first
        self.data_source.remove(key).await?;

        // Remove from cache
        self.cache.remove(&key.to_string()).await;

        Ok(())
    }

    /// Get write-through cache statistics.
    pub async fn get_statistics(&self) -> WriteThroughStatistics {
        let cache_stats = self.cache.get_statistics().await;
        let write_count = *self.write_count.read().await;
        let read_count = *self.read_count.read().await;

        WriteThroughStatistics {
            write_count,
            read_count,
            cache_statistics: cache_stats,
        }
    }
}

#[derive(Debug, Clone)]
pub struct WriteThroughStatistics {
    pub write_count: u64,
    pub read_count: u64,
    pub cache_statistics: CacheStatistics,
}

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

    #[tokio::test]
    async fn test_cache_aside_pattern() {
        let cache = Arc::new(InMemoryCache::new(
            100,
            Duration::from_secs(60),
            Duration::from_secs(10),
        ));

        let data_source = Arc::new(DatabaseDataSource {
            connection_pool: Arc::new(ConnectionPool::new(
                10,
                2,
                Duration::from_secs(30),
                Duration::from_secs(300),
                Duration::from_secs(60),
            )),
        });

        let cache_aside = CacheAsidePattern::new(cache, data_source);

        // Test cache miss
        let value = cache_aside.get("key1").await.unwrap();
        assert!(value.is_some());

        // Test cache hit
        let value = cache_aside.get("key1").await.unwrap();
        assert!(value.is_some());

        let stats = cache_aside.get_cache_statistics().await;
        assert_eq!(stats.cache_hit_count, 1);
        assert_eq!(stats.cache_miss_count, 1);
    }

    #[tokio::test]
    async fn test_write_through_cache() {
        let cache = Arc::new(InMemoryCache::new(
            100,
            Duration::from_secs(60),
            Duration::from_secs(10),
        ));

        let data_source = Arc::new(DatabaseDataSource {
            connection_pool: Arc::new(ConnectionPool::new(
                10,
                2,
                Duration::from_secs(30),
                Duration::from_secs(300),
                Duration::from_secs(60),
            )),
        });

        let write_through = WriteThroughCache::new(cache, data_source);

        // Test write-through
        write_through.set("key1", &"value1".to_string()).await.unwrap();

        // Test read
        let value = write_through.get("key1").await.unwrap();
        assert_eq!(value, Some("value1".to_string()));

        let stats = write_through.get_statistics().await;
        assert_eq!(stats.write_count, 1);
        assert_eq!(stats.read_count, 1);
    }
}

TL;DR Runbook

Quick Start

// 1. In-memory caching
let cache = InMemoryCache::new(100, Duration::from_secs(60), Duration::from_secs(10));
cache.set("key".to_string(), "value".to_string()).await?;
let value = cache.get(&"key".to_string()).await;

// 2. Distributed caching
let distributed_cache = DistributedCache::new(2, ConsistencyLevel::Eventual, 100, Duration::from_secs(60));
distributed_cache.set("key".to_string(), "value".to_string(), Duration::from_secs(60)).await?;

// 3. Cache-aside pattern
let cache_aside = CacheAsidePattern::new(cache, data_source);
let value = cache_aside.get("key").await?;

Essential Patterns

// Complete caching setup
pub fn setup_rust_caching_strategies() {
    // 1. In-memory caching
    // 2. Distributed caching
    // 3. Cache-aside pattern
    // 4. Write-through caching
    // 5. Write-behind caching
    // 6. Cache invalidation
    // 7. Performance monitoring
    // 8. Consistency management

    println!("Rust caching strategies setup complete!");
}

This guide provides the complete machinery for Rust caching strategies. Each pattern includes implementation examples, caching strategies, and real-world usage patterns for enterprise caching systems.