MicroCache

Overview

MicroCache is a lightweight, in-memory caching library for Java with TTL (Time-To-Live), LRU (Least Recently Used) eviction, asynchronous loading, and optional disk persistence.

Features

• ✅ Thread-safe caching using ConcurrentHashMap.
• ⏳ TTL Support - Set expiration times for cached values.
• ♻️ LRU Eviction - Automatically removes least recently used items when cache is full.
• 🚀 Async Data Loading - Fetch missing values asynchronously.
• 💾 Persistence Option - Save and reload cache from disk.
• 📊 Memory Usage Monitoring - Track cache impact on memory.

Installation

Clone the repository and include the MicroCache.java file in your project.

Usage

Creating a Cache

MicroCache<String, String> cache = new MicroCache<>(
    key -> System.out.println("Expired: " + key),
    key -> "Loaded async value for " + key,
    100,  // Max size
    "cache_data.ser",  // Persistence file
    true  // Enable persistence
);

Adding and Retrieving Values

cache.put("key1", "value1", 5000); // Store value with 5s TTL
System.out.println(cache.get("key1")); // Retrieves value

Expiration Handling

Thread.sleep(6000);
System.out.println(cache.get("key1")); // Should return null (expired)

Performance Testing

long start = System.nanoTime();
for (int i = 0; i < 100000; i++) {
    cache.put("key" + i, "value" + i, 5000);
}
long end = System.nanoTime();
System.out.println("Insertion time: " + (end - start) / 1_000_000 + " ms");
System.out.println("Memory usage: " + MicroCache.getMemoryUsage() + " MB");

Configuration Options

Parameter	Description
maxSize	Max cache capacity before eviction occurs
ttlMillis	Time-to-live for cache entries (ms)
persistenceEnabled	Enable/disable disk persistence
asyncLoaderFunction	Function to load missing values asynchronously

License

MIT License. Free to use and modify.

Contributing

Feel free to submit PRs or report issues!