A high-performance, concurrency-safe in-memory cache system with TTL support, persistence, and pluggable LRU & LFU eviction policies.

• Thread-safe caching with fine-grained locking.
• Pluggable eviction strategies (LRU, LFU via factory).
• TTL support with background sweeper.
• Disk persistence via JSON serialization.
• GoogleTest suite for unit and integration testing.
• Benchmarking with Google Benchmark.
• Clean architecture with SOLID principles.
• Configurable via external JSON file.

Exposes a thread-safe key-value cache with support for expiration and disk persistence. Allows switching between eviction strategies at runtime using the factory pattern.

graph TD

    Main[Main.cpp] -->|load config| Factory[EvictionFactory]
    Factory --> Cache[Cache LRU/LFU]
    Cache --> Entry[CacheEntry]
    Cache --> Sweeper[CacheSweeper]
    Cache --> Persistence[PersistenceManager]
    Main --> Logger[Logger]

sequenceDiagram
    participant Main
    participant Cache
    participant Sweeper
    participant Entry

    Main->>Sweeper: Start cleanup thread
    loop every interval
        Sweeper->>Cache: snapshot()
        Sweeper->>Entry: check isExpired()
        alt expired
            Sweeper->>Cache: remove(key)
        end
    end

• put(key, value, ttl)
• get(key)
• remove(key)
• snapshot()

• Eviction strategy implementations
• Backed by unordered_map + list or priority structures

• Encapsulates value, TTL, and access metadata

• Returns the appropriate cache policy at runtime

• Saves and loads cache state as JSON

• Background thread that removes expired keys

• Thread-safe logger with log level control

• Factory – Eviction policy switching
• Strategy – TTL vs non-TTL handling
• Adapter – Persistence via JSON interface
• RAII + Scoped Locking – Safe concurrency

mkdir build && cd build
cmake ..
make

./cacheit

Uses config.json to configure:

{
  "eviction_policy": "LRU",
  "capacity": 50000,
  "default_ttl": 10,
  "sweep_interval_seconds": 5,
  "log_level": "INFO",
  "persistence_file": "cache_dump.json"
}

To run cache benchmarks:

./benchmarks

Output:

BM_Get/50000  20166475 ns  items_per_second=2.47M/s

./tests