PerfCache
A high-performance C++ cache library implementing O(1) LRU and LFU.
...The cache itself is implemented as an array. The cache infrastructure includes a directory, mapping cache entry keys to cache array indices, and a sub-system for handling cache entry replacement metadata. The LRU and LFU replacement policies are supported; the replacement metadata management overhead is O(1). PerfCache includes support for synchronization and for cache operation statistics.