A lock-free cache invalidation protocol for the atom system

The Automatic Transaction-Oriented Memoization (ATOM) system is a thread-safe memoization tool specifically designed for multi-threaded object-oriented programs. Currently, searching the ATOM's memo cache for a hit is still an expensive operation with linear time complexity. We present a new lock-free cache invalidation protocol for the ATOM that allows multiple threads to concurrently search and invalidate cache entries, resorting to helping from threads to decrease the time spent with cache operations. Results with the STMBench7 benchmark show that for a read-only workload the new algorithm increases the throughput of the benchmark up to 14-fold and that it scales well up to 48 cores, the maximum number of physical cores available on the machine used for the tests.