Analysis of Concurrent Lock-Free Hash Tries with Constant-Time Operations

Abstract: Ctrie is a scalable concurrent non-blocking dictionary data structure, with good cache locality, and non-blocking linearizable iterators. However, operations on most existing concurrent hash tries run in O(log n) time. In this technical report, we extend the standard concurrent hash-tries with an auxiliary data structure called a cache. The cache is essentially an array that stores pointers to a specific level of the hash trie. We analyze the performance implications of adding a cache, and prove that the running time of the basic operations becomes O(1).