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

Ctrie is a scalable concurrent non-blocking dictionary data structure, with good cache locality, and non-blocking linearizable iterators [4]. However, operations on most existing concurrent hash tries run in O(logn) time. In this technical report, we extend the standard concurrent hash-tries [3] with an auxiliary data structure called a cache1. 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).