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 [4]. 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 [3] with an auxiliary data structure called a cache 1 . 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).Keywords concurrent data structures, lock-free hash tries, constant-time hash tries, expected running time analysis