Safe, Regular, and Atomic Read/Write Registers

Abstract

For self-containment, this chapter starts with a short presentation of the notions of safe, regular, and atomic read/write registers (which were introduced in Chap. 2). It then presents simple wait-free implementations of “high-level” registers from “low-level” registers. The notions of “high-level” and “low-level” used here are not related to the computability power but to the abstraction level. This is because, as we will see in the next two chapters, while a regular register is easier to use than a safe register and an atomic register is easier to use than a regular register, they are all computationally equivalent; i.e., any of them can be built wait-free from any other without enriching the underlying system with additional computational power.

The proofs of the theorems stated in this chapter use the definitions and terminology introduced in Chap. 4.