Self-Stabilizing Set-Constrained Delivery Broadcast (extended abstract)

Fault-tolerant distributed applications require communication abstractions with provable guarantees on message deliveries. For example, Set-Constrained Delivery Broadcast (SCD-broadcast) is a communication abstraction for broadcasting messages in a manner that, if a process delivers a set of messages that includes m and later delivers a set of messages that includes m , no process delivers first a set of messages that includes m′ and later a set of messages that includes m.Imbs et al. proposed this communication abstraction and its first implementation. They have demonstrated that SCD-broadcast has the computational power of read/write registers and allows for an easy building of distributed objects such as snapshot objects and consistent counters. Imbs et al. focused on fault-tolerant implementations for asynchronous message-passing systems that are prone to process crashes. This paper aims to design an even more robust SCD-broadcast communication abstraction, namely a self-stabilizing SCD-broadcast. In addition to process and communication failures, self-stabilizing algorithms can recover after the occurrence of arbitrary transient faults; these faults represent any violation of the assumptions according to which the system was designed to operate (as long as the algorithm code stays intact).This work proposes the first self-stabilizing SCD-broadcast algorithm for asynchronous message-passing systems that are prone to process crash failures. The proposed self-stabilizing SCD-broadcast algorithm has an $\mathcal{O}(1)$ stabilization time (in terms of asynchronous cycles). The communication costs of our algorithm are similar to the ones of the non-self-stabilizing state-of-the-art. The main differences are that our proposal considers repeated gossiping of $\mathcal{O}(1)$ bits messages and deals with bounded space (which is a prerequisite for self-stabilization). We advance the state-of-the-art also by two new self-stabilizing applications: an atomic construction of snapshot objects and sequentially consistent counters.