Summary: The Instancy of Snapshots and Commuting Objects \Lambda
Yehuda Afek Eytan Weisberger y
Computer Science Department,
Tel­Aviv University, Israel 69978.
Abstract
We present a sequence of constructions of commuting synchronization objects (e.g.,
fetch­and­increment and fetch­and­add) in a system of n processors from any two processor syn­
chronization object whose consensus number is two or more [Her91a]. Each implementation in
the sequence uses a particular type of shared memory snapshot, as a building block. Later imple­
mentations in the sequence are based on higher quality snapshots. The first implementation of a
fetch­and­increment uses the standard atomic snapshot concept, introduced in [AAD + 93, And90],
while the last construction in the sequence, of fetch­and­add, is based on the immediate snap­
shot concept introduced in [BG93b]. This last construction also yields an implementation of a
stronger snapshot which we call Write­and­snapshot. In addition this work solves an open ques­
tion of Borowsky and Gafni by presenting an implementation of a multi­shot immediate snapshot
object.
Additional implications of our constructions are: (1) The existence of fault­tolerant self imple­
mentations of commuting objects, (2) improvements in the efficiency of randomized constructions
of commuting objects from read/write registers, and (3) low contention constructions of com­
muting objects.

Source: Afek, Yehuda - School of Computer Science, Tel Aviv University

Collections: Computer Technologies and Information Sciences