On specification of Read/Write shared variables

• Published in: Journal of the ACM Vol. 54; no. 6; p. 31
• Main Authors: Haldar, Sibsankar, Vidyasankar, K.
• Format: Journal Article
• Language: English
• Published: New York, NY Association for Computing Machinery 01.12.2007
• Subjects: Algorithmics. Computability. Computer arithmetics; Applied sciences; Communication; Computer science; control theory; systems; Consistency; Exact sciences and technology; Exchange; Information processing; Information sharing; Processors; Specifications; Stores; Studies; Theoretical computing; Variables; Input output; Theory; illegality; Partial ordering; Specification; defining condition; Abstraction; defining relation; consistency; Multiprocessor; Atomicity; framework; nonatomic operation execution; Causality; linear extension; Shared memory; partial order; Information exchange; shared variable; system execution; Linearization; axiom
• ISSN: 0004-5411; 1557-735X
• DOI: 10.1145/1314690.1314695

A shared variable is an abstraction of persistent interprocess communication. Processors execute operations, often concurrently, on shared variables to exchange information among themselves. The behavior of operation executions is required to be “consistent” for effective interprocess communication. Consequently, a consistency specification of a shared variable describes some guarantees on the behavior of the operation executions. A Read/Write shared variable has two operations: a Write stores a specified value in the variable and a Read returns a value from the variable. For Read/Write variables, a consistency specification describes what values Reads may return. Using an intuitive notion of illegality of Reads, we propose a framework that facilitates specifying a large variety of Read/Write variables.