Finding incorrect compositions of atomicity

Abstract

In object-oriented code, atomicity is ideally isolated in a library which encapsulates shared program state and provides atomic APIs for access. The library provides a convenient way for programmers to reason about the needed synchronization. However, as the library exports a limited set of APIs, it cannot satisfy every unplanned atomicity demand; therefore, clients may have to compose invocations of the library APIs to obtain new atomic functionality. This process is error-prone due to the complexity of reasoning required, hence tool support for uncovering incorrect compositions (i.e., atomic compositions that are implemented incorrectly) would be very helpful. A key difficulty is how to determine the intended atomic compositions, which are rarely documented. Existing inference techniques cannot be used to infer the atomic compositions because they cannot recognize the library and the client, which requires understanding the related program state. Even if extended to support the library/client, they lead to many false positives or false negatives because they miss the key program logic which reflects programmers’ coding paradigms for atomic compositions.