Composable asynchronous events

Abstract

Although asynchronous communication is an important feature of many concurrent systems, building composable abstractions that leverage asynchrony is challenging. This is because an asynchronous operation necessarily involves two distinct threads of control -- the thread that initiates the operation, and the thread that discharges it. Existing attempts to marry composability with asynchrony either entail sacrificing performance (by limiting the degree of asynchrony permitted), or modularity (by forcing natural abstraction boundaries to be broken).