Title: Work Analysis with Resource-Aware Session Types,
Abstract: While there exist several successful techniques for supporting programmers in
deriving static resource bounds for sequential code, analyzing the resource
usage of message-passing concurrent processes poses additional challenges. To
meet these challenges, this article presents an analysis for statically
deriving worst-case bounds on the total work performed by message-passing
processes. To decompose interacting processes into components that can be
analyzed in isolation, the analysis is based on novel resource-aware session
types, which describe protocols and resource contracts for inter-process
communication. A key innovation is that both messages and processes carry
potential to share and amortize cost while communicating. To symbolically
express resource usage in a setting without static data structures and
intrinsic sizes, resource contracts describe bounds that are functions of
interactions between processes. Resource-aware session types combine standard
binary session types and type-based amortized resource analysis in a linear
type system. This type system is formulated for a core session-type calculus of
the language SILL and proved sound with respect to a multiset-based operational
cost semantics that tracks the total number of messages that are exchanged in a
system. The effectiveness of the analysis is demonstrated by analyzing standard
examples from amortized analysis and the literature on session types and by a
comparative performance analysis of different concurrent programs implementing
the same interface.