A FIFO Queue Class Library as a State Variable of Time Warp Logical Processes

Abstract

We describe SsQueue(SnapshotQueue), an implementation for an efficient and user-friendly class library for FIFO queue that can be used for state vectors in simulated queuing network constructs under Time Warp parallel discrete event simulation (PDES) protocol. There exists a general purpose Time Warp simulation kernel warped, where users have only to define a state vector and do not have to care about rollback and state recovery. However, since the state vector should be defined as an inlined data structure, it is not suitable for dynamic data structures such as FIFO queue. This class can also serve as an element of such a state vector, then both libraries and users can handle each instance as snapshot of the queue. Taking advantages of FCFS nature of the above data structure, operation histories rather than all contained items can be safely stored and restored using this class library with virtually minimum overhead. When the kernel deletes instances in the simulated past, corresponding methods perform garbage collections transparently.