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EventSimulation.jl

An event based Discrete Event Simulation engine for Julia.

Intended as a support library for teaching basic principles of Discrete Event Simulation.

Package features

  • register/interrupt execution of events
  • resource (continuous homogenous good) reservoir
  • queue (arbitrary objects) reservoir

Examples

A quick start tutorial can be found here.

Examples contained in /examples/ directory:

  • mm1_minimal.jl: a minimal M/M/1 queue implementaton
  • gg1_minimal.jl: a minimal G/G/1 queue implementaton
  • mms_example.jl: comparison of several implementations of M/M/s queue
  • mm1_example.jl: basic implementation of M/M/1 queue with use of monitor
  • bank_renege_1.jl: bank renege model (reimplementation of SimPy example)
  • bank_renege_2.jl: bank renege model (reimplementation of SimPy example)
  • movie_renege.jl: movie renege model (reimplementation of SimPy example)
  • faxqueue.jl: a two-stage fax queue model; adaptation of B. Nelson (2013): Foundations and Methods of Stochastic Simulation, chap. 4.6, example
  • seq_queue.jl: Experiment 4.1 from: C.-H. Chen, L.H. Lee (2011): Stochastic Simulation Optimization
  • repair.jl: a rewrite of SimJulia.jl example of S. Ross (2012): Simulation, 5th edition, Section 7.7, p. 124-126
  • computer.jl: Example 2.5 from A. Law (2013): Simulation Modeling and Analysis, 5ed
  • lookup.jl: model with s queues and s servers with different queue choice policies

The models that are reimplemnetation of SimPy run an order of magnitude (>20x) faster than in SimPy or SimJulia process oriented DES engines.

Quck overview of EventSimulation functionality

General functionality

  • Action: information that a given function should be executed at given time
  • AbstractState: abstract type used for holding global simulation state
  • EmptyState: simplest empty concrete subtype of AbstractState
  • Scheduler: central object in the library jused to store information about event queue
  • register!: puts Action into Scheduler queue
  • repeat_register!: puts Action into Scheduler queue repeatedly
  • bulk_register!: puts Action into Scheduler that will affect multiple objects
  • repeat_bulk_register!: puts Action into Scheduler that will affect multiple objects repeatedly
  • interrupt!: removes one given event from Scheduler queue
  • terminate!: removes all events from Scheduler queue
  • go!: executes the simulation

Containers

  • AbstractReservoir: abstract type for defining reservoirs
  • SimResource: reservoir for divisible and homogeneous matter
  • ResourceRequest: information about request for a resource
  • SimQueue: reservoir for objects having unique identity
  • request!: registers demand for a resource/object
  • waive!: remove registered request from waiting list
  • provide!: add resource/object to reservoir (or remove resource from SimResource)
  • withdraw!: remove object from SimQueue
  • length: number of objects in SimQueue

Utilities

  • PriorityTime: custom subtype of Real providing additional attribute priority to normal time. Useful for giving execution priority of events happening at the same time.

Full documentation of types and functions defined in EventSimulation package can be found here.