CMSC132 Summer 2018

Project: Concurrency Project

Multithreading

This project consists of simulating the movements of office workers in an office building. Each worker implements Runnable and will be managed by a single thread. Throughout the day, the worker must attend several meetings that occur on different floors of the building. To travel to different floors, the worker must take an elevator. Every time a worker boards, or exits an elevator, a message must be generated and sent to the Logger class. A message must also be generated whenever an Elevator changes direction. This Logger is what we will be using to check the output of your program so it is important that it is correct. Due to the nature of concurrency, the exact order that output is added to the logger is not important. What is important is that output is added in a possible order. How efficient your elevators is not really that important, but you should make sure that each worker is able to visit all of their meetings that day.

Getting Started

LogMsg

The output of your program is checked through a series of Log Messages. You're program must generate a valid series of log messages in order to pass the tests. There are four different types of Log Messages.

• makeElevatorMovedLogMsg: This message is generated every time an elevator moves from floor to floor. It is not necessary to move from each floor one at a time. i.e. an elevator may move from floor 3 to floor 7
• makeElevatorChangedDirectionLogMsg: This message is generated every time an elevator changed direction, i.e. from up to down. This message is required before an elevator can move in another direction
• makeWorkerGotOnElevatorLogMsg: This message is generated every time a worker boards an elevator. In order for a worker to board an elevator, both the worker and the elevator need to be on the same floor.
• makeWorkerGotOffElevatorLogMsg: This message is generated every time a worker exits an elevator. In order for a worker to exit an elevator, the elevator that the last boarded needs to be on the floor they are exiting. In addition, workers should only get off elevators on floors in which they have meetings.

Worker

The majority of the work you need to do for this project is in the run method for the Worker class. Each worker needs to go to every meeting in their schedule. Each worker has an array of Elevator's that they can use to move between floors. These elevators are shared between multiple workers so operations performed on an elevator will need to be synchronized. To do this, each worker will search for an elevator and call that Elevator's move method, causing it to move to the worker's current floor. When a worker gets on the elevator, the worker must queue which floor their meeting is on. Note: it is not necessary to handle a case where multiple workers get on the same elevator at one time.

Elevator

You will need to implement the move method for this class. This method, when called by a worker, will cause the Elevator to move to the next floor in its queue depending on the elevator's current set direction.

Objectives

This project will allow you to practice the principles of concurrency and multithreading.

Grading

• (80%) Release Tests
• (10%) Synchronization Requirement (avoiding data races)
• (10%) Style

Clarifications

Any clarifications or corrections associated with this project will be available at Project Clarifications.

Code Distribution

The project's code distribution is available by checking out the project named ElevatorOperator. The code distribution provides you with the following:

• model package → Where classes dealing with simulation will appear. You are also given a Simulation class to give you an idea of what tests will look like

Specifications

• Workers must visit all of their meetings
• Workers must visit all of their meetings in order
• Log messages must be generated in a plausible order.
• The only methods you may NOT modify are run(), public getters, and public constructors. You are allowed to add any instance variables or helper methods you see necessary to the Elevator or Worker class. You are not required to use all of the methods or fields given to you but they are there to help guide you!

Requirements

• See Style Guidelines for information regarding style.