Traffic Light Simulator

This application is part of COSC 3360 - Operating System Fundamentals class at the University of Houston. This application

uses the process creation mechanism in UNIX using the fork function.

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Specs

a program to simulate a traffic light controlling how cars use a four-way intersection. Each road has a direction (northbound, southbound, eastbound, and westbound). The program will receive from STDIN the information about the parameters of the traffic light and the cars that want to cross the intersection. After defining the order that the cars will follow to use the intersection, The program must create a child process per car. Each child process will print the information about the car and will sleep for the number of seconds specified in the input file.

Implementation

The program has two types of processes:

1. Parent process: is the process that reads the input file, defines the order that cars will follow to use the intersection, creates the child processes (one at a time), prints the current direction of the traffic light (per each direction change), and waits for all the child processes to complete before ending its execution.

2. Child processes: these are the processes created by the parent process. Each child process will perform the following operations: prints the information about the car (license plate, time), and sleeps for the number of seconds specified by the time parameter.

Input and Output

Input	Output
E //Initial Direction	Current direction: Eastbound Car DEF is using the intersection for 2 sec(s).
1 // Max number of cars per direction	Current direction: Southbound Car CDE is using the intersection for 3 sec(s).
ABC N 2 // Car info(Plate,direction,time)	Current direction: Westbound Car FGH is using the intersection for 1 sec(s).
BCD N 2	Current direction: Northbound Car ABC is using the intersection for 2 sec(s).
CDE S 3	Current direction: Southbound Car EFG is using the intersection for 1 sec(s).
DEF E 2	Current direction: Northbound Car BCD is using the intersection for 2 sec(s).
EFG S 1
FGH W 1

• The initial direction represents the starting direction (N, E, S, or W) of the simulation. The direction of the traffic light will change using a clockwise pattern.

• The max number of cars limits the number of cars that can use the intersection based on the current direction of the traffic light.

• The car information will have: (a) the license plate (only letters and numbers); (b) the direction (N=northbound, E=eastbound, S=southbound, W=westbound); and (c) the time (seconds) using the intersection. These parameters are separated by whitespace.

• The order in which the cars arrive at the intersection is defined by their position in the input file.

• Only one car can use the intersection at a time.