asishadhikari/singleserversimulation

Single Server Queue Simulation

This is a project on creating a single server based queuing system

To Dos:

• Implement main()
• void initialize();
• void timing();
• void arrive();
• void depart();
• void report();
• void update_stats();
• float generator();
• Implement arrive()
• Implement depart()

Definitions of the global variables used(shared across functions):

State Variables:

• int:
  • num_custs_delayed: instant of time a customer is delayed
  • num_delays_required: How many customers to run simulation for? => input.txt line 3
  • next_event_type: 1 is arrive() 2 is depart()
  • num_events: 2 events possible so set at 2 used by timing()
  • num_in_queue: number of cust in a queue at an instant
  • server_status: state of server BUSY or IDLE
• float:
  • sim_time: time of simulation
  • time_last_event: time of last arrival or departure
  • time_next_event[2]:
    • time_next_event[0] : represents the time next arrival will occur
    • time_next_event[1] : represents the time next departure will occur

Statistical counters:

• *float:
  • avg_num_in_q: average number of cust in queue
  • avg_server_util: average utilisation of server (0-1)
  • avg_interarrival: What is the average rate at which customers arrive. i.e. mean of Poisson process to be => input.txt line 1
  • avg_service_time: We assume that a service usually takes about a fixed time. i.e. Approximation how long service takes => input.txt line 2
  • time_arrival[Q_LIMIT+1]: The arrival time array of all customers in the queue at any instant
  • total_delays: Used to calculate average delay in report(). Holds cumilitive delay for all customers.

Building and running

After cloning into a local repo:

• compile as gcc main.c -lm
• load 3 lines of input values into input.txt:
  • line 1: mean for arrival rate (used to generate arrival time in Poisson distribution )
  • line 2: mean for service rate (an estimation of how long each service take)
  • line 3: desired number of customers to run simulation for (imported as num_delays_required)
• run binary program as ./a.out

Feel free to leave any comments. Peace! ✌