A Common-Sense Guide to Data Structures and Algorithms

Queues in Action

Queues are common in many applications, ranging from printing jobs to background workers in web applications.

Let’s say you were programming a simple Ruby interface for a printer that can accept printing jobs from various computers across a network. By utilizing the Ruby array’s push method, which adds data to the end of the array, and the shift method, which removes data from the beginning of the array, you may create a class like this:

class PrintManager

  def initialize
    @queue = []
  end

  def queue_print_job(document)
    @queue.push(document)
  end

  def run
    while @queue.any?
      # the Ruby shift method removes and returns the
      # first element of an array:
      print(@queue.shift)
  ...