This is a modification of the solution to Basic Barber Shop Project (semaphores, shared memory, and multilevel queues). The Barber Shop operation has been reported to the Inspector General. It seems in its current instantiation, starvation is possible, i.e., Grunts can wait all day for haircuts because Officers and NonComs have priority. In an effort to keep the Grunts happy and the IG off your tail, you have decided to modify your queue and priority system. Now Grunts are guaranteed to have their priority increased in the following way.

• After waiting a maximum of 5 haircuts (where the current haircut counts as a haircut), a Grunt is moved into the NonCom queue at the tail of that queue (i.e., given the priority of a NonCom and put on the NonCom queue), where queueing continues on a 1st come 1st serve basis.
• After waiting a maximum of 4 more haircuts, a Grunt is moved into the Officer queue, but this time at the head of the queue but behind any Grunts who are already there, (i.e., given the priority of an Officer and moved to the Officer queue, but not in front of any Grunts already there) where queueing continues on a 1st come 1st serve basis.
• Yes, it is true that a Grunt can move up in front of a NonCom, but being a Grunt does have some privileges.

In order to handle this mess, the Barber Shop has changed its queueing system. There are still a max of 20 chairs. People are managed in chairs by setting priorities associated with the chair. For example, if a Grunt enters in chair 11, he can be viewed as having priority 0 (Grunt level) and in a FIFO queue of Grunts. When he is moved because of slow processing to the NonCom level, the Grunt is still in chair 11, but now has priority 1 (NonCom level) and in a FIFO queue of NonComs. When he is moved because of slow processing to the Officer level, the Grunt is still in chair 11, but now has priority 2 (Officer level) and in a FIFO queue of Officers.

Hair cuts still take the time as found in the input stream.

Implementation Notes:

• You should use a file containing random sleep times (integers between 01 and 05 for Grunts, between 11 and 15 for NonComs, and between 21 and 25 for Officers to drive your Producer process:
  • the first digit provides the food chain position
  • the second digit provides the time for a haircut.
• For the chairs, one implementation choice is to make each chair a structure, (rank, time waiting, queue, position in queue). You can implement such a structure using arrays (thus shared memory is still viable).
• You are to manage the Barber Shop wait area as priority queues, where each queue is a FIFO list. People do not move to new chairs, rather through list and priority queue management, the Producer and Consumer know the next chair, i.e., person to get their hair cut or available chairs. One approach is to have a free list of chairs and 3 other lists, one for each level's FIFO list.
• The Sergeant, the Producer, must also manage the wait area (incoming area, the sidewalk) outside the Barber Shop. He cannot let someone in unless there is a chair at the appropriate level. Each time he awakes (time defaults to 3, but is a startup parameter), he checks his waiting area (the input file) and, he will seat someone as long as there is room in the Barber Shop.
• You Do Not have a pointer datatype for the Barber Shop. Use arrays with a MAX_SIZE and implement an array version of a linked list for the waiting area.
• You still need another process, the Lieutenant, who monitors the overall Barber Shop. Because he is still young and ignorant, every 2 seconds the lieutenant pokes his head into the Barber Shop to determine:
  • Total number of Officers that have entered the system.
  • How many Officers are waiting in the Barber Shop.
  • How many Officers have gotten their hair cut.
  • Total number of NonComs that have entered the system.
  • How many NonComs are waiting in the Barber Shop.
  • How many NonComs have gotten their hair cut.
  • Total number of Grunts that have entered the system.
  • How many Grunts are waiting in the Barber Shop.
  • How many Grunts have gotten their hair cut.
  • How many Grunts are currently waiting in other queues, i.e., have moved up in priority.
  • Total number of empty chairs.
  • Total number of occupied chairs.
  • Who is in the Barber Chair - Officer, NonCom, or Grunt.
  • The Lieutenant numbers each output sequentially (easier to watch the time fly).
  • Possible output also includes the 3 queues (everyone in the queue, their chair number, etc.) - see discussion of parameters. Also, use the format of the example output found on the web page.
• Termination. When the input file is empty, the Sergeant terminates, but the Barber continues until the last long hair has had his hair cut and the Lieutenant continues until both the Sergeant and Barber have terminated. Look at some of the semaphore operations for ways to do this. Thus, the final output from the Lieutenant should show an equal number of long hairs entering the system and short hairs produced with an empty waiting room.
• There are 3 parameters to the program:
  1. Parameter 1 - How long (in seconds) the Consumer process should sleep before starting, default = 1.
  2. Parameter 2 - Used to determine if the Barber Shop contents should be printed out by the Monitor/Lieutenant (print entire circular buffer: default = 0, no print).
  3. Parameter 3 - How long the Producer should sleep between each search of the wait area, default = 3.