// *****************************************************************
// * Mike Erlinger
// * CS 110
// * Dining Philosophers
// * Project 2
// * $Id: phil2.cc,v 1.1 1998/03/17 17:24:50 mike Exp mike $
// *
// *
// * This program is an implementation of the Dining Philosophers
// * It starts with the solution from Tanenbaum's book.
// * There are either 4 input parameters or defaults are used:
// *   Number of Phils  - Default 5
// *   Eating Time      - Default 6 sec
// *   # of Eats        - Default 4
// *   Thinking Time    - Default 3 sec
// *
// * Semaphores:
// *    Mutex, controls shared memory, initialized to 1.
// *    Sems array of semaphores used to allow hungry phils to block
// *       waiting for a fork,  initialized to 1
// *    Done, controls when all processes done, initialized to number
// *       of phils + 1.
// *
// * Shared Memory
// *    An array of state variables for each phil.
// *      Values are:  Thinking, Hungry, Eating, Done.
// *    Shared memory is acquired and attached in main.
// *
// * Operation
// *   there is a main program which sets up all the semaphores
// *       and shared data area.
// *   It then forks off a number of phils, each phil is its own process.
// *   main also forks off a waiter process, which prints out the status
// *       of the table every 2 seconds.
// *   main waits for all the phils and waiter to finish and then cleansup
// *       and dies.
// *   phils, think, then get hungry, then eat, then think, ...
// *     eventually, they are done.
// *


// * A run of the program follows.  Look at it  for  format.  I did a lot of output
// *  reformatting to get this and it may have actual runtime errors.

turing:phils
Dining Philosophers program
No parameters, then there are 5 philosophers, 
 who eat for 4 sessions with 6 seconds a session 
 otherwise: 
 parameter 1 = Number Philosophers: 
 parameter 2 = Eating Time: 
 parameter 3 = Number of Eating Sessions: 



--------------------------------------
 I AM THE WAITER 
 #:   Phil 0    Phil 1    Phil 2    Phil 3    Phil 4  Thinking Hungry Eating Left  
 1    Thinking  Thinking  Thinking  Thinking  Thinking       5     0     0     0

 2    Thinking  Thinking  Thinking  Thinking  Thinking       5     0     0     0

 3    Hungry    Eating    Hungry    Hungry    Eating         0     3     2     0

 4    Hungry    Eating    Hungry    Hungry    Eating         0     3     2     0

 5    Hungry    Eating    Hungry    Hungry    Eating         0     3     2     0

 6    Thinking  Thinking  Thinking  Thinking  Thinking       5     0     0     0

 7    Hungry    Eating    Hungry    Hungry    Eating         0     3     2     0

 8    Hungry    Eating    Hungry    Hungry    Eating         0     3     2     0

 9    Hungry    Eating    Hungry    Hungry    Eating         0     3     2     0
 
 10    Thinking  Thinking  Eating    Thinking  Thinking       4     0     1     0

 11    Thinking  Thinking  Eating    Thinking  Thinking       4     0     1     0

 12    Hungry    Hungry    Eating    Hungry    Eating         0     3     2     0

 13    Hungry    Eating    Thinking  Hungry    Eating         1     2     2     0

 14    Hungry    Eating    Thinking  Hungry    Eating         1     2     2     0

 15    Thinking  Thinking  Eating    Thinking  Thinking       4     0     1     0

 16    Hungry    Hungry    Eating    Hungry    Eating         0     3     2     0

etc....