Eat, Sleep, Spaghetti, repeat. This project is about learning how threads work by precisely timing a group of philosophers on when to pick up forks and eat spaghetti without dying from hunger.
The Dining Philosophers problem is a classic OS problem originally formulated by Edsger Dijkstra.
The problem states that K philosophers seated around a circular table with one chopstick between each pair of philosophers.
There is one chopstick between each philosopher.
A philosopher may eat if he can pick up the two chopsticks adjacent to him.
One chopstick may be picked up by any one of its adjacent followers but not both.
Here are the things you need to know if you want to succeed this assignment:
- One or more philosophers sit at a round table. There is a large bowl of spaghetti in the middle of the table.
- The philosophers alternatively eat, think, or sleep. While they are eating, they are not thinking nor sleeping; while thinking, they are not eating nor sleeping; and, of course, while sleeping, they are not eating nor thinking.
- There are also forks on the table. There are as many forks as philosophers.
- Because serving and eating spaghetti with only one fork is very inconvenient, a philosopher takes their right and their left forks to eat, one in each hand.
- When a philosopher has finished eating, they put their forks back on the table and start sleeping. Once awake, they start thinking again. The simulation stops when a philosopher dies of starvation.
- Every philosopher needs to eat and should never starve.
- Philosophers don’t speak with each other.
- Philosophers don’t know if another philosopher is about to die.
- No need to say that philosophers should avoid dying!
- Global variables are forbidden!
- Your(s) program(s) should take the following arguments: number_of_philosophers time_to_die time_to_eat time_to_sleep [number_of_times_each_philosopher_must_eat]
- number_of_philosophers: The number of philosophers and also the number of forks.
- time_to_die (in milliseconds): If a philosopher didn’t start eating time_to_die milliseconds since the beginning of their last meal or the beginning of the simulation, they die.
- time_to_eat (in milliseconds): The time it takes for a philosopher to eat. During that time, they will need to hold two forks.
- time_to_sleep (in milliseconds): The time a philosopher will spend sleeping.
- number_of_times_each_philosopher_must_eat (optional argument): If all philosophers have eaten at least number_of_times_each_philosopher_must_eat times, the simulation stops. If not specified, the simulation stops when a philosopher dies.
- Each philosopher has a number ranging from 1 to number_of_philosophers.
- Philosopher number 1 sits next to philosopher number number_of_philosophers. Any other philosopher number N sits between philosopher number N - 1 and philosopher number N + 1.
- Your program must not have any data races.
About the logs of your program:
- Any state change of a philosopher must be formatted as follows:
- timestamp_in_ms X has taken a fork
- timestamp_in_ms X is eating
- timestamp_in_ms X is sleeping
- timestamp_in_ms X is thinking
- timestamp_in_ms X died
- Replace timestamp_in_ms with the current timestamp in milliseconds and X with the philosopher number.
- A displayed state message should not be mixed up with another message.
- A message announcing a philosopher died should be displayed no more than 10 ms after the actual death of the philosopher.
- Again, philosophers should avoid dying!
- Each philosopher should be a thread.
- There is one fork between each pair of philosophers. Therefore, if there are several philosophers, each philosopher has a fork on their left side and a fork on their right side. If there is only one philosopher, there should be only one fork on the table.
- To prevent philosophers from duplicating forks, you should protect the forks state with a mutex for each of them.