42 Project : philosophers

philosophers

Who thought treading on parallelism & concurrency land could be so philosophically deadly 🕱

Table o'Contents

About 📌
philosophers Problem 🜎
philosophers Requirements Overview ✅
philosophers Mandatory Implementation 📜
philosophers Bonus Implementation 📜
Usage 🏁
Tests & Debug 🧪
References 📚
Documentation
Research Papers
Tools
Articles
License 📖

About 📌

This is a classic CS exercise conceived as an introduction to the basics of threading a process. It gives an introductory glance into the difficulties contingent to the non-deterministic nature of multi-threaded applications.

`philosophers` Problem 🜎

One or more philosophers sit at a round table. There is a large bowl of spaghetti in the middle of the table.
The philosophers alternate between eating, thinking, or sleeping:
- While they are eating, they are not thinking nor sleeping;
- while thinking, they are not eating nor sleeping;
- While sleeping, they are not eating nor thinking.
There are also forks on the table. There are as many forks as philosophers.
A philosopher must take two forks to eat, one in each hand.
When 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.

`philosophers` Requirements Overview ✅

The program must not include any global variables.
It should accept the following command line arguments (as positive integers):

./philo <n_philos> <time_to_die> <time_to_eat> <time_to_sleep> [max_meals]

n_philos also the number of forks.
time_to_die the time to die in milliseconds (length of philo's life).
time_to_eat the time to eat in milliseconds (length of time to hold forks).
time_to_sleep the time to sleep in milliseconds (length of time to rest).
max_meals the maximum number of meals for the simulation (optional argument).
Each philosopher is numbered from 1 to n_philos.
Philosophers number 1 should be sitting next to philosopher n_philos and philosophers number 2.

Regarding logs, the program should report any state change of a philosopher formatted as:

timestamp_in_ms <philo_n> has taken a fork.
timestamp_in_ms <philo_n> is eating.
timestamp_in_ms <philo_n> is sleeping.
timestamp_in_ms <philo_n> is thinking.
timestamp_in_ms <philo_n> has died.
Messages should not mix with each other.
A message announcing the end of the simulation should be displayed no more than 10ms after the time of death of the philosopher.

`philosophers` Mandatory Implementation 📜

Each philosopher should be represented by a thread.
There is a fork between each pair of philosophers.
If there is only one philosopher, there should be only one fork on the table.
Each forks must be pretended by a mutex.

`philosophers` Bonus Implementation 📜

All forks are placed in the middle of the table.
They have no states in memory. The number of available forks is represented by a semaphore.
Each philosopher should be represented by a process, but the main process should not be a philosopher

Important

The code for both implementations is documented with doxygen comments. Enjoy!

Usage 🏁

Clone the repository and cd into either the mandatory (philo) or bonus implementation (philo_bonus):

git clone https://github.com/PedroZappa/42_philosophers.git 42_philosophers_passunca
# For the mandatory (Threads implementation w/ mutexes)
cd 42_philosophers_passunca/philo
# For the bonus (Processes implementation w/ semaphores)
cd 42_philosophers_passunca/philo_bonus

Build the program:

# For the mandatory
make

Run the program:

./philo 5 800 200 200
# or with a set max number of meals
./philo 5 800 200 200 7

Note

To execute the bonus implementation, you will need to instead call ./philo_bonus command.

Tests & Debug 🧪

Run the following command and look at the Test Rules 🧪 & Debug Rules  to get a comprehensive list of all available test/debug commands:

make help

Note

If you use tmux you are in for treat 😏

References 📚

Documentation

Research Papers

Tools

Articles

License 📖

This work is published under the terms of 42 Unlicense.

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PedroZappa/42_philosophers