From: Lukas Jiriste <ljiriste@student.42prague.com>
Date: Tue, 28 May 2024 12:48:39 +0000 (+0200)
Subject: Rewrite semaphore initialization, add end semaphore
X-Git-Url: https://git.ljiriste.work/?a=commitdiff_plain;h=a124a0c436276fb0a6578a940d7b7259580df202;p=42%2Fphilosophers.git

Rewrite semaphore initialization, add end semaphore

It is better to create semaphores at 0 than at some value and then
subtracting them to 0.

The end semaphore will be used to signal to philosophers they should
end. This mechanism was chosen instead of kill function, because the
philosophers have to clean after themselves and signal
handlers cannot be used.
---

diff --git a/philo_bonus/mem_management.c b/philo_bonus/mem_management.c
index 1fc290d..b79c3d5 100644
--- a/philo_bonus/mem_management.c
+++ b/philo_bonus/mem_management.c
@@ -22,35 +22,27 @@ static int	open_semaphores(unsigned int count, t_sems *semaphores)
 	semaphores->forks = sem_open(FORKS_SEM, O_CREAT | O_EXCL,
 			S_IRUSR | S_IWUSR, count);
 	semaphores->fed = sem_open(WELL_FED_SEM, O_CREAT | O_EXCL,
-			 S_IRUSR | S_IWUSR, count);
+			S_IRUSR | S_IWUSR, 0);
 	semaphores->death = sem_open(DEATH_SEM, O_CREAT | O_EXCL,
-			 S_IRUSR | S_IWUSR, count);
+			S_IRUSR | S_IWUSR, 0);
 	semaphores->term = sem_open(TERM_SEM, O_CREAT | O_EXCL,
-			 S_IRUSR | S_IWUSR, 1);
+			S_IRUSR | S_IWUSR, 0);
+	semaphores->end = sem_open(END_SEM, O_CREAT | O_EXCL,
+			S_IRUSR | S_IWUSR, 0);
 	if (semaphores->forks == SEM_FAILED || semaphores->fed == SEM_FAILED
-			|| semaphores->death == SEM_FAILED || semaphores->term == SEM_FAILED)
+			|| semaphores->death == SEM_FAILED || semaphores->term == SEM_FAILED
+			|| semaphores->end == SEM_FAILED)
 		return (1);
 	return (0);
 }
 
 int	init(unsigned int count, pid_t **philo_pids, t_sems *semaphores)
 {
-	size_t	i;
-
 	*philo_pids = malloc(count * sizeof(**philo_pids));
 	if (!*philo_pids)
 		return (1);
 	if (open_semaphores(count, semaphores))
 		return (1);
-	i = 0;
-	while (i < count)
-	{
-		(*philo_pids)[i] = 0;
-		sem_wait(semaphores->death);
-		sem_wait(semaphores->fed);
-		++i;
-	}
-	sem_wait(semaphores->term);
 	return (0);
 }
 
@@ -60,6 +52,7 @@ void	close_semaphores(t_sems *semaphores)
 	sem_close(semaphores->fed);
 	sem_close(semaphores->death);
 	sem_close(semaphores->term);
+	sem_close(semaphores->end);
 	return ;
 }
 
@@ -70,6 +63,7 @@ void	cleanup(pid_t *philo_pids, t_sems *semaphores)
 	sem_unlink(WELL_FED_SEM);
 	sem_unlink(DEATH_SEM);
 	sem_unlink(TERM_SEM);
+	sem_unlink(END_SEM);
 	free(philo_pids);
 	return ;
 }
diff --git a/philo_bonus/philo.h b/philo_bonus/philo.h
index b7d461c..b31e659 100644
--- a/philo_bonus/philo.h
+++ b/philo_bonus/philo.h
@@ -23,6 +23,7 @@
 # define WELL_FED_SEM "philosophers_fed"
 # define DEATH_SEM "philosophers_death"
 # define TERM_SEM "philosophers_terminal"
+# define END_SEM "philosophers_end"
 
 //	The .start member holds the result of gettimeofday
 //	Every other member that holds time info counts
@@ -44,6 +45,7 @@ typedef struct s_important_semaphores
 	sem_t	*fed;
 	sem_t	*death;
 	sem_t	*term;
+	sem_t	*end;
 }			t_sems;
 
 //	As mutex is not available in bonus, the idea is to have