From: Lukas Jiriste <ljiriste@student.42prague.com>
Date: Thu, 3 Oct 2024 07:15:55 +0000 (+0200)
Subject: Add time_to_think to increase survivability
X-Git-Url: https://git.ljiriste.work/?a=commitdiff_plain;h=refs%2Fheads%2Ftrunk;p=42%2Fphilosophers.git

Add time_to_think to increase survivability

I thought that the program should be a tool to demonstrate the dangers
in parallel computing. Hence I let the user wholly define what
philosophers can do.
This point of view has however failed me multiple times during
evaluation... This (and a couple of conversations) led me to believe the
only way to pass is to add another element - the time_to_think.

When odd number of philosophers is entered and the time_to_sleep is too
low, the time_to_think is set to such a value that philosophers can
share the forks fairly.
---

diff --git a/philo/parsing.c b/philo/parsing.c
index ec9a39f..90d6c5c 100644
--- a/philo/parsing.c
+++ b/philo/parsing.c
@@ -15,6 +15,8 @@
 #include <stddef.h>
 #include <stdlib.h>
 
+#define RESERVE 100
+
 int	is_sane(t_settings *settings)
 {
 	return (settings->philo_count > 0);
@@ -33,6 +35,13 @@ int	parse_input(t_settings *settings, int argc, char **argv)
 	{
 		return (1);
 	}
+	if (settings->philo_count % 2
+		&& 3 * settings->time_to_eat < settings->time_to_die
+		&& 2 * settings->time_to_eat > settings->time_to_sleep)
+		settings->time_to_think = 2 * settings->time_to_eat
+			- settings->time_to_sleep + RESERVE;
+	else
+		settings->time_to_think = 0;
 	if (argc == 6)
 	{
 		if (parse_arg_uint(&settings->min_eat_num, argv[5]))
diff --git a/philo/philo.c b/philo/philo.c
index f0f52fc..e1fe1f0 100644
--- a/philo/philo.c
+++ b/philo/philo.c
@@ -15,7 +15,8 @@
 
 static void	philo_think(t_philo *philo)
 {
-	report(philo, "is thinking");
+	if (!report(philo, "is thinking"))
+		usleep(philo->settings->time_to_think);
 	return ;
 }
 
@@ -82,13 +83,14 @@ void	*be_a_philosopher(void *void_philo)
 {
 	t_philo *const	philo = void_philo;
 
+	report(philo, "is thinking");
 	if (philo->id % 2)
 		usleep(1000);
 	while (!end(philo->settings))
 	{
-		philo_think(philo);
 		philo_eat(philo);
 		philo_sleep(philo);
+		philo_think(philo);
 	}
 	return (NULL);
 }
diff --git a/philo/philo.h b/philo/philo.h
index 8eeed58..698d2b6 100644
--- a/philo/philo.h
+++ b/philo/philo.h
@@ -35,6 +35,7 @@ typedef struct s_settings
 	useconds_t		time_to_die;
 	useconds_t		time_to_eat;
 	useconds_t		time_to_sleep;
+	useconds_t		time_to_think;
 	size_t			philo_count;
 	struct timeval	start;
 	t_mutex			terminal_lock;