From 8e31a53bb3412bea5c083d09ea540487534f6162 Mon Sep 17 00:00:00 2001
From: Lukas Jiriste <ljiriste@student.42prague.com>
Date: Thu, 5 Sep 2024 11:32:45 +0200
Subject: [PATCH] Make main wait for a possible philo death

This makes main less demanding as it also enters sleep when no
philosopher's death is near.
---
 philo/main.c | 49 +++++++++++++++++++++++++++++--------------------
 1 file changed, 29 insertions(+), 20 deletions(-)

diff --git a/philo/main.c b/philo/main.c
index 11c1ceb..2e75583 100644
--- a/philo/main.c
+++ b/philo/main.c
@@ -6,7 +6,7 @@
 /*   By: ljiriste <marvin@42.fr>                    +#+  +:+       +#+        */
 /*                                                +#+#+#+#+#+   +#+           */
 /*   Created: 2024/03/22 11:19:48 by ljiriste          #+#    #+#             */
-/*   Updated: 2024/05/09 12:31:31 by ljiriste         ###   ########.fr       */
+/*   Updated: 2024/09/05 11:32:29 by ljiriste         ###   ########.fr       */
 /*                                                                            */
 /* ************************************************************************** */
 
@@ -41,17 +41,28 @@ static int	seat_philosophers(t_diner *diner, pthread_t *threads)
 	return (0);
 }
 
-static int	is_dead(t_philo *philo)
+static void	get_closest_to_death(t_diner *diner,
+				size_t *philo_ind_out, useconds_t *closest_death_time)
 {
-	mutex_lock(&philo->philo_lock);
-	if (usecs_since_start(philo->settings->start) - philo->last_eaten
-		> philo->settings->time_to_die)
+	size_t		i;
+	t_philo		*philo;
+	useconds_t	death_time;
+
+	i = 0;
+	while (i < diner->setting.philo_count)
 	{
+		philo = diner->philos + i;
+		mutex_lock(&philo->philo_lock);
+		death_time = philo->last_eaten + diner->setting.time_to_die;
 		mutex_unlock(&philo->philo_lock);
-		return (1);
+		if (i == 0 || death_time < *closest_death_time)
+		{
+			*philo_ind_out = i;
+			*closest_death_time = death_time;
+		}
+		++i;
 	}
-	mutex_unlock(&philo->philo_lock);
-	return (0);
+	return ;
 }
 
 static int	all_full(t_diner *diner)
@@ -76,22 +87,19 @@ static int	all_full(t_diner *diner)
 
 static enum e_end	watch_philosophers(t_diner *diner)
 {
-	size_t	i;
+	size_t		philo_ind;
+	useconds_t	closest_death_time;
 
 	while (1)
 	{
-		i = 0;
-		while (i < diner->setting.philo_count)
+		get_closest_to_death(diner, &philo_ind, &closest_death_time);
+		if (closest_death_time < usecs_since_start(diner->setting.start))
 		{
-			if (is_dead(diner->philos + i))
-			{
-				mutex_lock(&diner->setting.end_lock);
-				diner->setting.end = 1;
-				mutex_unlock(&diner->setting.end_lock);
-				print_timestamp(diner->philos + i, "died");
-				return (death);
-			}
-			++i;
+			mutex_lock(&diner->setting.end_lock);
+			diner->setting.end = 1;
+			mutex_unlock(&diner->setting.end_lock);
+			print_timestamp(diner->philos + philo_ind, "died");
+			return (death);
 		}
 		if (all_full(diner))
 		{
@@ -100,6 +108,7 @@ static enum e_end	watch_philosophers(t_diner *diner)
 			mutex_unlock(&diner->setting.end_lock);
 			return (well_fed);
 		}
+		usleep(closest_death_time - usecs_since_start(diner->setting.start));
 	}
 }
 
-- 
2.30.2