From 51d91042da7078443ba00243e19bd082c99d41f7 Mon Sep 17 00:00:00 2001
From: Mylloon <kennel.anri@tutanota.com>
Date: Thu, 18 Apr 2024 17:41:41 +0200
Subject: [PATCH] wip: deuxieme solution

---
 includes/sched.h |  21 +++++++++-
 src/sched.c      | 101 ++++++++++++++++++++++++++++++++++++++++-------
 2 files changed, 106 insertions(+), 16 deletions(-)

diff --git a/includes/sched.h b/includes/sched.h
index b0832bb..d7e695d 100644
--- a/includes/sched.h
+++ b/includes/sched.h
@@ -1,13 +1,30 @@
 #pragma once
 
-#include <errno.h>
+#include <pthread.h>
 #include <unistd.h>
 
+#define MAX_TASKS 1024
+
 struct scheduler;
 
 typedef void (*taskfunc)(void *, struct scheduler *);
 
-static inline int sched_default_threads() {
+struct scheduler {
+  /* Mutex qui protège la pile */
+  pthread_mutex_t mutex;
+
+  /* Indicateur de changement d'état de la pile */
+  pthread_cond_t cond;
+
+  /* Position actuelle dans la pile */
+  int top;
+
+  /* Tâches */
+  taskfunc tasks[MAX_TASKS];
+  void *closures[MAX_TASKS];
+};
+
+static inline int sched_default_threads(void) {
   return sysconf(_SC_NPROCESSORS_ONLN);
 }
 
diff --git a/src/sched.c b/src/sched.c
index 801a52f..6cf4703 100644
--- a/src/sched.c
+++ b/src/sched.c
@@ -1,29 +1,102 @@
 #include "../includes/sched.h"
 
-#include <pthread.h>
+#include <errno.h>
 #include <stdio.h>
 
+static struct scheduler sched;
+
+/* Lance une tâche de la pile */
+void *worker_routine(void *arg) {
+  struct scheduler *s = (struct scheduler *)arg;
+
+  while (1) {
+    // Attente d'un changement d'état
+    pthread_cond_wait(&s->cond, &s->mutex);
+
+    pthread_mutex_lock(&s->mutex);
+    if (s->top == -1) {
+      // Il n'y a plus de tâches à exécuter
+      pthread_mutex_unlock(&s->mutex);
+      break;
+    }
+
+    // Extrait la tâche de la pile
+    taskfunc f = s->tasks[s->top];
+    void *closure = s->closures[s->top];
+    s->top--;
+
+    pthread_mutex_unlock(&s->mutex);
+
+    // Exécute la tâche
+    f(closure, s);
+
+    // Signale que la tâche est terminée
+    pthread_cond_signal(&s->cond);
+  }
+
+  return NULL;
+}
+
 int sched_init(int nthreads, int qlen, taskfunc f, void *closure) {
-  sched_spawn(f, closure, NULL);
-  return 0;
+  if (nthreads == 0) {
+    nthreads = sched_default_threads();
+  }
+
+  // Actuellement on n'utilises pas qlen
+  // => On utilise une pile de taille fixe
+  (void)qlen;
+
+  sched.top = -1;
+
+  if (pthread_mutex_init(&sched.mutex, NULL) != 0) {
+    fprintf(stderr, "Can't init mutex\n");
+    return -1;
+  }
+
+  if (pthread_cond_init(&sched.cond, NULL) != 0) {
+    fprintf(stderr, "Can't init condition variable\n");
+    return -1;
+  }
+
+  pthread_t threads[nthreads];
+  for (int i = 0; i < nthreads; ++i) {
+    if (pthread_create(&threads[i], NULL, worker_routine, &sched) != 0) {
+      fprintf(stderr, "Can't create threads\n");
+      return -1;
+    }
+  }
+
+  if (sched_spawn(f, closure, &sched) != 0) {
+    fprintf(stderr, "Can't create a new task\n");
+    return -1;
+  }
+
+  for (int i = 0; i < nthreads; ++i) {
+    if ((pthread_join(threads[i], NULL) != 0)) {
+      fprintf(stderr, "Can't wait the thread %d\n", i);
+      return -1;
+    }
+  }
+
+  return 1;
 }
 
 int sched_spawn(taskfunc f, void *closure, struct scheduler *s) {
-  pthread_t thread;
-  int err;
+  pthread_mutex_lock(&s->mutex);
 
-  // Création d'un thread pour la tâche
-  if ((err = pthread_create(&thread, NULL, (void *(*)(void *))f, closure)) !=
-      0) {
-    fprintf(stderr, "pthread_create error %d\n", errno);
+  if (s->top + 1 >= MAX_TASKS) {
+    pthread_mutex_unlock(&s->mutex);
+    errno = EAGAIN;
+    fprintf(stderr, "Stack full\n");
     return -1;
   }
 
-  // Attend la fin du thread
-  if ((err = pthread_join(thread, NULL)) != 0) {
-    fprintf(stderr, "pthread_join error %d\n", errno);
-    return -1;
-  }
+  s->top++;
+  s->tasks[s->top] = f;
+  s->closures[s->top] = closure;
+
+  pthread_mutex_unlock(&s->mutex);
+  pthread_cond_signal(&s->cond);
 
   return 0;
 }