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work-stealing-scheduler/src/sched-lifo.c
2024-04-24 17:14:34 +02:00

175 lines
4 KiB
C

#include "../includes/sched.h"
#include <errno.h>
#include <pthread.h>
#include <stdio.h>
#include <stdlib.h>
struct task_info {
void *closure;
taskfunc f;
};
struct scheduler {
/* Indicateur de changement d'état */
pthread_cond_t cond;
/* Mutex qui protège la structure */
pthread_mutex_t mutex;
/* Nombre de threads instanciés */
int nthreads;
/* Nombre de threads en attente */
int nthsleep;
/* Taille de la pile */
int qlen;
/* Pile de tâches */
struct task_info *tasks;
/* Position actuelle dans la pile */
int top;
};
/* Lance une tâche de la pile */
void *sched_worker(void *);
int
sched_init(int nthreads, int qlen, taskfunc f, void *closure)
{
static struct scheduler sched;
if(qlen <= 0) {
fprintf(stderr, "qlen must be greater than 0\n");
return -1;
}
sched.qlen = qlen;
if(nthreads < 0) {
fprintf(stderr, "nthreads must be greater than 0\n");
return -1;
} else if(nthreads == 0) {
nthreads = sched_default_threads();
}
sched.nthreads = nthreads;
sched.nthsleep = 0;
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;
}
sched.top = -1;
if((sched.tasks = malloc(qlen * sizeof(struct task_info))) == NULL) {
perror("Stack");
return -1;
}
pthread_t threads[nthreads];
for(int i = 0; i < nthreads; ++i) {
if(pthread_create(&threads[i], NULL, sched_worker, &sched) != 0) {
fprintf(stderr, "Can't create the thread %d", i);
if(i > 0) {
fprintf(stderr, ", cancelling already created threads...\n");
for(int j = 0; j < i; ++j) {
if(pthread_cancel(threads[j]) != 0) {
fprintf(stderr, "Can't cancel the thread %d\n", j);
}
}
} else {
fprintf(stderr, "\n");
}
free(sched.tasks);
return -1;
}
}
if(sched_spawn(f, closure, &sched) < 0) {
fprintf(stderr, "Can't create the initial 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;
}
}
free(sched.tasks);
pthread_mutex_destroy(&sched.mutex);
pthread_cond_destroy(&sched.cond);
return 1;
}
int
sched_spawn(taskfunc f, void *closure, struct scheduler *s)
{
pthread_mutex_lock(&s->mutex);
if(s->top + 1 >= s->qlen) {
pthread_mutex_unlock(&s->mutex);
errno = EAGAIN;
fprintf(stderr, "Stack is full\n");
return -1;
}
s->top++;
s->tasks[s->top] = (struct task_info){closure, f};
pthread_cond_signal(&s->cond);
pthread_mutex_unlock(&s->mutex);
return 0;
}
void *
sched_worker(void *arg)
{
struct scheduler *s = (struct scheduler *)arg;
struct task_info task;
while(1) {
pthread_mutex_lock(&s->mutex);
// S'il on a rien à faire
if(s->top == -1) {
s->nthsleep++;
if(s->nthsleep == s->nthreads) {
// Signal a tout les threads que il n'y a plus rien à faire
// si un thread attend une tâche
pthread_cond_broadcast(&s->cond);
pthread_mutex_unlock(&s->mutex);
break;
}
pthread_cond_wait(&s->cond, &s->mutex);
s->nthsleep--;
pthread_mutex_unlock(&s->mutex);
continue;
}
// Extrait la tâche de la pile
task = s->tasks[s->top];
s->top--;
pthread_mutex_unlock(&s->mutex);
// Exécute la tâche
task.f(task.closure, s);
}
return NULL;
}