sched: Introduce alternative task API.

[paraslash.git] / sched.c

diff --git a/sched.c b/sched.c
index 85f4238b1233de58adcf07e8ac3265a1cbab9f0d..101cc4c0dad3706e841881b2a6d2989825fc58b0 100644 (file)
--- a/sched.c
+++ b/sched.c
@@ -41,6 +41,14 @@ static void sched_preselect(struct sched *s)
        }
 }
 
+static void unlink_and_free_task(struct task *t)
+{
+       PARA_INFO_LOG("freeing task %s\n", t->status);
+       list_del(&t->node);
+       if (t->owned_by_sched)
+               free(t);
+}
+
 //#define SCHED_DEBUG 1
 static inline void call_post_select(struct sched *s, struct task *t)
 {
@@ -61,16 +69,23 @@ static inline void call_post_select(struct sched *s, struct task *t)
 #endif
 }
 
-static void sched_post_select(struct sched *s)
+static unsigned sched_post_select(struct sched *s)
 {
        struct task *t, *tmp;
+       unsigned num_running_tasks = 0;
 
        list_for_each_entry_safe(t, tmp, &s->task_list, node) {
+               if (t->error < 0)
+                       continue;
                call_post_select(s, t);
                t->notification = 0;
-               if (t->error < 0)
-                       list_del(&t->node);
+               if (t->error < 0) {
+                       if (!t->owned_by_sched)
+                               list_del(&t->node);
+               } else
+                       num_running_tasks++;
        }
+       return num_running_tasks;
 }
 
 /**
@@ -91,6 +106,7 @@ static void sched_post_select(struct sched *s)
 int schedule(struct sched *s)
 {
        int ret;
+       unsigned num_running_tasks;
 
        if (!s->select_function)
                s->select_function = para_select;
@@ -116,14 +132,34 @@ again:
                FD_ZERO(&s->wfds);
        }
        clock_get_realtime(now);
-       sched_post_select(s);
-       if (list_empty(&s->task_list))
+       num_running_tasks = sched_post_select(s);
+       if (num_running_tasks == 0)
                return 0;
        goto again;
 }
 
 /**
- * Add a task to the scheduler.
+ * Deallocate all resources of all tasks of a scheduler instance.
+ *
+ * \param s The scheduler instance.
+ *
+ * This should only be called after \ref schedule() has returned.
+ */
+void sched_shutdown(struct sched *s)
+{
+       struct task *t, *tmp;
+
+       list_for_each_entry_safe(t, tmp, &s->task_list, node) {
+               if (t->error >= 0)
+                       /* The task list should contain only terminated tasks. */
+                       PARA_WARNING_LOG("shutting down running task %s\n",
+                               t->status);
+               unlink_and_free_task(t);
+       }
+}
+
+/**
+ * Add a task to the scheduler. Deprecated.
  *
  * \param t The task to add.
  * \param s The scheduler instance to add the task to.
@@ -135,9 +171,54 @@ void register_task(struct sched *s, struct task *t)
        PARA_INFO_LOG("registering %s (%p)\n", t->status, t);
        assert(t->post_select);
        t->notification = 0;
+       t->owned_by_sched = false;
+       if (!s->task_list.next)
+               INIT_LIST_HEAD(&s->task_list);
+       list_add_tail(&t->node, &s->task_list);
+}
+
+/**
+ * Add a task to the scheduler task list.
+ *
+ * \param info Task information supplied by the caller.
+ * \param s The scheduler instance.
+ *
+ * \return A pointer to a newly allocated task structure. It will be
+ * freed by sched_shutdown().
+ */
+struct task *task_register(struct task_info *info, struct sched *s)
+{
+       struct task *t = para_malloc(sizeof(*t));
+
+       assert(info->post_select);
+
        if (!s->task_list.next)
                INIT_LIST_HEAD(&s->task_list);
+
+       snprintf(t->status, sizeof(t->status) - 1, "%s", info->name);
+       t->status[sizeof(t->status) - 1] = '\0';
+       t->notification = 0;
+       t->error = 0;
+       t->pre_select = info->pre_select;
+       t->post_select = info->post_select;
+       t->context = info->context;
+       t->owned_by_sched = true;
        list_add_tail(&t->node, &s->task_list);
+       return t;
+}
+
+/**
+ * Obtain the context pointer of a task.
+ *
+ * \param t Return this task's context pointer.
+ *
+ * \return A pointer to the memory location specified previously as \a
+ * task_info->context when the task was registered with \ref task_register().
+ */
+void *task_context(struct task *t)
+{
+       assert(t->owned_by_sched);
+       return t->context;
 }
 
 /**
@@ -157,7 +238,9 @@ char *get_task_list(struct sched *s)
 
        list_for_each_entry_safe(t, tmp, &s->task_list, node) {
                char *tmp_msg;
-               tmp_msg = make_message("%s%p\t%s\n", msg? msg : "", t, t->status);
+               tmp_msg = make_message("%s%p\t%s\t%s\n", msg? msg : "", t,
+                       t->error < 0? "zombie" : "running",
+                       t->status);
                free(msg);
                msg = tmp_msg;
        }