client.c: supervisor task should use post_select instead of pre_select.

[paraslash.git] / sched.c

diff --git a/sched.c b/sched.c
index 90df5933689c377ad2c570e36bb340eda74e9dae..02793124f38b2c8a185dbe6fa7e1b27fd5306ab2 100644 (file)
--- a/sched.c
+++ b/sched.c
@@ -4,7 +4,7 @@
  * Licensed under the GPL v2. For licencing details see COPYING.
  */
 
-/** \file sched.c paraslash's scheduling functions */
+/** \file sched.c Paraslash's scheduling functions. */
 
 #include <dirent.h> /* readdir() */
 #include <assert.h>
@@ -27,22 +27,22 @@ struct timeval *now = &now_struct;
 /**
  * Remove a task from the scheduler.
  *
- * \param t the task to remove
+ * \param t The task to remove.
  *
  * If the pre_select pointer of \a t is not \p NULL, it is removed from
  * the pre_select list of the scheduler. Same goes for \a post_select.
  */
-void unregister_task(struct task *t)
+static void unregister_task(struct task *t)
 {
        if (!initialized)
                return;
-       PARA_INFO_LOG("unregistering %s (%p)\n", t->status, t);
+       PARA_INFO_LOG("unregistering %s (%s)\n", t->status,
+               t->error <0? para_strerror(-t->error) : "shutdown");
        if (t->pre_select)
                list_del(&t->pre_select_node);
        if (t->post_select)
                list_del(&t->post_select_node);
-       if (t->error >= 0)
-               t->error = -E_TASK_KILLED;
+       t->error = -E_TASK_UNREGISTERED;
 };
 
 
@@ -50,10 +50,19 @@ static void sched_preselect(struct sched *s)
 {
        struct task *t, *tmp;
        list_for_each_entry_safe(t, tmp, &pre_select_list, pre_select_node) {
-               t->pre_select(s, t);
+               if (t->error >= 0)
+                       t->pre_select(s, t);
 //             PARA_INFO_LOG("%s \n", t->status);
                if (t->error >= 0)
                        continue;
+               /*
+                * We have to check whether the list is empty because the call
+                * to ->pre_select() might have called sched_shutdown(). In
+                * this case t has been unregistered already, so we must not
+                * unregister it again.
+                */
+               if (list_empty(&pre_select_list))
+                       return;
                unregister_task(t);
        }
 }
@@ -63,18 +72,22 @@ static void sched_post_select(struct sched *s)
        struct task *t, *tmp;
 
        list_for_each_entry_safe(t, tmp, &post_select_list, post_select_node) {
-               t->post_select(s, t);
+               if (t->error >= 0)
+                       t->post_select(s, t);
 //             PARA_INFO_LOG("%s: %d\n", t->status, t->ret);
                if (t->error >= 0)
                        continue;
+               /* nec., see sched_preselect() */
+               if (list_empty(&post_select_list))
+                       return;
                unregister_task(t);
        }
 }
 
 /**
- * the core function for all paraslash programs
+ * The core function for all paraslash programs.
  *
- * \param s pointer to the scheduler struct
+ * \param s Pointer to the scheduler struct.
  *
  * This function updates the global \a now pointer, calls all registered
  * pre_select hooks which may set the timeout and add any file descriptors to
@@ -99,6 +112,8 @@ again:
        s->timeout = s->default_timeout;
        s->max_fileno = -1;
        sched_preselect(s);
+       if (list_empty(&pre_select_list) && list_empty(&post_select_list))
+               return 0;
        ret = para_select(s->max_fileno + 1, &s->rfds, &s->wfds, &s->timeout);
        if (ret < 0)
                return ret;
@@ -110,7 +125,7 @@ again:
 }
 
 /**
- * initialize the paraslash scheduler
+ * Initialize the paraslash scheduler.
  */
 static void init_sched(void)
 {
@@ -121,7 +136,7 @@ static void init_sched(void)
 };
 
 /**
- * add a task to the scheduler
+ * Add a task to the scheduler.
  *
  * \param t the task to add
  *
@@ -146,7 +161,7 @@ void register_task(struct task *t)
 }
 
 /**
- * unregister all tasks
+ * Unregister all tasks.
  *
  * This will cause \a schedule() to return immediately because both the
  * \a pre_select_list and the \a post_select_list are empty.
@@ -159,16 +174,15 @@ void sched_shutdown(void)
                return;
        list_for_each_entry_safe(t, tmp, &pre_select_list, pre_select_node)
                unregister_task(t);
-       /* remove tasks which do not have a pre_select hook */
        list_for_each_entry_safe(t, tmp, &post_select_list, post_select_node)
                unregister_task(t);
        initialized = 0;
 };
 
 /**
- * get the list of all registered tasks.
+ * Get the list of all registered tasks.
  *
- * \return the task list
+ * \return The task list.
  *
  * Each entry of the list contains an identifier which is simply a hex number
  * that may be used in \a kill_task() to terminate the task.
@@ -200,9 +214,9 @@ char *get_task_list(void)
 }
 
 /**
- * simulate an error for the given task
+ * Simulate an error for the given task.
  *
- * \param id the task identifier
+ * \param id The task identifier.
  *
  * Find the task identified by \a id, set the tasks' error value to
  * \p -E_TASK_KILLED and unregister the task.
@@ -222,7 +236,6 @@ int kill_task(char *id)
                if (strcmp(id, buf))
                        continue;
                t->error = -E_TASK_KILLED;
-               unregister_task(t);
                return 1;
        }
        list_for_each_entry_safe(t, tmp, &post_select_list, post_select_node) {
@@ -230,7 +243,6 @@ int kill_task(char *id)
                if (strcmp(id, buf))
                        continue;
                t->error = -E_TASK_KILLED;
-               unregister_task(t);
                return 1;
        }
        return -E_NO_SUCH_TASK;