/*
- * Copyright (C) 2006-2008 Andre Noll <maan@systemlinux.org>
+ * Copyright (C) 2006-2009 Andre Noll <maan@systemlinux.org>
*
* 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>
/**
* 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);
-};
+ t->error = -E_TASK_UNREGISTERED;
+}
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)
+ 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);
}
}
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
if (!initialized)
return -E_NOT_INITIALIZED;
+ if (!s->select_function)
+ s->select_function = para_select;
gettimeofday(now, NULL);
again:
FD_ZERO(&s->rfds);
s->timeout = s->default_timeout;
s->max_fileno = -1;
sched_preselect(s);
- ret = para_select(s->max_fileno + 1, &s->rfds, &s->wfds, &s->timeout);
+ if (list_empty(&pre_select_list) && list_empty(&post_select_list))
+ return 0;
+ ret = s->select_function(s->max_fileno + 1, &s->rfds, &s->wfds, &s->timeout);
if (ret < 0)
return ret;
gettimeofday(now, NULL);
}
/**
- * initialize the paraslash scheduler
+ * Initialize the paraslash scheduler.
*/
static void init_sched(void)
{
INIT_LIST_HEAD(&pre_select_list);
INIT_LIST_HEAD(&post_select_list);
initialized = 1;
-};
+}
/**
- * add a task to the scheduler
+ * Add a task to the scheduler.
*
* \param t the task to add
*
list_add_tail(&t->pre_select_node, &pre_select_list);
}
if (t->post_select) {
- PARA_DEBUG_LOG("post_select: %p\n", &t->pre_select);
+ PARA_DEBUG_LOG("post_select: %p\n", &t->post_select);
list_add_tail(&t->post_select_node, &post_select_list);
}
}
/**
- * 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.
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.
}
/**
- * 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.
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) {
if (strcmp(id, buf))
continue;
t->error = -E_TASK_KILLED;
- unregister_task(t);
return 1;
}
return -E_NO_SUCH_TASK;