2 * Copyright (C) 2006-2008 Andre Noll <maan@systemlinux.org>
4 * Licensed under the GPL v2. For licencing details see COPYING.
7 /** \file sched.c paraslash's scheduling functions */
9 #include <dirent.h> /* readdir() */
21 static struct list_head pre_select_list, post_select_list;
22 static int initialized;
24 static struct timeval now_struct;
25 struct timeval *now = &now_struct;
28 * Remove a task from the scheduler.
30 * \param t the task to remove
32 * If the pre_select pointer of \a t is not \p NULL, it is removed from
33 * the pre_select list of the scheduler. Same goes for \a post_select.
35 void unregister_task(struct task *t)
39 PARA_INFO_LOG("unregistering %s (%p)\n", t->status, t);
41 list_del(&t->pre_select_node);
43 list_del(&t->post_select_node);
45 t->error = -E_TASK_KILLED;
49 static void sched_preselect(struct sched *s)
52 list_for_each_entry_safe(t, tmp, &pre_select_list, pre_select_node) {
54 // PARA_INFO_LOG("%s \n", t->status);
61 static void sched_post_select(struct sched *s)
65 list_for_each_entry_safe(t, tmp, &post_select_list, post_select_node) {
67 // PARA_INFO_LOG("%s: %d\n", t->status, t->ret);
75 * the core function for all paraslash programs
77 * \param s pointer to the scheduler struct
79 * This function updates the global \a now pointer, calls all registered
80 * pre_select hooks which may set the timeout and add any file descriptors to
81 * the fd sets of \a s. Next, it calls para_select() and makes the result available
82 * to the registered tasks by calling their post_select hook.
84 * \return Zero if no more tasks are left in either of the two lists, negative
85 * if para_select returned an error.
89 int schedule(struct sched *s)
94 return -E_NOT_INITIALIZED;
95 gettimeofday(now, NULL);
99 s->timeout = s->default_timeout;
102 ret = para_select(s->max_fileno + 1, &s->rfds, &s->wfds, &s->timeout);
105 gettimeofday(now, NULL);
106 sched_post_select(s);
107 if (list_empty(&pre_select_list) && list_empty(&post_select_list))
113 * initialize the paraslash scheduler
115 static void init_sched(void)
117 PARA_INFO_LOG("initializing scheduler\n");
118 INIT_LIST_HEAD(&pre_select_list);
119 INIT_LIST_HEAD(&post_select_list);
124 * add a task to the scheduler
126 * \param t the task to add
128 * If the pre_select pointer of \a t is not \p NULL, it is added to
129 * the pre_select list of the scheduler. Same goes for post_select.
131 * \sa task::pre_select, task::post_select
133 void register_task(struct task *t)
137 PARA_INFO_LOG("registering %s (%p)\n", t->status, t);
139 PARA_DEBUG_LOG("pre_select: %p\n", &t->pre_select);
140 list_add_tail(&t->pre_select_node, &pre_select_list);
142 if (t->post_select) {
143 PARA_DEBUG_LOG("post_select: %p\n", &t->pre_select);
144 list_add_tail(&t->post_select_node, &post_select_list);
149 * unregister all tasks
151 * This will cause \a schedule() to return immediately because both the
152 * \a pre_select_list and the \a post_select_list are empty.
154 void sched_shutdown(void)
156 struct task *t, *tmp;
160 list_for_each_entry_safe(t, tmp, &pre_select_list, pre_select_node)
162 /* remove tasks which do not have a pre_select hook */
163 list_for_each_entry_safe(t, tmp, &post_select_list, post_select_node)
169 * get the list of all registered tasks.
171 * \return the task list
173 * Each entry of the list contains an identifier which is simply a hex number
174 * that may be used in \a kill_task() to terminate the task.
175 * The result ist dynamically allocated and must be freed by the caller.
177 char *get_task_list(void)
179 struct task *t, *tmp;
184 list_for_each_entry_safe(t, tmp, &pre_select_list, pre_select_node) {
186 tmp_msg = make_message("%s%p\tpre\t%s\n", msg? msg : "", t, t->status);
190 list_for_each_entry_safe(t, tmp, &post_select_list, post_select_node) {
192 // if (t->pre_select)
194 tmp_msg = make_message("%s%p\tpost\t%s\n", msg? msg : "", t, t->status);
198 //PARA_DEBUG_LOG("task list:\n%s", msg);
203 * simulate an error for the given task
205 * \param id the task identifier
207 * Find the task identified by \a id, set the tasks' error value to
208 * \p -E_TASK_KILLED and unregister the task.
210 * \return Positive on success, negative on errors (e.g. if \a id does not
211 * correspond to a registered task).
213 int kill_task(char *id)
215 struct task *t, *tmp;
219 return -E_NOT_INITIALIZED;
220 list_for_each_entry_safe(t, tmp, &pre_select_list, pre_select_node) {
221 sprintf(buf, "%p", t);
224 t->error = -E_TASK_KILLED;
228 list_for_each_entry_safe(t, tmp, &post_select_list, post_select_node) {
229 sprintf(buf, "%p", t);
232 t->error = -E_TASK_KILLED;
236 return -E_NO_SUCH_TASK;