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);
58 * We have to check whether the list is empty because the call
59 * to ->pre_select() might have called sched_shutdown(). In
60 * this case t has been unregistered already, so we must not
61 * unregister it again.
63 if (list_empty(&pre_select_list))
69 static void sched_post_select(struct sched *s)
73 list_for_each_entry_safe(t, tmp, &post_select_list, post_select_node) {
75 // PARA_INFO_LOG("%s: %d\n", t->status, t->ret);
78 /* nec., see sched_preselect() */
79 if (list_empty(&post_select_list))
86 * the core function for all paraslash programs
88 * \param s pointer to the scheduler struct
90 * This function updates the global \a now pointer, calls all registered
91 * pre_select hooks which may set the timeout and add any file descriptors to
92 * the fd sets of \a s. Next, it calls para_select() and makes the result available
93 * to the registered tasks by calling their post_select hook.
95 * \return Zero if no more tasks are left in either of the two lists, negative
96 * if para_select returned an error.
100 int schedule(struct sched *s)
105 return -E_NOT_INITIALIZED;
106 gettimeofday(now, NULL);
110 s->timeout = s->default_timeout;
113 if (list_empty(&pre_select_list) && list_empty(&post_select_list))
115 ret = para_select(s->max_fileno + 1, &s->rfds, &s->wfds, &s->timeout);
118 gettimeofday(now, NULL);
119 sched_post_select(s);
120 if (list_empty(&pre_select_list) && list_empty(&post_select_list))
126 * initialize the paraslash scheduler
128 static void init_sched(void)
130 PARA_INFO_LOG("initializing scheduler\n");
131 INIT_LIST_HEAD(&pre_select_list);
132 INIT_LIST_HEAD(&post_select_list);
137 * add a task to the scheduler
139 * \param t the task to add
141 * If the pre_select pointer of \a t is not \p NULL, it is added to
142 * the pre_select list of the scheduler. Same goes for post_select.
144 * \sa task::pre_select, task::post_select
146 void register_task(struct task *t)
150 PARA_INFO_LOG("registering %s (%p)\n", t->status, t);
152 PARA_DEBUG_LOG("pre_select: %p\n", &t->pre_select);
153 list_add_tail(&t->pre_select_node, &pre_select_list);
155 if (t->post_select) {
156 PARA_DEBUG_LOG("post_select: %p\n", &t->pre_select);
157 list_add_tail(&t->post_select_node, &post_select_list);
162 * unregister all tasks
164 * This will cause \a schedule() to return immediately because both the
165 * \a pre_select_list and the \a post_select_list are empty.
167 void sched_shutdown(void)
169 struct task *t, *tmp;
173 list_for_each_entry_safe(t, tmp, &pre_select_list, pre_select_node)
175 /* remove tasks which do not have a pre_select hook */
176 list_for_each_entry_safe(t, tmp, &post_select_list, post_select_node)
182 * get the list of all registered tasks.
184 * \return the task list
186 * Each entry of the list contains an identifier which is simply a hex number
187 * that may be used in \a kill_task() to terminate the task.
188 * The result ist dynamically allocated and must be freed by the caller.
190 char *get_task_list(void)
192 struct task *t, *tmp;
197 list_for_each_entry_safe(t, tmp, &pre_select_list, pre_select_node) {
199 tmp_msg = make_message("%s%p\tpre\t%s\n", msg? msg : "", t, t->status);
203 list_for_each_entry_safe(t, tmp, &post_select_list, post_select_node) {
205 // if (t->pre_select)
207 tmp_msg = make_message("%s%p\tpost\t%s\n", msg? msg : "", t, t->status);
211 //PARA_DEBUG_LOG("task list:\n%s", msg);
216 * simulate an error for the given task
218 * \param id the task identifier
220 * Find the task identified by \a id, set the tasks' error value to
221 * \p -E_TASK_KILLED and unregister the task.
223 * \return Positive on success, negative on errors (e.g. if \a id does not
224 * correspond to a registered task).
226 int kill_task(char *id)
228 struct task *t, *tmp;
232 return -E_NOT_INITIALIZED;
233 list_for_each_entry_safe(t, tmp, &pre_select_list, pre_select_node) {
234 sprintf(buf, "%p", t);
237 t->error = -E_TASK_KILLED;
241 list_for_each_entry_safe(t, tmp, &post_select_list, post_select_node) {
242 sprintf(buf, "%p", t);
245 t->error = -E_TASK_KILLED;
249 return -E_NO_SUCH_TASK;