add -Wbad-function-cast to +CPPFLAGS and fix two compiler warnings
[paraslash.git] / sched.c
1 /*
2 * Copyright (C) 2006-2007 Andre Noll <maan@systemlinux.org>
3 *
4 * This program is free software; you can redistribute it and/or modify
5 * it under the terms of the GNU General Public License as published by
6 * the Free Software Foundation; either version 2 of the License, or
7 * (at your option) any later version.
8 *
9 * This program is distributed in the hope that it will be useful,
10 * but WITHOUT ANY WARRANTY; without even the implied warranty of
11 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
12 * GNU General Public License for more details.
13 *
14 * You should have received a copy of the GNU General Public License
15 * along with this program; if not, write to the Free Software
16 * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111, USA.
17 */
18
19 /** \file sched.c paraslash's scheduling functions */
20
21 #include <sys/time.h>
22 #include "para.h"
23 #include "ipc.h"
24 #include "fd.h"
25 #include "list.h"
26 #include "sched.h"
27 #include "string.h"
28 #include "error.h"
29
30 static struct list_head pre_select_list, post_select_list;
31 static int initialized;
32
33 static struct timeval now_struct;
34 struct timeval *now = &now_struct;
35
36 static void sched_preselect(struct sched *s)
37 {
38 struct task *t, *tmp;
39 again:
40 list_for_each_entry_safe(t, tmp, &pre_select_list, pre_select_node) {
41 t->pre_select(s, t);
42 // PARA_INFO_LOG("%s \n", t->status);
43 if (t->ret > 0)
44 continue;
45 if (!t->event_handler)
46 continue;
47 t->event_handler(t);
48 goto again;
49 }
50 }
51
52 static void sched_post_select(struct sched *s)
53 {
54 struct task *t, *tmp;
55
56 list_for_each_entry_safe(t, tmp, &post_select_list, post_select_node) {
57 t->post_select(s, t);
58 // PARA_INFO_LOG("%s: %d\n", t->status, t->ret);
59 if (t->ret > 0 || !t->event_handler)
60 continue;
61 t->event_handler(t);
62 }
63 }
64
65 /**
66 * the core function for all paraslash programs
67 *
68 * \param s pointer to the scheduler struct
69 *
70 * This function updates the global \a now pointer, calls all registered
71 * pre_select hooks which may set the timeout and add any file descriptors to
72 * the fd sets of \a s. Next, it calls para_select() and makes the result available
73 * to the registered tasks by calling their post_select hook.
74 *
75 * \return Zero if no more tasks are left in either of the two lists, negative
76 * if para_select returned an error.
77 *
78 * \sa task, now.
79 */
80 int sched(struct sched *s)
81 {
82 if (!initialized)
83 return -E_NOT_INITIALIZED;
84 gettimeofday(now, NULL);
85 again:
86 FD_ZERO(&s->rfds);
87 FD_ZERO(&s->wfds);
88 s->timeout = s->default_timeout;
89 s->max_fileno = -1;
90 sched_preselect(s);
91 s->select_ret = para_select(s->max_fileno + 1, &s->rfds,
92 &s->wfds, &s->timeout);
93 if (s->select_ret < 0)
94 return s->select_ret;
95 gettimeofday(now, NULL);
96 sched_post_select(s);
97 if (list_empty(&pre_select_list) && list_empty(&post_select_list))
98 return 0;
99 goto again;
100 }
101
102 /**
103 * initialize the paraslash scheduler
104 */
105 static void init_sched(void)
106 {
107 PARA_INFO_LOG("%s", "initializing scheduler\n");
108 INIT_LIST_HEAD(&pre_select_list);
109 INIT_LIST_HEAD(&post_select_list);
110 initialized = 1;
111 };
112
113 /**
114 * add a task to the scheduler
115 *
116 * \param t the task to add
117 *
118 * If the pre_select pointer of \a t is not \p NULL, it is added to
119 * the pre_select list of the scheduler. Same goes for post_select.
120 *
121 * \sa task::pre_select, task::post_select
122 */
123 void register_task(struct task *t)
124 {
125 if (!initialized)
126 init_sched();
127 PARA_INFO_LOG("registering %s (%p)\n", t->status, t);
128 if (t->pre_select) {
129 PARA_DEBUG_LOG("pre_select: %p\n", &t->pre_select);
130 para_list_add(&t->pre_select_node, &pre_select_list);
131 }
132 if (t->post_select) {
133 PARA_DEBUG_LOG("post_select: %p\n", &t->pre_select);
134 para_list_add(&t->post_select_node, &post_select_list);
135 }
136 }
137
138 /**
139 * remove a task from the scheduler
140 *
141 * \param t the task to remove
142 *
143 * If the pre_select pointer of \a t is not \p NULL, it is removed from
144 * the pre_select list of the scheduler. Same goes for \a post_select.
145 */
146 void unregister_task(struct task *t)
147 {
148 if (!initialized)
149 return;
150 PARA_INFO_LOG("unregistering %s (%p)\n", t->status, t);
151 if (t->pre_select)
152 list_del(&t->pre_select_node);
153 if (t->post_select)
154 list_del(&t->post_select_node);
155 };
156
157 /**
158 * unregister all tasks
159 *
160 * This will cause \a sched() to return immediately because both the
161 * \a pre_select_list and the \a post_select_list are empty.
162 */
163 void sched_shutdown(void)
164 {
165 struct task *t, *tmp;
166
167 if (!initialized)
168 return;
169 list_for_each_entry_safe(t, tmp, &pre_select_list, pre_select_node)
170 unregister_task(t);
171 /* remove tasks which do not have a pre_select hook */
172 list_for_each_entry_safe(t, tmp, &post_select_list, post_select_node)
173 unregister_task(t);
174 initialized = 0;
175 };
176
177 /**
178 * get the list of all registered tasks.
179 *
180 * \return the task list
181 *
182 * Each entry of the list contains an identifier which is simply a hex number
183 * that may be used in \a kill_task() to terminate the task.
184 * The result ist dynamically allocated and must be freed by the caller.
185 */
186 char *get_task_list(void)
187 {
188 struct task *t, *tmp;
189 char *msg = NULL;
190
191 if (!initialized)
192 return NULL;
193 list_for_each_entry_safe(t, tmp, &pre_select_list, pre_select_node) {
194 char *tmp_msg;
195 tmp_msg = make_message("%s%p\tpre\t%s\n", msg? msg : "", t, t->status);
196 free(msg);
197 msg = tmp_msg;
198 }
199 list_for_each_entry_safe(t, tmp, &post_select_list, post_select_node) {
200 char *tmp_msg;
201 // if (t->pre_select)
202 // continue;
203 tmp_msg = make_message("%s%p\tpost\t%s\n", msg? msg : "", t, t->status);
204 free(msg);
205 msg = tmp_msg;
206 }
207 //PARA_DEBUG_LOG("task list:\n%s", msg);
208 return msg;
209 }
210
211 /**
212 * simulate an error for the given task
213 *
214 * \param id the task identifier
215 *
216 * Find the task identified by \a id, set the tasks' return value to
217 * \p -E_TASK_KILLED and call the event handler of the task.
218 *
219 * \return Positive on success, negative on errors (e.g. if \a id does not
220 * correspond to a registered task).
221 */
222 int kill_task(char *id)
223 {
224 struct task *t, *tmp;
225 char buf[20];
226
227 if (!initialized)
228 return -E_NOT_INITIALIZED;
229 list_for_each_entry_safe(t, tmp, &pre_select_list, pre_select_node) {
230 sprintf(buf, "%p", t);
231 if (strcmp(id, buf))
232 continue;
233 t->ret = -E_TASK_KILLED;
234 if (t->event_handler)
235 t->event_handler(t);
236 return 1;
237 }
238 list_for_each_entry_safe(t, tmp, &post_select_list, post_select_node) {
239 sprintf(buf, "%p", t);
240 if (strcmp(id, buf))
241 continue;
242 t->ret = -E_TASK_KILLED;
243 if (t->event_handler)
244 t->event_handler(t);
245 return 1;
246 }
247 return -E_NO_SUCH_TASK;
248 }