ungegister_task(): Set task error value to -E_TASK_KILLED.
[paraslash.git] / sched.c
1 /*
2 * Copyright (C) 2006-2008 Andre Noll <maan@systemlinux.org>
3 *
4 * Licensed under the GPL v2. For licencing details see COPYING.
5 */
6
7 /** \file sched.c paraslash's scheduling functions */
8
9 #include <dirent.h> /* readdir() */
10 #include <assert.h>
11 #include <sys/time.h>
12
13 #include "para.h"
14 #include "ipc.h"
15 #include "fd.h"
16 #include "list.h"
17 #include "sched.h"
18 #include "string.h"
19 #include "error.h"
20
21 static struct list_head pre_select_list, post_select_list;
22 static int initialized;
23
24 static struct timeval now_struct;
25 struct timeval *now = &now_struct;
26
27 /**
28 * Remove a task from the scheduler.
29 *
30 * \param t the task to remove
31 *
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.
34 */
35 void unregister_task(struct task *t)
36 {
37 if (!initialized)
38 return;
39 PARA_INFO_LOG("unregistering %s (%p)\n", t->status, t);
40 if (t->pre_select)
41 list_del(&t->pre_select_node);
42 if (t->post_select)
43 list_del(&t->post_select_node);
44 if (t->error >= 0)
45 t->error = -E_TASK_KILLED;
46 };
47
48
49 static void sched_preselect(struct sched *s)
50 {
51 struct task *t, *tmp;
52 list_for_each_entry_safe(t, tmp, &pre_select_list, pre_select_node) {
53 t->pre_select(s, t);
54 // PARA_INFO_LOG("%s \n", t->status);
55 if (t->error >= 0)
56 continue;
57 unregister_task(t);
58 }
59 }
60
61 static void sched_post_select(struct sched *s)
62 {
63 struct task *t, *tmp;
64
65 list_for_each_entry_safe(t, tmp, &post_select_list, post_select_node) {
66 t->post_select(s, t);
67 // PARA_INFO_LOG("%s: %d\n", t->status, t->ret);
68 if (t->error >= 0)
69 continue;
70 unregister_task(t);
71 }
72 }
73
74 /**
75 * the core function for all paraslash programs
76 *
77 * \param s pointer to the scheduler struct
78 *
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.
83 *
84 * \return Zero if no more tasks are left in either of the two lists, negative
85 * if para_select returned an error.
86 *
87 * \sa task, now.
88 */
89 int schedule(struct sched *s)
90 {
91 int ret;
92
93 if (!initialized)
94 return -E_NOT_INITIALIZED;
95 gettimeofday(now, NULL);
96 again:
97 FD_ZERO(&s->rfds);
98 FD_ZERO(&s->wfds);
99 s->timeout = s->default_timeout;
100 s->max_fileno = -1;
101 sched_preselect(s);
102 ret = para_select(s->max_fileno + 1, &s->rfds, &s->wfds, &s->timeout);
103 if (ret < 0)
104 return ret;
105 gettimeofday(now, NULL);
106 sched_post_select(s);
107 if (list_empty(&pre_select_list) && list_empty(&post_select_list))
108 return 0;
109 goto again;
110 }
111
112 /**
113 * initialize the paraslash scheduler
114 */
115 static void init_sched(void)
116 {
117 PARA_INFO_LOG("initializing scheduler\n");
118 INIT_LIST_HEAD(&pre_select_list);
119 INIT_LIST_HEAD(&post_select_list);
120 initialized = 1;
121 };
122
123 /**
124 * add a task to the scheduler
125 *
126 * \param t the task to add
127 *
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.
130 *
131 * \sa task::pre_select, task::post_select
132 */
133 void register_task(struct task *t)
134 {
135 if (!initialized)
136 init_sched();
137 PARA_INFO_LOG("registering %s (%p)\n", t->status, t);
138 if (t->pre_select) {
139 PARA_DEBUG_LOG("pre_select: %p\n", &t->pre_select);
140 list_add_tail(&t->pre_select_node, &pre_select_list);
141 }
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);
145 }
146 }
147
148 /**
149 * unregister all tasks
150 *
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.
153 */
154 void sched_shutdown(void)
155 {
156 struct task *t, *tmp;
157
158 if (!initialized)
159 return;
160 list_for_each_entry_safe(t, tmp, &pre_select_list, pre_select_node)
161 unregister_task(t);
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)
164 unregister_task(t);
165 initialized = 0;
166 };
167
168 /**
169 * get the list of all registered tasks.
170 *
171 * \return the task list
172 *
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.
176 */
177 char *get_task_list(void)
178 {
179 struct task *t, *tmp;
180 char *msg = NULL;
181
182 if (!initialized)
183 return NULL;
184 list_for_each_entry_safe(t, tmp, &pre_select_list, pre_select_node) {
185 char *tmp_msg;
186 tmp_msg = make_message("%s%p\tpre\t%s\n", msg? msg : "", t, t->status);
187 free(msg);
188 msg = tmp_msg;
189 }
190 list_for_each_entry_safe(t, tmp, &post_select_list, post_select_node) {
191 char *tmp_msg;
192 // if (t->pre_select)
193 // continue;
194 tmp_msg = make_message("%s%p\tpost\t%s\n", msg? msg : "", t, t->status);
195 free(msg);
196 msg = tmp_msg;
197 }
198 //PARA_DEBUG_LOG("task list:\n%s", msg);
199 return msg;
200 }
201
202 /**
203 * simulate an error for the given task
204 *
205 * \param id the task identifier
206 *
207 * Find the task identified by \a id, set the tasks' error value to
208 * \p -E_TASK_KILLED and unregister the task.
209 *
210 * \return Positive on success, negative on errors (e.g. if \a id does not
211 * correspond to a registered task).
212 */
213 int kill_task(char *id)
214 {
215 struct task *t, *tmp;
216 char buf[20];
217
218 if (!initialized)
219 return -E_NOT_INITIALIZED;
220 list_for_each_entry_safe(t, tmp, &pre_select_list, pre_select_node) {
221 sprintf(buf, "%p", t);
222 if (strcmp(id, buf))
223 continue;
224 t->error = -E_TASK_KILLED;
225 unregister_task(t);
226 return 1;
227 }
228 list_for_each_entry_safe(t, tmp, &post_select_list, post_select_node) {
229 sprintf(buf, "%p", t);
230 if (strcmp(id, buf))
231 continue;
232 t->error = -E_TASK_KILLED;
233 unregister_task(t);
234 return 1;
235 }
236 return -E_NO_SUCH_TASK;
237 }