para_filter: Decode also small ogg vorbis files properly.
[paraslash.git] / sched.c
1 /*
2 * Copyright (C) 2006-2011 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 <regex.h>
10 #include <assert.h>
11 #include <sys/time.h>
12 #include <stdbool.h>
13
14 #include "para.h"
15 #include "ipc.h"
16 #include "fd.h"
17 #include "list.h"
18 #include "sched.h"
19 #include "string.h"
20 #include "time.h"
21 #include "error.h"
22
23 static struct list_head pre_select_list, post_select_list;
24 static int initialized;
25
26 static struct timeval now_struct;
27 struct timeval *now = &now_struct;
28
29 /*
30 * Remove a task from the scheduler.
31 *
32 * \param t The task to remove.
33 *
34 * If the pre_select pointer of \a t is not \p NULL, it is removed from
35 * the pre_select list of the scheduler. Same goes for \a post_select.
36 */
37 static void unregister_task(struct task *t)
38 {
39 if (!initialized)
40 return;
41 assert(t->error < 0);
42 PARA_INFO_LOG("unregistering %s (%s)\n", t->status,
43 para_strerror(-t->error));
44 if (t->pre_select)
45 list_del(&t->pre_select_node);
46 if (t->post_select)
47 list_del(&t->post_select_node);
48 }
49
50 static inline bool timeout_is_zero(struct sched *s)
51 {
52 struct timeval *tv = &s->select_timeout;
53 return tv->tv_sec == 0 && tv->tv_usec == 0;
54 }
55
56 static void sched_preselect(struct sched *s)
57 {
58 struct task *t, *tmp;
59 list_for_each_entry_safe(t, tmp, &pre_select_list, pre_select_node) {
60 if (t->error < 0) {
61 unregister_task(t);
62 continue;
63 }
64 if (!t->pre_select)
65 continue;
66 t->pre_select(s, t);
67 if (timeout_is_zero(s))
68 break;
69 }
70 }
71
72 //#define SCHED_DEBUG 1
73 static inline void call_post_select(struct sched *s, struct task *t)
74 {
75 #ifndef SCHED_DEBUG
76 t->post_select(s, t);
77 #else
78 struct timeval t1, t2, diff;
79 unsigned long pst;
80
81 gettimeofday(&t1, NULL);
82 t->post_select(s, t);
83 gettimeofday(&t2, NULL);
84 tv_diff(&t1, &t2, &diff);
85 pst = tv2ms(&diff);
86 if (pst > 50)
87 PARA_WARNING_LOG("%s: post_select time: %lums\n",
88 t->status, pst);
89 #endif
90 }
91
92 static void sched_post_select(struct sched *s)
93 {
94 struct task *t, *tmp;
95
96 list_for_each_entry_safe(t, tmp, &post_select_list, post_select_node) {
97 if (t->error >= 0)
98 call_post_select(s, t);
99 // PARA_INFO_LOG("%s: %d\n", t->status, t->ret);
100 if (t->error >= 0)
101 continue;
102 /*
103 * We have to check whether the list is empty because the call
104 * to ->post_select() might have called sched_shutdown(). In
105 * this case t has been unregistered already, so we must not
106 * unregister it again.
107 */
108 if (list_empty(&post_select_list))
109 return;
110 unregister_task(t);
111 }
112 }
113
114 /**
115 * The core function for all paraslash programs.
116 *
117 * \param s Pointer to the scheduler struct.
118 *
119 * This function updates the global \a now pointer, calls all registered
120 * pre_select hooks which may set the timeout and add any file descriptors to
121 * the fd sets of \a s. Next, it calls para_select() and makes the result available
122 * to the registered tasks by calling their post_select hook.
123 *
124 * \return Zero if no more tasks are left in either of the two lists, negative
125 * if para_select returned an error.
126 *
127 * \sa task, now.
128 */
129 int schedule(struct sched *s)
130 {
131 int ret;
132
133 if (!initialized)
134 return -E_NOT_INITIALIZED;
135 if (!s->select_function)
136 s->select_function = para_select;
137 again:
138 FD_ZERO(&s->rfds);
139 FD_ZERO(&s->wfds);
140 s->select_timeout = s->default_timeout;
141 s->max_fileno = -1;
142 gettimeofday(now, NULL);
143 sched_preselect(s);
144 if (list_empty(&pre_select_list) && list_empty(&post_select_list))
145 return 0;
146 if (!timeout_is_zero(s)) {
147 ret = s->select_function(s->max_fileno + 1, &s->rfds, &s->wfds,
148 &s->select_timeout);
149 if (ret < 0)
150 return ret;
151 if (ret == 0) {
152 /*
153 * APUE: Be careful not to check the descriptor sets on return
154 * unless the return value is greater than zero. The return
155 * state of the descriptor sets is implementation dependent if
156 * either a signal is caught or the timer expires.
157 */
158 FD_ZERO(&s->rfds);
159 FD_ZERO(&s->wfds);
160 }
161 gettimeofday(now, NULL);
162 } else {
163 FD_ZERO(&s->rfds);
164 FD_ZERO(&s->wfds);
165 }
166 sched_post_select(s);
167 if (list_empty(&pre_select_list) && list_empty(&post_select_list))
168 return 0;
169 goto again;
170 }
171
172 /*
173 * Initialize the paraslash scheduler.
174 */
175 static void init_sched(void)
176 {
177 PARA_INFO_LOG("initializing scheduler\n");
178 INIT_LIST_HEAD(&pre_select_list);
179 INIT_LIST_HEAD(&post_select_list);
180 initialized = 1;
181 }
182
183 /**
184 * Add a task to the scheduler.
185 *
186 * \param t the task to add
187 *
188 * If the pre_select pointer of \a t is not \p NULL, it is added to
189 * the pre_select list of the scheduler. Same goes for post_select.
190 *
191 * \sa task::pre_select, task::post_select
192 */
193 void register_task(struct task *t)
194 {
195 if (!initialized)
196 init_sched();
197 PARA_INFO_LOG("registering %s (%p)\n", t->status, t);
198 if (t->pre_select) {
199 PARA_DEBUG_LOG("pre_select: %p\n", &t->pre_select);
200 list_add_tail(&t->pre_select_node, &pre_select_list);
201 }
202 if (t->post_select) {
203 PARA_DEBUG_LOG("post_select: %p\n", &t->post_select);
204 list_add_tail(&t->post_select_node, &post_select_list);
205 }
206 }
207
208 /**
209 * Unregister all tasks.
210 *
211 * This will cause \a schedule() to return immediately because both the
212 * \a pre_select_list and the \a post_select_list are empty. This function
213 * must be called from the post_select (rather than the pre_select) method.
214 */
215 void sched_shutdown(void)
216 {
217 struct task *t, *tmp;
218
219 if (!initialized)
220 return;
221 list_for_each_entry_safe(t, tmp, &pre_select_list, pre_select_node) {
222 t->error = -E_SCHED_SHUTDOWN;
223 unregister_task(t);
224 }
225 list_for_each_entry_safe(t, tmp, &post_select_list, post_select_node) {
226 t->error = -E_SCHED_SHUTDOWN;
227 unregister_task(t);
228 }
229 initialized = 0;
230 }
231
232 /**
233 * Get the list of all registered tasks.
234 *
235 * \return The task list.
236 *
237 * Each entry of the list contains an identifier which is simply a hex number.
238 * The result is dynamically allocated and must be freed by the caller.
239 */
240 char *get_task_list(void)
241 {
242 struct task *t, *tmp;
243 char *msg = NULL;
244
245 if (!initialized)
246 return NULL;
247 list_for_each_entry_safe(t, tmp, &pre_select_list, pre_select_node) {
248 char *tmp_msg;
249 tmp_msg = make_message("%s%p\tpre\t%s\n", msg? msg : "", t, t->status);
250 free(msg);
251 msg = tmp_msg;
252 }
253 list_for_each_entry_safe(t, tmp, &post_select_list, post_select_node) {
254 char *tmp_msg;
255 // if (t->pre_select)
256 // continue;
257 tmp_msg = make_message("%s%p\tpost\t%s\n", msg? msg : "", t, t->status);
258 free(msg);
259 msg = tmp_msg;
260 }
261 //PARA_DEBUG_LOG("task list:\n%s", msg);
262 return msg;
263 }
264
265 /**
266 * Set the select timeout to the minimal possible value.
267 *
268 * \param s Pointer to the scheduler struct.
269 *
270 * This causes the next select() call to return immediately.
271 */
272 void sched_min_delay(struct sched *s)
273 {
274 s->select_timeout.tv_sec = s->select_timeout.tv_usec = 0;
275 }
276
277 /**
278 * Impose an upper bound for the timeout of the next select() call.
279 *
280 * \param to Maximal allowed timeout.
281 * \param s Pointer to the scheduler struct.
282 *
283 * If the current scheduler timeout is already smaller than \a to, this
284 * function does nothing. Otherwise the timeout for the next select() call is
285 * set to the given value.
286 *
287 * \sa sched_request_timeout_ms().
288 */
289 void sched_request_timeout(struct timeval *to, struct sched *s)
290 {
291 if (tv_diff(&s->select_timeout, to, NULL) > 0)
292 s->select_timeout = *to;
293 }
294
295 /**
296 * Force the next select() call to return before the given amount of milliseconds.
297 *
298 * \param ms The maximal allowed timeout in milliseconds.
299 * \param s Pointer to the scheduler struct.
300 *
301 * Like sched_request_timeout() this imposes an upper bound on the timeout
302 * value for the next select() call.
303 */
304 void sched_request_timeout_ms(long unsigned ms, struct sched *s)
305 {
306 struct timeval tv;
307 ms2tv(ms, &tv);
308 sched_request_timeout(&tv, s);
309 }
310
311 /**
312 * Force the next select() call to return before the given future time.
313 *
314 * \param barrier Absolute time before select() should return.
315 * \param s Pointer to the scheduler struct.
316 *
317 * \return If \a barrier is in the past, this function does nothing and returns
318 * zero. Otherwise it returns one.
319 *
320 * \sa sched_request_barrier_or_min_delay().
321 */
322 int sched_request_barrier(struct timeval *barrier, struct sched *s)
323 {
324 struct timeval diff;
325
326 if (tv_diff(now, barrier, &diff) > 0)
327 return 0;
328 sched_request_timeout(&diff, s);
329 return 1;
330 }
331
332 /**
333 * Force the next select() call to return before the given time.
334 *
335 * \param barrier Absolute time before select() should return.
336 * \param s Pointer to the scheduler struct.
337 *
338 * If \a barrier is in the past, this function requests a minimal timeout and
339 * returns zero. Otherwise it returns one.
340 *
341 * \sa sched_min_delay(), sched_request_barrier().
342 */
343 int sched_request_barrier_or_min_delay(struct timeval *barrier, struct sched *s)
344 {
345 struct timeval diff;
346
347 if (tv_diff(now, barrier, &diff) > 0) {
348 sched_min_delay(s);
349 return 0;
350 }
351 sched_request_timeout(&diff, s);
352 return 1;
353 }