1 /* -*- mode: c; c-basic-offset: 4; tab-width: 4; indent-tabs-mode: t -*-
3 * timed_thread.c: Abstraction layer for timed threads
5 * Copyright (C) 2006-2007 Philip Kovacs pkovacs@users.sourceforge.net
7 * This library is free software; you can redistribute it and/or
8 * modify it under the terms of the GNU Lesser General Public
9 * License as published by the Free Software Foundation; either
10 * version 2.1 of the License, or (at your option) any later version.
12 * This library is distributed in the hope that it will be useful,
13 * but WITHOUT ANY WARRANTY; without even the implied warranty of
14 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
15 * Lesser General Public License for more details.
17 * You should have received a copy of the GNU Lesser General Public
18 * License along with this library; if not, write to the Free Software
19 * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301
22 * vim: ts=4 sw=4 noet ai cindent syntax=c
35 #ifndef HAVE_CLOCK_GETTIME
38 #include "timed_thread.h"
40 /* Abstraction layer for timed threads */
42 static int now(struct timespec *);
45 struct _timed_thread {
46 pthread_t thread; /* thread itself */
47 pthread_attr_t thread_attr; /* thread attributes */
48 pthread_mutex_t cs_mutex; /* critical section mutex */
49 pthread_mutex_t runnable_mutex; /* only for the runnable_cond */
50 pthread_cond_t runnable_cond; /* signalled to stop the thread */
51 void *(*start_routine)(void *); /* thread function to run */
52 void *arg; /* thread function argument */
53 struct timespec interval_time; /* interval_usecs as a struct timespec */
54 struct timespec wait_time; /* absolute future time next timed_thread_test will wait until */
59 /* linked list of created threads */
60 typedef struct _timed_thread_list {
61 timed_thread *p_timed_thread;
62 timed_thread **addr_of_p_timed_thread;
63 struct _timed_thread_list *next;
64 } timed_thread_node, timed_thread_list;
66 static timed_thread_list *p_timed_thread_list_head = NULL;
67 static timed_thread_list *p_timed_thread_list_tail = NULL;
69 int timed_thread_readfd(timed_thread *p_timed_thread)
71 return p_timed_thread->pipefd[0];
74 static int now(struct timespec *abstime)
76 #ifndef HAVE_CLOCK_GETTIME
84 #ifdef HAVE_CLOCK_GETTIME
85 return clock_gettime(CLOCK_REALTIME, abstime);
87 /* fallback to gettimeofday () */
88 if (gettimeofday(&tv, NULL) != 0) {
92 abstime->tv_sec = tv.tv_sec;
93 abstime->tv_nsec = tv.tv_usec * 1000;
98 /* create a timed thread (object creation only) */
99 timed_thread *timed_thread_create(void *start_routine(void *), void *arg,
100 unsigned int interval_usecs)
102 timed_thread *p_timed_thread;
104 assert(start_routine != NULL);
105 assert(interval_usecs >= MINIMUM_INTERVAL_USECS);
107 if ((p_timed_thread = calloc(sizeof(timed_thread), 1)) == 0) {
111 /* create thread pipe (used to tell threads to die) */
112 if (pipe(p_timed_thread->pipefd)) {
116 /* init attributes, e.g. joinable thread */
117 pthread_attr_init(&p_timed_thread->thread_attr);
118 pthread_attr_setdetachstate(&p_timed_thread->thread_attr,
119 PTHREAD_CREATE_JOINABLE);
121 pthread_mutex_init(&p_timed_thread->cs_mutex, NULL);
122 pthread_mutex_init(&p_timed_thread->runnable_mutex, NULL);
124 pthread_cond_init(&p_timed_thread->runnable_cond, NULL);
126 p_timed_thread->start_routine = start_routine;
127 p_timed_thread->arg = arg;
129 /* set wait time to current time */
130 if (now(&p_timed_thread->wait_time)) {
134 /* seconds portion of the microseconds interval */
135 p_timed_thread->interval_time.tv_sec = (time_t) (interval_usecs / 1000000);
136 /* remaining microseconds convert to nanoseconds */
137 p_timed_thread->interval_time.tv_nsec =
138 (long) ((interval_usecs % 1000000) * 1000);
140 /* printf("interval_time.tv_sec = %li, .tv_nsec = %li\n",
141 p_timed_thread->interval_time.tv_sec,
142 p_timed_thread->interval_time.tv_nsec); */
143 return p_timed_thread;
146 /* run a timed thread (drop the thread and run it) */
147 int timed_thread_run(timed_thread *p_timed_thread)
149 return pthread_create(&p_timed_thread->thread, &p_timed_thread->thread_attr,
150 p_timed_thread->start_routine, p_timed_thread->arg);
153 /* destroy a timed thread.
154 * optional addr_of_p_timed_thread to set callers pointer to NULL as a
156 void timed_thread_destroy(timed_thread *p_timed_thread,
157 timed_thread **addr_of_p_timed_thread)
159 assert(p_timed_thread != NULL);
160 assert((addr_of_p_timed_thread == NULL)
161 || (*addr_of_p_timed_thread == p_timed_thread));
163 /* signal thread to stop */
164 pthread_mutex_lock(&p_timed_thread->runnable_mutex);
165 pthread_cond_signal(&p_timed_thread->runnable_cond);
166 p_timed_thread->die = 1;
167 pthread_mutex_unlock(&p_timed_thread->runnable_mutex);
168 write(p_timed_thread->pipefd[1], "die", 3);
170 /* join the terminating thread */
171 if (p_timed_thread->thread) {
172 pthread_join(p_timed_thread->thread, NULL);
176 pthread_attr_destroy(&p_timed_thread->thread_attr);
177 pthread_mutex_destroy(&p_timed_thread->cs_mutex);
178 pthread_mutex_destroy(&p_timed_thread->runnable_mutex);
179 pthread_cond_destroy(&p_timed_thread->runnable_cond);
181 free(p_timed_thread);
182 if (addr_of_p_timed_thread) {
183 *addr_of_p_timed_thread = NULL;
187 /* lock a timed thread for critical section activity */
188 int timed_thread_lock(timed_thread *p_timed_thread)
190 assert(p_timed_thread != NULL);
192 return pthread_mutex_lock(&p_timed_thread->cs_mutex);
195 /* unlock a timed thread after critical section activity */
196 int timed_thread_unlock(timed_thread *p_timed_thread)
198 assert(p_timed_thread != NULL);
200 return pthread_mutex_unlock(&p_timed_thread->cs_mutex);
203 /* thread waits interval_usecs for runnable_cond to be signaled.
204 * returns 1 if signaled, -1 on error, and 0 otherwise.
205 * caller should call timed_thread_exit() on any non-zero return value. */
206 int timed_thread_test(timed_thread *p_timed_thread, int override_wait_time)
208 struct timespec now_time;
211 assert(p_timed_thread != NULL);
213 /* acquire runnable_cond mutex */
214 if (pthread_mutex_lock(&p_timed_thread->runnable_mutex)) {
215 /* could not acquire runnable_cond mutex,
216 * so tell caller to exit thread */
220 if (p_timed_thread->die) {
221 /* if we were kindly asked to die, then die */
225 if (override_wait_time && now(&p_timed_thread->wait_time)) {
229 /* release mutex and wait until future time for runnable_cond to signal */
230 rc = pthread_cond_timedwait(&p_timed_thread->runnable_cond,
231 &p_timed_thread->runnable_mutex, &p_timed_thread->wait_time);
232 /* mutex re-acquired, so release it */
233 pthread_mutex_unlock(&p_timed_thread->runnable_mutex);
235 if (now(&now_time)) {
240 /* runnable_cond was signaled, so tell caller to exit thread */
244 /* absolute future time for next pass */
245 p_timed_thread->wait_time.tv_sec += p_timed_thread->interval_time.tv_sec;
246 p_timed_thread->wait_time.tv_nsec += p_timed_thread->interval_time.tv_nsec;
247 p_timed_thread->wait_time.tv_sec += p_timed_thread->wait_time.tv_nsec / 1000000000;
248 p_timed_thread->wait_time.tv_nsec = p_timed_thread->wait_time.tv_nsec % 1000000000;
250 /* ensure our future wait time is sane */
251 if (p_timed_thread->wait_time.tv_sec > (now_time.tv_sec + p_timed_thread->interval_time.tv_sec) || p_timed_thread->wait_time.tv_sec < now_time.tv_sec) {
252 p_timed_thread->wait_time.tv_sec = now_time.tv_sec + p_timed_thread->interval_time.tv_sec;
253 p_timed_thread->wait_time.tv_nsec = now_time.tv_nsec + p_timed_thread->interval_time.tv_nsec;
254 p_timed_thread->wait_time.tv_sec += p_timed_thread->wait_time.tv_nsec / 1000000000;
255 p_timed_thread->wait_time.tv_nsec = p_timed_thread->wait_time.tv_nsec % 1000000000;
258 /* tell caller not to exit yet */
262 /* exit a timed thread */
263 void timed_thread_exit(timed_thread *p_timed_thread)
265 assert(p_timed_thread != NULL);
267 close(p_timed_thread->pipefd[0]);
268 close(p_timed_thread->pipefd[1]);
273 /* register a timed thread for future destruction via
274 * timed_thread_destroy_registered_threads() */
275 int timed_thread_register(timed_thread *p_timed_thread,
276 timed_thread **addr_of_p_timed_thread)
278 timed_thread_node *p_node;
280 assert((addr_of_p_timed_thread == NULL)
281 || (*addr_of_p_timed_thread == p_timed_thread));
283 if ((p_node = calloc(sizeof(timed_thread_node), 1)) == 0) {
287 p_node->p_timed_thread = p_timed_thread;
288 p_node->addr_of_p_timed_thread = addr_of_p_timed_thread;
291 if (!p_timed_thread_list_tail) {
292 /* first node of empty list */
293 p_timed_thread_list_tail = p_node;
294 p_timed_thread_list_head = p_node;
296 /* add node to tail of non-empty list */
297 p_timed_thread_list_tail->next = p_node;
298 p_timed_thread_list_tail = p_node;
304 /* destroy all registered timed threads */
305 void timed_thread_destroy_registered_threads(void)
307 timed_thread_node *p_node, *p_next;
309 for (p_node = p_timed_thread_list_head; p_node; p_node = p_next) {
310 p_next = p_node->next;
311 timed_thread_destroy(p_node->p_timed_thread,
312 p_node->addr_of_p_timed_thread);
317 p_timed_thread_list_head = NULL;
318 p_timed_thread_list_tail = NULL;