1 /*
2 * CDDL HEADER START
3 *
4 * The contents of this file are subject to the terms of the
5 * Common Development and Distribution License, Version 1.0 only
6 * (the "License"). You may not use this file except in compliance
7 * with the License.
8 *
9 * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
10 * or http://www.opensolaris.org/os/licensing.
11 * See the License for the specific language governing permissions
12 * and limitations under the License.
13 *
14 * When distributing Covered Code, include this CDDL HEADER in each
15 * file and include the License file at usr/src/OPENSOLARIS.LICENSE.
16 * If applicable, add the following below this CDDL HEADER, with the
17 * fields enclosed by brackets "[]" replaced with your own identifying
18 * information: Portions Copyright [yyyy] [name of copyright owner]
19 *
20 * CDDL HEADER END
21 */
22 /*
23 * Copyright 2004 Sun Microsystems, Inc. All rights reserved.
24 * Use is subject to license terms.
25 */
26
27 #pragma ident "%Z%%M% %I% %E% SMI"
28
29 #include <signal.h>
30 #include <strings.h>
31 #include <limits.h>
32
33 #include <fmd_alloc.h>
34 #include <fmd_subr.h>
35 #include <fmd_thread.h>
36 #include <fmd_timerq.h>
37
38 #include <fmd.h>
39
40 /*
41 * Install a new timer to fire after at least 'delta' nanoseconds have elapsed.
42 * Timers are associated with persistent integer identifiers in some idspace.
43 * We allocate a new timer structure or re-use one from our freelist, and then
44 * place it on the queue's list in sorted order by expiration time. If the new
45 * timer is now the earliest to expire, we awaken the fmd_timerq_exec() thread.
46 */
47 id_t
fmd_timerq_install(fmd_timerq_t * tmq,fmd_idspace_t * ids,fmd_timer_f * func,void * arg,fmd_event_t * ep,hrtime_t delta)48 fmd_timerq_install(fmd_timerq_t *tmq, fmd_idspace_t *ids,
49 fmd_timer_f *func, void *arg, fmd_event_t *ep, hrtime_t delta)
50 {
51 hrtime_t now = fmd_time_gethrtime();
52 hrtime_t base = ep ? fmd_event_hrtime(ep) : now;
53
54 fmd_timer_t *tp, *up;
55 hrtime_t hrt;
56 id_t id;
57
58 (void) pthread_mutex_lock(&tmq->tmq_lock);
59
60 if ((tp = fmd_list_next(&tmq->tmq_free)) == NULL) {
61 tp = fmd_zalloc(sizeof (fmd_timer_t), FMD_SLEEP);
62 (void) pthread_cond_init(&tp->tmr_cv, NULL);
63 } else
64 fmd_list_delete(&tmq->tmq_free, tp);
65
66 if ((id = fmd_idspace_alloc(ids, tp)) == -1) {
67 fmd_list_prepend(&tmq->tmq_free, tp);
68 (void) pthread_mutex_unlock(&tmq->tmq_lock);
69 return (id);
70 }
71
72 if (delta < 0)
73 delta = 0; /* ensure delta is at least 0ns from now */
74
75 if (base + delta < base)
76 hrt = INT64_MAX; /* if wrap-around, set timer for apocalypse */
77 else
78 hrt = base + delta;
79
80 tp->tmr_hrt = hrt;
81 tp->tmr_ids = ids;
82 tp->tmr_id = id;
83 tp->tmr_func = func;
84 tp->tmr_arg = arg;
85
86 /*
87 * For now we use a simple insertion sort for tmq_list. If we have
88 * scaling problems here due to heavy use of our timer subsystem,
89 * then tmq_list can and should be replaced with a O(logN) heap.
90 */
91 for (up = fmd_list_next(&tmq->tmq_list); up; up = fmd_list_next(up)) {
92 if (tp->tmr_hrt < up->tmr_hrt)
93 break;
94 }
95
96 if (up != NULL)
97 fmd_list_insert_before(&tmq->tmq_list, up, tp);
98 else
99 fmd_list_insert_after(&tmq->tmq_list, up, tp);
100
101 if (up != NULL && fmd_list_next(&tmq->tmq_list) == tp)
102 fmd_time_waitcancel(tmq->tmq_thread->thr_tid);
103 else if (up == NULL && fmd_list_next(&tmq->tmq_list) == tp)
104 (void) pthread_cond_signal(&tmq->tmq_cv);
105
106 (void) pthread_mutex_unlock(&tmq->tmq_lock);
107
108 TRACE((FMD_DBG_TMR, "timer %s:%ld insert +%lldns",
109 ids->ids_name, id, delta));
110
111 return (id);
112 }
113
114 /*
115 * Remove the specified timer. If the 'id' is invalid, we'll panic inside of
116 * fmd_idspace_free(). If the timer is still set, we move it to the freelist
117 * and update the timer thread as needed. If the timer 'id' is valid but
118 * tmr_id is not equal to id, then the timer callback is running: we wait for
119 * tmr_id to change to zero (indicating tmr_func is done) before returning.
120 */
121 void *
fmd_timerq_remove(fmd_timerq_t * tmq,fmd_idspace_t * ids,id_t id)122 fmd_timerq_remove(fmd_timerq_t *tmq, fmd_idspace_t *ids, id_t id)
123 {
124 hrtime_t delta = 0;
125 void *arg = NULL;
126 fmd_timer_t *tp;
127
128 (void) pthread_mutex_lock(&tmq->tmq_lock);
129 tp = fmd_idspace_free(ids, id);
130 ASSERT(tp == NULL || tp->tmr_ids == ids);
131
132 if (tp == NULL) {
133 (void) pthread_mutex_unlock(&tmq->tmq_lock);
134 return (NULL); /* timer is no longer active */
135 }
136
137 if (tp->tmr_id == id) {
138 fmd_list_delete(&tmq->tmq_list, tp);
139 delta = tp->tmr_hrt - fmd_time_gethrtime();
140 arg = tp->tmr_arg;
141 tp->tmr_id = 0;
142 fmd_list_append(&tmq->tmq_free, tp);
143
144 /*
145 * If tmq_list is now empty, we must awaken the exec thread so
146 * it will sleep on tmq_cv waiting for the list to change. We
147 * could also awaken the exec thread if we removed the head of
148 * tmq_list, but an early wakeup is harmless so we do nothing.
149 */
150 if (fmd_list_next(&tmq->tmq_list) == NULL)
151 fmd_time_waitcancel(tmq->tmq_thread->thr_tid);
152 } else {
153 /*
154 * Wait until tmr_id is zero, indicating that tmr_func is done.
155 * This relies on expired fmd_timer_t's being returned to our
156 * free list rather than having the data structure deallocated.
157 */
158 while (tp->tmr_id != 0)
159 (void) pthread_cond_wait(&tp->tmr_cv, &tmq->tmq_lock);
160 }
161
162 (void) pthread_mutex_unlock(&tmq->tmq_lock);
163
164 TRACE((FMD_DBG_TMR, "timer %s:%ld remove -%lldns",
165 ids->ids_name, id, delta > 0 ? delta : 0LL));
166
167 return (arg);
168 }
169
170 /*
171 * fmd_timerq_exec() is the main loop of the thread that runs the timer queue.
172 * We sleep on tmq_cv waiting for timers to show up on tmq_list. When the list
173 * is non-empty, we execute the callback function for each expired timer. If
174 * timers remain that are not yet expired, we nanosleep() until the next expiry
175 * time. We awaken whenever nanosleep() expires or we are interrupted by a
176 * SIGALRM from fmd_timerq_install indicating that we need to rescan our list.
177 */
178 static void
fmd_timerq_exec(fmd_timerq_t * tmq)179 fmd_timerq_exec(fmd_timerq_t *tmq)
180 {
181 fmd_timer_t *tp;
182 sigset_t set;
183 hrtime_t now;
184
185 /*
186 * fmd_thread_create() initializes threads with all signals blocked.
187 * We must unblock SIGALRM (whose disposition has been to set to call
188 * an empty function by fmd_timerq_init()) in order to permit directed
189 * signals to interrupt our nanosleep() and make it return EINTR.
190 * This SIGALRM mechanism is used by the native clock (see fmd_time.c).
191 */
192 (void) sigemptyset(&set);
193 (void) sigaddset(&set, SIGALRM);
194 (void) pthread_sigmask(SIG_UNBLOCK, &set, NULL);
195 (void) pthread_mutex_lock(&tmq->tmq_lock);
196
197 for (;;) {
198 while (!tmq->tmq_abort && fmd_list_next(&tmq->tmq_list) == NULL)
199 (void) pthread_cond_wait(&tmq->tmq_cv, &tmq->tmq_lock);
200
201 if (tmq->tmq_abort) {
202 (void) pthread_mutex_unlock(&tmq->tmq_lock);
203 return; /* abort timerq thread */
204 }
205
206 for (now = fmd_time_gethrtime(); (tp = fmd_list_next(
207 &tmq->tmq_list)) != NULL; now = fmd_time_gethrtime()) {
208
209 if (now == INT64_MAX || tp->tmr_hrt > now)
210 break; /* no more timers left to expire */
211
212 tp->tmr_id = -tp->tmr_id;
213 fmd_list_delete(&tmq->tmq_list, tp);
214 (void) pthread_mutex_unlock(&tmq->tmq_lock);
215
216 TRACE((FMD_DBG_TMR, "tmr %s:%ld exec start (hrt=%llx)",
217 tp->tmr_ids->ids_name, -tp->tmr_id, tp->tmr_hrt));
218
219 tp->tmr_func(tp->tmr_arg, -tp->tmr_id, tp->tmr_hrt);
220
221 TRACE((FMD_DBG_TMR, "tmr %s:%ld exec end",
222 tp->tmr_ids->ids_name, -tp->tmr_id));
223
224 (void) pthread_mutex_lock(&tmq->tmq_lock);
225 (void) fmd_idspace_free(tp->tmr_ids, -tp->tmr_id);
226 fmd_list_append(&tmq->tmq_free, tp);
227 tp->tmr_id = 0; /* for fmd_timer_remove() */
228
229 (void) pthread_cond_broadcast(&tp->tmr_cv);
230 }
231
232 if (tp != NULL) {
233 (void) pthread_mutex_unlock(&tmq->tmq_lock);
234 fmd_time_waithrtime(tp->tmr_hrt - now);
235 (void) pthread_mutex_lock(&tmq->tmq_lock);
236 }
237 }
238 }
239
240 static void
fmd_timerq_alrm(int sig)241 fmd_timerq_alrm(int sig)
242 {
243 TRACE((FMD_DBG_TMR, "timer thread received alarm sig#%d", sig));
244 }
245
246 fmd_timerq_t *
fmd_timerq_create(void)247 fmd_timerq_create(void)
248 {
249 fmd_timerq_t *tmq = fmd_zalloc(sizeof (fmd_timerq_t), FMD_SLEEP);
250 struct sigaction act;
251
252 (void) pthread_mutex_init(&tmq->tmq_lock, NULL);
253 (void) pthread_cond_init(&tmq->tmq_cv, NULL);
254
255 act.sa_handler = fmd_timerq_alrm;
256 act.sa_flags = 0;
257 (void) sigemptyset(&act.sa_mask);
258 (void) sigaction(SIGALRM, &act, NULL);
259
260 if ((tmq->tmq_thread = fmd_thread_create(fmd.d_rmod,
261 (fmd_thread_f *)fmd_timerq_exec, tmq)) == NULL)
262 fmd_panic("failed to create timer thread");
263
264 return (tmq);
265 }
266
267 void
fmd_timerq_destroy(fmd_timerq_t * tmq)268 fmd_timerq_destroy(fmd_timerq_t *tmq)
269 {
270 struct sigaction act;
271 fmd_timer_t *tmr;
272
273 (void) pthread_mutex_lock(&tmq->tmq_lock);
274 tmq->tmq_abort++;
275
276 if (fmd_list_next(&tmq->tmq_list) != NULL)
277 fmd_time_waitcancel(tmq->tmq_thread->thr_tid);
278 else
279 (void) pthread_cond_signal(&tmq->tmq_cv);
280
281 (void) pthread_mutex_unlock(&tmq->tmq_lock);
282 fmd_thread_destroy(tmq->tmq_thread, FMD_THREAD_JOIN);
283 (void) pthread_mutex_lock(&tmq->tmq_lock);
284
285 while ((tmr = fmd_list_next(&tmq->tmq_list)) != NULL) {
286 fmd_list_delete(&tmq->tmq_list, tmr);
287 (void) fmd_idspace_free(tmr->tmr_ids, tmr->tmr_id);
288 fmd_free(tmr, sizeof (fmd_timer_t));
289 }
290
291 while ((tmr = fmd_list_next(&tmq->tmq_free)) != NULL) {
292 fmd_list_delete(&tmq->tmq_free, tmr);
293 ASSERT(tmr->tmr_id == 0);
294 fmd_free(tmr, sizeof (fmd_timer_t));
295 }
296
297 act.sa_handler = SIG_DFL;
298 act.sa_flags = 0;
299 (void) sigemptyset(&act.sa_mask);
300 (void) sigaction(SIGALRM, &act, NULL);
301
302 fmd_free(tmq, sizeof (fmd_timerq_t));
303 }
304