45  *    running and wakes up the zthr.
46  * 2] The zthr wakes up, checks the indicator and starts working.
55  * ensure that they fit your use-case well before using them.
61  * 1] A user-defined checker function (checkfunc) that decides whether
67  * 2] A user-defined ZTHR function (func) which the zthr executes when
91  * NOTE: ZTHR threads could potentially wake up spuriously and the
108  * signal every time func returns and every time it wakes up [see
112  * time. This may be very time-consuming for some operations that
129  * Cancelling a zthr doesn't clean up its metadata (internal locks,
142  *      |      woke up
143  *      |   +--------------+ sleep
149  *   cancelled? +---------> checkfunc?
155  *      |   +---------------+ func
196 	 * if this is 0, the thread doesn't wake up until it gets
201 	/* consumer-provided callbacks & data */
212 	mutex_enter(&t->zthr_state_lock);  in zthr_procedure()
213 	ASSERT3P(t->zthr_thread, ==, curthread);  in zthr_procedure()
215 	while (!t->zthr_cancel) {  in zthr_procedure()
216 		if (t->zthr_checkfunc(t->zthr_arg, t)) {  in zthr_procedure()
217 			mutex_exit(&t->zthr_state_lock);  in zthr_procedure()
218 			t->zthr_func(t->zthr_arg, t);  in zthr_procedure()
219 			mutex_enter(&t->zthr_state_lock);  in zthr_procedure()
222 			if (t->zthr_wait_time == 0) {  in zthr_procedure()
223 				cv_wait(&t->zthr_cv, &t->zthr_state_lock);  in zthr_procedure()
225 				(void) cv_timedwait_hires(&t->zthr_cv,  in zthr_procedure()
226 				    &t->zthr_state_lock, t->zthr_wait_time,  in zthr_procedure()
236 	t->zthr_thread = NULL;  in zthr_procedure()
237 	t->zthr_cancel = B_FALSE;  in zthr_procedure()
238 	cv_broadcast(&t->zthr_cv);  in zthr_procedure()
240 	mutex_exit(&t->zthr_state_lock);  in zthr_procedure()
260 	mutex_init(&t->zthr_state_lock, NULL, MUTEX_DEFAULT, NULL);  in zthr_create_timer()
261 	mutex_init(&t->zthr_request_lock, NULL, MUTEX_DEFAULT, NULL);  in zthr_create_timer()
262 	cv_init(&t->zthr_cv, NULL, CV_DEFAULT, NULL);  in zthr_create_timer()
264 	mutex_enter(&t->zthr_state_lock);  in zthr_create_timer()
265 	t->zthr_checkfunc = checkfunc;  in zthr_create_timer()
266 	t->zthr_func = func;  in zthr_create_timer()
267 	t->zthr_arg = arg;  in zthr_create_timer()
268 	t->zthr_wait_time = max_sleep;  in zthr_create_timer()
270 	t->zthr_thread = thread_create(NULL, 0, zthr_procedure, t,  in zthr_create_timer()
272 	mutex_exit(&t->zthr_state_lock);  in zthr_create_timer()
280 	ASSERT(!MUTEX_HELD(&t->zthr_state_lock));  in zthr_destroy()
281 	ASSERT(!MUTEX_HELD(&t->zthr_request_lock));  in zthr_destroy()
282 	VERIFY3P(t->zthr_thread, ==, NULL);  in zthr_destroy()
283 	mutex_destroy(&t->zthr_request_lock);  in zthr_destroy()
284 	mutex_destroy(&t->zthr_state_lock);  in zthr_destroy()
285 	cv_destroy(&t->zthr_cv);  in zthr_destroy()
290  * Wake up the zthr if it is sleeping. If the thread has been
296 	mutex_enter(&t->zthr_request_lock);  in zthr_wakeup()
297 	mutex_enter(&t->zthr_state_lock);  in zthr_wakeup()
304 	 *     point the broadcast will wake it up.  in zthr_wakeup()
305 	 * [2] The thread has been cancelled. Waking up a cancelled  in zthr_wakeup()
306 	 *     thread is a no-op. Any work that is still left to be  in zthr_wakeup()
309 	 * [3] The thread is doing work and is already up, so this  in zthr_wakeup()
310 	 *     is basically a no-op.  in zthr_wakeup()
314 	cv_broadcast(&t->zthr_cv);  in zthr_wakeup()
316 	mutex_exit(&t->zthr_state_lock);  in zthr_wakeup()
317 	mutex_exit(&t->zthr_request_lock);  in zthr_wakeup()
323  * already), this is a no-op.
328 	mutex_enter(&t->zthr_request_lock);  in zthr_cancel()
329 	mutex_enter(&t->zthr_state_lock);  in zthr_cancel()
338 	 *     to wake it up and then we set the flag and we are  in zthr_cancel()
349 	if (t->zthr_thread != NULL) {  in zthr_cancel()
350 		t->zthr_cancel = B_TRUE;  in zthr_cancel()
353 		cv_broadcast(&t->zthr_cv);  in zthr_cancel()
355 		while (t->zthr_thread != NULL)  in zthr_cancel()
356 			cv_wait(&t->zthr_cv, &t->zthr_state_lock);  in zthr_cancel()
358 		ASSERT(!t->zthr_cancel);  in zthr_cancel()
361 	mutex_exit(&t->zthr_state_lock);  in zthr_cancel()
362 	mutex_exit(&t->zthr_request_lock);  in zthr_cancel()
367  * already running this is a no-op.
372 	mutex_enter(&t->zthr_request_lock);  in zthr_resume()
373 	mutex_enter(&t->zthr_state_lock);  in zthr_resume()
375 	ASSERT3P(&t->zthr_checkfunc, !=, NULL);  in zthr_resume()
376 	ASSERT3P(&t->zthr_func, !=, NULL);  in zthr_resume()
377 	ASSERT(!t->zthr_cancel);  in zthr_resume()
385 	 * [2] The zthr is running at which point this is a no-op.  in zthr_resume()
386 	 * [3] The zthr is sleeping at which point this is a no-op.  in zthr_resume()
388 	 *     no-op.  in zthr_resume()
390 	if (t->zthr_thread == NULL) {  in zthr_resume()
391 		t->zthr_thread = thread_create(NULL, 0, zthr_procedure, t,  in zthr_resume()
395 	mutex_exit(&t->zthr_state_lock);  in zthr_resume()
396 	mutex_exit(&t->zthr_request_lock);  in zthr_resume()
413 	ASSERT3P(t->zthr_thread, ==, curthread);  in zthr_iscancelled()
427 	mutex_enter(&t->zthr_state_lock);  in zthr_iscancelled()
428 	boolean_t cancelled = t->zthr_cancel;  in zthr_iscancelled()
429 	mutex_exit(&t->zthr_state_lock);  in zthr_iscancelled()