2 * Copyright (c) 2016 Cisco and/or its affiliates.
3 * Licensed under the Apache License, Version 2.0 (the "License");
4 * you may not use this file except in compliance with the License.
5 * You may obtain a copy of the License at:
7 * http://www.apache.org/licenses/LICENSE-2.0
9 * Unless required by applicable law or agreed to in writing, software
10 * distributed under the License is distributed on an "AS IS" BASIS,
11 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
12 * See the License for the specific language governing permissions and
13 * limitations under the License.
17 * @brief TW timer implementation TEMPLATE ONLY, do not compile directly
21 #if TW_START_STOP_TRACE_SIZE > 0
23 void TW (tw_timer_trace) (TWT (tw_timer_wheel) * tw, u32 timer_id,
24 u32 pool_index, u32 handle)
26 TWT (trace) * t = &tw->traces[tw->trace_index];
28 t->timer_id = timer_id;
29 t->pool_index = pool_index;
33 if (tw->trace_index == TW_START_STOP_TRACE_SIZE)
40 void TW (tw_search_trace) (TWT (tw_timer_wheel) * tw, u32 handle)
46 /* reverse search for the supplied handle */
48 start_pos = tw->trace_index;
50 start_pos = TW_START_STOP_TRACE_SIZE - 1;
54 for (i = start_pos; i > 0; i--)
57 if (t->handle == handle)
71 fformat (stderr, "handle 0x%x (%d) %s at trace %d\n",
72 handle, handle, s, i);
75 if (tw->trace_wrapped > 0)
77 for (i = TW_START_STOP_TRACE_SIZE; i >= tw->trace_index; i--)
80 if (t->handle == handle)
94 fformat (stderr, "handle 0x%x (%d) %s at trace %d\n",
95 handle, handle, s, i);
100 #endif /* TW_START_STOP_TRACE_SIZE > 0 */
103 TW (make_internal_timer_handle) (u32 pool_index, u32 timer_id)
107 ASSERT (timer_id < TW_TIMERS_PER_OBJECT);
108 #if LOG2_TW_TIMERS_PER_OBJECT > 0
109 ASSERT (pool_index < (1 << (32 - LOG2_TW_TIMERS_PER_OBJECT)));
111 handle = (timer_id << (32 - LOG2_TW_TIMERS_PER_OBJECT)) | (pool_index);
119 timer_addhead (TWT (tw_timer) * pool, u32 head_index, u32 new_index)
121 TWT (tw_timer) * head = pool_elt_at_index (pool, head_index);
122 TWT (tw_timer) * old_first;
124 TWT (tw_timer) * new;
126 new = pool_elt_at_index (pool, new_index);
128 if (PREDICT_FALSE (head->next == head_index))
130 head->next = head->prev = new_index;
131 new->next = new->prev = head_index;
135 old_first_index = head->next;
136 old_first = pool_elt_at_index (pool, old_first_index);
138 new->next = old_first_index;
139 new->prev = old_first->prev;
140 old_first->prev = new_index;
141 head->next = new_index;
145 timer_remove (TWT (tw_timer) * pool, u32 index)
147 TWT (tw_timer) * elt = pool_elt_at_index (pool, index);
148 TWT (tw_timer) * next_elt, *prev_elt;
150 ASSERT (elt->user_handle != ~0);
152 next_elt = pool_elt_at_index (pool, elt->next);
153 prev_elt = pool_elt_at_index (pool, elt->prev);
155 next_elt->prev = elt->prev;
156 prev_elt->next = elt->next;
158 elt->prev = elt->next = ~0;
162 * @brief Start a Tw Timer
163 * @param tw_timer_wheel_t * tw timer wheel object pointer
164 * @param u32 pool_index user pool index, presumably for a tw session
165 * @param u32 timer_id app-specific timer ID. 4 bits.
166 * @param u64 interval timer interval in ticks
167 * @returns handle needed to cancel the timer
170 TW (tw_timer_start) (TWT (tw_timer_wheel) * tw, u32 pool_index, u32 timer_id,
173 #if TW_TIMER_WHEELS > 1
174 u16 slow_ring_offset;
177 #if TW_TIMER_WHEELS > 2
178 u16 glacier_ring_offset;
180 #if TW_OVERFLOW_VECTOR > 0
181 u64 interval_plus_time_to_wrap, triple_wrap_mask;
183 u16 fast_ring_offset;
184 tw_timer_wheel_slot_t *ts;
189 pool_get (tw->timers, t);
190 memset (t, 0xff, sizeof (*t));
192 t->user_handle = TW (make_internal_timer_handle) (pool_index, timer_id);
194 /* Factor interval into 1..3 wheel offsets */
195 #if TW_TIMER_WHEELS > 2
196 #if TW_OVERFLOW_VECTOR > 0
198 * This is tricky. Put a timer onto the overflow
199 * vector if the interval PLUS the time
200 * until the next triple-wrap exceeds one full revolution
201 * of all three wheels.
203 triple_wrap_mask = (1 << (3 * TW_RING_SHIFT)) - 1;
204 interval_plus_time_to_wrap =
205 interval + (tw->current_tick & triple_wrap_mask);
206 if ((interval_plus_time_to_wrap >= 1 << (3 * TW_RING_SHIFT)))
208 t->expiration_time = tw->current_tick + interval;
210 timer_addhead (tw->timers, ts->head_index, t - tw->timers);
211 #if TW_START_STOP_TRACE_SIZE > 0
212 TW (tw_timer_trace) (tw, timer_id, pool_index, t - tw->timers);
214 return t - tw->timers;
218 glacier_ring_offset = interval >> (2 * TW_RING_SHIFT);
219 ASSERT ((u64) glacier_ring_offset < TW_SLOTS_PER_RING);
220 interval -= (((u64) glacier_ring_offset) << (2 * TW_RING_SHIFT));
222 #if TW_TIMER_WHEELS > 1
223 slow_ring_offset = interval >> TW_RING_SHIFT;
224 ASSERT ((u64) slow_ring_offset < TW_SLOTS_PER_RING);
225 interval -= (((u64) slow_ring_offset) << TW_RING_SHIFT);
227 fast_ring_offset = interval & TW_RING_MASK;
230 * Account for the current wheel positions(s)
231 * This is made slightly complicated by the fact that the current
232 * index vector will contain (TW_SLOTS_PER_RING, ...) when
233 * the actual position is (0, ...)
236 fast_ring_offset += tw->current_index[TW_TIMER_RING_FAST] & TW_RING_MASK;
238 #if TW_TIMER_WHEELS > 1
239 carry = fast_ring_offset >= TW_SLOTS_PER_RING ? 1 : 0;
240 fast_ring_offset %= TW_SLOTS_PER_RING;
241 slow_ring_offset += (tw->current_index[TW_TIMER_RING_SLOW] & TW_RING_MASK)
243 carry = slow_ring_offset >= TW_SLOTS_PER_RING ? 1 : 0;
244 slow_ring_offset %= TW_SLOTS_PER_RING;
247 #if TW_TIMER_WHEELS > 2
248 glacier_ring_offset +=
249 (tw->current_index[TW_TIMER_RING_GLACIER] & TW_RING_MASK) + carry;
250 glacier_ring_offset %= TW_SLOTS_PER_RING;
253 #if TW_TIMER_WHEELS > 2
254 if (glacier_ring_offset !=
255 (tw->current_index[TW_TIMER_RING_GLACIER] & TW_RING_MASK))
257 /* We'll need slow and fast ring offsets later */
258 t->slow_ring_offset = slow_ring_offset;
259 t->fast_ring_offset = fast_ring_offset;
261 ts = &tw->w[TW_TIMER_RING_GLACIER][glacier_ring_offset];
263 timer_addhead (tw->timers, ts->head_index, t - tw->timers);
264 #if TW_START_STOP_TRACE_SIZE > 0
265 TW (tw_timer_trace) (tw, timer_id, pool_index, t - tw->timers);
267 return t - tw->timers;
271 #if TW_TIMER_WHEELS > 1
272 /* Timer expires more than 51.2 seconds from now? */
273 if (slow_ring_offset !=
274 (tw->current_index[TW_TIMER_RING_SLOW] & TW_RING_MASK))
276 /* We'll need the fast ring offset later... */
277 t->fast_ring_offset = fast_ring_offset;
279 ts = &tw->w[TW_TIMER_RING_SLOW][slow_ring_offset];
281 timer_addhead (tw->timers, ts->head_index, t - tw->timers);
282 #if TW_START_STOP_TRACE_SIZE > 0
283 TW (tw_timer_trace) (tw, timer_id, pool_index, t - tw->timers);
285 return t - tw->timers;
288 fast_ring_offset %= TW_SLOTS_PER_RING;
291 /* Timer expires less than one fast-ring revolution from now */
292 ts = &tw->w[TW_TIMER_RING_FAST][fast_ring_offset];
294 timer_addhead (tw->timers, ts->head_index, t - tw->timers);
296 #if TW_FAST_WHEEL_BITMAP
297 tw->fast_slot_bitmap = clib_bitmap_set (tw->fast_slot_bitmap,
298 fast_ring_offset, 1);
300 #if TW_START_STOP_TRACE_SIZE > 0
301 TW (tw_timer_trace) (tw, timer_id, pool_index, t - tw->timers);
303 return t - tw->timers;
306 #if TW_TIMER_SCAN_FOR_HANDLE > 0
307 int TW (scan_for_handle) (TWT (tw_timer_wheel) * tw, u32 handle)
310 tw_timer_wheel_slot_t *ts;
311 TWT (tw_timer) * t, *head;
315 for (i = 0; i < TW_TIMER_WHEELS; i++)
317 for (j = 0; j < TW_SLOTS_PER_RING; j++)
320 head = pool_elt_at_index (tw->timers, ts->head_index);
321 next_index = head->next;
323 while (next_index != ts->head_index)
325 t = pool_elt_at_index (tw->timers, next_index);
326 if (next_index == handle)
328 clib_warning ("handle %d found in ring %d slot %d",
330 clib_warning ("user handle 0x%x", t->user_handle);
333 next_index = t->next;
339 #endif /* TW_TIMER_SCAN_FOR_HANDLE */
342 * @brief Stop a tw timer
343 * @param tw_timer_wheel_t * tw timer wheel object pointer
344 * @param u32 handle timer cancellation returned by tw_timer_start
346 void TW (tw_timer_stop) (TWT (tw_timer_wheel) * tw, u32 handle)
350 #if TW_TIMER_ALLOW_DUPLICATE_STOP
352 * A vlib process may have its timer expire, and receive
353 * an event before the expiration is processed.
354 * That results in a duplicate tw_timer_stop.
356 if (pool_is_free_index (tw->timers, handle))
359 #if TW_START_STOP_TRACE_SIZE > 0
360 TW (tw_timer_trace) (tw, ~0, ~0, handle);
363 t = pool_elt_at_index (tw->timers, handle);
365 /* in case of idiotic handle (e.g. passing a listhead index) */
366 ASSERT (t->user_handle != ~0);
368 timer_remove (tw->timers, handle);
370 pool_put_index (tw->timers, handle);
374 * @brief Initialize a tw timer wheel template instance
375 * @param tw_timer_wheel_t * tw timer wheel object pointer
376 * @param void * expired_timer_callback. Passed a u32 * vector of
377 * expired timer handles. The callback is optional.
378 * @param f64 timer_interval_in_seconds
381 TW (tw_timer_wheel_init) (TWT (tw_timer_wheel) * tw,
382 void *expired_timer_callback,
383 f64 timer_interval_in_seconds, u32 max_expirations)
386 tw_timer_wheel_slot_t *ts;
388 memset (tw, 0, sizeof (*tw));
389 tw->expired_timer_callback = expired_timer_callback;
390 tw->max_expirations = max_expirations;
391 if (timer_interval_in_seconds == 0.0)
393 clib_warning ("timer interval is zero");
396 tw->timer_interval = timer_interval_in_seconds;
397 tw->ticks_per_second = 1.0 / timer_interval_in_seconds;
398 tw->first_expires_tick = ~0ULL;
400 vec_validate (tw->expired_timer_handles, 0);
401 _vec_len (tw->expired_timer_handles) = 0;
403 for (ring = 0; ring < TW_TIMER_WHEELS; ring++)
405 for (slot = 0; slot < TW_SLOTS_PER_RING; slot++)
407 ts = &tw->w[ring][slot];
408 pool_get (tw->timers, t);
409 memset (t, 0xff, sizeof (*t));
410 t->next = t->prev = t - tw->timers;
411 ts->head_index = t - tw->timers;
415 #if TW_OVERFLOW_VECTOR > 0
417 pool_get (tw->timers, t);
418 memset (t, 0xff, sizeof (*t));
419 t->next = t->prev = t - tw->timers;
420 ts->head_index = t - tw->timers;
425 * @brief Free a tw timer wheel template instance
426 * @param tw_timer_wheel_t * tw timer wheel object pointer
428 void TW (tw_timer_wheel_free) (TWT (tw_timer_wheel) * tw)
431 tw_timer_wheel_slot_t *ts;
432 TWT (tw_timer) * head, *t;
435 for (i = 0; i < TW_TIMER_WHEELS; i++)
437 for (j = 0; j < TW_SLOTS_PER_RING; j++)
440 head = pool_elt_at_index (tw->timers, ts->head_index);
441 next_index = head->next;
443 while (next_index != ts->head_index)
445 t = pool_elt_at_index (tw->timers, next_index);
446 next_index = t->next;
447 pool_put (tw->timers, t);
449 pool_put (tw->timers, head);
453 #if TW_OVERFLOW_VECVOR > 0
455 head = pool_elt_at_index (tw->timers, ts->head_index);
456 next_index = head->next;
458 while (next_index != ts->head_index)
460 t = pool_elt_at_index (tw->timers, next_index);
461 next_index = t->next;
462 pool_put (tw->timers, t);
464 pool_put (tw->timers, head);
467 memset (tw, 0, sizeof (*tw));
471 * @brief Advance a tw timer wheel. Calls the expired timer callback
472 * as needed. This routine should be called once every timer_interval seconds
473 * @param tw_timer_wheel_t * tw timer wheel template instance pointer
474 * @param f64 now the current time, e.g. from vlib_time_now(vm)
475 * @returns u32 * vector of expired user handles
478 u32 * TW (tw_timer_expire_timers_internal) (TWT (tw_timer_wheel) * tw,
480 u32 * callback_vector_arg)
483 tw_timer_wheel_slot_t *ts;
484 TWT (tw_timer) * t, *head;
485 u32 *callback_vector;
486 u32 fast_wheel_index;
488 u32 slow_wheel_index __attribute__ ((unused));
489 u32 glacier_wheel_index __attribute__ ((unused));
491 /* Shouldn't happen */
492 if (PREDICT_FALSE (now < tw->next_run_time))
493 return callback_vector_arg;
495 /* Number of ticks which have occurred */
496 nticks = tw->ticks_per_second * (now - tw->last_run_time);
498 return callback_vector_arg;
500 /* Remember when we ran, compute next runtime */
501 tw->next_run_time = (now + tw->timer_interval);
503 if (callback_vector_arg == 0)
505 _vec_len (tw->expired_timer_handles) = 0;
506 callback_vector = tw->expired_timer_handles;
509 callback_vector = callback_vector_arg;
511 for (i = 0; i < nticks; i++)
513 fast_wheel_index = tw->current_index[TW_TIMER_RING_FAST];
514 if (TW_TIMER_WHEELS > 1)
515 slow_wheel_index = tw->current_index[TW_TIMER_RING_SLOW];
516 if (TW_TIMER_WHEELS > 2)
517 glacier_wheel_index = tw->current_index[TW_TIMER_RING_GLACIER];
519 #if TW_OVERFLOW_VECTOR > 0
520 /* Triple odometer-click? Process the overflow vector... */
521 if (PREDICT_FALSE (fast_wheel_index == TW_SLOTS_PER_RING
522 && slow_wheel_index == TW_SLOTS_PER_RING
523 && glacier_wheel_index == TW_SLOTS_PER_RING))
526 u32 new_glacier_ring_offset, new_slow_ring_offset;
527 u32 new_fast_ring_offset;
530 head = pool_elt_at_index (tw->timers, ts->head_index);
531 next_index = head->next;
533 /* Make slot empty */
534 head->next = head->prev = ts->head_index;
536 /* traverse slot, place timers wherever they go */
537 while (next_index != head - tw->timers)
539 t = pool_elt_at_index (tw->timers, next_index);
540 next_index = t->next;
542 /* Remove from the overflow vector (hammer) */
543 t->next = t->prev = ~0;
545 ASSERT (t->expiration_time >= tw->current_tick);
547 interval = t->expiration_time - tw->current_tick;
549 /* Right back onto the overflow vector? */
550 if (interval >= (1 << (3 * TW_RING_SHIFT)))
553 timer_addhead (tw->timers, ts->head_index, t - tw->timers);
556 /* Compute ring offsets */
557 new_glacier_ring_offset = interval >> (2 * TW_RING_SHIFT);
559 interval -= (new_glacier_ring_offset << (2 * TW_RING_SHIFT));
561 /* Note: the wheels are at (0,0,0), no add-with-carry needed */
562 new_slow_ring_offset = interval >> TW_RING_SHIFT;
563 interval -= (new_slow_ring_offset << TW_RING_SHIFT);
564 new_fast_ring_offset = interval & TW_RING_MASK;
565 t->slow_ring_offset = new_slow_ring_offset;
566 t->fast_ring_offset = new_fast_ring_offset;
568 /* Timer expires Right Now */
569 if (PREDICT_FALSE (t->slow_ring_offset == 0 &&
570 t->fast_ring_offset == 0 &&
571 new_glacier_ring_offset == 0))
573 vec_add1 (callback_vector, t->user_handle);
574 #if TW_START_STOP_TRACE_SIZE > 0
575 TW (tw_timer_trace) (tw, 0xfe, ~0, t - tw->timers);
577 pool_put (tw->timers, t);
579 /* Timer moves to the glacier ring */
580 else if (new_glacier_ring_offset)
582 ts = &tw->w[TW_TIMER_RING_GLACIER][new_glacier_ring_offset];
583 timer_addhead (tw->timers, ts->head_index, t - tw->timers);
585 /* Timer moves to the slow ring */
586 else if (t->slow_ring_offset)
588 /* Add to slow ring */
589 ts = &tw->w[TW_TIMER_RING_SLOW][t->slow_ring_offset];
590 timer_addhead (tw->timers, ts->head_index, t - tw->timers);
592 /* Timer timer moves to the fast ring */
595 ts = &tw->w[TW_TIMER_RING_FAST][t->fast_ring_offset];
596 timer_addhead (tw->timers, ts->head_index, t - tw->timers);
597 #if TW_FAST_WHEEL_BITMAP
598 tw->fast_slot_bitmap =
599 clib_bitmap_set (tw->fast_slot_bitmap,
600 t->fast_ring_offset, 1);
607 #if TW_TIMER_WHEELS > 2
609 * Double odometer-click? Process one slot in the glacier ring...
611 if (PREDICT_FALSE (fast_wheel_index == TW_SLOTS_PER_RING
612 && slow_wheel_index == TW_SLOTS_PER_RING))
614 glacier_wheel_index %= TW_SLOTS_PER_RING;
615 ts = &tw->w[TW_TIMER_RING_GLACIER][glacier_wheel_index];
617 head = pool_elt_at_index (tw->timers, ts->head_index);
618 next_index = head->next;
620 /* Make slot empty */
621 head->next = head->prev = ts->head_index;
623 /* traverse slot, deal timers into slow ring */
624 while (next_index != head - tw->timers)
626 t = pool_elt_at_index (tw->timers, next_index);
627 next_index = t->next;
629 /* Remove from glacier ring slot (hammer) */
630 t->next = t->prev = ~0;
632 /* Timer expires Right Now */
633 if (PREDICT_FALSE (t->slow_ring_offset == 0 &&
634 t->fast_ring_offset == 0))
636 vec_add1 (callback_vector, t->user_handle);
637 #if TW_START_STOP_TRACE_SIZE > 0
638 TW (tw_timer_trace) (tw, 0xfe, ~0, t - tw->timers);
640 pool_put (tw->timers, t);
642 /* Timer expires during slow-wheel tick 0 */
643 else if (PREDICT_FALSE (t->slow_ring_offset == 0))
645 ts = &tw->w[TW_TIMER_RING_FAST][t->fast_ring_offset];
646 timer_addhead (tw->timers, ts->head_index, t - tw->timers);
647 #if TW_FAST_WHEEL_BITMAP
648 tw->fast_slot_bitmap =
649 clib_bitmap_set (tw->fast_slot_bitmap,
650 t->fast_ring_offset, 1);
653 else /* typical case */
655 /* Add to slow ring */
656 ts = &tw->w[TW_TIMER_RING_SLOW][t->slow_ring_offset];
657 timer_addhead (tw->timers, ts->head_index, t - tw->timers);
663 #if TW_TIMER_WHEELS > 1
665 * Single odometer-click? Process a slot in the slow ring,
667 if (PREDICT_FALSE (fast_wheel_index == TW_SLOTS_PER_RING))
669 slow_wheel_index %= TW_SLOTS_PER_RING;
670 ts = &tw->w[TW_TIMER_RING_SLOW][slow_wheel_index];
672 head = pool_elt_at_index (tw->timers, ts->head_index);
673 next_index = head->next;
675 /* Make slot empty */
676 head->next = head->prev = ts->head_index;
678 /* traverse slot, deal timers into fast ring */
679 while (next_index != head - tw->timers)
681 t = pool_elt_at_index (tw->timers, next_index);
682 next_index = t->next;
684 /* Remove from sloe ring slot (hammer) */
685 t->next = t->prev = ~0;
687 /* Timer expires Right Now */
688 if (PREDICT_FALSE (t->fast_ring_offset == 0))
690 vec_add1 (callback_vector, t->user_handle);
691 #if TW_START_STOP_TRACE_SIZE > 0
692 TW (tw_timer_trace) (tw, 0xfe, ~0, t - tw->timers);
694 pool_put (tw->timers, t);
696 else /* typical case */
698 /* Add to fast ring */
699 ts = &tw->w[TW_TIMER_RING_FAST][t->fast_ring_offset];
700 timer_addhead (tw->timers, ts->head_index, t - tw->timers);
701 #if TW_FAST_WHEEL_BITMAP
702 tw->fast_slot_bitmap =
703 clib_bitmap_set (tw->fast_slot_bitmap,
704 t->fast_ring_offset, 1);
711 /* Handle the fast ring */
712 fast_wheel_index %= TW_SLOTS_PER_RING;
713 ts = &tw->w[TW_TIMER_RING_FAST][fast_wheel_index];
715 head = pool_elt_at_index (tw->timers, ts->head_index);
716 next_index = head->next;
718 /* Make slot empty */
719 head->next = head->prev = ts->head_index;
721 /* Construct vector of expired timer handles to give the user */
722 while (next_index != ts->head_index)
724 t = pool_elt_at_index (tw->timers, next_index);
725 next_index = t->next;
726 vec_add1 (callback_vector, t->user_handle);
727 #if TW_START_STOP_TRACE_SIZE > 0
728 TW (tw_timer_trace) (tw, 0xfe, ~0, t - tw->timers);
730 pool_put (tw->timers, t);
733 /* If any timers expired, tell the user */
734 if (callback_vector_arg == 0 && vec_len (callback_vector))
736 /* The callback is optional. We return the u32 * handle vector */
737 if (tw->expired_timer_callback)
738 tw->expired_timer_callback (callback_vector);
739 tw->expired_timer_handles = callback_vector;
742 #if TW_FAST_WHEEL_BITMAP
743 tw->fast_slot_bitmap = clib_bitmap_set (tw->fast_slot_bitmap,
744 fast_wheel_index, 0);
749 tw->current_index[TW_TIMER_RING_FAST] = fast_wheel_index;
751 #if TW_TIMER_WHEELS > 1
752 if (PREDICT_FALSE (fast_wheel_index == TW_SLOTS_PER_RING))
754 tw->current_index[TW_TIMER_RING_SLOW] = slow_wheel_index;
757 #if TW_TIMER_WHEELS > 2
758 if (PREDICT_FALSE (slow_wheel_index == TW_SLOTS_PER_RING))
759 glacier_wheel_index++;
760 tw->current_index[TW_TIMER_RING_GLACIER] = glacier_wheel_index;
763 if (vec_len (callback_vector) >= tw->max_expirations)
767 if (callback_vector_arg == 0)
768 tw->expired_timer_handles = callback_vector;
770 tw->last_run_time += i * tw->timer_interval;
771 return callback_vector;
774 u32 *TW (tw_timer_expire_timers) (TWT (tw_timer_wheel) * tw, f64 now)
776 return TW (tw_timer_expire_timers_internal) (tw, now, 0 /* no vector */ );
779 u32 *TW (tw_timer_expire_timers_vec) (TWT (tw_timer_wheel) * tw, f64 now,
782 return TW (tw_timer_expire_timers_internal) (tw, now, vec);
785 #if TW_FAST_WHEEL_BITMAP
786 /** Returns an approximation to the first timer expiration in
787 * timer-ticks from "now". To avoid wasting an unjustifiable
788 * amount of time on the problem, we maintain an approximate fast-wheel slot
789 * occupancy bitmap. We don't worry about clearing fast wheel bits
790 * when timers are removed from fast wheel slots.
793 u32 TW (tw_timer_first_expires_in_ticks) (TWT (tw_timer_wheel) * tw)
795 u32 first_expiring_index, fast_ring_index;
798 if (clib_bitmap_is_zero (tw->fast_slot_bitmap))
799 return TW_SLOTS_PER_RING;
801 fast_ring_index = tw->current_index[TW_TIMER_RING_FAST];
802 if (fast_ring_index == TW_SLOTS_PER_RING)
805 first_expiring_index = clib_bitmap_next_set (tw->fast_slot_bitmap,
807 if (first_expiring_index == ~0 && fast_ring_index != 0)
808 first_expiring_index = clib_bitmap_first_set (tw->fast_slot_bitmap);
810 ASSERT (first_expiring_index != ~0);
812 delta = (i32) first_expiring_index - (i32) fast_ring_index;
814 delta += TW_SLOTS_PER_RING;
824 * fd.io coding-style-patch-verification: ON
827 * eval: (c-set-style "gnu")