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tw_timer_template.c
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1 /*
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:
6  *
7  * http://www.apache.org/licenses/LICENSE-2.0
8  *
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.
14  */
15 
16 /** @file
17  * @brief TW timer implementation TEMPLATE ONLY, do not compile directly
18  *
19  *
20  */
21 #if TW_START_STOP_TRACE_SIZE > 0
22 
23 void TW (tw_timer_trace) (TWT (tw_timer_wheel) * tw, u32 timer_id,
24  u32 pool_index, u32 handle)
25 {
26  TWT (trace) * t = &tw->traces[tw->trace_index];
27 
28  t->timer_id = timer_id;
29  t->pool_index = pool_index;
30  t->handle = handle;
31 
32  tw->trace_index++;
33  if (tw->trace_index == TW_START_STOP_TRACE_SIZE)
34  {
35  tw->trace_index = 0;
36  tw->trace_wrapped++;
37  }
38 }
39 
40 void TW (tw_search_trace) (TWT (tw_timer_wheel) * tw, u32 handle)
41 {
42  u32 i, start_pos;
43  TWT (trace) * t;
44  char *s = "bogus!";
45 
46  /* reverse search for the supplied handle */
47 
48  start_pos = tw->trace_index;
49  if (start_pos == 0)
50  start_pos = TW_START_STOP_TRACE_SIZE - 1;
51  else
52  start_pos--;
53 
54  for (i = start_pos; i > 0; i--)
55  {
56  t = &tw->traces[i];
57  if (t->handle == handle)
58  {
59  switch (t->timer_id)
60  {
61  case 0xFF:
62  s = "stopped";
63  break;
64  case 0xFE:
65  s = "expired";
66  break;
67  default:
68  s = "started";
69  break;
70  }
71  fformat (stderr, "handle 0x%x (%d) %s at trace %d\n",
72  handle, handle, s, i);
73  }
74  }
75  if (tw->trace_wrapped > 0)
76  {
77  for (i = TW_START_STOP_TRACE_SIZE; i >= tw->trace_index; i--)
78  {
79  t = &tw->traces[i];
80  if (t->handle == handle)
81  {
82  switch (t->timer_id)
83  {
84  case 0xFF:
85  s = "stopped";
86  break;
87  case 0xFE:
88  s = "expired";
89  break;
90  default:
91  s = "started";
92  break;
93  }
94  fformat (stderr, "handle 0x%x (%d) %s at trace %d\n",
95  handle, handle, s, i);
96  }
97  }
98  }
99 }
100 #endif /* TW_START_STOP_TRACE_SIZE > 0 */
101 
102 static inline u32
103 TW (make_internal_timer_handle) (u32 pool_index, u32 timer_id)
104 {
105  u32 handle;
106 
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)));
110 
111  handle = (timer_id << (32 - LOG2_TW_TIMERS_PER_OBJECT)) | (pool_index);
112 #else
113  handle = pool_index;
114 #endif
115  return handle;
116 }
117 
118 static inline void
119 timer_addhead (TWT (tw_timer) * pool, u32 head_index, u32 new_index)
120 {
121  TWT (tw_timer) * head = pool_elt_at_index (pool, head_index);
122  TWT (tw_timer) * old_first;
123  u32 old_first_index;
124  TWT (tw_timer) * new;
125 
126  new = pool_elt_at_index (pool, new_index);
127 
128  if (PREDICT_FALSE (head->next == head_index))
129  {
130  head->next = head->prev = new_index;
131  new->next = new->prev = head_index;
132  return;
133  }
134 
135  old_first_index = head->next;
136  old_first = pool_elt_at_index (pool, old_first_index);
137 
138  new->next = old_first_index;
139  new->prev = old_first->prev;
140  old_first->prev = new_index;
141  head->next = new_index;
142 }
143 
144 static inline void
145 timer_remove (TWT (tw_timer) * pool, u32 index)
146 {
147  TWT (tw_timer) * elt = pool_elt_at_index (pool, index);
148  TWT (tw_timer) * next_elt, *prev_elt;
149 
150  ASSERT (elt->user_handle != ~0);
151 
152  next_elt = pool_elt_at_index (pool, elt->next);
153  prev_elt = pool_elt_at_index (pool, elt->prev);
154 
155  next_elt->prev = elt->prev;
156  prev_elt->next = elt->next;
157 
158  elt->prev = elt->next = ~0;
159 }
160 
161 /**
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
168  */
169 u32
170 TW (tw_timer_start) (TWT (tw_timer_wheel) * tw, u32 pool_index, u32 timer_id,
171  u64 interval)
172 {
173 #if TW_TIMER_WHEELS > 1
174  u16 slow_ring_offset;
175  u32 carry;
176 #endif
177 #if TW_TIMER_WHEELS > 2
178  u16 glacier_ring_offset;
179 #endif
180 #if TW_OVERFLOW_VECTOR > 0
181  u64 interval_plus_time_to_wrap, triple_wrap_mask;
182 #endif
183  u16 fast_ring_offset;
185  TWT (tw_timer) * t;
186 
187  ASSERT (interval);
188 
189  pool_get (tw->timers, t);
190  memset (t, 0xff, sizeof (*t));
191 
192  t->user_handle = TW (make_internal_timer_handle) (pool_index, timer_id);
193 
194  /* Factor interval into 1..3 wheel offsets */
195 #if TW_TIMER_WHEELS > 2
196 #if TW_OVERFLOW_VECTOR > 0
197  /*
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.
202  */
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)))
207  {
208  t->expiration_time = tw->current_tick + interval;
209  ts = &tw->overflow;
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);
213 #endif
214  return t - tw->timers;
215  }
216 #endif
217 
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));
221 #endif
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);
226 #endif
227  fast_ring_offset = interval & TW_RING_MASK;
228 
229  /*
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, ...)
234  */
235 
236  fast_ring_offset += tw->current_index[TW_TIMER_RING_FAST] & TW_RING_MASK;
237 
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)
242  + carry;
243  carry = slow_ring_offset >= TW_SLOTS_PER_RING ? 1 : 0;
244  slow_ring_offset %= TW_SLOTS_PER_RING;
245 #endif
246 
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;
251 #endif
252 
253 #if TW_TIMER_WHEELS > 2
254  if (glacier_ring_offset !=
255  (tw->current_index[TW_TIMER_RING_GLACIER] & TW_RING_MASK))
256  {
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;
260 
261  ts = &tw->w[TW_TIMER_RING_GLACIER][glacier_ring_offset];
262 
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);
266 #endif
267  return t - tw->timers;
268  }
269 #endif
270 
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))
275  {
276  /* We'll need the fast ring offset later... */
277  t->fast_ring_offset = fast_ring_offset;
278 
279  ts = &tw->w[TW_TIMER_RING_SLOW][slow_ring_offset];
280 
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);
284 #endif
285  return t - tw->timers;
286  }
287 #else
288  fast_ring_offset %= TW_SLOTS_PER_RING;
289 #endif
290 
291  /* Timer expires less than one fast-ring revolution from now */
292  ts = &tw->w[TW_TIMER_RING_FAST][fast_ring_offset];
293 
294  timer_addhead (tw->timers, ts->head_index, t - tw->timers);
295 
296 #if TW_FAST_WHEEL_BITMAP
297  tw->fast_slot_bitmap = clib_bitmap_set (tw->fast_slot_bitmap,
298  fast_ring_offset, 1);
299 #endif
300 #if TW_START_STOP_TRACE_SIZE > 0
301  TW (tw_timer_trace) (tw, timer_id, pool_index, t - tw->timers);
302 #endif
303  return t - tw->timers;
304 }
305 
306 #if TW_TIMER_SCAN_FOR_HANDLE > 0
307 int TW (scan_for_handle) (TWT (tw_timer_wheel) * tw, u32 handle)
308 {
309  int i, j;
311  TWT (tw_timer) * t, *head;
312  u32 next_index;
313  int rv = 0;
314 
315  for (i = 0; i < TW_TIMER_WHEELS; i++)
316  {
317  for (j = 0; j < TW_SLOTS_PER_RING; j++)
318  {
319  ts = &tw->w[i][j];
320  head = pool_elt_at_index (tw->timers, ts->head_index);
321  next_index = head->next;
322 
323  while (next_index != ts->head_index)
324  {
325  t = pool_elt_at_index (tw->timers, next_index);
326  if (next_index == handle)
327  {
328  clib_warning ("handle %d found in ring %d slot %d",
329  handle, i, j);
330  clib_warning ("user handle 0x%x", t->user_handle);
331  rv = 1;
332  }
333  next_index = t->next;
334  }
335  }
336  }
337  return rv;
338 }
339 #endif /* TW_TIMER_SCAN_FOR_HANDLE */
340 
341 /**
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
345  */
346 void TW (tw_timer_stop) (TWT (tw_timer_wheel) * tw, u32 handle)
347 {
348  TWT (tw_timer) * t;
349 
350 #if TW_TIMER_ALLOW_DUPLICATE_STOP
351  /*
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.
355  */
356  if (pool_is_free_index (tw->timers, handle))
357  return;
358 #endif
359 #if TW_START_STOP_TRACE_SIZE > 0
360  TW (tw_timer_trace) (tw, ~0, ~0, handle);
361 #endif
362 
363  t = pool_elt_at_index (tw->timers, handle);
364 
365  /* in case of idiotic handle (e.g. passing a listhead index) */
366  ASSERT (t->user_handle != ~0);
367 
368  timer_remove (tw->timers, handle);
369 
370  pool_put_index (tw->timers, handle);
371 }
372 
373 /**
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
379  */
380 void
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)
384 {
385  int ring, slot;
387  TWT (tw_timer) * t;
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)
392  {
393  clib_warning ("timer interval is zero");
394  abort ();
395  }
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;
399 
400  vec_validate (tw->expired_timer_handles, 0);
401  _vec_len (tw->expired_timer_handles) = 0;
402 
403  for (ring = 0; ring < TW_TIMER_WHEELS; ring++)
404  {
405  for (slot = 0; slot < TW_SLOTS_PER_RING; slot++)
406  {
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;
412  }
413  }
414 
415 #if TW_OVERFLOW_VECTOR > 0
416  ts = &tw->overflow;
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;
421 #endif
422 }
423 
424 /**
425  * @brief Free a tw timer wheel template instance
426  * @param tw_timer_wheel_t * tw timer wheel object pointer
427  */
428 void TW (tw_timer_wheel_free) (TWT (tw_timer_wheel) * tw)
429 {
430  int i, j;
432  TWT (tw_timer) * head, *t;
433  u32 next_index;
434 
435  for (i = 0; i < TW_TIMER_WHEELS; i++)
436  {
437  for (j = 0; j < TW_SLOTS_PER_RING; j++)
438  {
439  ts = &tw->w[i][j];
440  head = pool_elt_at_index (tw->timers, ts->head_index);
441  next_index = head->next;
442 
443  while (next_index != ts->head_index)
444  {
445  t = pool_elt_at_index (tw->timers, next_index);
446  next_index = t->next;
447  pool_put (tw->timers, t);
448  }
449  pool_put (tw->timers, head);
450  }
451  }
452 
453 #if TW_OVERFLOW_VECVOR > 0
454  ts = &tw->overflow;
455  head = pool_elt_at_index (tw->timers, ts->head_index);
456  next_index = head->next;
457 
458  while (next_index != ts->head_index)
459  {
460  t = pool_elt_at_index (tw->timers, next_index);
461  next_index = t->next;
462  pool_put (tw->timers, t);
463  }
464  pool_put (tw->timers, head);
465 #endif
466 
467  memset (tw, 0, sizeof (*tw));
468 }
469 
470 /**
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
476  */
477 static inline
478  u32 * TW (tw_timer_expire_timers_internal) (TWT (tw_timer_wheel) * tw,
479  f64 now,
480  u32 * callback_vector_arg)
481 {
482  u32 nticks, i;
484  TWT (tw_timer) * t, *head;
485  u32 *callback_vector;
486  u32 fast_wheel_index;
487  u32 next_index;
488  u32 slow_wheel_index __attribute__ ((unused));
489  u32 glacier_wheel_index __attribute__ ((unused));
490 
491  /* Shouldn't happen */
492  if (PREDICT_FALSE (now < tw->next_run_time))
493  return callback_vector_arg;
494 
495  /* Number of ticks which have occurred */
496  nticks = tw->ticks_per_second * (now - tw->last_run_time);
497  if (nticks == 0)
498  return callback_vector_arg;
499 
500  /* Remember when we ran, compute next runtime */
501  tw->next_run_time = (now + tw->timer_interval);
502 
503  if (callback_vector_arg == 0)
504  {
505  _vec_len (tw->expired_timer_handles) = 0;
506  callback_vector = tw->expired_timer_handles;
507  }
508  else
509  callback_vector = callback_vector_arg;
510 
511  for (i = 0; i < nticks; i++)
512  {
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];
518 
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))
524  {
525  u64 interval;
526  u32 new_glacier_ring_offset, new_slow_ring_offset;
527  u32 new_fast_ring_offset;
528 
529  ts = &tw->overflow;
530  head = pool_elt_at_index (tw->timers, ts->head_index);
531  next_index = head->next;
532 
533  /* Make slot empty */
534  head->next = head->prev = ts->head_index;
535 
536  /* traverse slot, place timers wherever they go */
537  while (next_index != head - tw->timers)
538  {
539  t = pool_elt_at_index (tw->timers, next_index);
540  next_index = t->next;
541 
542  /* Remove from the overflow vector (hammer) */
543  t->next = t->prev = ~0;
544 
545  ASSERT (t->expiration_time >= tw->current_tick);
546 
547  interval = t->expiration_time - tw->current_tick;
548 
549  /* Right back onto the overflow vector? */
550  if (interval >= (1 << (3 * TW_RING_SHIFT)))
551  {
552  ts = &tw->overflow;
553  timer_addhead (tw->timers, ts->head_index, t - tw->timers);
554  continue;
555  }
556  /* Compute ring offsets */
557  new_glacier_ring_offset = interval >> (2 * TW_RING_SHIFT);
558 
559  interval -= (new_glacier_ring_offset << (2 * TW_RING_SHIFT));
560 
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;
567 
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))
572  {
573  vec_add1 (callback_vector, t->user_handle);
574 #if TW_START_STOP_TRACE_SIZE > 0
575  TW (tw_timer_trace) (tw, 0xfe, t->user_handle,
576  t - tw->timers);
577 #endif
578  pool_put (tw->timers, t);
579  }
580  /* Timer moves to the glacier ring */
581  else if (new_glacier_ring_offset)
582  {
583  ts = &tw->w[TW_TIMER_RING_GLACIER][new_glacier_ring_offset];
584  timer_addhead (tw->timers, ts->head_index, t - tw->timers);
585  }
586  /* Timer moves to the slow ring */
587  else if (t->slow_ring_offset)
588  {
589  /* Add to slow ring */
590  ts = &tw->w[TW_TIMER_RING_SLOW][t->slow_ring_offset];
591  timer_addhead (tw->timers, ts->head_index, t - tw->timers);
592  }
593  /* Timer timer moves to the fast ring */
594  else
595  {
596  ts = &tw->w[TW_TIMER_RING_FAST][t->fast_ring_offset];
597  timer_addhead (tw->timers, ts->head_index, t - tw->timers);
598 #if TW_FAST_WHEEL_BITMAP
599  tw->fast_slot_bitmap =
600  clib_bitmap_set (tw->fast_slot_bitmap,
601  t->fast_ring_offset, 1);
602 #endif
603  }
604  }
605  }
606 #endif
607 
608 #if TW_TIMER_WHEELS > 2
609  /*
610  * Double odometer-click? Process one slot in the glacier ring...
611  */
612  if (PREDICT_FALSE (fast_wheel_index == TW_SLOTS_PER_RING
613  && slow_wheel_index == TW_SLOTS_PER_RING))
614  {
615  glacier_wheel_index %= TW_SLOTS_PER_RING;
616  ts = &tw->w[TW_TIMER_RING_GLACIER][glacier_wheel_index];
617 
618  head = pool_elt_at_index (tw->timers, ts->head_index);
619  next_index = head->next;
620 
621  /* Make slot empty */
622  head->next = head->prev = ts->head_index;
623 
624  /* traverse slot, deal timers into slow ring */
625  while (next_index != head - tw->timers)
626  {
627  t = pool_elt_at_index (tw->timers, next_index);
628  next_index = t->next;
629 
630  /* Remove from glacier ring slot (hammer) */
631  t->next = t->prev = ~0;
632 
633  /* Timer expires Right Now */
634  if (PREDICT_FALSE (t->slow_ring_offset == 0 &&
635  t->fast_ring_offset == 0))
636  {
637  vec_add1 (callback_vector, t->user_handle);
638 #if TW_START_STOP_TRACE_SIZE > 0
639  TW (tw_timer_trace) (tw, 0xfe, t->user_handle,
640  t - tw->timers);
641 #endif
642  pool_put (tw->timers, t);
643  }
644  /* Timer expires during slow-wheel tick 0 */
645  else if (PREDICT_FALSE (t->slow_ring_offset == 0))
646  {
647  ts = &tw->w[TW_TIMER_RING_FAST][t->fast_ring_offset];
648  timer_addhead (tw->timers, ts->head_index, t - tw->timers);
649 #if TW_FAST_WHEEL_BITMAP
650  tw->fast_slot_bitmap =
651  clib_bitmap_set (tw->fast_slot_bitmap,
652  t->fast_ring_offset, 1);
653 #endif
654  }
655  else /* typical case */
656  {
657  /* Add to slow ring */
658  ts = &tw->w[TW_TIMER_RING_SLOW][t->slow_ring_offset];
659  timer_addhead (tw->timers, ts->head_index, t - tw->timers);
660  }
661  }
662  }
663 #endif
664 
665 #if TW_TIMER_WHEELS > 1
666  /*
667  * Single odometer-click? Process a slot in the slow ring,
668  */
669  if (PREDICT_FALSE (fast_wheel_index == TW_SLOTS_PER_RING))
670  {
671  slow_wheel_index %= TW_SLOTS_PER_RING;
672  ts = &tw->w[TW_TIMER_RING_SLOW][slow_wheel_index];
673 
674  head = pool_elt_at_index (tw->timers, ts->head_index);
675  next_index = head->next;
676 
677  /* Make slot empty */
678  head->next = head->prev = ts->head_index;
679 
680  /* traverse slot, deal timers into fast ring */
681  while (next_index != head - tw->timers)
682  {
683  t = pool_elt_at_index (tw->timers, next_index);
684  next_index = t->next;
685 
686  /* Remove from sloe ring slot (hammer) */
687  t->next = t->prev = ~0;
688 
689  /* Timer expires Right Now */
690  if (PREDICT_FALSE (t->fast_ring_offset == 0))
691  {
692  vec_add1 (callback_vector, t->user_handle);
693 #if TW_START_STOP_TRACE_SIZE > 0
694  TW (tw_timer_trace) (tw, 0xfe, t->user_handle,
695  t - tw->timers);
696 #endif
697  pool_put (tw->timers, t);
698  }
699  else /* typical case */
700  {
701  /* Add to fast ring */
702  ts = &tw->w[TW_TIMER_RING_FAST][t->fast_ring_offset];
703  timer_addhead (tw->timers, ts->head_index, t - tw->timers);
704 #if TW_FAST_WHEEL_BITMAP
705  tw->fast_slot_bitmap =
706  clib_bitmap_set (tw->fast_slot_bitmap,
707  t->fast_ring_offset, 1);
708 #endif
709  }
710  }
711  }
712 #endif
713 
714  /* Handle the fast ring */
715  fast_wheel_index %= TW_SLOTS_PER_RING;
716  ts = &tw->w[TW_TIMER_RING_FAST][fast_wheel_index];
717 
718  head = pool_elt_at_index (tw->timers, ts->head_index);
719  next_index = head->next;
720 
721  /* Make slot empty */
722  head->next = head->prev = ts->head_index;
723 
724  /* Construct vector of expired timer handles to give the user */
725  while (next_index != ts->head_index)
726  {
727  t = pool_elt_at_index (tw->timers, next_index);
728  next_index = t->next;
729  vec_add1 (callback_vector, t->user_handle);
730 #if TW_START_STOP_TRACE_SIZE > 0
731  TW (tw_timer_trace) (tw, 0xfe, t->user_handle, t - tw->timers);
732 #endif
733  pool_put (tw->timers, t);
734  }
735 
736  /* If any timers expired, tell the user */
737  if (callback_vector_arg == 0 && vec_len (callback_vector))
738  {
739  /* The callback is optional. We return the u32 * handle vector */
740  if (tw->expired_timer_callback)
741  tw->expired_timer_callback (callback_vector);
742  tw->expired_timer_handles = callback_vector;
743  }
744 
745 #if TW_FAST_WHEEL_BITMAP
746  tw->fast_slot_bitmap = clib_bitmap_set (tw->fast_slot_bitmap,
747  fast_wheel_index, 0);
748 #endif
749 
750  tw->current_tick++;
751  fast_wheel_index++;
752  tw->current_index[TW_TIMER_RING_FAST] = fast_wheel_index;
753 
754 #if TW_TIMER_WHEELS > 1
755  if (PREDICT_FALSE (fast_wheel_index == TW_SLOTS_PER_RING))
756  slow_wheel_index++;
757  tw->current_index[TW_TIMER_RING_SLOW] = slow_wheel_index;
758 #endif
759 
760 #if TW_TIMER_WHEELS > 2
761  if (PREDICT_FALSE (slow_wheel_index == TW_SLOTS_PER_RING))
762  glacier_wheel_index++;
763  tw->current_index[TW_TIMER_RING_GLACIER] = glacier_wheel_index;
764 #endif
765 
766  if (vec_len (callback_vector) >= tw->max_expirations)
767  break;
768  }
769 
770  if (callback_vector_arg == 0)
771  tw->expired_timer_handles = callback_vector;
772 
773  tw->last_run_time += i * tw->timer_interval;
774  return callback_vector;
775 }
776 
777 u32 *TW (tw_timer_expire_timers) (TWT (tw_timer_wheel) * tw, f64 now)
778 {
779  return TW (tw_timer_expire_timers_internal) (tw, now, 0 /* no vector */ );
780 }
781 
782 u32 *TW (tw_timer_expire_timers_vec) (TWT (tw_timer_wheel) * tw, f64 now,
783  u32 * vec)
784 {
785  return TW (tw_timer_expire_timers_internal) (tw, now, vec);
786 }
787 
788 #if TW_FAST_WHEEL_BITMAP
789 /** Returns an approximation to the first timer expiration in
790  * timer-ticks from "now". To avoid wasting an unjustifiable
791  * amount of time on the problem, we maintain an approximate fast-wheel slot
792  * occupancy bitmap. We don't worry about clearing fast wheel bits
793  * when timers are removed from fast wheel slots.
794  */
795 
796 u32 TW (tw_timer_first_expires_in_ticks) (TWT (tw_timer_wheel) * tw)
797 {
798  u32 first_expiring_index, fast_ring_index;
799  i32 delta;
800 
801  if (clib_bitmap_is_zero (tw->fast_slot_bitmap))
802  return TW_SLOTS_PER_RING;
803 
804  fast_ring_index = tw->current_index[TW_TIMER_RING_FAST];
805  if (fast_ring_index == TW_SLOTS_PER_RING)
806  fast_ring_index = 0;
807 
808  first_expiring_index = clib_bitmap_next_set (tw->fast_slot_bitmap,
809  fast_ring_index);
810  if (first_expiring_index == ~0 && fast_ring_index != 0)
811  first_expiring_index = clib_bitmap_first_set (tw->fast_slot_bitmap);
812 
813  ASSERT (first_expiring_index != ~0);
814 
815  delta = (i32) first_expiring_index - (i32) fast_ring_index;
816  if (delta < 0)
817  delta += TW_SLOTS_PER_RING;
818 
819  ASSERT (delta >= 0);
820 
821  return (u32) delta;
822 }
823 
824 #endif
825 
826 /*
827  * fd.io coding-style-patch-verification: ON
828  *
829  * Local Variables:
830  * eval: (c-set-style "gnu")
831  * End:
832  */
#define vec_validate(V, I)
Make sure vector is long enough for given index (no header, unspecified alignment) ...
Definition: vec.h:432
void TW() tw_timer_wheel_init(TWT(tw_timer_wheel)*tw, void *expired_timer_callback, f64 timer_interval_in_seconds, u32 max_expirations)
Initialize a tw timer wheel template instance.
sll srl srl sll sra u16x4 i
Definition: vector_sse2.h:337
static vlib_cli_command_t trace
(constructor) VLIB_CLI_COMMAND (trace)
Definition: memory_vlib.c:1296
#define TW_TIMERS_PER_OBJECT
u32 *TW() tw_timer_expire_timers_vec(TWT(tw_timer_wheel)*tw, f64 now, u32 *vec)
#define vec_add1(V, E)
Add 1 element to end of vector (unspecified alignment).
Definition: vec.h:518
#define TW_TIMER_WHEELS
static uword * clib_bitmap_set(uword *ai, uword i, uword value)
Sets the ith bit of a bitmap to new_value Removes trailing zeros from the bitmap. ...
Definition: bitmap.h:167
#define pool_get(P, E)
Allocate an object E from a pool P (unspecified alignment).
Definition: pool.h:225
static uword clib_bitmap_is_zero(uword *ai)
predicate function; is an entire bitmap empty?
Definition: bitmap.h:57
#define LOG2_TW_TIMERS_PER_OBJECT
int i32
Definition: types.h:81
unsigned long u64
Definition: types.h:89
u32 TW() tw_timer_start(TWT(tw_timer_wheel)*tw, u32 pool_index, u32 timer_id, u64 interval)
Start a Tw Timer.
static void timer_addhead(TWT(tw_timer)*pool, u32 head_index, u32 new_index)
#define pool_elt_at_index(p, i)
Returns pointer to element at given index.
Definition: pool.h:458
static uword clib_bitmap_first_set(uword *ai)
Return the lowest numbered set bit in a bitmap.
Definition: bitmap.h:385
#define TW_SLOTS_PER_RING
static u32 *TW() tw_timer_expire_timers_internal(TWT(tw_timer_wheel)*tw, f64 now, u32 *callback_vector_arg)
Advance a tw timer wheel.
#define pool_put(P, E)
Free an object E in pool P.
Definition: pool.h:270
#define TWT(a)
#define PREDICT_FALSE(x)
Definition: clib.h:97
word fformat(FILE *f, char *fmt,...)
Definition: format.c:453
#define TW_RING_SHIFT
#define clib_warning(format, args...)
Definition: error.h:59
void TW() tw_timer_stop(TWT(tw_timer_wheel)*tw, u32 handle)
Stop a tw timer.
static void timer_remove(TWT(tw_timer)*pool, u32 index)
#define pool_is_free_index(P, I)
Use free bitmap to query whether given index is free.
Definition: pool.h:267
u32 *TW() tw_timer_expire_timers(TWT(tw_timer_wheel)*tw, f64 now)
Fast timer ring ID.
#define pool_put_index(p, i)
Free pool element with given index.
Definition: pool.h:293
#define ASSERT(truth)
unsigned int u32
Definition: types.h:88
#define TW_RING_MASK
unsigned short u16
Definition: types.h:57
#define vec_len(v)
Number of elements in vector (rvalue-only, NULL tolerant)
double f64
Definition: types.h:142
#define TW(a)
static uword clib_bitmap_next_set(uword *ai, uword i)
Return the next set bit in a bitmap starting at bit i.
Definition: bitmap.h:630
static u32 TW() make_internal_timer_handle(u32 pool_index, u32 timer_id)
void TW() tw_timer_wheel_free(TWT(tw_timer_wheel)*tw)
Free a tw timer wheel template instance.
u32 head_index
Listhead of timers which expire in this interval.
Slow timer ring ID.