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Vector Packet Processing
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, TWT (tw_timer) * elt)
146 {
147  TWT (tw_timer) * next_elt, *prev_elt;
148 
149  ASSERT (elt->user_handle != ~0);
150 
151  next_elt = pool_elt_at_index (pool, elt->next);
152  prev_elt = pool_elt_at_index (pool, elt->prev);
153 
154  next_elt->prev = elt->prev;
155  prev_elt->next = elt->next;
156 
157  elt->prev = elt->next = ~0;
158 }
159 
160 static inline void
161 timer_add (TWT (tw_timer_wheel) * tw, TWT (tw_timer) * t, u64 interval)
162 {
163 #if TW_TIMER_WHEELS > 1
164  u16 slow_ring_offset;
165  u32 carry;
166 #endif
167 #if TW_TIMER_WHEELS > 2
168  u16 glacier_ring_offset;
169 #endif
170 #if TW_OVERFLOW_VECTOR > 0
171  u64 interval_plus_time_to_wrap, triple_wrap_mask;
172 #endif
173  u16 fast_ring_offset;
175 
176  /* Factor interval into 1..3 wheel offsets */
177 #if TW_TIMER_WHEELS > 2
178 #if TW_OVERFLOW_VECTOR > 0
179  /*
180  * This is tricky. Put a timer onto the overflow
181  * vector if the interval PLUS the time
182  * until the next triple-wrap exceeds one full revolution
183  * of all three wheels.
184  */
185  triple_wrap_mask = (1 << (3 * TW_RING_SHIFT)) - 1;
186  interval_plus_time_to_wrap =
187  interval + (tw->current_tick & triple_wrap_mask);
188  if ((interval_plus_time_to_wrap >= 1 << (3 * TW_RING_SHIFT)))
189  {
190  t->expiration_time = tw->current_tick + interval;
191  ts = &tw->overflow;
192  timer_addhead (tw->timers, ts->head_index, t - tw->timers);
193 #if TW_START_STOP_TRACE_SIZE > 0
194  TW (tw_timer_trace) (tw, timer_id, user_id, t - tw->timers);
195 #endif
196  return;
197  }
198 #endif
199 
200  glacier_ring_offset = interval >> (2 * TW_RING_SHIFT);
201  ASSERT ((u64) glacier_ring_offset < TW_SLOTS_PER_RING);
202  interval -= (((u64) glacier_ring_offset) << (2 * TW_RING_SHIFT));
203 #endif
204 #if TW_TIMER_WHEELS > 1
205  slow_ring_offset = interval >> TW_RING_SHIFT;
206  ASSERT ((u64) slow_ring_offset < TW_SLOTS_PER_RING);
207  interval -= (((u64) slow_ring_offset) << TW_RING_SHIFT);
208 #endif
209  fast_ring_offset = interval & TW_RING_MASK;
210 
211  /*
212  * Account for the current wheel positions(s)
213  * This is made slightly complicated by the fact that the current
214  * index vector will contain (TW_SLOTS_PER_RING, ...) when
215  * the actual position is (0, ...)
216  */
217 
218  fast_ring_offset += tw->current_index[TW_TIMER_RING_FAST] & TW_RING_MASK;
219 
220 #if TW_TIMER_WHEELS > 1
221  carry = fast_ring_offset >= TW_SLOTS_PER_RING ? 1 : 0;
222  fast_ring_offset %= TW_SLOTS_PER_RING;
223  slow_ring_offset += (tw->current_index[TW_TIMER_RING_SLOW] & TW_RING_MASK)
224  + carry;
225  carry = slow_ring_offset >= TW_SLOTS_PER_RING ? 1 : 0;
226  slow_ring_offset %= TW_SLOTS_PER_RING;
227 #endif
228 
229 #if TW_TIMER_WHEELS > 2
230  glacier_ring_offset +=
231  (tw->current_index[TW_TIMER_RING_GLACIER] & TW_RING_MASK) + carry;
232  glacier_ring_offset %= TW_SLOTS_PER_RING;
233 #endif
234 
235 #if TW_TIMER_WHEELS > 2
236  if (glacier_ring_offset !=
237  (tw->current_index[TW_TIMER_RING_GLACIER] & TW_RING_MASK))
238  {
239  /* We'll need slow and fast ring offsets later */
240  t->slow_ring_offset = slow_ring_offset;
241  t->fast_ring_offset = fast_ring_offset;
242 
243  ts = &tw->w[TW_TIMER_RING_GLACIER][glacier_ring_offset];
244 
245  timer_addhead (tw->timers, ts->head_index, t - tw->timers);
246 #if TW_START_STOP_TRACE_SIZE > 0
247  TW (tw_timer_trace) (tw, timer_id, user_id, t - tw->timers);
248 #endif
249  return;
250  }
251 #endif
252 
253 #if TW_TIMER_WHEELS > 1
254  /* Timer expires more than 51.2 seconds from now? */
255  if (slow_ring_offset !=
256  (tw->current_index[TW_TIMER_RING_SLOW] & TW_RING_MASK))
257  {
258  /* We'll need the fast ring offset later... */
259  t->fast_ring_offset = fast_ring_offset;
260 
261  ts = &tw->w[TW_TIMER_RING_SLOW][slow_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, user_id, t - tw->timers);
266 #endif
267  return;
268  }
269 #else
270  fast_ring_offset %= TW_SLOTS_PER_RING;
271 #endif
272 
273  /* Timer expires less than one fast-ring revolution from now */
274  ts = &tw->w[TW_TIMER_RING_FAST][fast_ring_offset];
275 
276  timer_addhead (tw->timers, ts->head_index, t - tw->timers);
277 
278 #if TW_FAST_WHEEL_BITMAP
279  tw->fast_slot_bitmap = clib_bitmap_set (tw->fast_slot_bitmap,
280  fast_ring_offset, 1);
281 #endif
282 #if TW_START_STOP_TRACE_SIZE > 0
283  TW (tw_timer_trace) (tw, timer_id, user_id, t - tw->timers);
284 #endif
285 }
286 
287 /**
288  * @brief Start a Tw Timer
289  * @param tw_timer_wheel_t * tw timer wheel object pointer
290  * @param u32 user_id user defined timer id, presumably for a tw session
291  * @param u32 timer_id app-specific timer ID. 4 bits.
292  * @param u64 interval timer interval in ticks
293  * @returns handle needed to cancel the timer
294  */
295 u32
296 TW (tw_timer_start) (TWT (tw_timer_wheel) * tw, u32 user_id, u32 timer_id,
297  u64 interval)
298 {
299  TWT (tw_timer) * t;
300 
301  ASSERT (interval);
302 
303  pool_get (tw->timers, t);
304  clib_memset (t, 0xff, sizeof (*t));
305 
306  t->user_handle = TW (make_internal_timer_handle) (user_id, timer_id);
307 
308  timer_add (tw, t, interval);
309  return t - tw->timers;
310 }
311 
312 #if TW_TIMER_SCAN_FOR_HANDLE > 0
313 int TW (scan_for_handle) (TWT (tw_timer_wheel) * tw, u32 handle)
314 {
315  int i, j;
317  TWT (tw_timer) * t, *head;
318  u32 next_index;
319  int rv = 0;
320 
321  for (i = 0; i < TW_TIMER_WHEELS; i++)
322  {
323  for (j = 0; j < TW_SLOTS_PER_RING; j++)
324  {
325  ts = &tw->w[i][j];
326  head = pool_elt_at_index (tw->timers, ts->head_index);
327  next_index = head->next;
328 
329  while (next_index != ts->head_index)
330  {
331  t = pool_elt_at_index (tw->timers, next_index);
332  if (next_index == handle)
333  {
334  clib_warning ("handle %d found in ring %d slot %d",
335  handle, i, j);
336  clib_warning ("user handle 0x%x", t->user_handle);
337  rv = 1;
338  }
339  next_index = t->next;
340  }
341  }
342  }
343  return rv;
344 }
345 #endif /* TW_TIMER_SCAN_FOR_HANDLE */
346 
347 /**
348  * @brief Stop a tw timer
349  * @param tw_timer_wheel_t * tw timer wheel object pointer
350  * @param u32 handle timer cancellation returned by tw_timer_start
351  */
352 void TW (tw_timer_stop) (TWT (tw_timer_wheel) * tw, u32 handle)
353 {
354  TWT (tw_timer) * t;
355 
356 #if TW_TIMER_ALLOW_DUPLICATE_STOP
357  /*
358  * A vlib process may have its timer expire, and receive
359  * an event before the expiration is processed.
360  * That results in a duplicate tw_timer_stop.
361  */
362  if (pool_is_free_index (tw->timers, handle))
363  return;
364 #endif
365 #if TW_START_STOP_TRACE_SIZE > 0
366  TW (tw_timer_trace) (tw, ~0, ~0, handle);
367 #endif
368 
369  t = pool_elt_at_index (tw->timers, handle);
370 
371  /* in case of idiotic handle (e.g. passing a listhead index) */
372  ASSERT (t->user_handle != ~0);
373 
374  timer_remove (tw->timers, t);
375 
376  pool_put_index (tw->timers, handle);
377 }
378 
379 int TW (tw_timer_handle_is_free) (TWT (tw_timer_wheel) * tw, u32 handle)
380 {
381  return pool_is_free_index (tw->timers, handle);
382 }
383 
384 /**
385  * @brief Update a tw timer
386  * @param tw_timer_wheel_t * tw timer wheel object pointer
387  * @param u32 handle timer returned by tw_timer_start
388  * @param u32 interval timer interval in ticks
389  */
390 void TW (tw_timer_update) (TWT (tw_timer_wheel) * tw, u32 handle,
391  u64 interval)
392 {
393  TWT (tw_timer) * t;
394  t = pool_elt_at_index (tw->timers, handle);
395  timer_remove (tw->timers, t);
396  timer_add (tw, t, interval);
397 }
398 
399 /**
400  * @brief Initialize a tw timer wheel template instance
401  * @param tw_timer_wheel_t * tw timer wheel object pointer
402  * @param void * expired_timer_callback. Passed a u32 * vector of
403  * expired timer handles. The callback is optional.
404  * @param f64 timer_interval_in_seconds
405  */
406 void
407 TW (tw_timer_wheel_init) (TWT (tw_timer_wheel) * tw,
408  void *expired_timer_callback,
409  f64 timer_interval_in_seconds, u32 max_expirations)
410 {
411  int ring, slot;
413  TWT (tw_timer) * t;
414  clib_memset (tw, 0, sizeof (*tw));
415  tw->expired_timer_callback = expired_timer_callback;
416  tw->max_expirations = max_expirations;
417  if (timer_interval_in_seconds == 0.0)
418  {
419  clib_warning ("timer interval is zero");
420  abort ();
421  }
422  tw->timer_interval = timer_interval_in_seconds;
423  tw->ticks_per_second = 1.0 / timer_interval_in_seconds;
424  tw->first_expires_tick = ~0ULL;
425 
426  vec_validate (tw->expired_timer_handles, 0);
427  _vec_len (tw->expired_timer_handles) = 0;
428 
429  for (ring = 0; ring < TW_TIMER_WHEELS; ring++)
430  {
431  for (slot = 0; slot < TW_SLOTS_PER_RING; slot++)
432  {
433  ts = &tw->w[ring][slot];
434  pool_get (tw->timers, t);
435  clib_memset (t, 0xff, sizeof (*t));
436  t->next = t->prev = t - tw->timers;
437  ts->head_index = t - tw->timers;
438  }
439  }
440 
441 #if TW_OVERFLOW_VECTOR > 0
442  ts = &tw->overflow;
443  pool_get (tw->timers, t);
444  clib_memset (t, 0xff, sizeof (*t));
445  t->next = t->prev = t - tw->timers;
446  ts->head_index = t - tw->timers;
447 #endif
448 }
449 
450 /**
451  * @brief Free a tw timer wheel template instance
452  * @param tw_timer_wheel_t * tw timer wheel object pointer
453  */
454 void TW (tw_timer_wheel_free) (TWT (tw_timer_wheel) * tw)
455 {
456  int i, j;
458  TWT (tw_timer) * head, *t;
459  u32 next_index;
460 
461  for (i = 0; i < TW_TIMER_WHEELS; i++)
462  {
463  for (j = 0; j < TW_SLOTS_PER_RING; j++)
464  {
465  ts = &tw->w[i][j];
466  head = pool_elt_at_index (tw->timers, ts->head_index);
467  next_index = head->next;
468 
469  while (next_index != ts->head_index)
470  {
471  t = pool_elt_at_index (tw->timers, next_index);
472  next_index = t->next;
473  pool_put (tw->timers, t);
474  }
475  pool_put (tw->timers, head);
476  }
477  }
478 
479 #if TW_OVERFLOW_VECVOR > 0
480  ts = &tw->overflow;
481  head = pool_elt_at_index (tw->timers, ts->head_index);
482  next_index = head->next;
483 
484  while (next_index != ts->head_index)
485  {
486  t = pool_elt_at_index (tw->timers, next_index);
487  next_index = t->next;
488  pool_put (tw->timers, t);
489  }
490  pool_put (tw->timers, head);
491 #endif
492 
493  clib_memset (tw, 0, sizeof (*tw));
494 }
495 
496 /**
497  * @brief Advance a tw timer wheel. Calls the expired timer callback
498  * as needed. This routine should be called once every timer_interval seconds
499  * @param tw_timer_wheel_t * tw timer wheel template instance pointer
500  * @param f64 now the current time, e.g. from vlib_time_now(vm)
501  * @returns u32 * vector of expired user handles
502  */
503 static inline
504  u32 * TW (tw_timer_expire_timers_internal) (TWT (tw_timer_wheel) * tw,
505  f64 now,
506  u32 * callback_vector_arg)
507 {
508  u32 nticks, i;
510  TWT (tw_timer) * t, *head;
511  u32 *callback_vector;
512  u32 fast_wheel_index;
513  u32 next_index;
514  u32 slow_wheel_index __attribute__ ((unused));
515  u32 glacier_wheel_index __attribute__ ((unused));
516 
517  /* Shouldn't happen */
518  if (PREDICT_FALSE (now < tw->next_run_time))
519  return callback_vector_arg;
520 
521  /* Number of ticks which have occurred */
522  nticks = tw->ticks_per_second * (now - tw->last_run_time);
523  if (nticks == 0)
524  return callback_vector_arg;
525 
526  /* Remember when we ran, compute next runtime */
527  tw->next_run_time = (now + tw->timer_interval);
528 
529  if (callback_vector_arg == 0)
530  {
531  _vec_len (tw->expired_timer_handles) = 0;
532  callback_vector = tw->expired_timer_handles;
533  }
534  else
535  callback_vector = callback_vector_arg;
536 
537  for (i = 0; i < nticks; i++)
538  {
539  fast_wheel_index = tw->current_index[TW_TIMER_RING_FAST];
540  if (TW_TIMER_WHEELS > 1)
541  slow_wheel_index = tw->current_index[TW_TIMER_RING_SLOW];
542  if (TW_TIMER_WHEELS > 2)
543  glacier_wheel_index = tw->current_index[TW_TIMER_RING_GLACIER];
544 
545 #if TW_OVERFLOW_VECTOR > 0
546  /* Triple odometer-click? Process the overflow vector... */
547  if (PREDICT_FALSE (fast_wheel_index == TW_SLOTS_PER_RING
548  && slow_wheel_index == TW_SLOTS_PER_RING
549  && glacier_wheel_index == TW_SLOTS_PER_RING))
550  {
551  u64 interval;
552  u32 new_glacier_ring_offset, new_slow_ring_offset;
553  u32 new_fast_ring_offset;
554 
555  ts = &tw->overflow;
556  head = pool_elt_at_index (tw->timers, ts->head_index);
557  next_index = head->next;
558 
559  /* Make slot empty */
560  head->next = head->prev = ts->head_index;
561 
562  /* traverse slot, place timers wherever they go */
563  while (next_index != head - tw->timers)
564  {
565  t = pool_elt_at_index (tw->timers, next_index);
566  next_index = t->next;
567 
568  /* Remove from the overflow vector (hammer) */
569  t->next = t->prev = ~0;
570 
571  ASSERT (t->expiration_time >= tw->current_tick);
572 
573  interval = t->expiration_time - tw->current_tick;
574 
575  /* Right back onto the overflow vector? */
576  if (interval >= (1 << (3 * TW_RING_SHIFT)))
577  {
578  ts = &tw->overflow;
579  timer_addhead (tw->timers, ts->head_index, t - tw->timers);
580  continue;
581  }
582  /* Compute ring offsets */
583  new_glacier_ring_offset = interval >> (2 * TW_RING_SHIFT);
584 
585  interval -= (new_glacier_ring_offset << (2 * TW_RING_SHIFT));
586 
587  /* Note: the wheels are at (0,0,0), no add-with-carry needed */
588  new_slow_ring_offset = interval >> TW_RING_SHIFT;
589  interval -= (new_slow_ring_offset << TW_RING_SHIFT);
590  new_fast_ring_offset = interval & TW_RING_MASK;
591  t->slow_ring_offset = new_slow_ring_offset;
592  t->fast_ring_offset = new_fast_ring_offset;
593 
594  /* Timer expires Right Now */
595  if (PREDICT_FALSE (t->slow_ring_offset == 0 &&
596  t->fast_ring_offset == 0 &&
597  new_glacier_ring_offset == 0))
598  {
599  vec_add1 (callback_vector, t->user_handle);
600 #if TW_START_STOP_TRACE_SIZE > 0
601  TW (tw_timer_trace) (tw, 0xfe, t->user_handle,
602  t - tw->timers);
603 #endif
604  pool_put (tw->timers, t);
605  }
606  /* Timer moves to the glacier ring */
607  else if (new_glacier_ring_offset)
608  {
609  ts = &tw->w[TW_TIMER_RING_GLACIER][new_glacier_ring_offset];
610  timer_addhead (tw->timers, ts->head_index, t - tw->timers);
611  }
612  /* Timer moves to the slow ring */
613  else if (t->slow_ring_offset)
614  {
615  /* Add to slow ring */
616  ts = &tw->w[TW_TIMER_RING_SLOW][t->slow_ring_offset];
617  timer_addhead (tw->timers, ts->head_index, t - tw->timers);
618  }
619  /* Timer timer moves to the fast ring */
620  else
621  {
622  ts = &tw->w[TW_TIMER_RING_FAST][t->fast_ring_offset];
623  timer_addhead (tw->timers, ts->head_index, t - tw->timers);
624 #if TW_FAST_WHEEL_BITMAP
625  tw->fast_slot_bitmap =
626  clib_bitmap_set (tw->fast_slot_bitmap,
627  t->fast_ring_offset, 1);
628 #endif
629  }
630  }
631  }
632 #endif
633 
634 #if TW_TIMER_WHEELS > 2
635  /*
636  * Double odometer-click? Process one slot in the glacier ring...
637  */
638  if (PREDICT_FALSE (fast_wheel_index == TW_SLOTS_PER_RING
639  && slow_wheel_index == TW_SLOTS_PER_RING))
640  {
641  glacier_wheel_index %= TW_SLOTS_PER_RING;
642  ts = &tw->w[TW_TIMER_RING_GLACIER][glacier_wheel_index];
643 
644  head = pool_elt_at_index (tw->timers, ts->head_index);
645  next_index = head->next;
646 
647  /* Make slot empty */
648  head->next = head->prev = ts->head_index;
649 
650  /* traverse slot, deal timers into slow ring */
651  while (next_index != head - tw->timers)
652  {
653  t = pool_elt_at_index (tw->timers, next_index);
654  next_index = t->next;
655 
656  /* Remove from glacier ring slot (hammer) */
657  t->next = t->prev = ~0;
658 
659  /* Timer expires Right Now */
660  if (PREDICT_FALSE (t->slow_ring_offset == 0 &&
661  t->fast_ring_offset == 0))
662  {
663  vec_add1 (callback_vector, t->user_handle);
664 #if TW_START_STOP_TRACE_SIZE > 0
665  TW (tw_timer_trace) (tw, 0xfe, t->user_handle,
666  t - tw->timers);
667 #endif
668  pool_put (tw->timers, t);
669  }
670  /* Timer expires during slow-wheel tick 0 */
671  else if (PREDICT_FALSE (t->slow_ring_offset == 0))
672  {
673  ts = &tw->w[TW_TIMER_RING_FAST][t->fast_ring_offset];
674  timer_addhead (tw->timers, ts->head_index, t - tw->timers);
675 #if TW_FAST_WHEEL_BITMAP
676  tw->fast_slot_bitmap =
677  clib_bitmap_set (tw->fast_slot_bitmap,
678  t->fast_ring_offset, 1);
679 #endif
680  }
681  else /* typical case */
682  {
683  /* Add to slow ring */
684  ts = &tw->w[TW_TIMER_RING_SLOW][t->slow_ring_offset];
685  timer_addhead (tw->timers, ts->head_index, t - tw->timers);
686  }
687  }
688  }
689 #endif
690 
691 #if TW_TIMER_WHEELS > 1
692  /*
693  * Single odometer-click? Process a slot in the slow ring,
694  */
695  if (PREDICT_FALSE (fast_wheel_index == TW_SLOTS_PER_RING))
696  {
697  slow_wheel_index %= TW_SLOTS_PER_RING;
698  ts = &tw->w[TW_TIMER_RING_SLOW][slow_wheel_index];
699 
700  head = pool_elt_at_index (tw->timers, ts->head_index);
701  next_index = head->next;
702 
703  /* Make slot empty */
704  head->next = head->prev = ts->head_index;
705 
706  /* traverse slot, deal timers into fast ring */
707  while (next_index != head - tw->timers)
708  {
709  t = pool_elt_at_index (tw->timers, next_index);
710  next_index = t->next;
711 
712  /* Remove from sloe ring slot (hammer) */
713  t->next = t->prev = ~0;
714 
715  /* Timer expires Right Now */
716  if (PREDICT_FALSE (t->fast_ring_offset == 0))
717  {
718  vec_add1 (callback_vector, t->user_handle);
719 #if TW_START_STOP_TRACE_SIZE > 0
720  TW (tw_timer_trace) (tw, 0xfe, t->user_handle,
721  t - tw->timers);
722 #endif
723  pool_put (tw->timers, t);
724  }
725  else /* typical case */
726  {
727  /* Add to fast ring */
728  ts = &tw->w[TW_TIMER_RING_FAST][t->fast_ring_offset];
729  timer_addhead (tw->timers, ts->head_index, t - tw->timers);
730 #if TW_FAST_WHEEL_BITMAP
731  tw->fast_slot_bitmap =
732  clib_bitmap_set (tw->fast_slot_bitmap,
733  t->fast_ring_offset, 1);
734 #endif
735  }
736  }
737  }
738 #endif
739 
740  /* Handle the fast ring */
741  fast_wheel_index %= TW_SLOTS_PER_RING;
742  ts = &tw->w[TW_TIMER_RING_FAST][fast_wheel_index];
743 
744  head = pool_elt_at_index (tw->timers, ts->head_index);
745  next_index = head->next;
746 
747  /* Make slot empty */
748  head->next = head->prev = ts->head_index;
749 
750  /* Construct vector of expired timer handles to give the user */
751  while (next_index != ts->head_index)
752  {
753  t = pool_elt_at_index (tw->timers, next_index);
754  next_index = t->next;
755  vec_add1 (callback_vector, t->user_handle);
756 #if TW_START_STOP_TRACE_SIZE > 0
757  TW (tw_timer_trace) (tw, 0xfe, t->user_handle, t - tw->timers);
758 #endif
759  pool_put (tw->timers, t);
760  }
761 
762  /* If any timers expired, tell the user */
763  if (callback_vector_arg == 0 && vec_len (callback_vector))
764  {
765  /* The callback is optional. We return the u32 * handle vector */
766  if (tw->expired_timer_callback)
767  {
768  tw->expired_timer_callback (callback_vector);
769  vec_reset_length (callback_vector);
770  }
771  tw->expired_timer_handles = callback_vector;
772  }
773 
774 #if TW_FAST_WHEEL_BITMAP
775  tw->fast_slot_bitmap = clib_bitmap_set (tw->fast_slot_bitmap,
776  fast_wheel_index, 0);
777 #endif
778 
779  tw->current_tick++;
780  fast_wheel_index++;
781  tw->current_index[TW_TIMER_RING_FAST] = fast_wheel_index;
782 
783 #if TW_TIMER_WHEELS > 1
784  if (PREDICT_FALSE (fast_wheel_index == TW_SLOTS_PER_RING))
785  slow_wheel_index++;
786  tw->current_index[TW_TIMER_RING_SLOW] = slow_wheel_index;
787 #endif
788 
789 #if TW_TIMER_WHEELS > 2
790  if (PREDICT_FALSE (slow_wheel_index == TW_SLOTS_PER_RING))
791  glacier_wheel_index++;
792  tw->current_index[TW_TIMER_RING_GLACIER] = glacier_wheel_index;
793 #endif
794 
795  if (vec_len (callback_vector) >= tw->max_expirations)
796  break;
797  }
798 
799  if (callback_vector_arg == 0)
800  tw->expired_timer_handles = callback_vector;
801 
802  tw->last_run_time += i * tw->timer_interval;
803  return callback_vector;
804 }
805 
806 u32 *TW (tw_timer_expire_timers) (TWT (tw_timer_wheel) * tw, f64 now)
807 {
808  return TW (tw_timer_expire_timers_internal) (tw, now, 0 /* no vector */ );
809 }
810 
811 u32 *TW (tw_timer_expire_timers_vec) (TWT (tw_timer_wheel) * tw, f64 now,
812  u32 * vec)
813 {
814  return TW (tw_timer_expire_timers_internal) (tw, now, vec);
815 }
816 
817 #if TW_FAST_WHEEL_BITMAP
818 /** Returns an approximation to the first timer expiration in
819  * timer-ticks from "now". To avoid wasting an unjustifiable
820  * amount of time on the problem, we maintain an approximate fast-wheel slot
821  * occupancy bitmap. We don't worry about clearing fast wheel bits
822  * when timers are removed from fast wheel slots.
823  */
824 
825 u32 TW (tw_timer_first_expires_in_ticks) (TWT (tw_timer_wheel) * tw)
826 {
827  u32 first_expiring_index, fast_ring_index;
828  i32 delta;
829 
830  if (clib_bitmap_is_zero (tw->fast_slot_bitmap))
831  return TW_SLOTS_PER_RING;
832 
833  fast_ring_index = tw->current_index[TW_TIMER_RING_FAST];
834  if (fast_ring_index == TW_SLOTS_PER_RING)
835  fast_ring_index = 0;
836 
837  first_expiring_index = clib_bitmap_next_set (tw->fast_slot_bitmap,
838  fast_ring_index);
839  if (first_expiring_index == ~0 && fast_ring_index != 0)
840  first_expiring_index = clib_bitmap_first_set (tw->fast_slot_bitmap);
841 
842  ASSERT (first_expiring_index != ~0);
843 
844  delta = (i32) first_expiring_index - (i32) fast_ring_index;
845  if (delta < 0)
846  delta += TW_SLOTS_PER_RING;
847 
848  ASSERT (delta >= 0);
849 
850  return (u32) delta;
851 }
852 
853 #endif
854 
855 /*
856  * fd.io coding-style-patch-verification: ON
857  *
858  * Local Variables:
859  * eval: (c-set-style "gnu")
860  * End:
861  */
#define vec_validate(V, I)
Make sure vector is long enough for given index (no header, unspecified alignment) ...
Definition: vec.h:439
u32 TW() tw_timer_start(TWT(tw_timer_wheel)*tw, u32 user_id, u32 timer_id, u64 interval)
Start a Tw Timer.
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.
static vlib_cli_command_t trace
(constructor) VLIB_CLI_COMMAND (trace)
Definition: vlib_api_cli.c:862
unsigned long u64
Definition: types.h:89
#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:522
int i
#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
clib_memset(h->entries, 0, sizeof(h->entries[0])*entries)
#define pool_get(P, E)
Allocate an object E from a pool P (unspecified alignment).
Definition: pool.h:236
#define vec_reset_length(v)
Reset vector length to zero NULL-pointer tolerant.
double f64
Definition: types.h:142
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
unsigned int u32
Definition: types.h:88
void TW() tw_timer_update(TWT(tw_timer_wheel)*tw, u32 handle, u64 interval)
Update 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:514
static uword clib_bitmap_first_set(uword *ai)
Return the lowest numbered set bit in a bitmap.
Definition: bitmap.h:385
unsigned short u16
Definition: types.h:57
#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:286
#define TWT(a)
#define PREDICT_FALSE(x)
Definition: clib.h:111
word fformat(FILE *f, char *fmt,...)
Definition: format.c:462
#define TW_RING_SHIFT
static void timer_add(TWT(tw_timer_wheel)*tw, TWT(tw_timer)*t, u64 interval)
static void timer_remove(TWT(tw_timer)*pool, TWT(tw_timer)*elt)
#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.
#define pool_is_free_index(P, I)
Use free bitmap to query whether given index is free.
Definition: pool.h:283
u32 *TW() tw_timer_expire_timers(TWT(tw_timer_wheel)*tw, f64 now)
Fast timer ring ID.
signed int i32
Definition: types.h:77
#define pool_put_index(p, i)
Free pool element with given index.
Definition: pool.h:311
#define ASSERT(truth)
#define TW_RING_MASK
#define vec_len(v)
Number of elements in vector (rvalue-only, NULL tolerant)
int TW() tw_timer_handle_is_free(TWT(tw_timer_wheel)*tw, u32 handle)
#define TW(a)
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.