FD.io VPP  v20.09-64-g4f7b92f0a
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,
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 
425  vec_validate (tw->expired_timer_handles, 0);
426  _vec_len (tw->expired_timer_handles) = 0;
427 
428  for (ring = 0; ring < TW_TIMER_WHEELS; ring++)
429  {
430  for (slot = 0; slot < TW_SLOTS_PER_RING; slot++)
431  {
432  ts = &tw->w[ring][slot];
433  pool_get (tw->timers, t);
434  clib_memset (t, 0xff, sizeof (*t));
435  t->next = t->prev = t - tw->timers;
436  ts->head_index = t - tw->timers;
437  }
438  }
439 
440 #if TW_OVERFLOW_VECTOR > 0
441  ts = &tw->overflow;
442  pool_get (tw->timers, t);
443  clib_memset (t, 0xff, sizeof (*t));
444  t->next = t->prev = t - tw->timers;
445  ts->head_index = t - tw->timers;
446 #endif
447 }
448 
449 /**
450  * @brief Free a tw timer wheel template instance
451  * @param tw_timer_wheel_t * tw timer wheel object pointer
452  */
453 void TW (tw_timer_wheel_free) (TWT (tw_timer_wheel) * tw)
454 {
455  int i, j;
457  TWT (tw_timer) * head, *t;
458  u32 next_index;
459 
460  for (i = 0; i < TW_TIMER_WHEELS; i++)
461  {
462  for (j = 0; j < TW_SLOTS_PER_RING; j++)
463  {
464  ts = &tw->w[i][j];
465  head = pool_elt_at_index (tw->timers, ts->head_index);
466  next_index = head->next;
467 
468  while (next_index != ts->head_index)
469  {
470  t = pool_elt_at_index (tw->timers, next_index);
471  next_index = t->next;
472  pool_put (tw->timers, t);
473  }
474  pool_put (tw->timers, head);
475  }
476  }
477 
478 #if TW_OVERFLOW_VECTOR > 0
479  ts = &tw->overflow;
480  head = pool_elt_at_index (tw->timers, ts->head_index);
481  next_index = head->next;
482 
483  while (next_index != ts->head_index)
484  {
485  t = pool_elt_at_index (tw->timers, next_index);
486  next_index = t->next;
487  pool_put (tw->timers, t);
488  }
489  pool_put (tw->timers, head);
490 #endif
491 
492  clib_memset (tw, 0, sizeof (*tw));
493 }
494 
495 /**
496  * @brief Advance a tw timer wheel. Calls the expired timer callback
497  * as needed. This routine should be called once every timer_interval seconds
498  * @param tw_timer_wheel_t * tw timer wheel template instance pointer
499  * @param f64 now the current time, e.g. from vlib_time_now(vm)
500  * @returns u32 * vector of expired user handles
501  */
502 static inline
503  u32 * TW (tw_timer_expire_timers_internal) (TWT (tw_timer_wheel) * tw,
504  f64 now,
505  u32 * callback_vector_arg)
506 {
507  u32 nticks, i;
509  TWT (tw_timer) * t, *head;
510  u32 *callback_vector;
511  u32 fast_wheel_index;
512  u32 next_index;
513  u32 slow_wheel_index __attribute__ ((unused));
514  u32 glacier_wheel_index __attribute__ ((unused));
515 
516  /* Called too soon to process new timer expirations? */
517  if (PREDICT_FALSE (now < tw->next_run_time))
518  return callback_vector_arg;
519 
520  /* Number of ticks which have occurred */
521  nticks = tw->ticks_per_second * (now - tw->last_run_time);
522  if (nticks == 0)
523  return callback_vector_arg;
524 
525  /* Remember when we ran, compute next runtime */
526  tw->next_run_time = (now + tw->timer_interval);
527 
528  /* First call, or time jumped backwards? */
529  if (PREDICT_FALSE
530  ((tw->last_run_time == 0.0) || (now <= tw->last_run_time)))
531  {
532  tw->last_run_time = now;
533  return callback_vector_arg;
534  }
535 
536  if (callback_vector_arg == 0)
537  {
538  _vec_len (tw->expired_timer_handles) = 0;
539  callback_vector = tw->expired_timer_handles;
540  }
541  else
542  callback_vector = callback_vector_arg;
543 
544  for (i = 0; i < nticks; i++)
545  {
546  fast_wheel_index = tw->current_index[TW_TIMER_RING_FAST];
547  if (TW_TIMER_WHEELS > 1)
548  slow_wheel_index = tw->current_index[TW_TIMER_RING_SLOW];
549  if (TW_TIMER_WHEELS > 2)
550  glacier_wheel_index = tw->current_index[TW_TIMER_RING_GLACIER];
551 
552 #if TW_OVERFLOW_VECTOR > 0
553  /* Triple odometer-click? Process the overflow vector... */
554  if (PREDICT_FALSE (fast_wheel_index == TW_SLOTS_PER_RING
555  && slow_wheel_index == TW_SLOTS_PER_RING
556  && glacier_wheel_index == TW_SLOTS_PER_RING))
557  {
558  u64 interval;
559  u32 new_glacier_ring_offset, new_slow_ring_offset;
560  u32 new_fast_ring_offset;
561 
562  ts = &tw->overflow;
563  head = pool_elt_at_index (tw->timers, ts->head_index);
564  next_index = head->next;
565 
566  /* Make slot empty */
567  head->next = head->prev = ts->head_index;
568 
569  /* traverse slot, place timers wherever they go */
570  while (next_index != head - tw->timers)
571  {
572  t = pool_elt_at_index (tw->timers, next_index);
573  next_index = t->next;
574 
575  /* Remove from the overflow vector (hammer) */
576  t->next = t->prev = ~0;
577 
578  ASSERT (t->expiration_time >= tw->current_tick);
579 
580  interval = t->expiration_time - tw->current_tick;
581 
582  /* Right back onto the overflow vector? */
583  if (interval >= (1 << (3 * TW_RING_SHIFT)))
584  {
585  ts = &tw->overflow;
586  timer_addhead (tw->timers, ts->head_index, t - tw->timers);
587  continue;
588  }
589  /* Compute ring offsets */
590  new_glacier_ring_offset = interval >> (2 * TW_RING_SHIFT);
591 
592  interval -= (new_glacier_ring_offset << (2 * TW_RING_SHIFT));
593 
594  /* Note: the wheels are at (0,0,0), no add-with-carry needed */
595  new_slow_ring_offset = interval >> TW_RING_SHIFT;
596  interval -= (new_slow_ring_offset << TW_RING_SHIFT);
597  new_fast_ring_offset = interval & TW_RING_MASK;
598  t->slow_ring_offset = new_slow_ring_offset;
599  t->fast_ring_offset = new_fast_ring_offset;
600 
601  /* Timer expires Right Now */
602  if (PREDICT_FALSE (t->slow_ring_offset == 0 &&
603  t->fast_ring_offset == 0 &&
604  new_glacier_ring_offset == 0))
605  {
606  vec_add1 (callback_vector, t->user_handle);
607 #if TW_START_STOP_TRACE_SIZE > 0
608  TW (tw_timer_trace) (tw, 0xfe, t->user_handle,
609  t - tw->timers);
610 #endif
611  pool_put (tw->timers, t);
612  }
613  /* Timer moves to the glacier ring */
614  else if (new_glacier_ring_offset)
615  {
616  ts = &tw->w[TW_TIMER_RING_GLACIER][new_glacier_ring_offset];
617  timer_addhead (tw->timers, ts->head_index, t - tw->timers);
618  }
619  /* Timer moves to the slow ring */
620  else if (t->slow_ring_offset)
621  {
622  /* Add to slow ring */
623  ts = &tw->w[TW_TIMER_RING_SLOW][t->slow_ring_offset];
624  timer_addhead (tw->timers, ts->head_index, t - tw->timers);
625  }
626  /* Timer timer moves to the fast ring */
627  else
628  {
629  ts = &tw->w[TW_TIMER_RING_FAST][t->fast_ring_offset];
630  timer_addhead (tw->timers, ts->head_index, t - tw->timers);
631 #if TW_FAST_WHEEL_BITMAP
632  tw->fast_slot_bitmap =
633  clib_bitmap_set (tw->fast_slot_bitmap,
634  t->fast_ring_offset, 1);
635 #endif
636  }
637  }
638  }
639 #endif
640 
641 #if TW_TIMER_WHEELS > 2
642  /*
643  * Double odometer-click? Process one slot in the glacier ring...
644  */
645  if (PREDICT_FALSE (fast_wheel_index == TW_SLOTS_PER_RING
646  && slow_wheel_index == TW_SLOTS_PER_RING))
647  {
648  glacier_wheel_index %= TW_SLOTS_PER_RING;
649  ts = &tw->w[TW_TIMER_RING_GLACIER][glacier_wheel_index];
650 
651  head = pool_elt_at_index (tw->timers, ts->head_index);
652  next_index = head->next;
653 
654  /* Make slot empty */
655  head->next = head->prev = ts->head_index;
656 
657  /* traverse slot, deal timers into slow ring */
658  while (next_index != head - tw->timers)
659  {
660  t = pool_elt_at_index (tw->timers, next_index);
661  next_index = t->next;
662 
663  /* Remove from glacier ring slot (hammer) */
664  t->next = t->prev = ~0;
665 
666  /* Timer expires Right Now */
667  if (PREDICT_FALSE (t->slow_ring_offset == 0 &&
668  t->fast_ring_offset == 0))
669  {
670  vec_add1 (callback_vector, t->user_handle);
671 #if TW_START_STOP_TRACE_SIZE > 0
672  TW (tw_timer_trace) (tw, 0xfe, t->user_handle,
673  t - tw->timers);
674 #endif
675  pool_put (tw->timers, t);
676  }
677  /* Timer expires during slow-wheel tick 0 */
678  else if (PREDICT_FALSE (t->slow_ring_offset == 0))
679  {
680  ts = &tw->w[TW_TIMER_RING_FAST][t->fast_ring_offset];
681  timer_addhead (tw->timers, ts->head_index, t - tw->timers);
682 #if TW_FAST_WHEEL_BITMAP
683  tw->fast_slot_bitmap =
684  clib_bitmap_set (tw->fast_slot_bitmap,
685  t->fast_ring_offset, 1);
686 #endif
687  }
688  else /* typical case */
689  {
690  /* Add to slow ring */
691  ts = &tw->w[TW_TIMER_RING_SLOW][t->slow_ring_offset];
692  timer_addhead (tw->timers, ts->head_index, t - tw->timers);
693  }
694  }
695  }
696 #endif
697 
698 #if TW_TIMER_WHEELS > 1
699  /*
700  * Single odometer-click? Process a slot in the slow ring,
701  */
702  if (PREDICT_FALSE (fast_wheel_index == TW_SLOTS_PER_RING))
703  {
704  slow_wheel_index %= TW_SLOTS_PER_RING;
705  ts = &tw->w[TW_TIMER_RING_SLOW][slow_wheel_index];
706 
707  head = pool_elt_at_index (tw->timers, ts->head_index);
708  next_index = head->next;
709 
710  /* Make slot empty */
711  head->next = head->prev = ts->head_index;
712 
713  /* traverse slot, deal timers into fast ring */
714  while (next_index != head - tw->timers)
715  {
716  t = pool_elt_at_index (tw->timers, next_index);
717  next_index = t->next;
718 
719  /* Remove from sloe ring slot (hammer) */
720  t->next = t->prev = ~0;
721 
722  /* Timer expires Right Now */
723  if (PREDICT_FALSE (t->fast_ring_offset == 0))
724  {
725  vec_add1 (callback_vector, t->user_handle);
726 #if TW_START_STOP_TRACE_SIZE > 0
727  TW (tw_timer_trace) (tw, 0xfe, t->user_handle,
728  t - tw->timers);
729 #endif
730  pool_put (tw->timers, t);
731  }
732  else /* typical case */
733  {
734  /* Add to fast ring */
735  ts = &tw->w[TW_TIMER_RING_FAST][t->fast_ring_offset];
736  timer_addhead (tw->timers, ts->head_index, t - tw->timers);
737 #if TW_FAST_WHEEL_BITMAP
738  tw->fast_slot_bitmap =
739  clib_bitmap_set (tw->fast_slot_bitmap,
740  t->fast_ring_offset, 1);
741 #endif
742  }
743  }
744  }
745 #endif
746 
747  /* Handle the fast ring */
748  fast_wheel_index %= TW_SLOTS_PER_RING;
749  ts = &tw->w[TW_TIMER_RING_FAST][fast_wheel_index];
750 
751  head = pool_elt_at_index (tw->timers, ts->head_index);
752  next_index = head->next;
753 
754  /* Make slot empty */
755  head->next = head->prev = ts->head_index;
756 
757  /* Construct vector of expired timer handles to give the user */
758  while (next_index != ts->head_index)
759  {
760  t = pool_elt_at_index (tw->timers, next_index);
761  next_index = t->next;
762  vec_add1 (callback_vector, t->user_handle);
763 #if TW_START_STOP_TRACE_SIZE > 0
764  TW (tw_timer_trace) (tw, 0xfe, t->user_handle, t - tw->timers);
765 #endif
766  pool_put (tw->timers, t);
767  }
768 
769  /* If any timers expired, tell the user */
770  if (callback_vector_arg == 0 && vec_len (callback_vector))
771  {
772  /* The callback is optional. We return the u32 * handle vector */
773  if (tw->expired_timer_callback)
774  {
775  tw->expired_timer_callback (callback_vector);
776  vec_reset_length (callback_vector);
777  }
778  tw->expired_timer_handles = callback_vector;
779  }
780 
781 #if TW_FAST_WHEEL_BITMAP
782  tw->fast_slot_bitmap = clib_bitmap_set (tw->fast_slot_bitmap,
783  fast_wheel_index, 0);
784 #endif
785 
786  tw->current_tick++;
787  fast_wheel_index++;
788  tw->current_index[TW_TIMER_RING_FAST] = fast_wheel_index;
789 
790 #if TW_TIMER_WHEELS > 1
791  if (PREDICT_FALSE (fast_wheel_index == TW_SLOTS_PER_RING))
792  slow_wheel_index++;
793  tw->current_index[TW_TIMER_RING_SLOW] = slow_wheel_index;
794 #endif
795 
796 #if TW_TIMER_WHEELS > 2
797  if (PREDICT_FALSE (slow_wheel_index == TW_SLOTS_PER_RING))
798  glacier_wheel_index++;
799  tw->current_index[TW_TIMER_RING_GLACIER] = glacier_wheel_index;
800 #endif
801 
802  if (vec_len (callback_vector) >= tw->max_expirations)
803  break;
804  }
805 
806  if (callback_vector_arg == 0)
807  tw->expired_timer_handles = callback_vector;
808 
809  tw->last_run_time += i * tw->timer_interval;
810  return callback_vector;
811 }
812 
813 u32 *TW (tw_timer_expire_timers) (TWT (tw_timer_wheel) * tw, f64 now)
814 {
815  return TW (tw_timer_expire_timers_internal) (tw, now, 0 /* no vector */ );
816 }
817 
818 u32 *TW (tw_timer_expire_timers_vec) (TWT (tw_timer_wheel) * tw, f64 now,
819  u32 * vec)
820 {
821  return TW (tw_timer_expire_timers_internal) (tw, now, vec);
822 }
823 
824 #if TW_FAST_WHEEL_BITMAP
825 /** Returns an approximation to the first timer expiration in
826  * timer-ticks from "now". To avoid wasting an unjustifiable
827  * amount of time on the problem, we maintain an approximate fast-wheel slot
828  * occupancy bitmap. We don't worry about clearing fast wheel bits
829  * when timers are removed from fast wheel slots.
830  */
831 
832 u32 TW (tw_timer_first_expires_in_ticks) (TWT (tw_timer_wheel) * tw)
833 {
834  u32 first_expiring_index, fast_ring_index;
835  i32 delta;
836 
837 #if TW_TIMER_WHEELS > 1
838  fast_ring_index = tw->current_index[TW_TIMER_RING_FAST];
839  if (fast_ring_index == TW_SLOTS_PER_RING)
840  return 1;
841 
842  first_expiring_index = clib_bitmap_next_set (tw->fast_slot_bitmap,
843  fast_ring_index);
844  if (first_expiring_index == ~0)
845  first_expiring_index = TW_SLOTS_PER_RING;
846 
847 #else
848 
849  if (clib_bitmap_is_zero (tw->fast_slot_bitmap))
850  return TW_SLOTS_PER_RING;
851 
852  fast_ring_index = tw->current_index[TW_TIMER_RING_FAST];
853  if (fast_ring_index == TW_SLOTS_PER_RING)
854  fast_ring_index = 0;
855 
856  first_expiring_index = clib_bitmap_next_set (tw->fast_slot_bitmap,
857  fast_ring_index);
858  if (first_expiring_index == ~0 && fast_ring_index != 0)
859  first_expiring_index = clib_bitmap_first_set (tw->fast_slot_bitmap);
860 #endif
861 
862  ASSERT (first_expiring_index != ~0);
863 
864  delta = (i32) first_expiring_index - (i32) fast_ring_index;
865  if (delta < 0)
866  delta += TW_SLOTS_PER_RING;
867 
868  ASSERT (delta >= 0);
869 
870  return (u32) delta;
871 }
872 
873 #endif
874 
875 /*
876  * fd.io coding-style-patch-verification: ON
877  *
878  * Local Variables:
879  * eval: (c-set-style "gnu")
880  * End:
881  */
#define vec_validate(V, I)
Make sure vector is long enough for given index (no header, unspecified alignment) ...
Definition: vec.h:509
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:899
unsigned long u64
Definition: types.h:89
#define TW_TIMERS_PER_OBJECT
clib_memset(h->entries, 0, sizeof(h->entries[0]) *entries)
#define vec_add1(V, E)
Add 1 element to end of vector (unspecified alignment).
Definition: vec.h:592
#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:252
#define vec_reset_length(v)
Reset vector length to zero NULL-pointer tolerant.
void TW() tw_timer_wheel_free(TWT(tw_timer_wheel) *tw)
Free a tw timer wheel template instance.
double f64
Definition: types.h:142
static void timer_addhead(TWT(tw_timer) *pool, u32 head_index, u32 new_index)
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
int TW() tw_timer_handle_is_free(TWT(tw_timer_wheel) *tw, u32 handle)
#define pool_elt_at_index(p, i)
Returns pointer to element at given index.
Definition: pool.h:534
static void timer_add(TWT(tw_timer_wheel) *tw, TWT(tw_timer) *t, u64 interval)
u32 *TW() tw_timer_expire_timers(TWT(tw_timer_wheel) *tw, f64 now)
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
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 TW_SLOTS_PER_RING
u32 *TW() tw_timer_expire_timers_vec(TWT(tw_timer_wheel) *tw, f64 now, u32 *vec)
#define pool_put(P, E)
Free an object E in pool P.
Definition: pool.h:302
#define TWT(a)
void TW() tw_timer_update(TWT(tw_timer_wheel) *tw, u32 handle, u64 interval)
Update a tw timer.
#define PREDICT_FALSE(x)
Definition: clib.h:120
word fformat(FILE *f, char *fmt,...)
Definition: format.c:462
u8 slot
Definition: pci_types.api:22
#define TW_RING_SHIFT
static void timer_remove(TWT(tw_timer) *pool, TWT(tw_timer) *elt)
sll srl srl sll sra u16x4 i
Definition: vector_sse42.h:317
#define clib_warning(format, args...)
Definition: error.h:59
#define pool_is_free_index(P, I)
Use free bitmap to query whether given index is free.
Definition: pool.h:299
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:331
#define ASSERT(truth)
u16 interval
Definition: vrrp.api:34
#define TW_RING_MASK
#define vec_len(v)
Number of elements in vector (rvalue-only, NULL tolerant)
u32 TW() tw_timer_start(TWT(tw_timer_wheel) *tw, u32 user_id, u32 timer_id, u64 interval)
Start a Tw Timer.
#define TW(a)
static void expired_timer_callback(u32 *expired_timers)
static u32 TW() make_internal_timer_handle(u32 pool_index, u32 timer_id)
void TW() tw_timer_stop(TWT(tw_timer_wheel) *tw, u32 handle)
Stop a tw timer.
u32 head_index
Listhead of timers which expire in this interval.
Slow timer ring ID.