aboutsummaryrefslogtreecommitdiffstats
path: root/src/svm/svm_fifo.h
blob: c4cc0382ab7ce427cef6e1edd51654c1da1f5597 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580
581
582
583
584
585
586
587
588
589
590
591
592
593
594
595
596
597
598
599
600
601
602
603
604
605
606
607
608
609
610
611
612
613
614
615
616
617
618
619
620
621
622
623
624
625
626
627
628
629
630
631
632
633
634
635
636
637
638
639
640
641
642
643
644
645
646
647
648
649
650
651
652
653
654
655
656
657
658
659
660
661
662
663
664
665
666
667
668
669
670
671
672
673
674
675
676
677
678
679
680
681
682
683
684
685
686
687
688
689
690
691
692
693
694
695
696
697
698
699
700
701
702
703
704
705
706
707
708
709
710
711
712
713
714
715
716
717
718
719
720
721
722
723
724
725
726
727
728
729
730
731
732
733
734
735
736
737
738
739
740
741
742
743
744
745
746
747
748
749
750
751
752
753
754
755
756
757
758
759
760
761
762
763
764
765
766
767
768
769
770
771
772
773
774
775
776
777
778
779
780
781
782
783
784
785
786
787
788
789
790
791
792
793
794
795
796
797
798
799
800
801
802
803
804
805
806
807
808
809
810
811
812
813
814
815
816
817
818
819
820
821
822
823
824
825
826
827
828
829
830
831
832
833
834
835
836
837
838
839
840
841
842
843
844
845
846
847
848
849
850
851
852
853
854
855
856
857
858
859
860
861
862
863
864
865
866
867
868
869
/*
 * Copyright (c) 2016-2019 Cisco and/or its affiliates.
 * Copyright (c) 2019 Arm Limited
 * Copyright (c) 2010-2017 Intel Corporation and/or its affiliates.
 * Copyright (c) 2007-2009 Kip Macy kmacy@freebsd.org
 * Inspired from DPDK rte_ring.h (SPSC only) (derived from freebsd bufring.h).
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at:
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
#ifndef __included_ssvm_fifo_h__
#define __included_ssvm_fifo_h__

#include <vppinfra/clib.h>
#include <vppinfra/vec.h>
#include <vppinfra/pool.h>
#include <vppinfra/format.h>
#include <svm/fifo_types.h>

#define OOO_SEGMENT_INVALID_INDEX 	((u32)~0)
#define SVM_FIFO_INVALID_SESSION_INDEX 	((u32)~0)
#define SVM_FIFO_INVALID_INDEX		((u32)~0)

typedef enum svm_fifo_deq_ntf_
{
  SVM_FIFO_NO_DEQ_NOTIF = 0,		/**< No notification requested */
  SVM_FIFO_WANT_DEQ_NOTIF = 1,		/**< Notify on dequeue */
  SVM_FIFO_WANT_DEQ_NOTIF_IF_FULL = 2,	/**< Notify on transition from full */
  SVM_FIFO_WANT_DEQ_NOTIF_IF_EMPTY = 4, /**< Notify on transition to empty */
} svm_fifo_deq_ntf_t;

typedef enum svm_fifo_flag_
{
  SVM_FIFO_F_LL_TRACKED = 1 << 0,
} svm_fifo_flag_t;

typedef enum
{
  SVM_FIFO_EFULL = -2,
  SVM_FIFO_EEMPTY = -3,
  SVM_FIFO_EGROW = -4,
} svm_fifo_err_t;

typedef struct svm_fifo_seg_
{
  u8 *data;
  u32 len;
} svm_fifo_seg_t;

#if SVM_FIFO_TRACE
#define svm_fifo_trace_add(_f, _s, _l, _t)		\
{							\
  svm_fifo_trace_elem_t *trace_elt;			\
  vec_add2(_f->trace, trace_elt, 1);			\
  trace_elt->offset = _s;				\
  trace_elt->len = _l;					\
  trace_elt->action = _t;				\
}
#else
#define svm_fifo_trace_add(_f, _s, _l, _t)
#endif

u8 *svm_fifo_dump_trace (u8 * s, svm_fifo_t * f);
u8 *svm_fifo_replay (u8 * s, svm_fifo_t * f, u8 no_read, u8 verbose);

/**
 * Load head and tail optimized for consumer
 *
 * Internal function.
 */
static inline void
f_load_head_tail_cons (svm_fifo_t * f, u32 * head, u32 * tail)
{
  /* load-relaxed: consumer owned index */
  *head = f->shr->head;
  /* load-acq: consumer foreign index (paired with store-rel in producer) */
  *tail = clib_atomic_load_acq_n (&f->shr->tail);
}

/** Load head and tail optimized for producer
 *
 * Internal function
 */
static inline void
f_load_head_tail_prod (svm_fifo_t * f, u32 * head, u32 * tail)
{
  /* load relaxed: producer owned index */
  *tail = f->shr->tail;
  /* load-acq: producer foreign index (paired with store-rel in consumer) */
  *head = clib_atomic_load_acq_n (&f->shr->head);
}

/**
 * Load head and tail independent of producer/consumer role
 *
 * Internal function.
 */
static inline void
f_load_head_tail_all_acq (svm_fifo_t * f, u32 * head, u32 * tail)
{
  /* load-acq : consumer foreign index (paired with store-rel) */
  *tail = clib_atomic_load_acq_n (&f->shr->tail);
  /* load-acq : producer foriegn index (paired with store-rel) */
  *head = clib_atomic_load_acq_n (&f->shr->head);
}

/**
 * Fifo current size, i.e., number of bytes enqueued
 *
 * Internal function.
 */
static inline u32
f_cursize (svm_fifo_t * f, u32 head, u32 tail)
{
  return tail - head;
}

/**
 * Fifo free bytes, i.e., number of free bytes
 *
 * Internal function
 */
static inline u32
f_free_count (svm_fifo_t * f, u32 head, u32 tail)
{
  return (f->shr->size - f_cursize (f, head, tail));
}

always_inline u32
f_chunk_end (svm_fifo_chunk_t * c)
{
  return c->start_byte + c->length;
}

always_inline int
f_pos_lt (u32 a, u32 b)
{
  return ((i32) (a - b) < 0);
}

always_inline int
f_pos_leq (u32 a, u32 b)
{
  return ((i32) (a - b) <= 0);
}

always_inline int
f_pos_gt (u32 a, u32 b)
{
  return ((i32) (a - b) > 0);
}

always_inline int
f_pos_geq (u32 a, u32 b)
{
  return ((i32) (a - b) >= 0);
}

always_inline u8
f_chunk_includes_pos (svm_fifo_chunk_t * c, u32 pos)
{
  return (f_pos_geq (pos, c->start_byte)
	  && f_pos_lt (pos, c->start_byte + c->length));
}

always_inline svm_fifo_chunk_t *
f_start_cptr (svm_fifo_t *f)
{
  return fs_chunk_ptr (f->fs_hdr, f->shr->start_chunk);
}

always_inline svm_fifo_chunk_t *
f_end_cptr (svm_fifo_t *f)
{
  return fs_chunk_ptr (f->fs_hdr, f->shr->end_chunk);
}

always_inline svm_fifo_chunk_t *
f_head_cptr (svm_fifo_t *f)
{
  return fs_chunk_ptr (f->fs_hdr, f->shr->head_chunk);
}

always_inline svm_fifo_chunk_t *
f_tail_cptr (svm_fifo_t *f)
{
  return fs_chunk_ptr (f->fs_hdr, f->shr->tail_chunk);
}

always_inline svm_fifo_chunk_t *
f_cptr (svm_fifo_t *f, fs_sptr_t cp)
{
  return fs_chunk_ptr (f->fs_hdr, cp);
}

always_inline fs_sptr_t
f_csptr (svm_fifo_t *f, svm_fifo_chunk_t *c)
{
  return fs_chunk_sptr (f->fs_hdr, c);
}

always_inline void
f_csptr_link (svm_fifo_t *f, fs_sptr_t cp, svm_fifo_chunk_t *c)
{
  fs_chunk_ptr (f->fs_hdr, cp)->next = fs_chunk_sptr (f->fs_hdr, c);
}

/**
 * Create fifo of requested size
 *
 * Allocates fifo on current heap.
 *
 * @param size		data size in bytes for fifo to be allocated. Will be
 * 			rounded to the next highest power-of-two value.
 * @return 		pointer to new fifo
 */
svm_fifo_t *svm_fifo_alloc (u32 size);
/**
 * Initialize fifo
 *
 * @param f		fifo
 * @param size		size for fifo
 */
void svm_fifo_init (svm_fifo_t * f, u32 size);
/**
 * Allocate a fifo chunk on heap
 *
 * If the chunk is allocated on a fifo segment, this should be called
 * with the segment's heap pushed.
 *
 * @param size	chunk size in bytes. Will be rounded to the next highest
 * 		power-of-two
 * @return	new chunk or 0 if alloc failed
 */
svm_fifo_chunk_t *svm_fifo_chunk_alloc (u32 size);
/**
 * Ensure the whole fifo size is writeable
 *
 * Allocates enough chunks to cover the whole fifo size.
 *
 * @param f	fifo
 */
int svm_fifo_fill_chunk_list (svm_fifo_t * f);
/**
 * Provision and return chunks for number of bytes requested
 *
 * Allocates enough chunks to cover the bytes requested and returns them
 * in the fifo segment array. The number of bytes provisioned may be less
 * than requested if not enough segments were provided.
 *
 * @param f		fifo
 * @param fs		array of fifo segments
 * @param n_segs	length of fifo segments array
 * @param len		number of bytes to preallocate
 * @return		number of fifo segments provisioned or error
 */
int svm_fifo_provision_chunks (svm_fifo_t *f, svm_fifo_seg_t *fs, u32 n_segs,
			       u32 len);
/**
 * Initialize rbtrees used for ooo lookups
 *
 * @param f		fifo
 * @param ooo_type	type of ooo operation (0 enqueue, 1 dequeue)
 */
void svm_fifo_init_ooo_lookup (svm_fifo_t * f, u8 ooo_type);
/**
 * Free fifo and associated state
 *
 * @param f	fifo
 */
void svm_fifo_free (svm_fifo_t * f);
/**
 * Cleanup fifo chunk lookup rb tree
 *
 * The rb tree is allocated in segment heap so this should be called
 * with it pushed.
 *
 * @param f 	fifo to cleanup
 */
void svm_fifo_free_chunk_lookup (svm_fifo_t * f);
/**
 * Cleanup fifo ooo data
 *
 * The ooo data is allocated in producer process memory. The fifo
 * segment heap should not be pushed.
 *
 * @param f	fifo to cleanup
 */
void svm_fifo_free_ooo_data (svm_fifo_t * f);
/**
 * Init fifo head and tail
 *
 * @param f	fifo
 * @param head	head value that will be matched to a chunk
 * @param tail	tail value that will be matched to a chunk
 */
void svm_fifo_init_pointers (svm_fifo_t * f, u32 head, u32 tail);
/**
 * Clone fifo
 *
 * Clones single/default chunk fifo. It does not work for fifos with
 * multiple chunks.
 */
void svm_fifo_clone (svm_fifo_t * df, svm_fifo_t * sf);
/**
 * Enqueue data to fifo
 *
 * Data is enqueued and tail pointer is updated atomically. If the new data
 * enqueued partly overlaps or "touches" an out-of-order segment, said segment
 * is "consumed" and the number of bytes returned is appropriately updated.
 *
 * @param f	fifo
 * @param len	length of data to copy
 * @param src	buffer from where to copy the data
 * @return	number of contiguous bytes that can be consumed or error
 */
int svm_fifo_enqueue (svm_fifo_t * f, u32 len, const u8 * src);
/**
 * Enqueue data to fifo with offset
 *
 * Data is enqueued without updating tail pointer. Instead, an out-of-order
 * list of segments is generated and maintained. Fifo takes care of coalescing
 * contiguous or overlapping segments.
 *
 * @param f		fifo
 * @param offset	offset at which to copy the data
 * @param len		len of data to copy
 * @param src		buffer from where to copy the data
 * @return		0 if enqueue was successful, error otherwise
 */
int svm_fifo_enqueue_with_offset (svm_fifo_t * f, u32 offset, u32 len,
				  u8 * src);

/**
 * Advance tail pointer
 *
 * Useful for moving tail pointer after external enqueue.
 *
 * @param f		fifo
 * @param len		number of bytes to add to tail
 */
void svm_fifo_enqueue_nocopy (svm_fifo_t * f, u32 len);
/**
 * Enqueue array of @ref svm_fifo_seg_t in order
 *
 * @param f		fifo
 * @param segs		array of segments to enqueue
 * @param n_segs	number of segments
 * @param allow_partial	if set partial enqueues are allowed
 * @return		len if enqueue was successful, error otherwise
 */
int svm_fifo_enqueue_segments (svm_fifo_t * f, const svm_fifo_seg_t segs[],
			       u32 n_segs, u8 allow_partial);
/**
 * Overwrite fifo head with new data
 *
 * This should be typically used by dgram transport protocols that need
 * to update the dgram header after dequeuing a chunk of data. It assumes
 * that the dgram header is at most spread over two chunks.
 *
 * @param f		fifo
 * @param src		src of new data
 * @param len		length of new data
 */
void svm_fifo_overwrite_head (svm_fifo_t * f, u8 * src, u32 len);
/**
 * Dequeue data from fifo
 *
 * Data is dequeued to consumer provided buffer and head is atomically
 * updated. This should not be used in combination with ooo lookups. If
 * ooo peeking of data is needed in combination with dequeuing use @ref
 * svm_fifo_dequeue_drop.
 *
 * @param f		fifo
 * @param len		length of data to dequeue
 * @param dst		buffer to where to dequeue the data
 * @return		number of bytes dequeued or error
 */
int svm_fifo_dequeue (svm_fifo_t * f, u32 len, u8 * dst);
/**
 * Peek data from fifo
 *
 * Data is copied from requested offset into provided dst buffer. Head is
 * not updated.
 *
 * @param f		fifo
 * @param offset	offset from which to copy the data
 * @param len		length of data to copy
 * @param dst		buffer to where to dequeue the data
 * @return		number of bytes peeked
 */
int svm_fifo_peek (svm_fifo_t * f, u32 offset, u32 len, u8 * dst);
/**
 * Dequeue and drop bytes from fifo
 *
 * Advances fifo head by requested amount of bytes.
 *
 * @param f		fifo
 * @param len		number of bytes to drop
 * @return		number of bytes dropped
 */
int svm_fifo_dequeue_drop (svm_fifo_t * f, u32 len);
/**
 * Dequeue and drop all bytes from fifo
 *
 * Advances head to tail position.
 *
 * @param f		fifo
 */
void svm_fifo_dequeue_drop_all (svm_fifo_t * f);
/**
 * Get pointers to fifo chunks data in @ref svm_fifo_seg_t array
 *
 * Populates fifo segment array with pointers to fifo chunk data and lengths.
 * Because this returns pointers to data, it must be paired with
 * @ref svm_fifo_dequeue_drop to actually release the fifo chunks after the
 * data is consumed.
 *
 * @param f		fifo
 * @param offset	offset from where to retrieve segments
 * @param fs		array of fifo segments allocated by caller
 * @param n_segs	number of fifo segments in array
 * @param max_bytes	max bytes to be mapped to fifo segments
 * @return 		number of bytes in fifo segments or SVM_FIFO_EEMPTY
 */
int svm_fifo_segments (svm_fifo_t *f, u32 offset, svm_fifo_seg_t *fs,
		       u32 *n_segs, u32 max_bytes);
/**
 * Add io events subscriber to list
 *
 * @param f	fifo
 * @param sub	subscriber opaque index (typically app worker index)
 */
void svm_fifo_add_subscriber (svm_fifo_t * f, u8 sub);
/**
 * Remove io events subscriber form list
 *
 * @param f	fifo
 * @param sub	subscriber index to be removed
 */
void svm_fifo_del_subscriber (svm_fifo_t * f, u8 subscriber);
/**
 * Number of out-of-order segments for fifo
 *
 * @param f	fifo
 * @return	number of out of order segments
 */
u32 svm_fifo_n_ooo_segments (svm_fifo_t * f);
/**
 * First out-of-order segment for fifo
 *
 * @param f	fifo
 * @return	first out-of-order segment for fifo
 */
ooo_segment_t *svm_fifo_first_ooo_segment (svm_fifo_t * f);
/**
 * Check if fifo is sane. Debug only.
 *
 * @param f	fifo
 * @return 	1 if sane, 0 otherwise
 */
u8 svm_fifo_is_sane (svm_fifo_t * f);
/**
 * Number of chunks linked into the fifo
 *
 * @param f	fifo
 * @return 	number of chunks in fifo linked list
 */
u32 svm_fifo_n_chunks (svm_fifo_t * f);
format_function_t format_svm_fifo;

/**
 * Fifo max bytes to dequeue optimized for consumer
 *
 * @param f	fifo
 * @return	max number of bytes that can be dequeued
 */
static inline u32
svm_fifo_max_dequeue_cons (svm_fifo_t * f)
{
  u32 tail, head;
  f_load_head_tail_cons (f, &head, &tail);
  return f_cursize (f, head, tail);
}

/**
 * Fifo max bytes to dequeue optimized for producer
 *
 * @param f	fifo
 * @return	max number of bytes that can be dequeued
 */
static inline u32
svm_fifo_max_dequeue_prod (svm_fifo_t * f)
{
  u32 tail, head;
  f_load_head_tail_prod (f, &head, &tail);
  return f_cursize (f, head, tail);
}

/**
 * Fifo max bytes to dequeue
 *
 * Note: use producer or consumer specific functions for performance:
 * @ref svm_fifo_max_dequeue_cons (svm_fifo_t *f)
 * @ref svm_fifo_max_dequeue_prod (svm_fifo_t *f)
 */
static inline u32
svm_fifo_max_dequeue (svm_fifo_t * f)
{
  u32 tail, head;
  f_load_head_tail_all_acq (f, &head, &tail);
  return f_cursize (f, head, tail);
}

/**
 * Check if fifo is full optimized for producer
 *
 * @param f	fifo
 * @return	1 if fifo is full 0 otherwise
 */
static inline int
svm_fifo_is_full_prod (svm_fifo_t * f)
{
  return (svm_fifo_max_dequeue_prod (f) == f->shr->size);
}

/* Check if fifo is full.
 *
 * Note: use producer or consumer specific functions for performance.
 * @ref svm_fifo_is_full_prod (svm_fifo_t * f)
 * add cons version if needed
 */
static inline int
svm_fifo_is_full (svm_fifo_t * f)
{
  return (svm_fifo_max_dequeue (f) == f->shr->size);
}

/**
 * Check if fifo is empty optimized for consumer
 *
 * @param f 	fifo
 * @return	1 if fifo is empty 0 otherwise
 */
static inline int
svm_fifo_is_empty_cons (svm_fifo_t * f)
{
  return (svm_fifo_max_dequeue_cons (f) == 0);
}

/**
 * Check if fifo is empty optimized for producer
 *
 * @param f	fifo
 * @return	1 if fifo is empty 0 otherwise
 */
static inline int
svm_fifo_is_empty_prod (svm_fifo_t * f)
{
  return (svm_fifo_max_dequeue_prod (f) == 0);
}

/**
 * Check if fifo is empty
 *
 * Note: use producer or consumer specific functions for perfomance.
 * @ref svm_fifo_is_empty_cons (svm_fifo_t * f)
 * @ref svm_fifo_is_empty_prod (svm_fifo_t * f)
 */
static inline int
svm_fifo_is_empty (svm_fifo_t * f)
{
  return (svm_fifo_max_dequeue (f) == 0);
}

/**
 * Check if fifo is wrapped
 *
 * @param f	fifo
 * @return 	1 if 'normalized' head is ahead of tail
 */
static inline u8
svm_fifo_is_wrapped (svm_fifo_t * f)
{
  u32 head, tail;
  f_load_head_tail_all_acq (f, &head, &tail);
  return head > tail;
}

/**
 * Maximum number of bytes that can be enqueued into fifo
 *
 * Optimized for producer
 *
 * @param f	fifo
 * @return	max number of bytes that can be enqueued into fifo
 */
static inline u32
svm_fifo_max_enqueue_prod (svm_fifo_t * f)
{
  u32 head, tail;
  f_load_head_tail_prod (f, &head, &tail);
  return f_free_count (f, head, tail);
}

/* Maximum number of bytes that can be enqueued into fifo
 *
 * Note: use producer or consumer specific functions for performance.
 * @ref svm_fifo_max_enqueue_prod (svm_fifo_t *f)
 * add consumer specific version if needed.
 */
static inline u32
svm_fifo_max_enqueue (svm_fifo_t * f)
{
  u32 head, tail;
  f_load_head_tail_all_acq (f, &head, &tail);
  return f_free_count (f, head, tail);
}

/**
 * Max contiguous chunk of data that can be read.
 *
 * Should only be called by consumers.
 */
u32 svm_fifo_max_read_chunk (svm_fifo_t * f);

/**
 * Max contiguous chunk of data that can be written
 *
 * Should only be called by producers
 */
u32 svm_fifo_max_write_chunk (svm_fifo_t * f);

/**
 * Fifo number of subscribers getter
 *
 * @param f	fifo
 * @return	number of subscribers
 */
static inline u8
svm_fifo_n_subscribers (svm_fifo_t * f)
{
  return f->shr->n_subscribers;
}

/**
 * Check if fifo has out-of-order data
 *
 * @param f	fifo
 * @return	1 if fifo has ooo data, 0 otherwise
 */
static inline u8
svm_fifo_has_ooo_data (svm_fifo_t * f)
{
  return f->ooos_list_head != OOO_SEGMENT_INVALID_INDEX;
}

static inline ooo_segment_t *
svm_fifo_newest_ooo_segment (svm_fifo_t * f)
{
  if (f->ooos_newest == OOO_SEGMENT_INVALID_INDEX)
    return 0;
  return pool_elt_at_index (f->ooo_segments, f->ooos_newest);
}

static inline void
svm_fifo_newest_ooo_segment_reset (svm_fifo_t * f)
{
  f->ooos_newest = OOO_SEGMENT_INVALID_INDEX;
}

static inline u32
ooo_segment_offset_prod (svm_fifo_t * f, ooo_segment_t * s)
{
  u32 tail;
  /* load-relaxed: producer owned index */
  tail = f->shr->tail;

  return (s->start - tail);
}

static inline u32
ooo_segment_length (svm_fifo_t * f, ooo_segment_t * s)
{
  return s->length;
}

static inline u32
svm_fifo_size (svm_fifo_t * f)
{
  return f->shr->size;
}

static inline void
svm_fifo_set_size (svm_fifo_t * f, u32 size)
{
  if (size > (1 << f->fs_hdr->max_log2_fifo_size))
    return;
  fsh_virtual_mem_update (f->fs_hdr, f->shr->slice_index,
			  (int) f->shr->size - size);
  f->shr->size = size;
}

/**
 * Check if fifo has io event
 *
 * @param f	fifo
 * @return	1 if fifo has event, 0 otherwise
 */
static inline int
svm_fifo_has_event (svm_fifo_t * f)
{
  return f->shr->has_event;
}

/**
 * Set fifo event flag.
 *
 * Forces release semantics.
 *
 * @param f	fifo
 * @return 	1 if flag was not set, 0 otherwise
 */
always_inline u8
svm_fifo_set_event (svm_fifo_t * f)
{
  return !clib_atomic_swap_rel_n (&f->shr->has_event, 1);
}

/**
 * Unset fifo event flag.
 *
 * Forces acquire semantics
 *
 * @param f	fifo
 */
always_inline void
svm_fifo_unset_event (svm_fifo_t * f)
{
  clib_atomic_swap_acq_n (&f->shr->has_event, 0);
}

/**
 * Set specific want notification flag
 *
 * For list of flags see @ref svm_fifo_deq_ntf_t
 *
 * @param f		fifo
 * @param ntf_type	type of notification requested
 */
static inline void
svm_fifo_add_want_deq_ntf (svm_fifo_t * f, u8 ntf_type)
{
  f->shr->want_deq_ntf |= ntf_type;
}

/**
 * Clear specific want notification flag
 *
 * For list of flags see @ref svm_fifo_ntf_t
 *
 * @param f 		fifo
 * @param ntf_type	type of notification to be cleared
 */
static inline void
svm_fifo_del_want_deq_ntf (svm_fifo_t * f, u8 ntf_type)
{
  f->shr->want_deq_ntf &= ~ntf_type;
}

/**
 * Clear the want notification flag and set has notification
 *
 * Should be used after enqueuing an event. This clears the
 * SVM_FIFO_WANT_NOTIF flag but it does not clear
 * SVM_FIFO_WANT_NOTIF_IF_FULL. If the latter was set, has_ntf is
 * set to avoid enqueueing events for for all dequeue operations until
 * it is manually cleared.
 *
 * @param f	fifo
 */
static inline void
svm_fifo_clear_deq_ntf (svm_fifo_t * f)
{
  /* Set the flag if want_notif_if_full was the only ntf requested */
  f->shr->has_deq_ntf =
    f->shr->want_deq_ntf == SVM_FIFO_WANT_DEQ_NOTIF_IF_FULL;
  svm_fifo_del_want_deq_ntf (f, SVM_FIFO_WANT_DEQ_NOTIF);
}

/**
 * Clear has notification flag
 *
 * The fifo generates only one event per SVM_FIFO_WANT_NOTIF_IF_FULL
 * request and sets has_ntf. To received new events the flag must be
 * cleared using this function.
 *
 * @param f	fifo
 */
static inline void
svm_fifo_reset_has_deq_ntf (svm_fifo_t * f)
{
  f->shr->has_deq_ntf = 0;
}

/**
 * Check if fifo needs dequeue notification
 *
 * Determines based on notification request flags and state of the fifo if
 * an event should be generated.
 *
 * @param f		fifo
 * @param n_last_deq	number of bytes last dequeued
 * @return		1 if event should be generated, 0 otherwise
 */
static inline u8
svm_fifo_needs_deq_ntf (svm_fifo_t * f, u32 n_last_deq)
{
  u8 want_ntf = f->shr->want_deq_ntf;

  if (PREDICT_TRUE (want_ntf == SVM_FIFO_NO_DEQ_NOTIF))
    return 0;
  else if (want_ntf & SVM_FIFO_WANT_DEQ_NOTIF)
    return (svm_fifo_max_enqueue (f) >= f->shr->deq_thresh);
  if (want_ntf & SVM_FIFO_WANT_DEQ_NOTIF_IF_FULL)
    {
      u32 max_deq = svm_fifo_max_dequeue_cons (f);
      u32 size = f->shr->size;
      if (!f->shr->has_deq_ntf && max_deq < size &&
	  max_deq + n_last_deq >= size)
	return 1;
    }
  if (want_ntf & SVM_FIFO_WANT_DEQ_NOTIF_IF_EMPTY)
    {
      if (!f->shr->has_deq_ntf && svm_fifo_is_empty (f))
	return 1;
    }
  return 0;
}

/**
 * Set the fifo dequeue threshold which will be used for notifications.
 *
 * Note: If not set, by default threshold is zero, equivalent to
 * generating notification on each dequeue event.
 */
static inline void
svm_fifo_set_deq_thresh (svm_fifo_t *f, u32 thresh)
{
  f->shr->deq_thresh = thresh;
}

#endif /* __included_ssvm_fifo_h__ */

/*
 * fd.io coding-style-patch-verification: ON
 *
 * Local Variables:
 * eval: (c-set-style "gnu")
 * End:
 */