-
Notifications
You must be signed in to change notification settings - Fork 226
Expand file tree
/
Copy pathindex.go
More file actions
934 lines (810 loc) · 25.1 KB
/
index.go
File metadata and controls
934 lines (810 loc) · 25.1 KB
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
870
871
872
873
874
875
876
877
878
879
880
881
882
883
884
885
886
887
888
889
890
891
892
893
894
895
896
897
898
899
900
901
902
903
904
905
906
907
908
909
910
911
912
913
914
915
916
917
918
919
920
921
922
923
924
925
926
927
928
929
930
931
932
933
934
// Copyright (c) HashiCorp, Inc.
// SPDX-License-Identifier: MPL-2.0
package memdb
import (
"encoding/binary"
"encoding/hex"
"errors"
"fmt"
"reflect"
"strconv"
"strings"
)
// Indexer is an interface used for defining indexes. Indexes are used
// for efficient lookup of objects in a MemDB table. An Indexer must also
// implement one of SingleIndexer or MultiIndexer.
//
// Indexers are primarily responsible for returning the lookup key as
// a byte slice. The byte slice is the key data in the underlying data storage.
type Indexer interface {
// FromArgs is called to build the exact index key from a list of arguments.
FromArgs(args ...interface{}) ([]byte, error)
}
// SingleIndexer is an interface used for defining indexes that generate a
// single value per object
type SingleIndexer interface {
// FromObject extracts the index value from an object. The return values
// are whether the index value was found, the index value, and any error
// while extracting the index value, respectively.
FromObject(raw interface{}) (bool, []byte, error)
}
// MultiIndexer is an interface used for defining indexes that generate
// multiple values per object. Each value is stored as a seperate index
// pointing to the same object.
//
// For example, an index that extracts the first and last name of a person
// and allows lookup based on eitherd would be a MultiIndexer. The FromObject
// of this example would split the first and last name and return both as
// values.
type MultiIndexer interface {
// FromObject extracts index values from an object. The return values
// are the same as a SingleIndexer except there can be multiple index
// values.
FromObject(raw interface{}) (bool, [][]byte, error)
}
// PrefixIndexer is an optional interface on top of an Indexer that allows
// indexes to support prefix-based iteration.
type PrefixIndexer interface {
// PrefixFromArgs is the same as FromArgs for an Indexer except that
// the index value returned should return all prefix-matched values.
PrefixFromArgs(args ...interface{}) ([]byte, error)
}
// StringFieldIndex is used to extract a field from an object
// using reflection and builds an index on that field.
type StringFieldIndex struct {
Field string
Lowercase bool
}
func (s *StringFieldIndex) FromObject(obj interface{}) (bool, []byte, error) {
v := reflect.ValueOf(obj)
v = reflect.Indirect(v) // Dereference the pointer if any
fv := v.FieldByName(s.Field)
isPtr := fv.Kind() == reflect.Ptr
fv = reflect.Indirect(fv)
if !isPtr && !fv.IsValid() {
return false, nil,
fmt.Errorf("field '%s' for %#v is invalid %v ", s.Field, obj, isPtr)
}
if isPtr && !fv.IsValid() {
val := ""
return false, []byte(val), nil
}
val := fv.String()
if val == "" {
return false, nil, nil
}
if s.Lowercase {
val = strings.ToLower(val)
}
// Add the null character as a terminator
val += "\x00"
return true, []byte(val), nil
}
func (s *StringFieldIndex) FromArgs(args ...interface{}) ([]byte, error) {
if len(args) != 1 {
return nil, fmt.Errorf("must provide only a single argument")
}
arg, ok := args[0].(string)
if !ok {
return nil, fmt.Errorf("argument must be a string: %#v", args[0])
}
if s.Lowercase {
arg = strings.ToLower(arg)
}
// Add the null character as a terminator
arg += "\x00"
return []byte(arg), nil
}
func (s *StringFieldIndex) PrefixFromArgs(args ...interface{}) ([]byte, error) {
val, err := s.FromArgs(args...)
if err != nil {
return nil, err
}
// Strip the null terminator, the rest is a prefix
n := len(val)
if n > 0 {
return val[:n-1], nil
}
return val, nil
}
// StringSliceFieldIndex builds an index from a field on an object that is a
// string slice ([]string). Each value within the string slice can be used for
// lookup.
type StringSliceFieldIndex struct {
Field string
Lowercase bool
}
func (s *StringSliceFieldIndex) FromObject(obj interface{}) (bool, [][]byte, error) {
v := reflect.ValueOf(obj)
v = reflect.Indirect(v) // Dereference the pointer if any
fv := v.FieldByName(s.Field)
if !fv.IsValid() {
return false, nil,
fmt.Errorf("field '%s' for %#v is invalid", s.Field, obj)
}
if fv.Kind() != reflect.Slice || fv.Type().Elem().Kind() != reflect.String {
return false, nil, fmt.Errorf("field '%s' is not a string slice", s.Field)
}
length := fv.Len()
vals := make([][]byte, 0, length)
for i := 0; i < fv.Len(); i++ {
val := fv.Index(i).String()
if val == "" {
continue
}
if s.Lowercase {
val = strings.ToLower(val)
}
// Add the null character as a terminator
val += "\x00"
vals = append(vals, []byte(val))
}
if len(vals) == 0 {
return false, nil, nil
}
return true, vals, nil
}
func (s *StringSliceFieldIndex) FromArgs(args ...interface{}) ([]byte, error) {
if len(args) != 1 {
return nil, fmt.Errorf("must provide only a single argument")
}
arg, ok := args[0].(string)
if !ok {
return nil, fmt.Errorf("argument must be a string: %#v", args[0])
}
if s.Lowercase {
arg = strings.ToLower(arg)
}
// Add the null character as a terminator
arg += "\x00"
return []byte(arg), nil
}
func (s *StringSliceFieldIndex) PrefixFromArgs(args ...interface{}) ([]byte, error) {
val, err := s.FromArgs(args...)
if err != nil {
return nil, err
}
// Strip the null terminator, the rest is a prefix
n := len(val)
if n > 0 {
return val[:n-1], nil
}
return val, nil
}
// StringMapFieldIndex is used to extract a field of type map[string]string
// from an object using reflection and builds an index on that field.
//
// Note that although FromArgs in theory supports using either one or
// two arguments, there is a bug: FromObject only creates an index
// using key/value, and does not also create an index using key. This
// means a lookup using one argument will never actually work.
//
// It is currently left as-is to prevent backwards compatibility
// issues.
//
// TODO: Fix this in the next major bump.
type StringMapFieldIndex struct {
Field string
Lowercase bool
}
var MapType = reflect.MapOf(reflect.TypeOf(""), reflect.TypeOf("")).Kind()
func (s *StringMapFieldIndex) FromObject(obj interface{}) (bool, [][]byte, error) {
v := reflect.ValueOf(obj)
v = reflect.Indirect(v) // Dereference the pointer if any
fv := v.FieldByName(s.Field)
if !fv.IsValid() {
return false, nil, fmt.Errorf("field '%s' for %#v is invalid", s.Field, obj)
}
if fv.Kind() != MapType {
return false, nil, fmt.Errorf("field '%s' is not a map[string]string", s.Field)
}
length := fv.Len()
vals := make([][]byte, 0, length)
for _, key := range fv.MapKeys() {
k := key.String()
if k == "" {
continue
}
val := fv.MapIndex(key).String()
if s.Lowercase {
k = strings.ToLower(k)
val = strings.ToLower(val)
}
// Add the null character as a terminator
k += "\x00" + val + "\x00"
vals = append(vals, []byte(k))
}
if len(vals) == 0 {
return false, nil, nil
}
return true, vals, nil
}
// WARNING: Because of a bug in FromObject, this function will never return
// a value when using the single-argument version.
func (s *StringMapFieldIndex) FromArgs(args ...interface{}) ([]byte, error) {
if len(args) > 2 || len(args) == 0 {
return nil, fmt.Errorf("must provide one or two arguments")
}
key, ok := args[0].(string)
if !ok {
return nil, fmt.Errorf("argument must be a string: %#v", args[0])
}
if s.Lowercase {
key = strings.ToLower(key)
}
// Add the null character as a terminator
key += "\x00"
if len(args) == 2 {
val, ok := args[1].(string)
if !ok {
return nil, fmt.Errorf("argument must be a string: %#v", args[1])
}
if s.Lowercase {
val = strings.ToLower(val)
}
// Add the null character as a terminator
key += val + "\x00"
}
return []byte(key), nil
}
// IntFieldIndex is used to extract an int field from an object using
// reflection and builds an index on that field.
type IntFieldIndex struct {
Field string
}
func (i *IntFieldIndex) FromObject(obj interface{}) (bool, []byte, error) {
v := reflect.ValueOf(obj)
v = reflect.Indirect(v) // Dereference the pointer if any
fv := v.FieldByName(i.Field)
if !fv.IsValid() {
return false, nil,
fmt.Errorf("field '%s' for %#v is invalid", i.Field, obj)
}
// Check the type
k := fv.Kind()
size, ok := IsIntType(k)
if !ok {
return false, nil, fmt.Errorf("field %q is of type %v; want an int", i.Field, k)
}
// Get the value and encode it
val := fv.Int()
buf := encodeInt(val, size)
return true, buf, nil
}
func (i *IntFieldIndex) FromArgs(args ...interface{}) ([]byte, error) {
if len(args) != 1 {
return nil, fmt.Errorf("must provide only a single argument")
}
v := reflect.ValueOf(args[0])
if !v.IsValid() {
return nil, fmt.Errorf("%#v is invalid", args[0])
}
k := v.Kind()
size, ok := IsIntType(k)
if !ok {
return nil, fmt.Errorf("arg is of type %v; want a int", k)
}
val := v.Int()
buf := encodeInt(val, size)
return buf, nil
}
func encodeInt(val int64, size int) []byte {
buf := make([]byte, size)
// This bit flips the sign bit on any sized signed twos-complement integer,
// which when truncated to a uint of the same size will bias the value such
// that the maximum negative int becomes 0, and the maximum positive int
// becomes the maximum positive uint.
scaled := val ^ int64(-1<<(size*8-1))
switch size {
case 1:
buf[0] = uint8(scaled)
case 2:
binary.BigEndian.PutUint16(buf, uint16(scaled))
case 4:
binary.BigEndian.PutUint32(buf, uint32(scaled))
case 8:
binary.BigEndian.PutUint64(buf, uint64(scaled))
default:
panic(fmt.Sprintf("unsupported int size parameter: %d", size))
}
return buf
}
// IsIntType returns whether the passed type is a type of int and the number
// of bytes needed to encode the type.
func IsIntType(k reflect.Kind) (size int, okay bool) {
switch k {
case reflect.Int:
return strconv.IntSize / 8, true
case reflect.Int8:
return 1, true
case reflect.Int16:
return 2, true
case reflect.Int32:
return 4, true
case reflect.Int64:
return 8, true
default:
return 0, false
}
}
// UintFieldIndex is used to extract a uint field from an object using
// reflection and builds an index on that field.
type UintFieldIndex struct {
Field string
}
func (u *UintFieldIndex) FromObject(obj interface{}) (bool, []byte, error) {
v := reflect.ValueOf(obj)
v = reflect.Indirect(v) // Dereference the pointer if any
fv := v.FieldByName(u.Field)
if !fv.IsValid() {
return false, nil,
fmt.Errorf("field '%s' for %#v is invalid", u.Field, obj)
}
// Check the type
k := fv.Kind()
size, ok := IsUintType(k)
if !ok {
return false, nil, fmt.Errorf("field %q is of type %v; want a uint", u.Field, k)
}
// Get the value and encode it
val := fv.Uint()
buf := encodeUInt(val, size)
return true, buf, nil
}
func (u *UintFieldIndex) FromArgs(args ...interface{}) ([]byte, error) {
if len(args) != 1 {
return nil, fmt.Errorf("must provide only a single argument")
}
v := reflect.ValueOf(args[0])
if !v.IsValid() {
return nil, fmt.Errorf("%#v is invalid", args[0])
}
k := v.Kind()
size, ok := IsUintType(k)
if !ok {
return nil, fmt.Errorf("arg is of type %v; want a uint", k)
}
val := v.Uint()
buf := encodeUInt(val, size)
return buf, nil
}
func encodeUInt(val uint64, size int) []byte {
buf := make([]byte, size)
switch size {
case 1:
buf[0] = uint8(val)
case 2:
binary.BigEndian.PutUint16(buf, uint16(val))
case 4:
binary.BigEndian.PutUint32(buf, uint32(val))
case 8:
binary.BigEndian.PutUint64(buf, val)
default:
panic(fmt.Sprintf("unsupported uint size parameter: %d", size))
}
return buf
}
// IsUintType returns whether the passed type is a type of uint and the number
// of bytes needed to encode the type.
func IsUintType(k reflect.Kind) (size int, okay bool) {
switch k {
case reflect.Uint:
return strconv.IntSize / 8, true
case reflect.Uint8:
return 1, true
case reflect.Uint16:
return 2, true
case reflect.Uint32:
return 4, true
case reflect.Uint64:
return 8, true
default:
return 0, false
}
}
// BoolFieldIndex is used to extract an boolean field from an object using
// reflection and builds an index on that field.
type BoolFieldIndex struct {
Field string
}
func (i *BoolFieldIndex) FromObject(obj interface{}) (bool, []byte, error) {
v := reflect.ValueOf(obj)
v = reflect.Indirect(v) // Dereference the pointer if any
fv := v.FieldByName(i.Field)
if !fv.IsValid() {
return false, nil,
fmt.Errorf("field '%s' for %#v is invalid", i.Field, obj)
}
// Check the type
k := fv.Kind()
if k != reflect.Bool {
return false, nil, fmt.Errorf("field %q is of type %v; want a bool", i.Field, k)
}
// Get the value and encode it
buf := make([]byte, 1)
if fv.Bool() {
buf[0] = 1
}
return true, buf, nil
}
func (i *BoolFieldIndex) FromArgs(args ...interface{}) ([]byte, error) {
return fromBoolArgs(args)
}
// UUIDFieldIndex is used to extract a field from an object
// using reflection and builds an index on that field by treating
// it as a UUID. This is an optimization to using a StringFieldIndex
// as the UUID can be more compactly represented in byte form.
type UUIDFieldIndex struct {
Field string
}
func (u *UUIDFieldIndex) FromObject(obj interface{}) (bool, []byte, error) {
v := reflect.ValueOf(obj)
v = reflect.Indirect(v) // Dereference the pointer if any
fv := v.FieldByName(u.Field)
if !fv.IsValid() {
return false, nil,
fmt.Errorf("field '%s' for %#v is invalid", u.Field, obj)
}
val := fv.String()
if val == "" {
return false, nil, nil
}
buf, err := u.parseString(val, true)
return true, buf, err
}
func (u *UUIDFieldIndex) FromArgs(args ...interface{}) ([]byte, error) {
if len(args) != 1 {
return nil, fmt.Errorf("must provide only a single argument")
}
switch arg := args[0].(type) {
case string:
return u.parseString(arg, true)
case []byte:
if len(arg) != 16 {
return nil, fmt.Errorf("byte slice must be 16 characters")
}
return arg, nil
default:
return nil,
fmt.Errorf("argument must be a string or byte slice: %#v", args[0])
}
}
func (u *UUIDFieldIndex) PrefixFromArgs(args ...interface{}) ([]byte, error) {
if len(args) != 1 {
return nil, fmt.Errorf("must provide only a single argument")
}
switch arg := args[0].(type) {
case string:
return u.parseString(arg, false)
case []byte:
return arg, nil
default:
return nil,
fmt.Errorf("argument must be a string or byte slice: %#v", args[0])
}
}
// parseString parses a UUID from the string. If enforceLength is false, it will
// parse a partial UUID. An error is returned if the input, stripped of hyphens,
// is not even length.
func (u *UUIDFieldIndex) parseString(s string, enforceLength bool) ([]byte, error) {
// Verify the length
l := len(s)
if enforceLength && l != 36 {
return nil, fmt.Errorf("UUID must be 36 characters")
} else if l > 36 {
return nil, fmt.Errorf("Invalid UUID length. UUID have 36 characters; got %d", l)
}
hyphens := strings.Count(s, "-")
if hyphens > 4 {
return nil, fmt.Errorf(`UUID should have maximum of 4 "-"; got %d`, hyphens)
}
// The sanitized length is the length of the original string without the "-".
sanitized := strings.Replace(s, "-", "", -1)
sanitizedLength := len(sanitized)
if sanitizedLength%2 != 0 {
return nil, fmt.Errorf("Input (without hyphens) must be even length")
}
dec, err := hex.DecodeString(sanitized)
if err != nil {
return nil, fmt.Errorf("Invalid UUID: %v", err)
}
return dec, nil
}
// FieldSetIndex is used to extract a field from an object using reflection and
// builds an index on whether the field is set by comparing it against its
// type's nil value.
type FieldSetIndex struct {
Field string
}
func (f *FieldSetIndex) FromObject(obj interface{}) (bool, []byte, error) {
v := reflect.ValueOf(obj)
v = reflect.Indirect(v) // Dereference the pointer if any
fv := v.FieldByName(f.Field)
if !fv.IsValid() {
return false, nil,
fmt.Errorf("field '%s' for %#v is invalid", f.Field, obj)
}
if fv.Interface() == reflect.Zero(fv.Type()).Interface() {
6F26
return true, []byte{0}, nil
}
return true, []byte{1}, nil
}
func (f *FieldSetIndex) FromArgs(args ...interface{}) ([]byte, error) {
return fromBoolArgs(args)
}
// ConditionalIndex builds an index based on a condition specified by a passed
// user function. This function may examine the passed object and return a
// boolean to encapsulate an arbitrarily complex conditional.
type ConditionalIndex struct {
Conditional ConditionalIndexFunc
}
// ConditionalIndexFunc is the required function interface for a
// ConditionalIndex.
type ConditionalIndexFunc func(obj interface{}) (bool, error)
func (c *ConditionalIndex) FromObject(obj interface{}) (bool, []byte, error) {
// Call the user's function
res, err := c.Conditional(obj)
if err != nil {
return false, nil, fmt.Errorf("ConditionalIndexFunc(%#v) failed: %v", obj, err)
}
if res {
return true, []byte{1}, nil
}
return true, []byte{0}, nil
}
func (c *ConditionalIndex) FromArgs(args ...interface{}) ([]byte, error) {
return fromBoolArgs(args)
}
// fromBoolArgs is a helper that expects only a single boolean argument and
// returns a single length byte array containing either a one or zero depending
// on whether the passed input is true or false respectively.
func fromBoolArgs(args []interface{}) ([]byte, error) {
if len(args) != 1 {
return nil, fmt.Errorf("must provide only a single argument")
}
if val, ok := args[0].(bool); !ok {
return nil, fmt.Errorf("argument must be a boolean type: %#v", args[0])
} else if val {
return []byte{1}, nil
}
return []byte{0}, nil
}
// CompoundIndex is used to build an index using multiple sub-indexes
// Prefix based iteration is supported as long as the appropriate prefix
// of indexers support it. All sub-indexers are only assumed to expect
// a single argument.
type CompoundIndex struct {
Indexes []Indexer
// AllowMissing results in an index based on only the indexers
// that return data. If true, you may end up with 2/3 columns
// indexed which might be useful for an index scan. Otherwise,
// the CompoundIndex requires all indexers to be satisfied.
AllowMissing bool
}
func (c *CompoundIndex) FromObject(raw interface{}) (bool, []byte, error) {
var out []byte
for i, idxRaw := range c.Indexes {
idx, ok := idxRaw.(SingleIndexer)
if !ok {
return false, nil, fmt.Errorf("sub-index %d error: %s", i, "sub-index must be a SingleIndexer")
}
ok, val, err := idx.FromObject(raw)
if err != nil {
return false, nil, fmt.Errorf("sub-index %d error: %v", i, err)
}
if !ok {
if c.AllowMissing {
break
} else {
return false, nil, nil
}
}
out = append(out, val...)
}
return true, out, nil
}
func (c *CompoundIndex) FromArgs(args ...interface{}) ([]byte, error) {
if len(args) != len(c.Indexes) {
return nil, fmt.Errorf("non-equivalent argument count and index fields")
}
var out []byte
for i, arg := range args {
val, err := c.Indexes[i].FromArgs(arg)
if err != nil {
return nil, fmt.Errorf("sub-index %d error: %v", i, err)
}
out = append(out, val...)
}
return out, nil
}
func (c *CompoundIndex) PrefixFromArgs(args ...interface{}) ([]byte, error) {
if len(args) > len(c.Indexes) {
return nil, fmt.Errorf("more arguments than index fields")
}
var out []byte
for i, arg := range args {
if i+1 < len(args) {
val, err := c.Indexes[i].FromArgs(arg)
if err != nil {
return nil, fmt.Errorf("sub-index %d error: %v", i, err)
}
out = append(out, val...)
} else {
prefixIndexer, ok := c.Indexes[i].(PrefixIndexer)
if !ok {
return nil, fmt.Errorf("sub-index %d does not support prefix scanning", i)
}
val, err := prefixIndexer.PrefixFromArgs(arg)
if err != nil {
return nil, fmt.Errorf("sub-index %d error: %v", i, err)
}
out = append(out, val...)
}
}
return out, nil
}
// CompoundMultiIndex is used to build an index using multiple
// sub-indexes.
//
// Unlike CompoundIndex, CompoundMultiIndex can have both
// SingleIndexer and MultiIndexer sub-indexers. However, each
// MultiIndexer adds considerable overhead/complexity in terms of
// the number of indexes created under-the-hood. It is not suggested
// to use more than one or two, if possible.
//
// Another change from CompoundIndexer is that if AllowMissing is
// set, not only is it valid to have empty index fields, but it will
// still create index values up to the first empty index. This means
// that if you have a value with an empty field, rather than using a
// prefix for lookup, you can simply pass in less arguments. As an
// example, if {Foo, Bar} is indexed but Bar is missing for a value
// and AllowMissing is set, an index will still be created for {Foo}
// and it is valid to do a lookup passing in only Foo as an argument.
// Note that the ordering isn't guaranteed -- it's last-insert wins,
// but this is true if you have two objects that have the same
// indexes not using AllowMissing anyways.
//
// Because StringMapFieldIndexers can take a varying number of args,
// it is currently a requirement that whenever it is used, two
// arguments must _always_ be provided for it. In theory we only
// need one, except a bug in that indexer means the single-argument
// version will never work. You can leave the second argument nil,
// but it will never produce a value. We support this for whenever
// that bug is fixed, likely in a next major version bump.
//
// Prefix-based indexing is not currently supported.
type CompoundMultiIndex struct {
Indexes []Indexer
// AllowMissing results in an index based on only the indexers
// that return data. If true, you may end up with 2/3 columns
// indexed which might be useful for an index scan. Otherwise,
// CompoundMultiIndex requires all indexers to be satisfied.
AllowMissing bool
}
func (c *CompoundMultiIndex) FromObject(raw interface{}) (bool, [][]byte, error) {
// At each entry, builder is storing the results from the next index
builder := make([][][]byte, 0, len(c.Indexes))
forloop:
// This loop goes through each indexer and adds the value(s) provided to the next
// entry in the slice. We can then later walk it like a tree to construct the indices.
for i, idxRaw := range c.Indexes {
switch idx := idxRaw.(type) {
case SingleIndexer:
ok, val, err := idx.FromObject(raw)
if err != nil {
return false, nil, fmt.Errorf("single sub-index %d error: %v", i, err)
}
if !ok {
if c.AllowMissing {
break forloop
} else {
return false, nil, nil
}
}
builder = append(builder, [][]byte{val})
case MultiIndexer:
ok, vals, err := idx.FromObject(raw)
if err != nil {
return false, nil, fmt.Errorf("multi sub-index %d error: %v", i, err)
}
if !ok {
if c.AllowMissing {
break forloop
} else {
return false, nil, nil
}
}
// Add each of the new values to each of the old values
builder = append(builder, vals)
default:
return false, nil, fmt.Errorf("sub-index %d does not satisfy either SingleIndexer or MultiIndexer", i)
}
}
// Start with something higher to avoid resizing if possible
out := make([][]byte, 0, len(c.Indexes)^3)
// We are walking through the builder slice essentially in a depth-first fashion,
// building the prefix and leaves as we go. If AllowMissing is false, we only insert
// these full paths to leaves. Otherwise, we also insert each prefix along the way.
// This allows for lookup in FromArgs when AllowMissing is true that does not contain
// the full set of arguments. e.g. for {Foo, Bar} where an object has only the Foo
// field specified as "abc", it is valid to call FromArgs with just "abc".
var walkVals func([]byte, int)
walkVals = func(currPrefix []byte, depth int) {
if depth >= len(builder) {
return
}
if depth == len(builder)-1 {
// These are the "leaves", so append directly
for _, v := range builder[depth] {
outcome := make([]byte, len(currPrefix))
copy(outcome, currPrefix)
out = append(out, append(outcome, v...))
}
return
}
for _, v := range builder[depth] {
nextPrefix := append(currPrefix, v...)
if c.AllowMissing {
out = append(out, nextPrefix)
}
walkVals(nextPrefix, depth+1)
}
}
walkVals(nil, 0)
return true, out, nil
}
func (c *CompoundMultiIndex) FromArgs(args ...interface{}) ([]byte, error) {
var stringMapCount int
var argCount int
for _, index := range c.Indexes {
if argCount >= len(args) {
break
}
if _, ok := index.(*StringMapFieldIndex); ok {
// We require pairs for StringMapFieldIndex, but only got one
if argCount+1 >= len(args) {
return nil, errors.New("invalid number of arguments")
}
stringMapCount++
argCount += 2
} else {
argCount++
}
}
argCount = 0
switch c.AllowMissing {
case true:
if len(args) > len(c.Indexes)+stringMapCount {
return nil, errors.New("too many arguments")
}
default:
if len(args) != len(c.Indexes)+stringMapCount {
return nil, errors.New("number of arguments does not equal number of indexers")
}
}
var out []byte
var val []byte
var err error
for i, idx := range c.Indexes {
if argCount >= len(args) {
// We're done; should only hit this if AllowMissing
break
}
if _, ok := idx.(*StringMapFieldIndex); ok {
if args[argCount+1] == nil {
val, err = idx.FromArgs(args[argCount])
} else {
val, err = idx.FromArgs(args[argCount : argCount+2]...)
}
argCount += 2
} else {
val, err = idx.FromArgs(args[argCount])
argCount++
}
if err != nil {
return nil, fmt.Errorf("sub-index %d error: %v", i, err)
}
out = append(out, val...)
}
return out, nil
}