/
reader.go
850 lines (792 loc) · 20.1 KB
/
reader.go
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
// Copyright (c) 2012, Suryandaru Triandana <syndtr@gmail.com>
// All rights reserved.
//
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
package table
import (
"encoding/binary"
"errors"
"fmt"
"io"
"sort"
"strings"
"code.google.com/p/snappy-go/snappy"
"github.com/FactomProject/goleveldb/leveldb/cache"
"github.com/FactomProject/goleveldb/leveldb/comparer"
"github.com/FactomProject/goleveldb/leveldb/filter"
"github.com/FactomProject/goleveldb/leveldb/iterator"
"github.com/FactomProject/goleveldb/leveldb/opt"
"github.com/FactomProject/goleveldb/leveldb/util"
)
var (
ErrNotFound = util.ErrNotFound
ErrIterReleased = errors.New("leveldb/table: iterator released")
)
func max(x, y int) int {
if x > y {
return x
}
return y
}
type block struct {
cmp comparer.BasicComparer
data []byte
restartsLen int
restartsOffset int
// Whether checksum is verified and valid.
checksum bool
}
func (b *block) seek(rstart, rlimit int, key []byte) (index, offset int, err error) {
n := b.restartsOffset
data := b.data
cmp := b.cmp
index = sort.Search(b.restartsLen-rstart-(b.restartsLen-rlimit), func(i int) bool {
offset := int(binary.LittleEndian.Uint32(data[n+4*(rstart+i):]))
offset += 1 // shared always zero, since this is a restart point
v1, n1 := binary.Uvarint(data[offset:]) // key length
_, n2 := binary.Uvarint(data[offset+n1:]) // value length
m := offset + n1 + n2
return cmp.Compare(data[m:m+int(v1)], key) > 0
}) + rstart - 1
if index < rstart {
// The smallest key is greater-than key sought.
index = rstart
}
offset = int(binary.LittleEndian.Uint32(data[n+4*index:]))
return
}
func (b *block) restartIndex(rstart, rlimit, offset int) int {
n := b.restartsOffset
data := b.data
return sort.Search(b.restartsLen-rstart-(b.restartsLen-rlimit), func(i int) bool {
return int(binary.LittleEndian.Uint32(data[n+4*(rstart+i):])) > offset
}) + rstart - 1
}
func (b *block) restartOffset(index int) int {
return int(binary.LittleEndian.Uint32(b.data[b.restartsOffset+4*index:]))
}
func (b *block) entry(offset int) (key, value []byte, nShared, n int, err error) {
if offset >= b.restartsOffset {
if offset != b.restartsOffset {
err = errors.New("leveldb/table: Reader: BlockEntry: invalid block (block entries offset not aligned)")
}
return
}
v0, n0 := binary.Uvarint(b.data[offset:]) // Shared prefix length
v1, n1 := binary.Uvarint(b.data[offset+n0:]) // Key length
v2, n2 := binary.Uvarint(b.data[offset+n0+n1:]) // Value length
m := n0 + n1 + n2
n = m + int(v1) + int(v2)
if n0 <= 0 || n1 <= 0 || n2 <= 0 || offset+n > b.restartsOffset {
err = errors.New("leveldb/table: Reader: invalid block (block entries corrupted)")
return
}
key = b.data[offset+m : offset+m+int(v1)]
value = b.data[offset+m+int(v1) : offset+n]
nShared = int(v0)
return
}
func (b *block) newIterator(slice *util.Range, inclLimit bool, cache util.Releaser) *blockIter {
bi := &blockIter{
block: b,
cache: cache,
// Valid key should never be nil.
key: make([]byte, 0),
dir: dirSOI,
riStart: 0,
riLimit: b.restartsLen,
offsetStart: 0,
offsetRealStart: 0,
offsetLimit: b.restartsOffset,
}
if slice != nil {
if slice.Start != nil {
if bi.Seek(slice.Start) {
bi.riStart = b.restartIndex(bi.restartIndex, b.restartsLen, bi.prevOffset)
bi.offsetStart = b.restartOffset(bi.riStart)
bi.offsetRealStart = bi.prevOffset
} else {
bi.riStart = b.restartsLen
bi.offsetStart = b.restartsOffset
bi.offsetRealStart = b.restartsOffset
}
}
if slice.Limit != nil {
if bi.Seek(slice.Limit) && (!inclLimit || bi.Next()) {
bi.offsetLimit = bi.prevOffset
bi.riLimit = bi.restartIndex + 1
}
}
bi.reset()
if bi.offsetStart > bi.offsetLimit {
bi.sErr(errors.New("leveldb/table: Reader: invalid slice range"))
}
}
return bi
}
type dir int
const (
dirReleased dir = iota - 1
dirSOI
dirEOI
dirBackward
dirForward
)
type blockIter struct {
block *block
cache, releaser util.Releaser
key, value []byte
offset int
// Previous offset, only filled by Next.
prevOffset int
prevNode []int
prevKeys []byte
restartIndex int
// Iterator direction.
dir dir
// Restart index slice range.
riStart int
riLimit int
// Offset slice range.
offsetStart int
offsetRealStart int
offsetLimit int
// Error.
err error
}
func (i *blockIter) sErr(err error) {
i.err = err
i.key = nil
i.value = nil
i.prevNode = nil
i.prevKeys = nil
}
func (i *blockIter) reset() {
if i.dir == dirBackward {
i.prevNode = i.prevNode[:0]
i.prevKeys = i.prevKeys[:0]
}
i.restartIndex = i.riStart
i.offset = i.offsetStart
i.dir = dirSOI
i.key = i.key[:0]
i.value = nil
}
func (i *blockIter) isFirst() bool {
switch i.dir {
case dirForward:
return i.prevOffset == i.offsetRealStart
case dirBackward:
return len(i.prevNode) == 1 && i.restartIndex == i.riStart
}
return false
}
func (i *blockIter) isLast() bool {
switch i.dir {
case dirForward, dirBackward:
return i.offset == i.offsetLimit
}
return false
}
func (i *blockIter) First() bool {
if i.err != nil {
return false
} else if i.dir == dirReleased {
i.err = ErrIterReleased
return false
}
if i.dir == dirBackward {
i.prevNode = i.prevNode[:0]
i.prevKeys = i.prevKeys[:0]
}
i.dir = dirSOI
return i.Next()
}
func (i *blockIter) Last() bool {
if i.err != nil {
return false
} else if i.dir == dirReleased {
i.err = ErrIterReleased
return false
}
if i.dir == dirBackward {
i.prevNode = i.prevNode[:0]
i.prevKeys = i.prevKeys[:0]
}
i.dir = dirEOI
return i.Prev()
}
func (i *blockIter) Seek(key []byte) bool {
if i.err != nil {
return false
} else if i.dir == dirReleased {
i.err = ErrIterReleased
return false
}
ri, offset, err := i.block.seek(i.riStart, i.riLimit, key)
if err != nil {
i.sErr(err)
return false
}
i.restartIndex = ri
i.offset = max(i.offsetStart, offset)
if i.dir == dirSOI || i.dir == dirEOI {
i.dir = dirForward
}
for i.Next() {
if i.block.cmp.Compare(i.key, key) >= 0 {
return true
}
}
return false
}
func (i *blockIter) Next() bool {
if i.dir == dirEOI || i.err != nil {
return false
} else if i.dir == dirReleased {
i.err = ErrIterReleased
return false
}
if i.dir == dirSOI {
i.restartIndex = i.riStart
i.offset = i.offsetStart
} else if i.dir == dirBackward {
i.prevNode = i.prevNode[:0]
i.prevKeys = i.prevKeys[:0]
}
for i.offset < i.offsetRealStart {
key, value, nShared, n, err := i.block.entry(i.offset)
if err != nil {
i.sErr(err)
return false
}
if n == 0 {
i.dir = dirEOI
return false
}
i.key = append(i.key[:nShared], key...)
i.value = value
i.offset += n
}
if i.offset >= i.offsetLimit {
i.dir = dirEOI
if i.offset != i.offsetLimit {
i.sErr(errors.New("leveldb/table: Reader: Next: invalid block (block entries offset not aligned)"))
}
return false
}
key, value, nShared, n, err := i.block.entry(i.offset)
if err != nil {
i.sErr(err)
return false
}
if n == 0 {
i.dir = dirEOI
return false
}
i.key = append(i.key[:nShared], key...)
i.value = value
i.prevOffset = i.offset
i.offset += n
i.dir = dirForward
return true
}
func (i *blockIter) Prev() bool {
if i.dir == dirSOI || i.err != nil {
return false
} else if i.dir == dirReleased {
i.err = ErrIterReleased
return false
}
var ri int
if i.dir == dirForward {
// Change direction.
i.offset = i.prevOffset
if i.offset == i.offsetRealStart {
i.dir = dirSOI
return false
}
ri = i.block.restartIndex(i.restartIndex, i.riLimit, i.offset)
i.dir = dirBackward
} else if i.dir == dirEOI {
// At the end of iterator.
i.restartIndex = i.riLimit
i.offset = i.offsetLimit
if i.offset == i.offsetRealStart {
i.dir = dirSOI
return false
}
ri = i.riLimit - 1
i.dir = dirBackward
} else if len(i.prevNode) == 1 {
// This is the end of a restart range.
i.offset = i.prevNode[0]
i.prevNode = i.prevNode[:0]
if i.restartIndex == i.riStart {
i.dir = dirSOI
return false
}
i.restartIndex--
ri = i.restartIndex
} else {
// In the middle of restart range, get from cache.
n := len(i.prevNode) - 3
node := i.prevNode[n:]
i.prevNode = i.prevNode[:n]
// Get the key.
ko := node[0]
i.key = append(i.key[:0], i.prevKeys[ko:]...)
i.prevKeys = i.prevKeys[:ko]
// Get the value.
vo := node[1]
vl := vo + node[2]
i.value = i.block.data[vo:vl]
i.offset = vl
return true
}
// Build entries cache.
i.key = i.key[:0]
i.value = nil
offset := i.block.restartOffset(ri)
if offset == i.offset {
ri -= 1
if ri < 0 {
i.dir = dirSOI
return false
}
offset = i.block.restartOffset(ri)
}
i.prevNode = append(i.prevNode, offset)
for {
key, value, nShared, n, err := i.block.entry(offset)
if err != nil {
i.sErr(err)
return false
}
if offset >= i.offsetRealStart {
if i.value != nil {
// Appends 3 variables:
// 1. Previous keys offset
// 2. Value offset in the data block
// 3. Value length
i.prevNode = append(i.prevNode, len(i.prevKeys), offset-len(i.value), len(i.value))
i.prevKeys = append(i.prevKeys, i.key...)
}
i.value = value
}
i.key = append(i.key[:nShared], key...)
offset += n
// Stop if target offset reached.
if offset >= i.offset {
if offset != i.offset {
i.sErr(errors.New("leveldb/table: Reader: Prev: invalid block (block entries offset not aligned)"))
return false
}
break
}
}
i.restartIndex = ri
i.offset = offset
return true
}
func (i *blockIter) Key() []byte {
if i.err != nil || i.dir <= dirEOI {
return nil
}
return i.key
}
func (i *blockIter) Value() []byte {
if i.err != nil || i.dir <= dirEOI {
return nil
}
return i.value
}
func (i *blockIter) Release() {
i.prevNode = nil
i.prevKeys = nil
i.key = nil
i.value = nil
i.dir = dirReleased
if i.cache != nil {
i.cache.Release()
i.cache = nil
}
if i.releaser != nil {
i.releaser.Release()
i.releaser = nil
}
}
func (i *blockIter) SetReleaser(releaser util.Releaser) {
if i.dir > dirReleased {
i.releaser = releaser
}
}
func (i *blockIter) Valid() bool {
return i.err == nil && (i.dir == dirBackward || i.dir == dirForward)
}
func (i *blockIter) Error() error {
return i.err
}
type filterBlock struct {
filter filter.Filter
data []byte
oOffset int
baseLg uint
filtersNum int
}
func (b *filterBlock) contains(offset uint64, key []byte) bool {
i := int(offset >> b.baseLg)
if i < b.filtersNum {
o := b.data[b.oOffset+i*4:]
n := int(binary.LittleEndian.Uint32(o))
m := int(binary.LittleEndian.Uint32(o[4:]))
if n < m && m <= b.oOffset {
return b.filter.Contains(b.data[n:m], key)
} else if n == m {
return false
}
}
return true
}
type indexIter struct {
blockIter
tableReader *Reader
slice *util.Range
// Options
checksum bool
fillCache bool
}
func (i *indexIter) Get() iterator.Iterator {
value := i.Value()
if value == nil {
return nil
}
dataBH, n := decodeBlockHandle(value)
if n == 0 {
return iterator.NewEmptyIterator(errors.New("leveldb/table: Reader: invalid table (bad data block handle)"))
}
var slice *util.Range
if i.slice != nil && (i.blockIter.isFirst() || i.blockIter.isLast()) {
slice = i.slice
}
return i.tableReader.getDataIter(dataBH, slice, i.checksum, i.fillCache)
}
// Reader is a table reader.
type Reader struct {
reader io.ReaderAt
cache cache.Namespace
err error
// Options
cmp comparer.Comparer
filter filter.Filter
checksum bool
strictIter bool
dataEnd int64
indexBlock *block
filterBlock *filterBlock
}
func verifyChecksum(data []byte) bool {
n := len(data) - 4
checksum0 := binary.LittleEndian.Uint32(data[n:])
checksum1 := util.NewCRC(data[:n]).Value()
return checksum0 == checksum1
}
func (r *Reader) readRawBlock(bh blockHandle, checksum bool) ([]byte, error) {
data := make([]byte, bh.length+blockTrailerLen)
if _, err := r.reader.ReadAt(data, int64(bh.offset)); err != nil && err != io.EOF {
return nil, err
}
if checksum || r.checksum {
if !verifyChecksum(data) {
return nil, errors.New("leveldb/table: Reader: invalid block (checksum mismatch)")
}
}
switch data[bh.length] {
case blockTypeNoCompression:
data = data[:bh.length]
case blockTypeSnappyCompression:
var err error
data, err = snappy.Decode(nil, data[:bh.length])
if err != nil {
return nil, err
}
default:
return nil, fmt.Errorf("leveldb/table: Reader: unknown block compression type: %d", data[bh.length])
}
return data, nil
}
func (r *Reader) readBlock(bh blockHandle, checksum bool) (*block, error) {
data, err := r.readRawBlock(bh, checksum)
if err != nil {
return nil, err
}
restartsLen := int(binary.LittleEndian.Uint32(data[len(data)-4:]))
b := &block{
cmp: r.cmp,
data: data,
restartsLen: restartsLen,
restartsOffset: len(data) - (restartsLen+1)*4,
checksum: checksum || r.checksum,
}
return b, nil
}
func (r *Reader) readFilterBlock(bh blockHandle, filter filter.Filter) (*filterBlock, error) {
data, err := r.readRawBlock(bh, true)
if err != nil {
return nil, err
}
n := len(data)
if n < 5 {
return nil, errors.New("leveldb/table: Reader: invalid filter block (too short)")
}
m := n - 5
oOffset := int(binary.LittleEndian.Uint32(data[m:]))
if oOffset > m {
return nil, errors.New("leveldb/table: Reader: invalid filter block (invalid offset)")
}
b := &filterBlock{
filter: filter,
data: data,
oOffset: oOffset,
baseLg: uint(data[n-1]),
filtersNum: (m - oOffset) / 4,
}
return b, nil
}
func (r *Reader) getDataIter(dataBH blockHandle, slice *util.Range, checksum, fillCache bool) iterator.Iterator {
if r.cache != nil {
// Get/set block cache.
var err error
cache, ok := r.cache.Get(dataBH.offset, func() (ok bool, value interface{}, charge int, fin cache.SetFin) {
if !fillCache {
return
}
var dataBlock *block
dataBlock, err = r.readBlock(dataBH, checksum)
if err == nil {
ok = true
value = dataBlock
charge = int(dataBH.length)
}
return
})
if err != nil {
return iterator.NewEmptyIterator(err)
}
if ok {
dataBlock := cache.Value().(*block)
if !dataBlock.checksum && (r.checksum || checksum) {
if !verifyChecksum(dataBlock.data) {
return iterator.NewEmptyIterator(errors.New("leveldb/table: Reader: invalid block (checksum mismatch)"))
}
dataBlock.checksum = true
}
iter := dataBlock.newIterator(slice, false, cache)
return iter
}
}
dataBlock, err := r.readBlock(dataBH, checksum)
if err != nil {
return iterator.NewEmptyIterator(err)
}
iter := dataBlock.newIterator(slice, false, nil)
return iter
}
// NewIterator creates an iterator from the table.
//
// Slice allows slicing the iterator to only contains keys in the given
// range. A nil Range.Start is treated as a key before all keys in the
// table. And a nil Range.Limit is treated as a key after all keys in
// the table.
//
// The returned iterator is not goroutine-safe and should be released
// when not used.
//
// Also read Iterator documentation of the leveldb/iterator package.
func (r *Reader) NewIterator(slice *util.Range, ro *opt.ReadOptions) iterator.Iterator {
if r.err != nil {
return iterator.NewEmptyIterator(r.err)
}
index := &indexIter{
blockIter: *r.indexBlock.newIterator(slice, true, nil),
tableReader: r,
slice: slice,
checksum: ro.GetStrict(opt.StrictBlockChecksum),
fillCache: !ro.GetDontFillCache(),
}
return iterator.NewIndexedIterator(index, r.strictIter || ro.GetStrict(opt.StrictIterator), false)
}
// Find finds key/value pair whose key is greater than or equal to the
// given key. It returns ErrNotFound if the table doesn't contain
// such pair.
//
// The caller should not modify the contents of the returned slice, but
// it is safe to modify the contents of the argument after Find returns.
func (r *Reader) Find(key []byte, ro *opt.ReadOptions) (rkey, value []byte, err error) {
if r.err != nil {
err = r.err
return
}
index := r.indexBlock.newIterator(nil, true, nil)
defer index.Release()
if !index.Seek(key) {
err = index.Error()
if err == nil {
err = ErrNotFound
}
return
}
dataBH, n := decodeBlockHandle(index.Value())
if n == 0 {
err = errors.New("leveldb/table: Reader: invalid table (bad data block handle)")
return
}
if r.filterBlock != nil && !r.filterBlock.contains(dataBH.offset, key) {
err = ErrNotFound
return
}
data := r.getDataIter(dataBH, nil, ro.GetStrict(opt.StrictBlockChecksum), !ro.GetDontFillCache())
defer data.Release()
if !data.Seek(key) {
err = data.Error()
if err == nil {
err = ErrNotFound
}
return
}
rkey = data.Key()
value = data.Value()
return
}
// Get gets the value for the given key. It returns errors.ErrNotFound
// if the table does not contain the key.
//
// The caller should not modify the contents of the returned slice, but
// it is safe to modify the contents of the argument after Get returns.
func (r *Reader) Get(key []byte, ro *opt.ReadOptions) (value []byte, err error) {
if r.err != nil {
err = r.err
return
}
rkey, value, err := r.Find(key, ro)
if err == nil && r.cmp.Compare(rkey, key) != 0 {
value = nil
err = ErrNotFound
}
return
}
// OffsetOf returns approximate offset for the given key.
//
// It is safe to modify the contents of the argument after Get returns.
func (r *Reader) OffsetOf(key []byte) (offset int64, err error) {
if r.err != nil {
err = r.err
return
}
index := r.indexBlock.newIterator(nil, true, nil)
defer index.Release()
if index.Seek(key) {
dataBH, n := decodeBlockHandle(index.Value())
if n == 0 {
err = errors.New("leveldb/table: Reader: invalid table (bad data block handle)")
return
}
offset = int64(dataBH.offset)
return
}
err = index.Error()
if err == nil {
offset = r.dataEnd
}
return
}
// NewReader creates a new initialized table reader for the file.
// The cache is optional and can be nil.
//
// The returned table reader instance is goroutine-safe.
func NewReader(f io.ReaderAt, size int64, cache cache.Namespace, o *opt.Options) *Reader {
r := &Reader{
reader: f,
cache: cache,
cmp: o.GetComparer(),
checksum: o.GetStrict(opt.StrictBlockChecksum),
strictIter: o.GetStrict(opt.StrictIterator),
}
if f == nil {
r.err = errors.New("leveldb/table: Reader: nil file")
return r
}
if size < footerLen {
r.err = errors.New("leveldb/table: Reader: invalid table (file size is too small)")
return r
}
var footer [footerLen]byte
if _, err := r.reader.ReadAt(footer[:], size-footerLen); err != nil && err != io.EOF {
r.err = fmt.Errorf("leveldb/table: Reader: invalid table (could not read footer): %v", err)
}
if string(footer[footerLen-len(magic):footerLen]) != magic {
r.err = errors.New("leveldb/table: Reader: invalid table (bad magic number)")
return r
}
// Decode the metaindex block handle.
metaBH, n := decodeBlockHandle(footer[:])
if n == 0 {
r.err = errors.New("leveldb/table: Reader: invalid table (bad metaindex block handle)")
return r
}
// Decode the index block handle.
indexBH, n := decodeBlockHandle(footer[n:])
if n == 0 {
r.err = errors.New("leveldb/table: Reader: invalid table (bad index block handle)")
return r
}
// Read index block.
r.indexBlock, r.err = r.readBlock(indexBH, true)
if r.err != nil {
return r
}
// Read metaindex block.
metaBlock, err := r.readBlock(metaBH, true)
if err != nil {
r.err = err
return r
}
// Set data end.
r.dataEnd = int64(metaBH.offset)
metaIter := metaBlock.newIterator(nil, false, nil)
for metaIter.Next() {
key := string(metaIter.Key())
if !strings.HasPrefix(key, "filter.") {
continue
}
fn := key[7:]
var filter filter.Filter
if f0 := o.GetFilter(); f0 != nil && f0.Name() == fn {
filter = f0
} else {
for _, f0 := range o.GetAltFilters() {
if f0.Name() == fn {
filter = f0
break
}
}
}
if filter != nil {
filterBH, n := decodeBlockHandle(metaIter.Value())
if n == 0 {
continue
}
// Update data end.
r.dataEnd = int64(filterBH.offset)
filterBlock, err := r.readFilterBlock(filterBH, filter)
if err != nil {
continue
}
r.filterBlock = filterBlock
break
}
}
metaIter.Release()
return r
}