-
Notifications
You must be signed in to change notification settings - Fork 1
/
rbtree.go
810 lines (672 loc) · 19.1 KB
/
rbtree.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
package rbtree
import (
"bytes"
"encoding/binary"
"fmt"
"math"
"sync"
"github.com/pkg/errors"
"github.com/vahagz/pager"
"github.com/vahagz/rbtree/pkg/stack"
)
var bin = binary.BigEndian
func Open[K, V EntryItem](fileName string, opts *Options) (*RBTree[K, V], error) {
pagerFile := fmt.Sprintf("%s.idx", fileName)
p, err := pager.Open(pagerFile, int(opts.PageSize), 0664)
if err != nil {
return nil, errors.Wrap(err, "failed to Open rbtree")
}
var k K
var v V
tree := &RBTree[K, V]{
file: pagerFile,
mu: &sync.RWMutex{},
pager: p,
pages: map[uint32]*page[K, V]{},
degree: opts.PageSize / uint16(nodeFixedSize + k.Size() + v.Size()),
nodeSize: uint16(nodeFixedSize + k.Size() + v.Size()),
meta: &metadata{},
}
if err := tree.open(opts); err != nil {
_ = tree.Close()
return nil, errors.Wrap(err, "failed to open tree")
}
return tree, nil
}
type RBTree[K, V EntryItem] struct {
file string
mu *sync.RWMutex
pager *pager.Pager
pages map[uint32]*page[K, V] // node cache to avoid IO
meta *metadata // metadata about tree structure
degree uint16 // number of nodes per page
nodeSize uint16
}
func (tree *RBTree[K, V]) Insert(e *Entry[K, V]) error {
if err := tree.InsertMem(e); err != nil {
return err
}
return errors.Wrap(tree.writeAll(), "failed to write all")
}
func (tree *RBTree[K, V]) InsertMem(e *Entry[K, V]) error {
tree.mu.Lock()
defer tree.mu.Unlock()
eSize := e.Size()
if eSize != int(tree.meta.nodeKeySize + tree.meta.nodeValSize) {
return errors.Wrapf(
ErrInvalidKeySize, "insert entry size missmatch, required:'%v', got:'%v'",
tree.meta.nodeKeySize + tree.meta.nodeValSize, eSize,
)
}
if _, err := tree.get(e.Key); err != nil && err != ErrNotFound {
return errors.Wrap(err, "failed to check key existence")
} else if err == nil {
return ErrKeyAlreadyExists
}
n, err := tree.alloc()
if err != nil {
return errors.Wrap(err, "failed to alloc 1 node")
}
tree.fetch(n).left = tree.meta.nullPtr
tree.fetch(n).right = tree.meta.nullPtr
tree.fetch(n).setRed()
tree.fetch(n).entry = e.Copy()
tree.insert(n)
return nil
}
func (tree *RBTree[K, V]) Get(key K) (*Entry[K, V], error) {
var e *Entry[K, V]
kSize := key.Size()
if kSize != int(tree.meta.nodeKeySize) {
return e, errors.Wrapf(
ErrInvalidKeySize, "key size missmatch, required:'%v', got:'%v'",
tree.meta.nodeKeySize, kSize,
)
}
tree.mu.RLock()
defer tree.mu.RUnlock()
ptr, err := tree.get(key)
if err != nil && err != ErrNotFound {
return e, errors.Wrap(err, "failed to find key")
} else if ptr == tree.meta.nullPtr {
return e, ErrNotFound
}
return tree.fetch(ptr).entry, err
}
func (tree *RBTree[K, V]) Delete(key K) error {
if err := tree.DeleteMem(key); err != nil {
return err
}
return errors.Wrap(tree.writeAll(), "failed to write all")
}
func (tree *RBTree[K, V]) DeleteMem(key K) error {
tree.mu.Lock()
defer tree.mu.Unlock()
kSize := key.Size()
if kSize != int(tree.meta.nodeKeySize) {
return errors.Wrapf(
ErrInvalidKeySize, "delete entry size missmatch, required:'%v', got:'%v'",
tree.meta.nodeKeySize, kSize,
)
}
ptr, err := tree.get(key)
if err != nil {
return errors.Wrapf(err, "failed to find key to delete => %v", key)
}
tree.fetch(ptr).entry.Key = key
tree.delete(ptr)
return nil
}
func (tree *RBTree[K, V]) Scan(key K, scanFn func(key K, val V) (bool, error)) error {
if tree.meta.rootPtr == tree.meta.nullPtr {
return nil
}
tree.mu.RLock()
defer tree.mu.RUnlock()
curr := tree.meta.rootPtr
if !key.IsNil() {
var err error
curr, err = tree.get(key)
if err != nil && err != ErrNotFound {
return errors.Wrap(err, "failed to find key")
}
}
s := stack.New[uint32](tree.height())
for curr != 0 && curr != tree.meta.nullPtr || s.Size() > 0 {
for curr != 0 && curr != tree.meta.nullPtr {
s.Push(curr)
if tree.fetch(curr).left == tree.meta.nullPtr {
break
}
curr = tree.fetch(curr).left
}
curr = s.Pop()
e := tree.fetch(curr).entry
stop, err := scanFn(e.Key, e.Val)
if stop || err != nil {
return err
}
if tree.fetch(curr).right == tree.meta.nullPtr {
curr = 0
} else {
curr = tree.fetch(curr).right
}
}
return nil
}
func (tree *RBTree[K, V]) Count() int {
return int(tree.meta.count)
}
func (tree *RBTree[K, V]) Print(count int) error {
tree.mu.RLock()
defer tree.mu.RUnlock()
return tree.print(tree.meta.rootPtr, 0, count)
}
func (tree *RBTree[K, V]) print(root uint32, space int, count int) error {
// count := tree.pager.Count()
// for i := uint32(1); i < uint32(count); i++ {
// p := tree.page(i)
// if err := tree.pager.Unmarshal(uint64(p.id), p); err != nil {
// return errors.Wrap(err, "failed to unmarshal page")
// }
// nodes := p.nodes[:tree.meta.count]
// fmt.Println(nodes)
// }
// return nil
if root == 0 {
return nil
}
// Increase distance between levels
space += count
// Process right child first
if root != tree.meta.nullPtr {
tree.print(tree.fetch(root).right, space, count)
}
// Print current node after space
// count
fmt.Println()
for i := count; i < space; i++ {
fmt.Print(" ")
}
fmt.Println(
tree.fetch(root).entry.Key,
tree.fetch(root).entry.Val,
tree.fetch(root).getFlag(FT_COLOR),
)
// Process left child
if root != tree.meta.nullPtr {
tree.print(tree.fetch(root).left, space, count)
}
return nil
}
func (tree *RBTree[K, V]) WriteAll() error {
tree.mu.Lock()
defer tree.mu.Unlock()
return tree.writeAll()
}
func (tree *RBTree[K, V]) Close() error {
if tree.pager == nil {
return nil
}
_ = tree.writeAll()
err := tree.pager.Close()
tree.pager = nil
return errors.Wrap(err, "failed to close RBTree")
}
func (tree *RBTree[K, V]) Remove() {
tree.pager.Remove()
}
func (tree *RBTree[K, V]) get(key K) (uint32, error) {
searchingKey, err := key.MarshalBinary()
if err != nil {
return 0, errors.Wrap(err, "failed to marshal entry")
}
lastGreaterPtr := tree.meta.nullPtr
ptr := tree.meta.rootPtr
for ptr != tree.meta.nullPtr {
k, err := tree.fetch(ptr).entry.Key.MarshalBinary()
if err != nil {
return 0, errors.Wrap(err, "failed to marshal entry")
}
cmp := bytes.Compare(k, searchingKey)
if cmp == -1 {
ptr = tree.fetch(ptr).right
} else if cmp == 1 {
lastGreaterPtr = ptr
ptr = tree.fetch(ptr).left
} else {
return ptr, nil
}
}
return lastGreaterPtr, ErrNotFound
}
func (tree *RBTree[K, V]) height() int {
return 2 * int(math.Ceil(math.Log2(float64(tree.meta.count)))) + 1
}
func (tree *RBTree[K, V]) fixDelete(x uint32) {
for x != tree.meta.rootPtr && tree.fetch(x).isBlack() {
if x == tree.fetch(tree.fetch(x).parent).left {
w := tree.fetch(tree.fetch(x).parent).right
if tree.fetch(w).isRed() { // case 1
tree.fetch(w).setBlack()
tree.fetch(tree.fetch(x).parent).setRed()
tree.leftRotate(tree.fetch(x).parent)
w = tree.fetch(tree.fetch(x).parent).right
}
if tree.fetch(tree.fetch(w).left).isBlack() && tree.fetch(tree.fetch(w).right).isBlack() { // case 2
tree.fetch(w).setRed()
x = tree.fetch(x).parent
} else { // case 3, 4
if tree.fetch(tree.fetch(w).right).isBlack() { // case 3
tree.fetch(tree.fetch(w).left).setBlack()
tree.fetch(w).setRed()
tree.rightRotate(w)
w = tree.fetch(tree.fetch(x).parent).right
}
// case 4
tree.fetch(w).setFlag(FT_COLOR, tree.fetch(tree.fetch(x).parent).getFlag(FT_COLOR))
tree.fetch(tree.fetch(x).parent).setBlack()
tree.fetch(tree.fetch(w).right).setBlack()
tree.leftRotate(tree.fetch(x).parent)
x = tree.meta.rootPtr
}
} else {
w := tree.fetch(tree.fetch(x).parent).left
if tree.fetch(w).isRed() { // case 1
tree.fetch(w).setBlack()
tree.fetch(tree.fetch(x).parent).setRed()
tree.rightRotate(tree.fetch(x).parent)
w = tree.fetch(tree.fetch(x).parent).left
}
if tree.fetch(tree.fetch(w).right).isBlack() && tree.fetch(tree.fetch(w).left).isBlack() { // case 2
tree.fetch(w).setRed()
x = tree.fetch(x).parent
} else { // case 3, 4
if tree.fetch(tree.fetch(w).left).isBlack() { // case 3
tree.fetch(tree.fetch(w).right).setBlack()
tree.fetch(w).setRed()
tree.leftRotate(w)
w = tree.fetch(tree.fetch(x).parent).left
}
// case 4
tree.fetch(w).setFlag(FT_COLOR, tree.fetch(tree.fetch(x).parent).getFlag(FT_COLOR))
tree.fetch(tree.fetch(x).parent).setBlack()
tree.fetch(tree.fetch(w).left).setBlack()
tree.rightRotate(tree.fetch(x).parent)
x = tree.meta.rootPtr
}
}
}
tree.fetch(x).setBlack()
}
func (tree *RBTree[K, V]) delete(z uint32) {
var x uint32
y := z
yOriginalColor := tree.fetch(y).getFlag(FT_COLOR)
if tree.fetch(z).left == tree.meta.nullPtr { // no children or only right
x = tree.fetch(z).right
tree.transplant(z, x)
} else if tree.fetch(z).right == tree.meta.nullPtr { // only left child
x = tree.fetch(z).left
tree.transplant(z, x)
} else { // both children
y = tree.minimum(tree.fetch(z).right)
yOriginalColor = tree.fetch(y).getFlag(FT_COLOR)
x = tree.fetch(y).right
if tree.fetch(y).parent == z { // y is direct child of z
tree.fetch(x).dirty = true
tree.fetch(x).parent = y
} else {
tree.transplant(y, x)
tree.fetch(y).dirty = true
tree.fetch(y).right = tree.fetch(z).right
tree.fetch(tree.fetch(y).right).dirty = true
tree.fetch(tree.fetch(y).right).parent = y
}
tree.transplant(z, y)
tree.fetch(y).dirty = true
tree.fetch(y).left = tree.fetch(z).left
tree.fetch(tree.fetch(y).left).dirty = true
tree.fetch(tree.fetch(y).left).parent = y
tree.fetch(y).setFlag(FT_COLOR, tree.fetch(z).getFlag(FT_COLOR))
}
if yOriginalColor == FV_COLOR_BLACK {
tree.fixDelete(x)
}
tree.free(z)
tree.meta.dirty = true
tree.meta.count--
}
func (tree *RBTree[K, V]) minimum(x uint32) uint32 {
for tree.fetch(x).left != tree.meta.nullPtr {
x = tree.fetch(x).left
}
return x
}
func (tree *RBTree[K, V]) transplant(u, v uint32) {
if tree.fetch(u).parent == tree.meta.nullPtr { // u is root
tree.meta.dirty = true
tree.meta.rootPtr = v
} else {
tree.fetch(tree.fetch(u).parent).dirty = true
if u == tree.fetch(tree.fetch(u).parent).left { // u is left child
tree.fetch(tree.fetch(u).parent).left = v
} else { // u is right child
tree.fetch(tree.fetch(u).parent).right = v
}
}
tree.fetch(v).dirty = true
tree.fetch(v).parent = tree.fetch(u).parent
}
func (tree *RBTree[K, V]) fixInsert(z uint32) {
for tree.fetch(tree.fetch(z).parent).isRed() {
if tree.fetch(z).parent == tree.fetch(tree.fetch(tree.fetch(z).parent).parent).left { // first 3 cases
y := tree.fetch(tree.fetch(tree.fetch(z).parent).parent).right // z uncle
// first subcase
if tree.fetch(y).isRed() {
tree.fetch(tree.fetch(z).parent).setBlack()
tree.fetch(y).setBlack()
tree.fetch(tree.fetch(tree.fetch(z).parent).parent).setRed()
z = tree.fetch(tree.fetch(z).parent).parent
} else { // second and third subcases
if z == tree.fetch(tree.fetch(z).parent).right { // second subcase, turning to third
z = tree.fetch(z).parent
tree.leftRotate(z)
}
// third case
tree.fetch(tree.fetch(z).parent).setBlack()
tree.fetch(tree.fetch(tree.fetch(z).parent).parent).setRed()
tree.rightRotate(tree.fetch(tree.fetch(z).parent).parent)
}
} else { // other 3 cases
y := tree.fetch(tree.fetch(tree.fetch(z).parent).parent).left // z uncle
// first subcase
if tree.fetch(y).isRed() {
tree.fetch(tree.fetch(z).parent).setBlack()
tree.fetch(y).setBlack()
tree.fetch(tree.fetch(tree.fetch(z).parent).parent).setRed()
z = tree.fetch(tree.fetch(z).parent).parent
} else { // second and third subcases
if z == tree.fetch(tree.fetch(z).parent).left { // second subcase, turning to third
z = tree.fetch(z).parent
tree.rightRotate(z)
}
// third case
tree.fetch(tree.fetch(z).parent).setBlack()
tree.fetch(tree.fetch(tree.fetch(z).parent).parent).setRed()
tree.leftRotate(tree.fetch(tree.fetch(z).parent).parent)
}
}
}
tree.fetch(tree.meta.rootPtr).setBlack()
}
func (tree *RBTree[K, V]) insert(z uint32) error {
y := tree.meta.nullPtr
temp := tree.meta.rootPtr
for temp != tree.meta.nullPtr {
y = temp
searchingKey, err := tree.fetch(z).entry.Key.MarshalBinary()
if err != nil {
return errors.Wrap(err, "failed to marshal searching entry key")
}
currentKey, err := tree.fetch(temp).entry.Key.MarshalBinary()
if err != nil {
return errors.Wrap(err, "failed to marshal current entry key")
}
if bytes.Compare(searchingKey, currentKey) == -1 {
temp = tree.fetch(temp).left
} else {
temp = tree.fetch(temp).right
}
}
tree.fetch(z).dirty = true
tree.fetch(z).parent = y
if y == tree.meta.nullPtr {
tree.meta.dirty = true
tree.meta.rootPtr = z
} else {
zKey, err := tree.fetch(z).entry.Key.MarshalBinary()
if err != nil {
return errors.Wrap(err, "failed to marshal searching entry key")
}
yKey, err := tree.fetch(y).entry.Key.MarshalBinary()
if err != nil {
return errors.Wrap(err, "failed to marshal current entry key")
}
if bytes.Compare(zKey, yKey) == -1 {
tree.fetch(y).dirty = true
tree.fetch(y).left = z
} else {
tree.fetch(y).dirty = true
tree.fetch(y).right = z
}
}
tree.fetch(z).left = tree.meta.nullPtr
tree.fetch(z).right = tree.meta.nullPtr
tree.fixInsert(z)
tree.meta.dirty = true
tree.meta.count++
return nil
}
func (tree *RBTree[K, V]) leftRotate(x uint32) {
y := tree.fetch(x).right
tree.fetch(x).dirty = true
tree.fetch(x).right = tree.fetch(y).left
if tree.fetch(y).left != tree.meta.nullPtr {
tree.fetch(tree.fetch(y).left).dirty = true
tree.fetch(tree.fetch(y).left).parent = x
}
tree.fetch(y).dirty = true
tree.fetch(y).parent = tree.fetch(x).parent
if tree.fetch(x).parent == tree.meta.nullPtr { // x is root
tree.meta.dirty = true
tree.meta.rootPtr = y
} else {
tree.fetch(tree.fetch(x).parent).dirty = true
if tree.fetch(tree.fetch(x).parent).left == x { // x is left child
tree.fetch(tree.fetch(x).parent).left = y
} else { // x is right child
tree.fetch(tree.fetch(x).parent).right = y
}
}
tree.fetch(y).left = x
tree.fetch(x).parent = y
}
func (tree *RBTree[K, V]) rightRotate(x uint32) {
y := tree.fetch(x).left
tree.fetch(x).dirty = true
tree.fetch(x).left = tree.fetch(y).right
if tree.fetch(y).right != tree.meta.nullPtr {
tree.fetch(tree.fetch(y).right).dirty = true
tree.fetch(tree.fetch(y).right).parent = x
}
tree.fetch(y).dirty = true
tree.fetch(y).parent = tree.fetch(x).parent
if tree.fetch(x).parent == tree.meta.nullPtr { // x is root
tree.meta.dirty = true
tree.meta.rootPtr = y
} else {
tree.fetch(tree.fetch(x).parent).dirty = true
if tree.fetch(tree.fetch(x).parent).right == x { // x is right child
tree.fetch(tree.fetch(x).parent).right = y
} else { // x is left child
tree.fetch(tree.fetch(x).parent).left = y
}
}
tree.fetch(y).right = x
tree.fetch(x).parent = y
}
func (tree *RBTree[K, V]) pointer(rawPtr uint32) *pointer {
return &pointer{
pageId: rawPtr / uint32(tree.meta.pageSize),
index: (uint16(rawPtr) % tree.meta.pageSize) / tree.nodeSize,
}
}
func (tree *RBTree[K, V]) pointerRaw(ptr *pointer) uint32 {
return ptr.pageId * uint32(tree.meta.pageSize) + uint32(ptr.index * tree.nodeSize)
}
func (tree *RBTree[K, V]) page(id uint32) *page[K, V] {
var k K
var v V
return &page[K, V]{
dirty: true,
id: id,
size: tree.meta.pageSize,
entry: &Entry[K, V]{k.New().(K), v.New().(V)},
nodes: make([]*node[K, V], tree.degree),
}
}
func (tree *RBTree[K, V]) fetch(rawPtr uint32) *node[K, V] {
if rawPtr == 0 {
panic(ErrInvalidPointer)
}
ptr := tree.pointer(rawPtr)
return tree.fetchPage(ptr.pageId).nodes[ptr.index]
}
func (tree *RBTree[K, V]) fetchPage(id uint32) *page[K, V] {
if p, ok := tree.pages[id]; ok {
return p
}
p := tree.page(id)
if err := tree.pager.Unmarshal(uint64(id), p); err != nil {
panic(errors.Wrap(err, "failed to unmarshal fetched page"))
}
p.dirty = false
tree.pages[id] = p
return p
}
func (tree *RBTree[K, V]) alloc() (uint32, error) {
topPtr := tree.pointer(tree.meta.top)
if topPtr.index == 0 {
var err error
_, err = tree.pager.Alloc(1)
if err != nil {
return 0, errors.Wrap(err, "failed to alloc page")
}
}
ptr := tree.meta.top
tree.meta.dirty = true
if topPtr.index == tree.degree - 1 {
topPtr.pageId++
topPtr.index = 0
} else {
topPtr.index++
}
tree.meta.top = tree.pointerRaw(topPtr)
return ptr, nil
}
func (tree *RBTree[K, V]) free(ptr uint32) error {
lnPtr := tree.pointer(tree.meta.top)
if lnPtr.index == 0 {
lnPtr.pageId--
lnPtr.index = tree.degree - 1
} else {
lnPtr.index--
}
lastNodePtr := tree.pointerRaw(lnPtr)
if ptr != lastNodePtr {
lastNode := tree.fetch(lastNodePtr)
parent := tree.fetch(lastNode.parent)
parent.dirty = true
if lastNodePtr == parent.left {
parent.left = ptr
} else {
parent.right = ptr
}
freedNode := tree.fetch(ptr)
freedNode.dirty = true
freedNode.flags = lastNode.flags
freedNode.left = lastNode.left
freedNode.parent = lastNode.parent
freedNode.right = lastNode.right
freedNode.entry = lastNode.entry
if freedNode.right != tree.meta.nullPtr {
fr := tree.fetch(freedNode.right)
fr.dirty = true
fr.parent = ptr
}
if freedNode.left != tree.meta.nullPtr {
fl := tree.fetch(freedNode.left)
fl.dirty = true
fl.parent = ptr
}
if lastNodePtr == tree.meta.rootPtr {
tree.meta.rootPtr = ptr
}
}
tree.meta.dirty = true
tree.meta.top = lastNodePtr
topPtr := tree.pointer(tree.meta.top)
if tree.pager.Count() > uint64(topPtr.pageId) + 1 {
err := tree.pager.Free(1)
if err != nil {
return errors.Wrap(err, "failed to free last page")
}
delete(tree.pages, topPtr.pageId + 1)
}
return nil
}
func (tree *RBTree[K, V]) open(opts *Options) error {
if tree.pager.Count() == 0 {
return tree.init(opts)
}
if err := tree.pager.Unmarshal(0, tree.meta); err != nil {
return errors.Wrap(err, "failed to unmarshal meta")
}
return nil
}
func (tree *RBTree[K, V]) init(opts *Options) error {
_, err := tree.pager.Alloc(1)
if err != nil {
return errors.Wrap(err, "failed to alloc first page for meta")
}
var k K
var v V
tree.meta = &metadata{
dirty: true,
pageSize: opts.PageSize,
nodeKeySize: uint16(k.Size()),
nodeValSize: uint16(v.Size()),
top: uint32(opts.PageSize),
}
nullNode, err := tree.alloc()
if err != nil {
return errors.Wrap(err, "failed to alloc null node")
}
tree.fetch(nullNode).setBlack()
tree.meta.dirty = true
tree.meta.nullPtr = nullNode
tree.meta.rootPtr = nullNode
return nil
}
func (tree *RBTree[K, V]) writeAll() error {
if tree.pager.ReadOnly() {
return nil
}
for _, p := range tree.pages {
if !p.dirty {
for _, n := range p.nodes {
if n.dirty {
p.dirty = true
n.dirty = false
break
}
}
}
if p.dirty {
if err := tree.pager.Marshal(uint64(p.id), p); err != nil {
return errors.Wrap(err, "failed to marshal dirty page")
}
p.dirty = false
}
}
return errors.Wrap(tree.writeMeta(), "failed to write meta")
}
func (tree *RBTree[K, V]) writeMeta() error {
if tree.meta.dirty {
err := tree.pager.Marshal(0, tree.meta)
tree.meta.dirty = false
return errors.Wrap(err, "failed to marshal dirty meta")
}
return nil
}