forked from dgraph-io/badger
-
Notifications
You must be signed in to change notification settings - Fork 0
/
memtable.go
633 lines (564 loc) · 17.4 KB
/
memtable.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
/*
* Copyright 2020 Dgraph Labs, Inc. and Contributors
*
* 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.
*/
package badger
import (
"bufio"
"bytes"
"crypto/aes"
cryptorand "crypto/rand"
"encoding/binary"
"fmt"
"hash/crc32"
"io"
"io/ioutil"
"os"
"path/filepath"
"sort"
"strconv"
"strings"
"sync"
"sync/atomic"
"github.com/0x5459/badger/v4/pb"
"github.com/0x5459/badger/v4/skl"
"github.com/0x5459/badger/v4/y"
"github.com/dgraph-io/ristretto/z"
"github.com/pkg/errors"
)
// memTable structure stores a skiplist and a corresponding WAL. Writes to memTable are written
// both to the WAL and the skiplist. On a crash, the WAL is replayed to bring the skiplist back to
// its pre-crash form.
type memTable struct {
// TODO: Give skiplist z.Calloc'd []byte.
sl *skl.Skiplist
wal *logFile
maxVersion uint64
opt Options
buf *bytes.Buffer
}
func (db *DB) openMemTables(opt Options) error {
// We don't need to open any tables in in-memory mode.
if db.opt.InMemory {
return nil
}
files, err := ioutil.ReadDir(db.opt.Dir)
if err != nil {
return errFile(err, db.opt.Dir, "Unable to open mem dir.")
}
var fids []int
for _, file := range files {
if !strings.HasSuffix(file.Name(), memFileExt) {
continue
}
fsz := len(file.Name())
fid, err := strconv.ParseInt(file.Name()[:fsz-len(memFileExt)], 10, 64)
if err != nil {
return errFile(err, file.Name(), "Unable to parse log id.")
}
fids = append(fids, int(fid))
}
// Sort in ascending order.
sort.Slice(fids, func(i, j int) bool {
return fids[i] < fids[j]
})
for _, fid := range fids {
flags := os.O_RDWR
if db.opt.ReadOnly {
flags = os.O_RDONLY
}
mt, err := db.openMemTable(fid, flags)
if err != nil {
return y.Wrapf(err, "while opening fid: %d", fid)
}
// If this memtable is empty we don't need to add it. This is a
// memtable that was completely truncated.
if mt.sl.Empty() {
mt.DecrRef()
continue
}
// These should no longer be written to. So, make them part of the imm.
db.imm = append(db.imm, mt)
}
if len(fids) != 0 {
db.nextMemFid = fids[len(fids)-1]
}
db.nextMemFid++
return nil
}
const memFileExt string = ".mem"
func (db *DB) openMemTable(fid, flags int) (*memTable, error) {
filepath := db.mtFilePath(fid)
s := skl.NewSkiplist(arenaSize(db.opt))
mt := &memTable{
sl: s,
opt: db.opt,
buf: &bytes.Buffer{},
}
// We don't need to create the wal for the skiplist in in-memory mode so return the mt.
if db.opt.InMemory {
return mt, z.NewFile
}
mt.wal = &logFile{
fid: uint32(fid),
path: filepath,
registry: db.registry,
writeAt: vlogHeaderSize,
opt: db.opt,
}
lerr := mt.wal.open(filepath, flags, 2*db.opt.MemTableSize)
if lerr != z.NewFile && lerr != nil {
return nil, y.Wrapf(lerr, "While opening memtable: %s", filepath)
}
// Have a callback set to delete WAL when skiplist reference count goes down to zero. That is,
// when it gets flushed to L0.
s.OnClose = func() {
if err := mt.wal.Delete(); err != nil {
db.opt.Errorf("while deleting file: %s, err: %v", filepath, err)
}
}
if lerr == z.NewFile {
return mt, lerr
}
err := mt.UpdateSkipList()
return mt, y.Wrapf(err, "while updating skiplist")
}
var errExpectingNewFile = errors.New("Expecting to create a new file, but found an existing file")
func (db *DB) newMemTable() (*memTable, error) {
mt, err := db.openMemTable(db.nextMemFid, os.O_CREATE|os.O_RDWR)
if err == z.NewFile {
db.nextMemFid++
return mt, nil
}
if err != nil {
db.opt.Errorf("Got error: %v for id: %d\n", err, db.nextMemFid)
return nil, y.Wrapf(err, "newMemTable")
}
return nil, errors.Errorf("File %s already exists", mt.wal.Fd.Name())
}
func (db *DB) mtFilePath(fid int) string {
return filepath.Join(db.opt.Dir, fmt.Sprintf("%05d%s", fid, memFileExt))
}
func (mt *memTable) SyncWAL() error {
return mt.wal.Sync()
}
func (mt *memTable) isFull() bool {
if mt.sl.MemSize() >= mt.opt.MemTableSize {
return true
}
if mt.opt.InMemory {
// InMemory mode doesn't have any WAL.
return false
}
return int64(mt.wal.writeAt) >= mt.opt.MemTableSize
}
func (mt *memTable) Put(key []byte, value y.ValueStruct) error {
entry := &Entry{
Key: key,
Value: value.Value,
UserMeta: value.UserMeta,
meta: value.Meta,
ExpiresAt: value.ExpiresAt,
}
// wal is nil only when badger in running in in-memory mode and we don't need the wal.
if mt.wal != nil {
// If WAL exceeds opt.ValueLogFileSize, we'll force flush the memTable. See logic in
// ensureRoomForWrite.
if err := mt.wal.writeEntry(mt.buf, entry, mt.opt); err != nil {
return y.Wrapf(err, "cannot write entry to WAL file")
}
}
// We insert the finish marker in the WAL but not in the memtable.
if entry.meta&bitFinTxn > 0 {
return nil
}
// Write to skiplist and update maxVersion encountered.
mt.sl.Put(key, value)
if ts := y.ParseTs(entry.Key); ts > mt.maxVersion {
mt.maxVersion = ts
}
return nil
}
func (mt *memTable) UpdateSkipList() error {
if mt.wal == nil || mt.sl == nil {
return nil
}
endOff, err := mt.wal.iterate(true, 0, mt.replayFunction(mt.opt))
if err != nil {
return y.Wrapf(err, "while iterating wal: %s", mt.wal.Fd.Name())
}
if endOff < mt.wal.size && mt.opt.ReadOnly {
return y.Wrapf(ErrTruncateNeeded, "end offset: %d < size: %d", endOff, mt.wal.size)
}
return mt.wal.Truncate(int64(endOff))
}
// IncrRef increases the refcount
func (mt *memTable) IncrRef() {
mt.sl.IncrRef()
}
// DecrRef decrements the refcount, deallocating the Skiplist when done using it
func (mt *memTable) DecrRef() {
mt.sl.DecrRef()
}
func (mt *memTable) replayFunction(opt Options) func(Entry, valuePointer) error {
first := true
return func(e Entry, _ valuePointer) error { // Function for replaying.
if first {
opt.Debugf("First key=%q\n", e.Key)
}
first = false
if ts := y.ParseTs(e.Key); ts > mt.maxVersion {
mt.maxVersion = ts
}
v := y.ValueStruct{
Value: e.Value,
Meta: e.meta,
UserMeta: e.UserMeta,
ExpiresAt: e.ExpiresAt,
}
// This is already encoded correctly. Value would be either a vptr, or a full value
// depending upon how big the original value was. Skiplist makes a copy of the key and
// value.
mt.sl.Put(e.Key, v)
return nil
}
}
type logFile struct {
*z.MmapFile
path string
// This is a lock on the log file. It guards the fd’s value, the file’s
// existence and the file’s memory map.
//
// Use shared ownership when reading/writing the file or memory map, use
// exclusive ownership to open/close the descriptor, unmap or remove the file.
lock sync.RWMutex
fid uint32
size uint32
dataKey *pb.DataKey
baseIV []byte
registry *KeyRegistry
writeAt uint32
opt Options
}
func (lf *logFile) Truncate(end int64) error {
if fi, err := lf.Fd.Stat(); err != nil {
return fmt.Errorf("while file.stat on file: %s, error: %v\n", lf.Fd.Name(), err)
} else if fi.Size() == end {
return nil
}
y.AssertTrue(!lf.opt.ReadOnly)
lf.size = uint32(end)
return lf.MmapFile.Truncate(end)
}
// encodeEntry will encode entry to the buf
// layout of entry
// +--------+-----+-------+-------+
// | header | key | value | crc32 |
// +--------+-----+-------+-------+
func (lf *logFile) encodeEntry(buf *bytes.Buffer, e *Entry, offset uint32) (int, error) {
h := header{
klen: uint32(len(e.Key)),
vlen: uint32(len(e.Value)),
expiresAt: e.ExpiresAt,
meta: e.meta,
userMeta: e.UserMeta,
}
hash := crc32.New(y.CastagnoliCrcTable)
writer := io.MultiWriter(buf, hash)
// encode header.
var headerEnc [maxHeaderSize]byte
sz := h.Encode(headerEnc[:])
y.Check2(writer.Write(headerEnc[:sz]))
// we'll encrypt only key and value.
if lf.encryptionEnabled() {
// TODO: no need to allocate the bytes. we can calculate the encrypted buf one by one
// since we're using ctr mode of AES encryption. Ordering won't changed. Need some
// refactoring in XORBlock which will work like stream cipher.
eBuf := make([]byte, 0, len(e.Key)+len(e.Value))
eBuf = append(eBuf, e.Key...)
eBuf = append(eBuf, e.Value...)
if err := y.XORBlockStream(
writer, eBuf, lf.dataKey.Data, lf.generateIV(offset)); err != nil {
return 0, y.Wrapf(err, "Error while encoding entry for vlog.")
}
} else {
// Encryption is disabled so writing directly to the buffer.
y.Check2(writer.Write(e.Key))
y.Check2(writer.Write(e.Value))
}
// write crc32 hash.
var crcBuf [crc32.Size]byte
binary.BigEndian.PutUint32(crcBuf[:], hash.Sum32())
y.Check2(buf.Write(crcBuf[:]))
// return encoded length.
return len(headerEnc[:sz]) + len(e.Key) + len(e.Value) + len(crcBuf), nil
}
func (lf *logFile) writeEntry(buf *bytes.Buffer, e *Entry, opt Options) error {
buf.Reset()
plen, err := lf.encodeEntry(buf, e, lf.writeAt)
if err != nil {
return err
}
y.AssertTrue(plen == copy(lf.Data[lf.writeAt:], buf.Bytes()))
lf.writeAt += uint32(plen)
lf.zeroNextEntry()
return nil
}
func (lf *logFile) decodeEntry(buf []byte, offset uint32) (*Entry, error) {
var h header
hlen := h.Decode(buf)
kv := buf[hlen:]
if lf.encryptionEnabled() {
var err error
// No need to worry about mmap. because, XORBlock allocates a byte array to do the
// xor. So, the given slice is not being mutated.
if kv, err = lf.decryptKV(kv, offset); err != nil {
return nil, err
}
}
e := &Entry{
meta: h.meta,
UserMeta: h.userMeta,
ExpiresAt: h.expiresAt,
offset: offset,
Key: kv[:h.klen],
Value: kv[h.klen : h.klen+h.vlen],
}
return e, nil
}
func (lf *logFile) decryptKV(buf []byte, offset uint32) ([]byte, error) {
return y.XORBlockAllocate(buf, lf.dataKey.Data, lf.generateIV(offset))
}
// KeyID returns datakey's ID.
func (lf *logFile) keyID() uint64 {
if lf.dataKey == nil {
// If there is no datakey, then we'll return 0. Which means no encryption.
return 0
}
return lf.dataKey.KeyId
}
func (lf *logFile) encryptionEnabled() bool {
return lf.dataKey != nil
}
// Acquire lock on mmap/file if you are calling this
func (lf *logFile) read(p valuePointer) (buf []byte, err error) {
var nbr int64
offset := p.Offset
// Do not convert size to uint32, because the lf.Data can be of size
// 4GB, which overflows the uint32 during conversion to make the size 0,
// causing the read to fail with ErrEOF. See issue #585.
size := int64(len(lf.Data))
valsz := p.Len
lfsz := atomic.LoadUint32(&lf.size)
if int64(offset) >= size || int64(offset+valsz) > size ||
// Ensure that the read is within the file's actual size. It might be possible that
// the offset+valsz length is beyond the file's actual size. This could happen when
// dropAll and iterations are running simultaneously.
int64(offset+valsz) > int64(lfsz) {
err = y.ErrEOF
} else {
buf = lf.Data[offset : offset+valsz]
nbr = int64(valsz)
}
y.NumReadsAdd(lf.opt.MetricsEnabled, 1)
y.NumBytesReadAdd(lf.opt.MetricsEnabled, nbr)
return buf, err
}
// generateIV will generate IV by appending given offset with the base IV.
func (lf *logFile) generateIV(offset uint32) []byte {
iv := make([]byte, aes.BlockSize)
// baseIV is of 12 bytes.
y.AssertTrue(12 == copy(iv[:12], lf.baseIV))
// remaining 4 bytes is obtained from offset.
binary.BigEndian.PutUint32(iv[12:], offset)
return iv
}
func (lf *logFile) doneWriting(offset uint32) error {
if lf.opt.SyncWrites {
if err := lf.Sync(); err != nil {
return y.Wrapf(err, "Unable to sync value log: %q", lf.path)
}
}
// Before we were acquiring a lock here on lf.lock, because we were invalidating the file
// descriptor due to reopening it as read-only. Now, we don't invalidate the fd, but unmap it,
// truncate it and remap it. That creates a window where we have segfaults because the mmap is
// no longer valid, while someone might be reading it. Therefore, we need a lock here again.
lf.lock.Lock()
defer lf.lock.Unlock()
if err := lf.Truncate(int64(offset)); err != nil {
return y.Wrapf(err, "Unable to truncate file: %q", lf.path)
}
// Previously we used to close the file after it was written and reopen it in read-only mode.
// We no longer open files in read-only mode. We keep all vlog files open in read-write mode.
return nil
}
// iterate iterates over log file. It doesn't not allocate new memory for every kv pair.
// Therefore, the kv pair is only valid for the duration of fn call.
func (lf *logFile) iterate(readOnly bool, offset uint32, fn logEntry) (uint32, error) {
if offset == 0 {
// If offset is set to zero, let's advance past the encryption key header.
offset = vlogHeaderSize
}
// For now, read directly from file, because it allows
reader := bufio.NewReader(lf.NewReader(int(offset)))
read := &safeRead{
k: make([]byte, 10),
v: make([]byte, 10),
recordOffset: offset,
lf: lf,
}
var lastCommit uint64
var validEndOffset uint32 = offset
var entries []*Entry
var vptrs []valuePointer
loop:
for {
e, err := read.Entry(reader)
switch {
// We have not reached the end of the file but the entry we read is
// zero. This happens because we have truncated the file and
// zero'ed it out.
case err == io.EOF:
break loop
case err == io.ErrUnexpectedEOF || err == errTruncate:
break loop
case err != nil:
return 0, err
case e == nil:
continue
case e.isZero():
break loop
}
var vp valuePointer
vp.Len = uint32(int(e.hlen) + len(e.Key) + len(e.Value) + crc32.Size)
read.recordOffset += vp.Len
vp.Offset = e.offset
vp.Fid = lf.fid
switch {
case e.meta&bitTxn > 0:
txnTs := y.ParseTs(e.Key)
if lastCommit == 0 {
lastCommit = txnTs
}
if lastCommit != txnTs {
break loop
}
entries = append(entries, e)
vptrs = append(vptrs, vp)
case e.meta&bitFinTxn > 0:
txnTs, err := strconv.ParseUint(string(e.Value), 10, 64)
if err != nil || lastCommit != txnTs {
break loop
}
// Got the end of txn. Now we can store them.
lastCommit = 0
validEndOffset = read.recordOffset
for i, e := range entries {
vp := vptrs[i]
if err := fn(*e, vp); err != nil {
if err == errStop {
break
}
return 0, errFile(err, lf.path, "Iteration function")
}
}
entries = entries[:0]
vptrs = vptrs[:0]
default:
if lastCommit != 0 {
// This is most likely an entry which was moved as part of GC.
// We shouldn't get this entry in the middle of a transaction.
break loop
}
validEndOffset = read.recordOffset
if err := fn(*e, vp); err != nil {
if err == errStop {
break
}
return 0, errFile(err, lf.path, "Iteration function")
}
}
}
return validEndOffset, nil
}
// Zero out the next entry to deal with any crashes.
func (lf *logFile) zeroNextEntry() {
z.ZeroOut(lf.Data, int(lf.writeAt), int(lf.writeAt+maxHeaderSize))
}
func (lf *logFile) open(path string, flags int, fsize int64) error {
mf, ferr := z.OpenMmapFile(path, flags, int(fsize))
lf.MmapFile = mf
if ferr == z.NewFile {
if err := lf.bootstrap(); err != nil {
os.Remove(path)
return err
}
lf.size = vlogHeaderSize
} else if ferr != nil {
return y.Wrapf(ferr, "while opening file: %s", path)
}
lf.size = uint32(len(lf.Data))
if lf.size < vlogHeaderSize {
// Every vlog file should have at least vlogHeaderSize. If it is less than vlogHeaderSize
// then it must have been corrupted. But no need to handle here. log replayer will truncate
// and bootstrap the logfile. So ignoring here.
return nil
}
// Copy over the encryption registry data.
buf := make([]byte, vlogHeaderSize)
y.AssertTruef(vlogHeaderSize == copy(buf, lf.Data),
"Unable to copy from %s, size %d", path, lf.size)
keyID := binary.BigEndian.Uint64(buf[:8])
// retrieve datakey.
if dk, err := lf.registry.DataKey(keyID); err != nil {
return y.Wrapf(err, "While opening vlog file %d", lf.fid)
} else {
lf.dataKey = dk
}
lf.baseIV = buf[8:]
y.AssertTrue(len(lf.baseIV) == 12)
// Preserved ferr so we can return if this was a new file.
return ferr
}
// bootstrap will initialize the log file with key id and baseIV.
// The below figure shows the layout of log file.
// +----------------+------------------+------------------+
// | keyID(8 bytes) | baseIV(12 bytes)| entry... |
// +----------------+------------------+------------------+
func (lf *logFile) bootstrap() error {
var err error
// generate data key for the log file.
var dk *pb.DataKey
if dk, err = lf.registry.LatestDataKey(); err != nil {
return y.Wrapf(err, "Error while retrieving datakey in logFile.bootstarp")
}
lf.dataKey = dk
// We'll always preserve vlogHeaderSize for key id and baseIV.
buf := make([]byte, vlogHeaderSize)
// write key id to the buf.
// key id will be zero if the logfile is in plain text.
binary.BigEndian.PutUint64(buf[:8], lf.keyID())
// generate base IV. It'll be used with offset of the vptr to encrypt the entry.
if _, err := cryptorand.Read(buf[8:]); err != nil {
return y.Wrapf(err, "Error while creating base IV, while creating logfile")
}
// Initialize base IV.
lf.baseIV = buf[8:]
y.AssertTrue(len(lf.baseIV) == 12)
// Copy over to the logFile.
y.AssertTrue(vlogHeaderSize == copy(lf.Data[0:], buf))
// Zero out the next entry.
lf.zeroNextEntry()
return nil
}