summaryrefslogtreecommitdiff
path: root/vendor/github.com/klauspost/compress/zstd/encoder.go
blob: dcc987a7cb68597de0da1f8f1bc6088354088387 (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
// Copyright 2019+ Klaus Post. All rights reserved.
// License information can be found in the LICENSE file.
// Based on work by Yann Collet, released under BSD License.

package zstd

import (
	"crypto/rand"
	"fmt"
	"io"
	rdebug "runtime/debug"
	"sync"

	"github.com/klauspost/compress/zstd/internal/xxhash"
)

// Encoder provides encoding to Zstandard.
// An Encoder can be used for either compressing a stream via the
// io.WriteCloser interface supported by the Encoder or as multiple independent
// tasks via the EncodeAll function.
// Smaller encodes are encouraged to use the EncodeAll function.
// Use NewWriter to create a new instance.
type Encoder struct {
	o        encoderOptions
	encoders chan encoder
	state    encoderState
	init     sync.Once
}

type encoder interface {
	Encode(blk *blockEnc, src []byte)
	EncodeNoHist(blk *blockEnc, src []byte)
	Block() *blockEnc
	CRC() *xxhash.Digest
	AppendCRC([]byte) []byte
	WindowSize(size int64) int32
	UseBlock(*blockEnc)
	Reset(d *dict, singleBlock bool)
}

type encoderState struct {
	w                io.Writer
	filling          []byte
	current          []byte
	previous         []byte
	encoder          encoder
	writing          *blockEnc
	err              error
	writeErr         error
	nWritten         int64
	nInput           int64
	frameContentSize int64
	headerWritten    bool
	eofWritten       bool
	fullFrameWritten bool

	// This waitgroup indicates an encode is running.
	wg sync.WaitGroup
	// This waitgroup indicates we have a block encoding/writing.
	wWg sync.WaitGroup
}

// NewWriter will create a new Zstandard encoder.
// If the encoder will be used for encoding blocks a nil writer can be used.
func NewWriter(w io.Writer, opts ...EOption) (*Encoder, error) {
	initPredefined()
	var e Encoder
	e.o.setDefault()
	for _, o := range opts {
		err := o(&e.o)
		if err != nil {
			return nil, err
		}
	}
	if w != nil {
		e.Reset(w)
	}
	return &e, nil
}

func (e *Encoder) initialize() {
	if e.o.concurrent == 0 {
		e.o.setDefault()
	}
	e.encoders = make(chan encoder, e.o.concurrent)
	for i := 0; i < e.o.concurrent; i++ {
		enc := e.o.encoder()
		e.encoders <- enc
	}
}

// Reset will re-initialize the writer and new writes will encode to the supplied writer
// as a new, independent stream.
func (e *Encoder) Reset(w io.Writer) {
	s := &e.state
	s.wg.Wait()
	s.wWg.Wait()
	if cap(s.filling) == 0 {
		s.filling = make([]byte, 0, e.o.blockSize)
	}
	if e.o.concurrent > 1 {
		if cap(s.current) == 0 {
			s.current = make([]byte, 0, e.o.blockSize)
		}
		if cap(s.previous) == 0 {
			s.previous = make([]byte, 0, e.o.blockSize)
		}
		s.current = s.current[:0]
		s.previous = s.previous[:0]
		if s.writing == nil {
			s.writing = &blockEnc{lowMem: e.o.lowMem}
			s.writing.init()
		}
		s.writing.initNewEncode()
	}
	if s.encoder == nil {
		s.encoder = e.o.encoder()
	}
	s.filling = s.filling[:0]
	s.encoder.Reset(e.o.dict, false)
	s.headerWritten = false
	s.eofWritten = false
	s.fullFrameWritten = false
	s.w = w
	s.err = nil
	s.nWritten = 0
	s.nInput = 0
	s.writeErr = nil
	s.frameContentSize = 0
}

// ResetContentSize will reset and set a content size for the next stream.
// If the bytes written does not match the size given an error will be returned
// when calling Close().
// This is removed when Reset is called.
// Sizes <= 0 results in no content size set.
func (e *Encoder) ResetContentSize(w io.Writer, size int64) {
	e.Reset(w)
	if size >= 0 {
		e.state.frameContentSize = size
	}
}

// Write data to the encoder.
// Input data will be buffered and as the buffer fills up
// content will be compressed and written to the output.
// When done writing, use Close to flush the remaining output
// and write CRC if requested.
func (e *Encoder) Write(p []byte) (n int, err error) {
	s := &e.state
	for len(p) > 0 {
		if len(p)+len(s.filling) < e.o.blockSize {
			if e.o.crc {
				_, _ = s.encoder.CRC().Write(p)
			}
			s.filling = append(s.filling, p...)
			return n + len(p), nil
		}
		add := p
		if len(p)+len(s.filling) > e.o.blockSize {
			add = add[:e.o.blockSize-len(s.filling)]
		}
		if e.o.crc {
			_, _ = s.encoder.CRC().Write(add)
		}
		s.filling = append(s.filling, add...)
		p = p[len(add):]
		n += len(add)
		if len(s.filling) < e.o.blockSize {
			return n, nil
		}
		err := e.nextBlock(false)
		if err != nil {
			return n, err
		}
		if debugAsserts && len(s.filling) > 0 {
			panic(len(s.filling))
		}
	}
	return n, nil
}

// nextBlock will synchronize and start compressing input in e.state.filling.
// If an error has occurred during encoding it will be returned.
func (e *Encoder) nextBlock(final bool) error {
	s := &e.state
	// Wait for current block.
	s.wg.Wait()
	if s.err != nil {
		return s.err
	}
	if len(s.filling) > e.o.blockSize {
		return fmt.Errorf("block > maxStoreBlockSize")
	}
	if !s.headerWritten {
		// If we have a single block encode, do a sync compression.
		if final && len(s.filling) == 0 && !e.o.fullZero {
			s.headerWritten = true
			s.fullFrameWritten = true
			s.eofWritten = true
			return nil
		}
		if final && len(s.filling) > 0 {
			s.current = e.EncodeAll(s.filling, s.current[:0])
			var n2 int
			n2, s.err = s.w.Write(s.current)
			if s.err != nil {
				return s.err
			}
			s.nWritten += int64(n2)
			s.nInput += int64(len(s.filling))
			s.current = s.current[:0]
			s.filling = s.filling[:0]
			s.headerWritten = true
			s.fullFrameWritten = true
			s.eofWritten = true
			return nil
		}

		var tmp [maxHeaderSize]byte
		fh := frameHeader{
			ContentSize:   uint64(s.frameContentSize),
			WindowSize:    uint32(s.encoder.WindowSize(s.frameContentSize)),
			SingleSegment: false,
			Checksum:      e.o.crc,
			DictID:        e.o.dict.ID(),
		}

		dst, err := fh.appendTo(tmp[:0])
		if err != nil {
			return err
		}
		s.headerWritten = true
		s.wWg.Wait()
		var n2 int
		n2, s.err = s.w.Write(dst)
		if s.err != nil {
			return s.err
		}
		s.nWritten += int64(n2)
	}
	if s.eofWritten {
		// Ensure we only write it once.
		final = false
	}

	if len(s.filling) == 0 {
		// Final block, but no data.
		if final {
			enc := s.encoder
			blk := enc.Block()
			blk.reset(nil)
			blk.last = true
			blk.encodeRaw(nil)
			s.wWg.Wait()
			_, s.err = s.w.Write(blk.output)
			s.nWritten += int64(len(blk.output))
			s.eofWritten = true
		}
		return s.err
	}

	// SYNC:
	if e.o.concurrent == 1 {
		src := s.filling
		s.nInput += int64(len(s.filling))
		if debugEncoder {
			println("Adding sync block,", len(src), "bytes, final:", final)
		}
		enc := s.encoder
		blk := enc.Block()
		blk.reset(nil)
		enc.Encode(blk, src)
		blk.last = final
		if final {
			s.eofWritten = true
		}

		err := errIncompressible
		// If we got the exact same number of literals as input,
		// assume the literals cannot be compressed.
		if len(src) != len(blk.literals) || len(src) != e.o.blockSize {
			err = blk.encode(src, e.o.noEntropy, !e.o.allLitEntropy)
		}
		switch err {
		case errIncompressible:
			if debugEncoder {
				println("Storing incompressible block as raw")
			}
			blk.encodeRaw(src)
			// In fast mode, we do not transfer offsets, so we don't have to deal with changing the.
		case nil:
		default:
			s.err = err
			return err
		}
		_, s.err = s.w.Write(blk.output)
		s.nWritten += int64(len(blk.output))
		s.filling = s.filling[:0]
		return s.err
	}

	// Move blocks forward.
	s.filling, s.current, s.previous = s.previous[:0], s.filling, s.current
	s.nInput += int64(len(s.current))
	s.wg.Add(1)
	go func(src []byte) {
		if debugEncoder {
			println("Adding block,", len(src), "bytes, final:", final)
		}
		defer func() {
			if r := recover(); r != nil {
				s.err = fmt.Errorf("panic while encoding: %v", r)
				rdebug.PrintStack()
			}
			s.wg.Done()
		}()
		enc := s.encoder
		blk := enc.Block()
		enc.Encode(blk, src)
		blk.last = final
		if final {
			s.eofWritten = true
		}
		// Wait for pending writes.
		s.wWg.Wait()
		if s.writeErr != nil {
			s.err = s.writeErr
			return
		}
		// Transfer encoders from previous write block.
		blk.swapEncoders(s.writing)
		// Transfer recent offsets to next.
		enc.UseBlock(s.writing)
		s.writing = blk
		s.wWg.Add(1)
		go func() {
			defer func() {
				if r := recover(); r != nil {
					s.writeErr = fmt.Errorf("panic while encoding/writing: %v", r)
					rdebug.PrintStack()
				}
				s.wWg.Done()
			}()
			err := errIncompressible
			// If we got the exact same number of literals as input,
			// assume the literals cannot be compressed.
			if len(src) != len(blk.literals) || len(src) != e.o.blockSize {
				err = blk.encode(src, e.o.noEntropy, !e.o.allLitEntropy)
			}
			switch err {
			case errIncompressible:
				if debugEncoder {
					println("Storing incompressible block as raw")
				}
				blk.encodeRaw(src)
				// In fast mode, we do not transfer offsets, so we don't have to deal with changing the.
			case nil:
			default:
				s.writeErr = err
				return
			}
			_, s.writeErr = s.w.Write(blk.output)
			s.nWritten += int64(len(blk.output))
		}()
	}(s.current)
	return nil
}

// ReadFrom reads data from r until EOF or error.
// The return value n is the number of bytes read.
// Any error except io.EOF encountered during the read is also returned.
//
// The Copy function uses ReaderFrom if available.
func (e *Encoder) ReadFrom(r io.Reader) (n int64, err error) {
	if debugEncoder {
		println("Using ReadFrom")
	}

	// Flush any current writes.
	if len(e.state.filling) > 0 {
		if err := e.nextBlock(false); err != nil {
			return 0, err
		}
	}
	e.state.filling = e.state.filling[:e.o.blockSize]
	src := e.state.filling
	for {
		n2, err := r.Read(src)
		if e.o.crc {
			_, _ = e.state.encoder.CRC().Write(src[:n2])
		}
		// src is now the unfilled part...
		src = src[n2:]
		n += int64(n2)
		switch err {
		case io.EOF:
			e.state.filling = e.state.filling[:len(e.state.filling)-len(src)]
			if debugEncoder {
				println("ReadFrom: got EOF final block:", len(e.state.filling))
			}
			return n, nil
		case nil:
		default:
			if debugEncoder {
				println("ReadFrom: got error:", err)
			}
			e.state.err = err
			return n, err
		}
		if len(src) > 0 {
			if debugEncoder {
				println("ReadFrom: got space left in source:", len(src))
			}
			continue
		}
		err = e.nextBlock(false)
		if err != nil {
			return n, err
		}
		e.state.filling = e.state.filling[:e.o.blockSize]
		src = e.state.filling
	}
}

// Flush will send the currently written data to output
// and block until everything has been written.
// This should only be used on rare occasions where pushing the currently queued data is critical.
func (e *Encoder) Flush() error {
	s := &e.state
	if len(s.filling) > 0 {
		err := e.nextBlock(false)
		if err != nil {
			return err
		}
	}
	s.wg.Wait()
	s.wWg.Wait()
	if s.err != nil {
		return s.err
	}
	return s.writeErr
}

// Close will flush the final output and close the stream.
// The function will block until everything has been written.
// The Encoder can still be re-used after calling this.
func (e *Encoder) Close() error {
	s := &e.state
	if s.encoder == nil {
		return nil
	}
	err := e.nextBlock(true)
	if err != nil {
		return err
	}
	if s.frameContentSize > 0 {
		if s.nInput != s.frameContentSize {
			return fmt.Errorf("frame content size %d given, but %d bytes was written", s.frameContentSize, s.nInput)
		}
	}
	if e.state.fullFrameWritten {
		return s.err
	}
	s.wg.Wait()
	s.wWg.Wait()

	if s.err != nil {
		return s.err
	}
	if s.writeErr != nil {
		return s.writeErr
	}

	// Write CRC
	if e.o.crc && s.err == nil {
		// heap alloc.
		var tmp [4]byte
		_, s.err = s.w.Write(s.encoder.AppendCRC(tmp[:0]))
		s.nWritten += 4
	}

	// Add padding with content from crypto/rand.Reader
	if s.err == nil && e.o.pad > 0 {
		add := calcSkippableFrame(s.nWritten, int64(e.o.pad))
		frame, err := skippableFrame(s.filling[:0], add, rand.Reader)
		if err != nil {
			return err
		}
		_, s.err = s.w.Write(frame)
	}
	return s.err
}

// EncodeAll will encode all input in src and append it to dst.
// This function can be called concurrently, but each call will only run on a single goroutine.
// If empty input is given, nothing is returned, unless WithZeroFrames is specified.
// Encoded blocks can be concatenated and the result will be the combined input stream.
// Data compressed with EncodeAll can be decoded with the Decoder,
// using either a stream or DecodeAll.
func (e *Encoder) EncodeAll(src, dst []byte) []byte {
	if len(src) == 0 {
		if e.o.fullZero {
			// Add frame header.
			fh := frameHeader{
				ContentSize:   0,
				WindowSize:    MinWindowSize,
				SingleSegment: true,
				// Adding a checksum would be a waste of space.
				Checksum: false,
				DictID:   0,
			}
			dst, _ = fh.appendTo(dst)

			// Write raw block as last one only.
			var blk blockHeader
			blk.setSize(0)
			blk.setType(blockTypeRaw)
			blk.setLast(true)
			dst = blk.appendTo(dst)
		}
		return dst
	}
	e.init.Do(e.initialize)
	enc := <-e.encoders
	defer func() {
		// Release encoder reference to last block.
		// If a non-single block is needed the encoder will reset again.
		e.encoders <- enc
	}()
	// Use single segments when above minimum window and below 1MB.
	single := len(src) < 1<<20 && len(src) > MinWindowSize
	if e.o.single != nil {
		single = *e.o.single
	}
	fh := frameHeader{
		ContentSize:   uint64(len(src)),
		WindowSize:    uint32(enc.WindowSize(int64(len(src)))),
		SingleSegment: single,
		Checksum:      e.o.crc,
		DictID:        e.o.dict.ID(),
	}

	// If less than 1MB, allocate a buffer up front.
	if len(dst) == 0 && cap(dst) == 0 && len(src) < 1<<20 && !e.o.lowMem {
		dst = make([]byte, 0, len(src))
	}
	dst, err := fh.appendTo(dst)
	if err != nil {
		panic(err)
	}

	// If we can do everything in one block, prefer that.
	if len(src) <= maxCompressedBlockSize {
		enc.Reset(e.o.dict, true)
		// Slightly faster with no history and everything in one block.
		if e.o.crc {
			_, _ = enc.CRC().Write(src)
		}
		blk := enc.Block()
		blk.last = true
		if e.o.dict == nil {
			enc.EncodeNoHist(blk, src)
		} else {
			enc.Encode(blk, src)
		}

		// If we got the exact same number of literals as input,
		// assume the literals cannot be compressed.
		err := errIncompressible
		oldout := blk.output
		if len(blk.literals) != len(src) || len(src) != e.o.blockSize {
			// Output directly to dst
			blk.output = dst
			err = blk.encode(src, e.o.noEntropy, !e.o.allLitEntropy)
		}

		switch err {
		case errIncompressible:
			if debugEncoder {
				println("Storing incompressible block as raw")
			}
			dst = blk.encodeRawTo(dst, src)
		case nil:
			dst = blk.output
		default:
			panic(err)
		}
		blk.output = oldout
	} else {
		enc.Reset(e.o.dict, false)
		blk := enc.Block()
		for len(src) > 0 {
			todo := src
			if len(todo) > e.o.blockSize {
				todo = todo[:e.o.blockSize]
			}
			src = src[len(todo):]
			if e.o.crc {
				_, _ = enc.CRC().Write(todo)
			}
			blk.pushOffsets()
			enc.Encode(blk, todo)
			if len(src) == 0 {
				blk.last = true
			}
			err := errIncompressible
			// If we got the exact same number of literals as input,
			// assume the literals cannot be compressed.
			if len(blk.literals) != len(todo) || len(todo) != e.o.blockSize {
				err = blk.encode(todo, e.o.noEntropy, !e.o.allLitEntropy)
			}

			switch err {
			case errIncompressible:
				if debugEncoder {
					println("Storing incompressible block as raw")
				}
				dst = blk.encodeRawTo(dst, todo)
				blk.popOffsets()
			case nil:
				dst = append(dst, blk.output...)
			default:
				panic(err)
			}
			blk.reset(nil)
		}
	}
	if e.o.crc {
		dst = enc.AppendCRC(dst)
	}
	// Add padding with content from crypto/rand.Reader
	if e.o.pad > 0 {
		add := calcSkippableFrame(int64(len(dst)), int64(e.o.pad))
		dst, err = skippableFrame(dst, add, rand.Reader)
		if err != nil {
			panic(err)
		}
	}
	return dst
}