vendor: github.com/klauspost/compress v1.15.0

intermediate bump for easier review

full diff: https://github.com/klauspost/compress/compare/v1.14.3...v1.15.0

Signed-off-by: Sebastiaan van Stijn <github@gone.nl>

vendor.mod

@@ -24,7 +24,7 @@ require (
 	github.com/google/go-cmp v0.5.7
 	github.com/google/shlex v0.0.0-20191202100458-e7afc7fbc510
 	github.com/imdario/mergo v0.3.12
-	github.com/klauspost/compress v1.14.3 // indirect
+	github.com/klauspost/compress v1.15.0 // indirect
 	github.com/mitchellh/mapstructure v1.3.2
 	github.com/moby/buildkit v0.8.2-0.20210615162540-9f254e18360a // master (v0.9.0-dev)
 	github.com/moby/sys/signal v0.7.0

vendor.sum

@@ -480,8 +480,8 @@ github.com/kisielk/gotool v1.0.0/go.mod h1:XhKaO+MFFWcvkIS/tQcRk01m1F5IRFswLeQ+o
 github.com/klauspost/compress v1.11.3/go.mod h1:aoV0uJVorq1K+umq18yTdKaF57EivdYsUV+/s2qKfXs=
 github.com/klauspost/compress v1.11.13/go.mod h1:aoV0uJVorq1K+umq18yTdKaF57EivdYsUV+/s2qKfXs=
 github.com/klauspost/compress v1.12.3/go.mod h1:8dP1Hq4DHOhN9w426knH3Rhby4rFm6D8eO+e+Dq5Gzg=
-github.com/klauspost/compress v1.14.3 h1:DQv1WP+iS4srNjibdnHtqu8JNWCDMluj5NzPnFJsnvk=
+github.com/klauspost/compress v1.15.0 h1:xqfchp4whNFxn5A4XFyyYtitiWI8Hy5EW59jEwcyL6U=
-github.com/klauspost/compress v1.14.3/go.mod h1:/3/Vjq9QcHkK5uEr5lBEmyoZ1iFhe47etQ6QUkpK6sk=
+github.com/klauspost/compress v1.15.0/go.mod h1:/3/Vjq9QcHkK5uEr5lBEmyoZ1iFhe47etQ6QUkpK6sk=
 github.com/konsorten/go-windows-terminal-sequences v1.0.1/go.mod h1:T0+1ngSBFLxvqU3pZ+m/2kptfBszLMUkC4ZK/EgS/cQ=
 github.com/konsorten/go-windows-terminal-sequences v1.0.2/go.mod h1:T0+1ngSBFLxvqU3pZ+m/2kptfBszLMUkC4ZK/EgS/cQ=
 github.com/konsorten/go-windows-terminal-sequences v1.0.3/go.mod h1:T0+1ngSBFLxvqU3pZ+m/2kptfBszLMUkC4ZK/EgS/cQ=

vendor/github.com/klauspost/compress/README.md

@@ -17,6 +17,17 @@ This package provides various compression algorithms.
 
 # changelog
 
+* Feb 22, 2022 (v1.14.4)
+	* flate: Fix rare huffman only (-2) corruption. [#503](https://github.com/klauspost/compress/pull/503)
+	* zip: Update deprecated CreateHeaderRaw to correctly call CreateRaw by @saracen in [#502](https://github.com/klauspost/compress/pull/502)
+	* zip: don't read data descriptor early by @saracen in [#501](https://github.com/klauspost/compress/pull/501)  #501
+	* huff0: Use static decompression buffer up to 30% faster by @klauspost in [#499](https://github.com/klauspost/compress/pull/499) [#500](https://github.com/klauspost/compress/pull/500)
+
+* Feb 17, 2022 (v1.14.3)
+	* flate: Improve fastest levels compression speed ~10% more throughput. [#482](https://github.com/klauspost/compress/pull/482) [#489](https://github.com/klauspost/compress/pull/489) [#490](https://github.com/klauspost/compress/pull/490) [#491](https://github.com/klauspost/compress/pull/491) [#494](https://github.com/klauspost/compress/pull/494)  [#478](https://github.com/klauspost/compress/pull/478)
+	* flate: Faster decompression speed, ~5-10%. [#483](https://github.com/klauspost/compress/pull/483)
+	* s2: Faster compression with Go v1.18 and amd64 microarch level 3+. [#484](https://github.com/klauspost/compress/pull/484) [#486](https://github.com/klauspost/compress/pull/486)
+
 * Jan 25, 2022 (v1.14.2)
 	* zstd: improve header decoder by @dsnet  [#476](https://github.com/klauspost/compress/pull/476)
 	* zstd: Add bigger default blocks  [#469](https://github.com/klauspost/compress/pull/469)
@@ -61,6 +72,9 @@ This package provides various compression algorithms.
 	* zstd: Detect short invalid signatures [#382](https://github.com/klauspost/compress/pull/382)
 	* zstd: Spawn decoder goroutine only if needed. [#380](https://github.com/klauspost/compress/pull/380)
 
+<details>
+	<summary>See changes to v1.12.x</summary>
+	
 * May 25, 2021 (v1.12.3)
 	* deflate: Better/faster Huffman encoding [#374](https://github.com/klauspost/compress/pull/374)
 	* deflate: Allocate less for history. [#375](https://github.com/klauspost/compress/pull/375)
@@ -82,9 +96,10 @@ This package provides various compression algorithms.
 	* s2c/s2d/s2sx: Always truncate when writing files [#352](https://github.com/klauspost/compress/pull/352)
 	* zstd: Reduce memory usage further when using [WithLowerEncoderMem](https://pkg.go.dev/github.com/klauspost/compress/zstd#WithLowerEncoderMem) [#346](https://github.com/klauspost/compress/pull/346)
 	* s2: Fix potential problem with amd64 assembly and profilers [#349](https://github.com/klauspost/compress/pull/349)
+</details>
 
 <details>
-	<summary>See changes prior to v1.12.1</summary>
+	<summary>See changes to v1.11.x</summary>
 	
 * Mar 26, 2021 (v1.11.13)
 	* zstd: Big speedup on small dictionary encodes [#344](https://github.com/klauspost/compress/pull/344) [#345](https://github.com/klauspost/compress/pull/345)
@@ -143,7 +158,7 @@ This package provides various compression algorithms.
 </details>
 
 <details>
-	<summary>See changes prior to v1.11.0</summary>
+	<summary>See changes to v1.10.x</summary>
  
 * July 8, 2020 (v1.10.11) 
 	* zstd: Fix extra block when compressing with ReadFrom. [#278](https://github.com/klauspost/compress/pull/278)
@@ -305,11 +320,6 @@ This package provides various compression algorithms.
 
 # deflate usage
 
-* [High Throughput Benchmark](http://blog.klauspost.com/go-gzipdeflate-benchmarks/).
-* [Small Payload/Webserver Benchmarks](http://blog.klauspost.com/gzip-performance-for-go-webservers/).
-* [Linear Time Compression](http://blog.klauspost.com/constant-time-gzipzip-compression/).
-* [Re-balancing Deflate Compression Levels](https://blog.klauspost.com/rebalancing-deflate-compression-levels/)
-
 The packages are drop-in replacements for standard libraries. Simply replace the import path to use them:
 
 | old import         | new import                              | Documentation
@@ -331,6 +341,8 @@ Memory usage is typically 1MB for a Writer. stdlib is in the same range.
 If you expect to have a lot of concurrently allocated Writers consider using 
 the stateless compress described below.
 
+For compression performance, see: [this spreadsheet](https://docs.google.com/spreadsheets/d/1nuNE2nPfuINCZJRMt6wFWhKpToF95I47XjSsc-1rbPQ/edit?usp=sharing).
+
 # Stateless compression
 
 This package offers stateless compression as a special option for gzip/deflate. 

vendor/github.com/klauspost/compress/huff0/bitreader.go

@@ -8,115 +8,10 @@ package huff0
 import (
 	"encoding/binary"
 	"errors"
+	"fmt"
 	"io"
 )
 
-// bitReader reads a bitstream in reverse.
-// The last set bit indicates the start of the stream and is used
-// for aligning the input.
-type bitReader struct {
-	in       []byte
-	off      uint // next byte to read is at in[off - 1]
-	value    uint64
-	bitsRead uint8
-}
-
-// init initializes and resets the bit reader.
-func (b *bitReader) init(in []byte) error {
-	if len(in) < 1 {
-		return errors.New("corrupt stream: too short")
-	}
-	b.in = in
-	b.off = uint(len(in))
-	// The highest bit of the last byte indicates where to start
-	v := in[len(in)-1]
-	if v == 0 {
-		return errors.New("corrupt stream, did not find end of stream")
-	}
-	b.bitsRead = 64
-	b.value = 0
-	if len(in) >= 8 {
-		b.fillFastStart()
-	} else {
-		b.fill()
-		b.fill()
-	}
-	b.bitsRead += 8 - uint8(highBit32(uint32(v)))
-	return nil
-}
-
-// peekBitsFast requires that at least one bit is requested every time.
-// There are no checks if the buffer is filled.
-func (b *bitReader) peekBitsFast(n uint8) uint16 {
-	const regMask = 64 - 1
-	v := uint16((b.value << (b.bitsRead & regMask)) >> ((regMask + 1 - n) & regMask))
-	return v
-}
-
-// fillFast() will make sure at least 32 bits are available.
-// There must be at least 4 bytes available.
-func (b *bitReader) fillFast() {
-	if b.bitsRead < 32 {
-		return
-	}
-
-	// 2 bounds checks.
-	v := b.in[b.off-4 : b.off]
-	v = v[:4]
-	low := (uint32(v[0])) | (uint32(v[1]) << 8) | (uint32(v[2]) << 16) | (uint32(v[3]) << 24)
-	b.value = (b.value << 32) | uint64(low)
-	b.bitsRead -= 32
-	b.off -= 4
-}
-
-func (b *bitReader) advance(n uint8) {
-	b.bitsRead += n
-}
-
-// fillFastStart() assumes the bitreader is empty and there is at least 8 bytes to read.
-func (b *bitReader) fillFastStart() {
-	// Do single re-slice to avoid bounds checks.
-	b.value = binary.LittleEndian.Uint64(b.in[b.off-8:])
-	b.bitsRead = 0
-	b.off -= 8
-}
-
-// fill() will make sure at least 32 bits are available.
-func (b *bitReader) fill() {
-	if b.bitsRead < 32 {
-		return
-	}
-	if b.off > 4 {
-		v := b.in[b.off-4:]
-		v = v[:4]
-		low := (uint32(v[0])) | (uint32(v[1]) << 8) | (uint32(v[2]) << 16) | (uint32(v[3]) << 24)
-		b.value = (b.value << 32) | uint64(low)
-		b.bitsRead -= 32
-		b.off -= 4
-		return
-	}
-	for b.off > 0 {
-		b.value = (b.value << 8) | uint64(b.in[b.off-1])
-		b.bitsRead -= 8
-		b.off--
-	}
-}
-
-// finished returns true if all bits have been read from the bit stream.
-func (b *bitReader) finished() bool {
-	return b.off == 0 && b.bitsRead >= 64
-}
-
-// close the bitstream and returns an error if out-of-buffer reads occurred.
-func (b *bitReader) close() error {
-	// Release reference.
-	b.in = nil
-	if b.bitsRead > 64 {
-		return io.ErrUnexpectedEOF
-	}
-	return nil
-}
-
 // bitReader reads a bitstream in reverse.
 // The last set bit indicates the start of the stream and is used
 // for aligning the input.
@@ -213,10 +108,17 @@ func (b *bitReaderBytes) finished() bool {
 	return b.off == 0 && b.bitsRead >= 64
 }
 
+func (b *bitReaderBytes) remaining() uint {
+	return b.off*8 + uint(64-b.bitsRead)
+}
+
 // close the bitstream and returns an error if out-of-buffer reads occurred.
 func (b *bitReaderBytes) close() error {
 	// Release reference.
 	b.in = nil
+	if b.remaining() > 0 {
+		return fmt.Errorf("corrupt input: %d bits remain on stream", b.remaining())
+	}
 	if b.bitsRead > 64 {
 		return io.ErrUnexpectedEOF
 	}
@@ -318,10 +220,17 @@ func (b *bitReaderShifted) finished() bool {
 	return b.off == 0 && b.bitsRead >= 64
 }
 
+func (b *bitReaderShifted) remaining() uint {
+	return b.off*8 + uint(64-b.bitsRead)
+}
+
 // close the bitstream and returns an error if out-of-buffer reads occurred.
 func (b *bitReaderShifted) close() error {
 	// Release reference.
 	b.in = nil
+	if b.remaining() > 0 {
+		return fmt.Errorf("corrupt input: %d bits remain on stream", b.remaining())
+	}
 	if b.bitsRead > 64 {
 		return io.ErrUnexpectedEOF
 	}

vendor/github.com/klauspost/compress/huff0/compress.go

@@ -2,6 +2,7 @@ package huff0
 
 import (
 	"fmt"
+	"math"
 	"runtime"
 	"sync"
 )
@@ -289,6 +290,10 @@ func (s *Scratch) compress4X(src []byte) ([]byte, error) {
 		if err != nil {
 			return nil, err
 		}
+		if len(s.Out)-idx > math.MaxUint16 {
+			// We cannot store the size in the jump table
+			return nil, ErrIncompressible
+		}
 		// Write compressed length as little endian before block.
 		if i < 3 {
 			// Last length is not written.
@@ -332,6 +337,10 @@ func (s *Scratch) compress4Xp(src []byte) ([]byte, error) {
 			return nil, errs[i]
 		}
 		o := s.tmpOut[i]
+		if len(o) > math.MaxUint16 {
+			// We cannot store the size in the jump table
+			return nil, ErrIncompressible
+		}
 		// Write compressed length as little endian before block.
 		if i < 3 {
 			// Last length is not written.

vendor/github.com/klauspost/compress/huff0/decompress.go

@@ -4,6 +4,7 @@ import (
 	"errors"
 	"fmt"
 	"io"
+	"sync"
 
 	"github.com/klauspost/compress/fse"
 )
@@ -216,6 +217,7 @@ func (s *Scratch) Decoder() *Decoder {
 	return &Decoder{
 		dt:             s.dt,
 		actualTableLog: s.actualTableLog,
+		bufs:           &s.decPool,
 	}
 }
 
@@ -223,6 +225,15 @@ func (s *Scratch) Decoder() *Decoder {
 type Decoder struct {
 	dt             dTable
 	actualTableLog uint8
+	bufs           *sync.Pool
+}
+
+func (d *Decoder) buffer() *[4][256]byte {
+	buf, ok := d.bufs.Get().(*[4][256]byte)
+	if ok {
+		return buf
+	}
+	return &[4][256]byte{}
 }
 
 // Decompress1X will decompress a 1X encoded stream.
@@ -249,7 +260,8 @@ func (d *Decoder) Decompress1X(dst, src []byte) ([]byte, error) {
 	dt := d.dt.single[:tlSize]
 
 	// Use temp table to avoid bound checks/append penalty.
-	var buf [256]byte
+	bufs := d.buffer()
+	buf := &bufs[0]
 	var off uint8
 
 	for br.off >= 8 {
@@ -277,6 +289,7 @@ func (d *Decoder) Decompress1X(dst, src []byte) ([]byte, error) {
 		if off == 0 {
 			if len(dst)+256 > maxDecodedSize {
 				br.close()
+				d.bufs.Put(bufs)
 				return nil, ErrMaxDecodedSizeExceeded
 			}
 			dst = append(dst, buf[:]...)
@@ -284,6 +297,7 @@ func (d *Decoder) Decompress1X(dst, src []byte) ([]byte, error) {
 	}
 
 	if len(dst)+int(off) > maxDecodedSize {
+		d.bufs.Put(bufs)
 		br.close()
 		return nil, ErrMaxDecodedSizeExceeded
 	}
@@ -310,6 +324,7 @@ func (d *Decoder) Decompress1X(dst, src []byte) ([]byte, error) {
 			}
 		}
 		if len(dst) >= maxDecodedSize {
+			d.bufs.Put(bufs)
 			br.close()
 			return nil, ErrMaxDecodedSizeExceeded
 		}
@@ -319,6 +334,7 @@ func (d *Decoder) Decompress1X(dst, src []byte) ([]byte, error) {
 		bitsLeft -= nBits
 		dst = append(dst, uint8(v.entry>>8))
 	}
+	d.bufs.Put(bufs)
 	return dst, br.close()
 }
 
@@ -341,7 +357,8 @@ func (d *Decoder) decompress1X8Bit(dst, src []byte) ([]byte, error) {
 	dt := d.dt.single[:256]
 
 	// Use temp table to avoid bound checks/append penalty.
-	var buf [256]byte
+	bufs := d.buffer()
+	buf := &bufs[0]
 	var off uint8
 
 	switch d.actualTableLog {
@@ -369,6 +386,7 @@ func (d *Decoder) decompress1X8Bit(dst, src []byte) ([]byte, error) {
 			if off == 0 {
 				if len(dst)+256 > maxDecodedSize {
 					br.close()
+					d.bufs.Put(bufs)
 					return nil, ErrMaxDecodedSizeExceeded
 				}
 				dst = append(dst, buf[:]...)
@@ -398,6 +416,7 @@ func (d *Decoder) decompress1X8Bit(dst, src []byte) ([]byte, error) {
 			if off == 0 {
 				if len(dst)+256 > maxDecodedSize {
 					br.close()
+					d.bufs.Put(bufs)
 					return nil, ErrMaxDecodedSizeExceeded
 				}
 				dst = append(dst, buf[:]...)
@@ -426,6 +445,7 @@ func (d *Decoder) decompress1X8Bit(dst, src []byte) ([]byte, error) {
 			off += 4
 			if off == 0 {
 				if len(dst)+256 > maxDecodedSize {
+					d.bufs.Put(bufs)
 					br.close()
 					return nil, ErrMaxDecodedSizeExceeded
 				}
@@ -455,6 +475,7 @@ func (d *Decoder) decompress1X8Bit(dst, src []byte) ([]byte, error) {
 			off += 4
 			if off == 0 {
 				if len(dst)+256 > maxDecodedSize {
+					d.bufs.Put(bufs)
 					br.close()
 					return nil, ErrMaxDecodedSizeExceeded
 				}
@@ -484,6 +505,7 @@ func (d *Decoder) decompress1X8Bit(dst, src []byte) ([]byte, error) {
 			off += 4
 			if off == 0 {
 				if len(dst)+256 > maxDecodedSize {
+					d.bufs.Put(bufs)
 					br.close()
 					return nil, ErrMaxDecodedSizeExceeded
 				}
@@ -513,6 +535,7 @@ func (d *Decoder) decompress1X8Bit(dst, src []byte) ([]byte, error) {
 			off += 4
 			if off == 0 {
 				if len(dst)+256 > maxDecodedSize {
+					d.bufs.Put(bufs)
 					br.close()
 					return nil, ErrMaxDecodedSizeExceeded
 				}
@@ -542,6 +565,7 @@ func (d *Decoder) decompress1X8Bit(dst, src []byte) ([]byte, error) {
 			off += 4
 			if off == 0 {
 				if len(dst)+256 > maxDecodedSize {
+					d.bufs.Put(bufs)
 					br.close()
 					return nil, ErrMaxDecodedSizeExceeded
 				}
@@ -571,6 +595,7 @@ func (d *Decoder) decompress1X8Bit(dst, src []byte) ([]byte, error) {
 			off += 4
 			if off == 0 {
 				if len(dst)+256 > maxDecodedSize {
+					d.bufs.Put(bufs)
 					br.close()
 					return nil, ErrMaxDecodedSizeExceeded
 				}
@@ -578,10 +603,12 @@ func (d *Decoder) decompress1X8Bit(dst, src []byte) ([]byte, error) {
 			}
 		}
 	default:
+		d.bufs.Put(bufs)
 		return nil, fmt.Errorf("invalid tablelog: %d", d.actualTableLog)
 	}
 
 	if len(dst)+int(off) > maxDecodedSize {
+		d.bufs.Put(bufs)
 		br.close()
 		return nil, ErrMaxDecodedSizeExceeded
 	}
@@ -601,6 +628,7 @@ func (d *Decoder) decompress1X8Bit(dst, src []byte) ([]byte, error) {
 		}
 		if len(dst) >= maxDecodedSize {
 			br.close()
+			d.bufs.Put(bufs)
 			return nil, ErrMaxDecodedSizeExceeded
 		}
 		v := dt[br.peekByteFast()>>shift]
@@ -609,6 +637,7 @@ func (d *Decoder) decompress1X8Bit(dst, src []byte) ([]byte, error) {
 		bitsLeft -= int8(nBits)
 		dst = append(dst, uint8(v.entry>>8))
 	}
+	d.bufs.Put(bufs)
 	return dst, br.close()
 }
 
@@ -628,7 +657,8 @@ func (d *Decoder) decompress1X8BitExactly(dst, src []byte) ([]byte, error) {
 	dt := d.dt.single[:256]
 
 	// Use temp table to avoid bound checks/append penalty.
-	var buf [256]byte
+	bufs := d.buffer()
+	buf := &bufs[0]
 	var off uint8
 
 	const shift = 56
@@ -655,6 +685,7 @@ func (d *Decoder) decompress1X8BitExactly(dst, src []byte) ([]byte, error) {
 		off += 4
 		if off == 0 {
 			if len(dst)+256 > maxDecodedSize {
+				d.bufs.Put(bufs)
 				br.close()
 				return nil, ErrMaxDecodedSizeExceeded
 			}
@@ -663,6 +694,7 @@ func (d *Decoder) decompress1X8BitExactly(dst, src []byte) ([]byte, error) {
 	}
 
 	if len(dst)+int(off) > maxDecodedSize {
+		d.bufs.Put(bufs)
 		br.close()
 		return nil, ErrMaxDecodedSizeExceeded
 	}
@@ -679,6 +711,7 @@ func (d *Decoder) decompress1X8BitExactly(dst, src []byte) ([]byte, error) {
 			}
 		}
 		if len(dst) >= maxDecodedSize {
+			d.bufs.Put(bufs)
 			br.close()
 			return nil, ErrMaxDecodedSizeExceeded
 		}
@@ -688,6 +721,7 @@ func (d *Decoder) decompress1X8BitExactly(dst, src []byte) ([]byte, error) {
 		bitsLeft -= int8(nBits)
 		dst = append(dst, uint8(v.entry>>8))
 	}
+	d.bufs.Put(bufs)
 	return dst, br.close()
 }
 
@@ -707,6 +741,7 @@ func (d *Decoder) Decompress4X(dst, src []byte) ([]byte, error) {
 	}
 
 	var br [4]bitReaderShifted
+	// Decode "jump table"
 	start := 6
 	for i := 0; i < 3; i++ {
 		length := int(src[i*2]) | (int(src[i*2+1]) << 8)
@@ -735,12 +770,12 @@ func (d *Decoder) Decompress4X(dst, src []byte) ([]byte, error) {
 	single := d.dt.single[:tlSize]
 
 	// Use temp table to avoid bound checks/append penalty.
-	var buf [256]byte
+	buf := d.buffer()
 	var off uint8
 	var decoded int
 
 	// Decode 2 values from each decoder/loop.
-	const bufoff = 256 / 4
+	const bufoff = 256
 	for {
 		if br[0].off < 4 || br[1].off < 4 || br[2].off < 4 || br[3].off < 4 {
 			break
@@ -758,8 +793,8 @@ func (d *Decoder) Decompress4X(dst, src []byte) ([]byte, error) {
 			v2 := single[val2&tlMask]
 			br[stream].advance(uint8(v.entry))
 			br[stream2].advance(uint8(v2.entry))
-			buf[off+bufoff*stream] = uint8(v.entry >> 8)
+			buf[stream][off] = uint8(v.entry >> 8)
-			buf[off+bufoff*stream2] = uint8(v2.entry >> 8)
+			buf[stream2][off] = uint8(v2.entry >> 8)
 
 			val = br[stream].peekBitsFast(d.actualTableLog)
 			val2 = br[stream2].peekBitsFast(d.actualTableLog)
@@ -767,8 +802,8 @@ func (d *Decoder) Decompress4X(dst, src []byte) ([]byte, error) {
 			v2 = single[val2&tlMask]
 			br[stream].advance(uint8(v.entry))
 			br[stream2].advance(uint8(v2.entry))
-			buf[off+bufoff*stream+1] = uint8(v.entry >> 8)
+			buf[stream][off+1] = uint8(v.entry >> 8)
-			buf[off+bufoff*stream2+1] = uint8(v2.entry >> 8)
+			buf[stream2][off+1] = uint8(v2.entry >> 8)
 		}
 
 		{
@@ -783,8 +818,8 @@ func (d *Decoder) Decompress4X(dst, src []byte) ([]byte, error) {
 			v2 := single[val2&tlMask]
 			br[stream].advance(uint8(v.entry))
 			br[stream2].advance(uint8(v2.entry))
-			buf[off+bufoff*stream] = uint8(v.entry >> 8)
+			buf[stream][off] = uint8(v.entry >> 8)
-			buf[off+bufoff*stream2] = uint8(v2.entry >> 8)
+			buf[stream2][off] = uint8(v2.entry >> 8)
 
 			val = br[stream].peekBitsFast(d.actualTableLog)
 			val2 = br[stream2].peekBitsFast(d.actualTableLog)
@@ -792,25 +827,26 @@ func (d *Decoder) Decompress4X(dst, src []byte) ([]byte, error) {
 			v2 = single[val2&tlMask]
 			br[stream].advance(uint8(v.entry))
 			br[stream2].advance(uint8(v2.entry))
-			buf[off+bufoff*stream+1] = uint8(v.entry >> 8)
+			buf[stream][off+1] = uint8(v.entry >> 8)
-			buf[off+bufoff*stream2+1] = uint8(v2.entry >> 8)
+			buf[stream2][off+1] = uint8(v2.entry >> 8)
 		}
 
 		off += 2
 
-		if off == bufoff {
+		if off == 0 {
 			if bufoff > dstEvery {
+				d.bufs.Put(buf)
 				return nil, errors.New("corruption detected: stream overrun 1")
 			}
-			copy(out, buf[:bufoff])
+			copy(out, buf[0][:])
-			copy(out[dstEvery:], buf[bufoff:bufoff*2])
+			copy(out[dstEvery:], buf[1][:])
-			copy(out[dstEvery*2:], buf[bufoff*2:bufoff*3])
+			copy(out[dstEvery*2:], buf[2][:])
-			copy(out[dstEvery*3:], buf[bufoff*3:bufoff*4])
+			copy(out[dstEvery*3:], buf[3][:])
-			off = 0
 			out = out[bufoff:]
-			decoded += 256
+			decoded += bufoff * 4
 			// There must at least be 3 buffers left.
 			if len(out) < dstEvery*3 {
+				d.bufs.Put(buf)
 				return nil, errors.New("corruption detected: stream overrun 2")
 			}
 		}
@@ -818,41 +854,31 @@ func (d *Decoder) Decompress4X(dst, src []byte) ([]byte, error) {
 	if off > 0 {
 		ioff := int(off)
 		if len(out) < dstEvery*3+ioff {
+			d.bufs.Put(buf)
 			return nil, errors.New("corruption detected: stream overrun 3")
 		}
-		copy(out, buf[:off])
+		copy(out, buf[0][:off])
-		copy(out[dstEvery:dstEvery+ioff], buf[bufoff:bufoff*2])
+		copy(out[dstEvery:], buf[1][:off])
-		copy(out[dstEvery*2:dstEvery*2+ioff], buf[bufoff*2:bufoff*3])
+		copy(out[dstEvery*2:], buf[2][:off])
-		copy(out[dstEvery*3:dstEvery*3+ioff], buf[bufoff*3:bufoff*4])
+		copy(out[dstEvery*3:], buf[3][:off])
 		decoded += int(off) * 4
 		out = out[off:]
 	}
 
 	// Decode remaining.
+	remainBytes := dstEvery - (decoded / 4)
 	for i := range br {
 		offset := dstEvery * i
+		endsAt := offset + remainBytes
+		if endsAt > len(out) {
+			endsAt = len(out)
+		}
 		br := &br[i]
-		bitsLeft := br.off*8 + uint(64-br.bitsRead)
+		bitsLeft := br.remaining()
 		for bitsLeft > 0 {
 			br.fill()
-			if false && br.bitsRead >= 32 {
+			if offset >= endsAt {
-				if br.off >= 4 {
+				d.bufs.Put(buf)
-					v := br.in[br.off-4:]
-					v = v[:4]
-					low := (uint32(v[0])) | (uint32(v[1]) << 8) | (uint32(v[2]) << 16) | (uint32(v[3]) << 24)
-					br.value = (br.value << 32) | uint64(low)
-					br.bitsRead -= 32
-					br.off -= 4
-				} else {
-					for br.off > 0 {
-						br.value = (br.value << 8) | uint64(br.in[br.off-1])
-						br.bitsRead -= 8
-						br.off--
-					}
-				}
-			}
-			// end inline...
-			if offset >= len(out) {
 				return nil, errors.New("corruption detected: stream overrun 4")
 			}
 
@@ -865,12 +891,17 @@ func (d *Decoder) Decompress4X(dst, src []byte) ([]byte, error) {
 			out[offset] = uint8(v >> 8)
 			offset++
 		}
+		if offset != endsAt {
+			d.bufs.Put(buf)
+			return nil, fmt.Errorf("corruption detected: short output block %d, end %d != %d", i, offset, endsAt)
+		}
 		decoded += offset - dstEvery*i
 		err = br.close()
 		if err != nil {
 			return nil, err
 		}
 	}
+	d.bufs.Put(buf)
 	if dstSize != decoded {
 		return nil, errors.New("corruption detected: short output block")
 	}
@@ -916,12 +947,12 @@ func (d *Decoder) decompress4X8bit(dst, src []byte) ([]byte, error) {
 	single := d.dt.single[:tlSize]
 
 	// Use temp table to avoid bound checks/append penalty.
-	var buf [256]byte
+	buf := d.buffer()
 	var off uint8
 	var decoded int
 
 	// Decode 4 values from each decoder/loop.
-	const bufoff = 256 / 4
+	const bufoff = 256
 	for {
 		if br[0].off < 4 || br[1].off < 4 || br[2].off < 4 || br[3].off < 4 {
 			break
@@ -942,8 +973,8 @@ func (d *Decoder) decompress4X8bit(dst, src []byte) ([]byte, error) {
 			br1.value <<= v & 63
 			br2.bitsRead += uint8(v2)
 			br2.value <<= v2 & 63
-			buf[off+bufoff*stream] = uint8(v >> 8)
+			buf[stream][off] = uint8(v >> 8)
-			buf[off+bufoff*stream2] = uint8(v2 >> 8)
+			buf[stream2][off] = uint8(v2 >> 8)
 
 			v = single[uint8(br1.value>>shift)].entry
 			v2 = single[uint8(br2.value>>shift)].entry
@@ -951,8 +982,8 @@ func (d *Decoder) decompress4X8bit(dst, src []byte) ([]byte, error) {
 			br1.value <<= v & 63
 			br2.bitsRead += uint8(v2)
 			br2.value <<= v2 & 63
-			buf[off+bufoff*stream+1] = uint8(v >> 8)
+			buf[stream][off+1] = uint8(v >> 8)
-			buf[off+bufoff*stream2+1] = uint8(v2 >> 8)
+			buf[stream2][off+1] = uint8(v2 >> 8)
 
 			v = single[uint8(br1.value>>shift)].entry
 			v2 = single[uint8(br2.value>>shift)].entry
@@ -960,8 +991,8 @@ func (d *Decoder) decompress4X8bit(dst, src []byte) ([]byte, error) {
 			br1.value <<= v & 63
 			br2.bitsRead += uint8(v2)
 			br2.value <<= v2 & 63
-			buf[off+bufoff*stream+2] = uint8(v >> 8)
+			buf[stream][off+2] = uint8(v >> 8)
-			buf[off+bufoff*stream2+2] = uint8(v2 >> 8)
+			buf[stream2][off+2] = uint8(v2 >> 8)
 
 			v = single[uint8(br1.value>>shift)].entry
 			v2 = single[uint8(br2.value>>shift)].entry
@@ -969,8 +1000,8 @@ func (d *Decoder) decompress4X8bit(dst, src []byte) ([]byte, error) {
 			br1.value <<= v & 63
 			br2.bitsRead += uint8(v2)
 			br2.value <<= v2 & 63
-			buf[off+bufoff*stream2+3] = uint8(v2 >> 8)
+			buf[stream][off+3] = uint8(v >> 8)
-			buf[off+bufoff*stream+3] = uint8(v >> 8)
+			buf[stream2][off+3] = uint8(v2 >> 8)
 		}
 
 		{
@@ -987,8 +1018,8 @@ func (d *Decoder) decompress4X8bit(dst, src []byte) ([]byte, error) {
 			br1.value <<= v & 63
 			br2.bitsRead += uint8(v2)
 			br2.value <<= v2 & 63
-			buf[off+bufoff*stream] = uint8(v >> 8)
+			buf[stream][off] = uint8(v >> 8)
-			buf[off+bufoff*stream2] = uint8(v2 >> 8)
+			buf[stream2][off] = uint8(v2 >> 8)
 
 			v = single[uint8(br1.value>>shift)].entry
 			v2 = single[uint8(br2.value>>shift)].entry
@@ -996,8 +1027,8 @@ func (d *Decoder) decompress4X8bit(dst, src []byte) ([]byte, error) {
 			br1.value <<= v & 63
 			br2.bitsRead += uint8(v2)
 			br2.value <<= v2 & 63
-			buf[off+bufoff*stream+1] = uint8(v >> 8)
+			buf[stream][off+1] = uint8(v >> 8)
-			buf[off+bufoff*stream2+1] = uint8(v2 >> 8)
+			buf[stream2][off+1] = uint8(v2 >> 8)
 
 			v = single[uint8(br1.value>>shift)].entry
 			v2 = single[uint8(br2.value>>shift)].entry
@@ -1005,8 +1036,8 @@ func (d *Decoder) decompress4X8bit(dst, src []byte) ([]byte, error) {
 			br1.value <<= v & 63
 			br2.bitsRead += uint8(v2)
 			br2.value <<= v2 & 63
-			buf[off+bufoff*stream+2] = uint8(v >> 8)
+			buf[stream][off+2] = uint8(v >> 8)
-			buf[off+bufoff*stream2+2] = uint8(v2 >> 8)
+			buf[stream2][off+2] = uint8(v2 >> 8)
 
 			v = single[uint8(br1.value>>shift)].entry
 			v2 = single[uint8(br2.value>>shift)].entry
@@ -1014,25 +1045,26 @@ func (d *Decoder) decompress4X8bit(dst, src []byte) ([]byte, error) {
 			br1.value <<= v & 63
 			br2.bitsRead += uint8(v2)
 			br2.value <<= v2 & 63
-			buf[off+bufoff*stream2+3] = uint8(v2 >> 8)
+			buf[stream][off+3] = uint8(v >> 8)
-			buf[off+bufoff*stream+3] = uint8(v >> 8)
+			buf[stream2][off+3] = uint8(v2 >> 8)
 		}
 
 		off += 4
 
-		if off == bufoff {
+		if off == 0 {
 			if bufoff > dstEvery {
+				d.bufs.Put(buf)
 				return nil, errors.New("corruption detected: stream overrun 1")
 			}
-			copy(out, buf[:bufoff])
+			copy(out, buf[0][:])
-			copy(out[dstEvery:], buf[bufoff:bufoff*2])
+			copy(out[dstEvery:], buf[1][:])
-			copy(out[dstEvery*2:], buf[bufoff*2:bufoff*3])
+			copy(out[dstEvery*2:], buf[2][:])
-			copy(out[dstEvery*3:], buf[bufoff*3:bufoff*4])
+			copy(out[dstEvery*3:], buf[3][:])
-			off = 0
 			out = out[bufoff:]
-			decoded += 256
+			decoded += bufoff * 4
 			// There must at least be 3 buffers left.
 			if len(out) < dstEvery*3 {
+				d.bufs.Put(buf)
 				return nil, errors.New("corruption detected: stream overrun 2")
 			}
 		}
@@ -1040,23 +1072,31 @@ func (d *Decoder) decompress4X8bit(dst, src []byte) ([]byte, error) {
 	if off > 0 {
 		ioff := int(off)
 		if len(out) < dstEvery*3+ioff {
+			d.bufs.Put(buf)
 			return nil, errors.New("corruption detected: stream overrun 3")
 		}
-		copy(out, buf[:off])
+		copy(out, buf[0][:off])
-		copy(out[dstEvery:dstEvery+ioff], buf[bufoff:bufoff*2])
+		copy(out[dstEvery:], buf[1][:off])
-		copy(out[dstEvery*2:dstEvery*2+ioff], buf[bufoff*2:bufoff*3])
+		copy(out[dstEvery*2:], buf[2][:off])
-		copy(out[dstEvery*3:dstEvery*3+ioff], buf[bufoff*3:bufoff*4])
+		copy(out[dstEvery*3:], buf[3][:off])
 		decoded += int(off) * 4
 		out = out[off:]
 	}
 
 	// Decode remaining.
+	// Decode remaining.
+	remainBytes := dstEvery - (decoded / 4)
 	for i := range br {
 		offset := dstEvery * i
+		endsAt := offset + remainBytes
+		if endsAt > len(out) {
+			endsAt = len(out)
+		}
 		br := &br[i]
-		bitsLeft := int(br.off*8) + int(64-br.bitsRead)
+		bitsLeft := br.remaining()
 		for bitsLeft > 0 {
 			if br.finished() {
+				d.bufs.Put(buf)
 				return nil, io.ErrUnexpectedEOF
 			}
 			if br.bitsRead >= 56 {
@@ -1076,7 +1116,8 @@ func (d *Decoder) decompress4X8bit(dst, src []byte) ([]byte, error) {
 				}
 			}
 			// end inline...
-			if offset >= len(out) {
+			if offset >= endsAt {
+				d.bufs.Put(buf)
 				return nil, errors.New("corruption detected: stream overrun 4")
 			}
 
@@ -1084,16 +1125,22 @@ func (d *Decoder) decompress4X8bit(dst, src []byte) ([]byte, error) {
 			v := single[uint8(br.value>>shift)].entry
 			nBits := uint8(v)
 			br.advance(nBits)
-			bitsLeft -= int(nBits)
+			bitsLeft -= uint(nBits)
 			out[offset] = uint8(v >> 8)
 			offset++
 		}
+		if offset != endsAt {
+			d.bufs.Put(buf)
+			return nil, fmt.Errorf("corruption detected: short output block %d, end %d != %d", i, offset, endsAt)
+		}
 		decoded += offset - dstEvery*i
 		err = br.close()
 		if err != nil {
+			d.bufs.Put(buf)
 			return nil, err
 		}
 	}
+	d.bufs.Put(buf)
 	if dstSize != decoded {
 		return nil, errors.New("corruption detected: short output block")
 	}
@@ -1135,12 +1182,12 @@ func (d *Decoder) decompress4X8bitExactly(dst, src []byte) ([]byte, error) {
 	single := d.dt.single[:tlSize]
 
 	// Use temp table to avoid bound checks/append penalty.
-	var buf [256]byte
+	buf := d.buffer()
 	var off uint8
 	var decoded int
 
 	// Decode 4 values from each decoder/loop.
-	const bufoff = 256 / 4
+	const bufoff = 256
 	for {
 		if br[0].off < 4 || br[1].off < 4 || br[2].off < 4 || br[3].off < 4 {
 			break
@@ -1150,104 +1197,109 @@ func (d *Decoder) decompress4X8bitExactly(dst, src []byte) ([]byte, error) {
 			// Interleave 2 decodes.
 			const stream = 0
 			const stream2 = 1
-			br[stream].fillFast()
+			br1 := &br[stream]
-			br[stream2].fillFast()
+			br2 := &br[stream2]
+			br1.fillFast()
+			br2.fillFast()
 
-			v := single[uint8(br[stream].value>>shift)].entry
+			v := single[uint8(br1.value>>shift)].entry
-			v2 := single[uint8(br[stream2].value>>shift)].entry
+			v2 := single[uint8(br2.value>>shift)].entry
-			br[stream].bitsRead += uint8(v)
+			br1.bitsRead += uint8(v)
-			br[stream].value <<= v & 63
+			br1.value <<= v & 63
-			br[stream2].bitsRead += uint8(v2)
+			br2.bitsRead += uint8(v2)
-			br[stream2].value <<= v2 & 63
+			br2.value <<= v2 & 63
-			buf[off+bufoff*stream] = uint8(v >> 8)
+			buf[stream][off] = uint8(v >> 8)
-			buf[off+bufoff*stream2] = uint8(v2 >> 8)
+			buf[stream2][off] = uint8(v2 >> 8)
 
-			v = single[uint8(br[stream].value>>shift)].entry
+			v = single[uint8(br1.value>>shift)].entry
-			v2 = single[uint8(br[stream2].value>>shift)].entry
+			v2 = single[uint8(br2.value>>shift)].entry
-			br[stream].bitsRead += uint8(v)
+			br1.bitsRead += uint8(v)
-			br[stream].value <<= v & 63
+			br1.value <<= v & 63
-			br[stream2].bitsRead += uint8(v2)
+			br2.bitsRead += uint8(v2)
-			br[stream2].value <<= v2 & 63
+			br2.value <<= v2 & 63
-			buf[off+bufoff*stream+1] = uint8(v >> 8)
+			buf[stream][off+1] = uint8(v >> 8)
-			buf[off+bufoff*stream2+1] = uint8(v2 >> 8)
+			buf[stream2][off+1] = uint8(v2 >> 8)
 
-			v = single[uint8(br[stream].value>>shift)].entry
+			v = single[uint8(br1.value>>shift)].entry
-			v2 = single[uint8(br[stream2].value>>shift)].entry
+			v2 = single[uint8(br2.value>>shift)].entry
-			br[stream].bitsRead += uint8(v)
+			br1.bitsRead += uint8(v)
-			br[stream].value <<= v & 63
+			br1.value <<= v & 63
-			br[stream2].bitsRead += uint8(v2)
+			br2.bitsRead += uint8(v2)
-			br[stream2].value <<= v2 & 63
+			br2.value <<= v2 & 63
-			buf[off+bufoff*stream+2] = uint8(v >> 8)
+			buf[stream][off+2] = uint8(v >> 8)
-			buf[off+bufoff*stream2+2] = uint8(v2 >> 8)
+			buf[stream2][off+2] = uint8(v2 >> 8)
 
-			v = single[uint8(br[stream].value>>shift)].entry
+			v = single[uint8(br1.value>>shift)].entry
-			v2 = single[uint8(br[stream2].value>>shift)].entry
+			v2 = single[uint8(br2.value>>shift)].entry
-			br[stream].bitsRead += uint8(v)
+			br1.bitsRead += uint8(v)
-			br[stream].value <<= v & 63
+			br1.value <<= v & 63
-			br[stream2].bitsRead += uint8(v2)
+			br2.bitsRead += uint8(v2)
-			br[stream2].value <<= v2 & 63
+			br2.value <<= v2 & 63
-			buf[off+bufoff*stream+3] = uint8(v >> 8)
+			buf[stream][off+3] = uint8(v >> 8)
-			buf[off+bufoff*stream2+3] = uint8(v2 >> 8)
+			buf[stream2][off+3] = uint8(v2 >> 8)
 		}
 
 		{
 			const stream = 2
 			const stream2 = 3
-			br[stream].fillFast()
+			br1 := &br[stream]
-			br[stream2].fillFast()
+			br2 := &br[stream2]
+			br1.fillFast()
+			br2.fillFast()
 
-			v := single[uint8(br[stream].value>>shift)].entry
+			v := single[uint8(br1.value>>shift)].entry
-			v2 := single[uint8(br[stream2].value>>shift)].entry
+			v2 := single[uint8(br2.value>>shift)].entry
-			br[stream].bitsRead += uint8(v)
+			br1.bitsRead += uint8(v)
-			br[stream].value <<= v & 63
+			br1.value <<= v & 63
-			br[stream2].bitsRead += uint8(v2)
+			br2.bitsRead += uint8(v2)
-			br[stream2].value <<= v2 & 63
+			br2.value <<= v2 & 63
-			buf[off+bufoff*stream] = uint8(v >> 8)
+			buf[stream][off] = uint8(v >> 8)
-			buf[off+bufoff*stream2] = uint8(v2 >> 8)
+			buf[stream2][off] = uint8(v2 >> 8)
 
-			v = single[uint8(br[stream].value>>shift)].entry
+			v = single[uint8(br1.value>>shift)].entry
-			v2 = single[uint8(br[stream2].value>>shift)].entry
+			v2 = single[uint8(br2.value>>shift)].entry
-			br[stream].bitsRead += uint8(v)
+			br1.bitsRead += uint8(v)
-			br[stream].value <<= v & 63
+			br1.value <<= v & 63
-			br[stream2].bitsRead += uint8(v2)
+			br2.bitsRead += uint8(v2)
-			br[stream2].value <<= v2 & 63
+			br2.value <<= v2 & 63
-			buf[off+bufoff*stream+1] = uint8(v >> 8)
+			buf[stream][off+1] = uint8(v >> 8)
-			buf[off+bufoff*stream2+1] = uint8(v2 >> 8)
+			buf[stream2][off+1] = uint8(v2 >> 8)
 
-			v = single[uint8(br[stream].value>>shift)].entry
+			v = single[uint8(br1.value>>shift)].entry
-			v2 = single[uint8(br[stream2].value>>shift)].entry
+			v2 = single[uint8(br2.value>>shift)].entry
-			br[stream].bitsRead += uint8(v)
+			br1.bitsRead += uint8(v)
-			br[stream].value <<= v & 63
+			br1.value <<= v & 63
-			br[stream2].bitsRead += uint8(v2)
+			br2.bitsRead += uint8(v2)
-			br[stream2].value <<= v2 & 63
+			br2.value <<= v2 & 63
-			buf[off+bufoff*stream+2] = uint8(v >> 8)
+			buf[stream][off+2] = uint8(v >> 8)
-			buf[off+bufoff*stream2+2] = uint8(v2 >> 8)
+			buf[stream2][off+2] = uint8(v2 >> 8)
 
-			v = single[uint8(br[stream].value>>shift)].entry
+			v = single[uint8(br1.value>>shift)].entry
-			v2 = single[uint8(br[stream2].value>>shift)].entry
+			v2 = single[uint8(br2.value>>shift)].entry
-			br[stream].bitsRead += uint8(v)
+			br1.bitsRead += uint8(v)
-			br[stream].value <<= v & 63
+			br1.value <<= v & 63
-			br[stream2].bitsRead += uint8(v2)
+			br2.bitsRead += uint8(v2)
-			br[stream2].value <<= v2 & 63
+			br2.value <<= v2 & 63
-			buf[off+bufoff*stream+3] = uint8(v >> 8)
+			buf[stream][off+3] = uint8(v >> 8)
-			buf[off+bufoff*stream2+3] = uint8(v2 >> 8)
+			buf[stream2][off+3] = uint8(v2 >> 8)
 		}
 
 		off += 4
 
-		if off == bufoff {
+		if off == 0 {
 			if bufoff > dstEvery {
+				d.bufs.Put(buf)
 				return nil, errors.New("corruption detected: stream overrun 1")
 			}
-			copy(out, buf[:bufoff])
+			copy(out, buf[0][:])
-			copy(out[dstEvery:], buf[bufoff:bufoff*2])
+			copy(out[dstEvery:], buf[1][:])
-			copy(out[dstEvery*2:], buf[bufoff*2:bufoff*3])
+			copy(out[dstEvery*2:], buf[2][:])
-			copy(out[dstEvery*3:], buf[bufoff*3:bufoff*4])
+			copy(out[dstEvery*3:], buf[3][:])
-			off = 0
 			out = out[bufoff:]
-			decoded += 256
+			decoded += bufoff * 4
 			// There must at least be 3 buffers left.
 			if len(out) < dstEvery*3 {
+				d.bufs.Put(buf)
 				return nil, errors.New("corruption detected: stream overrun 2")
 			}
 		}
@@ -1257,21 +1309,27 @@ func (d *Decoder) decompress4X8bitExactly(dst, src []byte) ([]byte, error) {
 		if len(out) < dstEvery*3+ioff {
 			return nil, errors.New("corruption detected: stream overrun 3")
 		}
-		copy(out, buf[:off])
+		copy(out, buf[0][:off])
-		copy(out[dstEvery:dstEvery+ioff], buf[bufoff:bufoff*2])
+		copy(out[dstEvery:], buf[1][:off])
-		copy(out[dstEvery*2:dstEvery*2+ioff], buf[bufoff*2:bufoff*3])
+		copy(out[dstEvery*2:], buf[2][:off])
-		copy(out[dstEvery*3:dstEvery*3+ioff], buf[bufoff*3:bufoff*4])
+		copy(out[dstEvery*3:], buf[3][:off])
 		decoded += int(off) * 4
 		out = out[off:]
 	}
 
 	// Decode remaining.
+	remainBytes := dstEvery - (decoded / 4)
 	for i := range br {
 		offset := dstEvery * i
+		endsAt := offset + remainBytes
+		if endsAt > len(out) {
+			endsAt = len(out)
+		}
 		br := &br[i]
-		bitsLeft := int(br.off*8) + int(64-br.bitsRead)
+		bitsLeft := br.remaining()
 		for bitsLeft > 0 {
 			if br.finished() {
+				d.bufs.Put(buf)
 				return nil, io.ErrUnexpectedEOF
 			}
 			if br.bitsRead >= 56 {
@@ -1291,7 +1349,8 @@ func (d *Decoder) decompress4X8bitExactly(dst, src []byte) ([]byte, error) {
 				}
 			}
 			// end inline...
-			if offset >= len(out) {
+			if offset >= endsAt {
+				d.bufs.Put(buf)
 				return nil, errors.New("corruption detected: stream overrun 4")
 			}
 
@@ -1299,16 +1358,23 @@ func (d *Decoder) decompress4X8bitExactly(dst, src []byte) ([]byte, error) {
 			v := single[br.peekByteFast()].entry
 			nBits := uint8(v)
 			br.advance(nBits)
-			bitsLeft -= int(nBits)
+			bitsLeft -= uint(nBits)
 			out[offset] = uint8(v >> 8)
 			offset++
 		}
+		if offset != endsAt {
+			d.bufs.Put(buf)
+			return nil, fmt.Errorf("corruption detected: short output block %d, end %d != %d", i, offset, endsAt)
+		}
+
 		decoded += offset - dstEvery*i
 		err = br.close()
 		if err != nil {
+			d.bufs.Put(buf)
 			return nil, err
 		}
 	}
+	d.bufs.Put(buf)
 	if dstSize != decoded {
 		return nil, errors.New("corruption detected: short output block")
 	}

vendor/github.com/klauspost/compress/huff0/huff0.go

@@ -8,6 +8,7 @@ import (
 	"fmt"
 	"math"
 	"math/bits"
+	"sync"
 
 	"github.com/klauspost/compress/fse"
 )
@@ -116,6 +117,7 @@ type Scratch struct {
 	nodes          []nodeElt
 	tmpOut         [4][]byte
 	fse            *fse.Scratch
+	decPool        sync.Pool // *[4][256]byte buffers.
 	huffWeight     [maxSymbolValue + 1]byte
 }
 

vendor/github.com/klauspost/compress/zstd/README.md

@@ -78,6 +78,9 @@ of a stream. This is independent of the `WithEncoderConcurrency(n)`, but that is
 in the future. So if you want to limit concurrency for future updates, specify the concurrency
 you would like.
 
+If you would like stream encoding to be done without spawning async goroutines, use `WithEncoderConcurrency(1)`
+which will compress input as each block is completed, blocking on writes until each has completed.
+
 You can specify your desired compression level using `WithEncoderLevel()` option. Currently only pre-defined 
 compression settings can be specified.
 
@@ -104,7 +107,8 @@ and seems to ignore concatenated streams, even though [it is part of the spec](h
 For compressing small blocks, the returned encoder has a function called `EncodeAll(src, dst []byte) []byte`.
 
 `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.
+This function can be called concurrently. 
+Each call will only run on a same goroutine as the caller.
 
 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`.
@@ -283,8 +287,13 @@ func Decompress(in io.Reader, out io.Writer) error {
 }
 ```
 
-It is important to use the "Close" function when you no longer need the Reader to stop running goroutines. 
+It is important to use the "Close" function when you no longer need the Reader to stop running goroutines, 
-See "Allocation-less operation" below.
+when running with default settings.
+Goroutines will exit once an error has been returned, including `io.EOF` at the end of a stream.
+
+Streams are decoded concurrently in 4 asynchronous stages to give the best possible throughput.
+However, if you prefer synchronous decompression, use `WithDecoderConcurrency(1)` which will decompress data 
+as it is being requested only.
 
 For decoding buffers, it could look something like this:
 
@@ -293,7 +302,7 @@ import "github.com/klauspost/compress/zstd"
 
 // Create a reader that caches decompressors.
 // For this operation type we supply a nil Reader.
-var decoder, _ = zstd.NewReader(nil)
+var decoder, _ = zstd.NewReader(nil, WithDecoderConcurrency(0))
 
 // Decompress a buffer. We don't supply a destination buffer,
 // so it will be allocated by the decoder.
@@ -304,8 +313,11 @@ func Decompress(src []byte) ([]byte, error) {
 
 Both of these cases should provide the functionality needed. 
 The decoder can be used for *concurrent* decompression of multiple buffers.
+By default 4 decompressors will be created. 
+
 It will only allow a certain number of concurrent operations to run. 
 To tweak that yourself use the `WithDecoderConcurrency(n)` option when creating the decoder.
+It is possible to use `WithDecoderConcurrency(0)` to create GOMAXPROCS decoders.
 
 ### Dictionaries
 
@@ -357,18 +369,20 @@ In this case no unneeded allocations should be made.
 The buffer decoder does everything on the same goroutine and does nothing concurrently.
 It can however decode several buffers concurrently. Use `WithDecoderConcurrency(n)` to limit that.
 
-The stream decoder operates on
+The stream decoder will create goroutines that:
 
-* One goroutine reads input and splits the input to several block decoders.
+1) Reads input and splits the input into blocks.
-* A number of decoders will decode blocks.
+2) Decompression of literals.
-* A goroutine coordinates these blocks and sends history from one to the next.
+3) Decompression of sequences.
+4) Reconstruction of output stream.
 
 So effectively this also means the decoder will "read ahead" and prepare data to always be available for output.
 
+The concurrency level will, for streams, determine how many blocks ahead the compression will start.
+
 Since "blocks" are quite dependent on the output of the previous block stream decoding will only have limited concurrency.
 
-In practice this means that concurrency is often limited to utilizing about 2 cores effectively.
+In practice this means that concurrency is often limited to utilizing about 3 cores effectively.
- 
   
 ### Benchmarks
 

vendor/github.com/klauspost/compress/zstd/bitreader.go

@@ -7,6 +7,7 @@ package zstd
 import (
 	"encoding/binary"
 	"errors"
+	"fmt"
 	"io"
 	"math/bits"
 )
@@ -132,6 +133,9 @@ func (b *bitReader) remain() uint {
 func (b *bitReader) close() error {
 	// Release reference.
 	b.in = nil
+	if !b.finished() {
+		return fmt.Errorf("%d extra bits on block, should be 0", b.remain())
+	}
 	if b.bitsRead > 64 {
 		return io.ErrUnexpectedEOF
 	}

vendor/github.com/klauspost/compress/zstd/blockdec.go

@@ -76,16 +76,25 @@ type blockDec struct {
 	// Window size of the block.
 	WindowSize uint64
 
-	history chan *history
-	input   chan struct{}
-	result  chan decodeOutput
 	err error
-	decWG   sync.WaitGroup
+
+	// Check against this crc
+	checkCRC []byte
 
 	// Frame to use for singlethreaded decoding.
 	// Should not be used by the decoder itself since parent may be another frame.
 	localFrame *frameDec
 
+	sequence []seqVals
+
+	async struct {
+		newHist  *history
+		literals []byte
+		seqData  []byte
+		seqSize  int // Size of uncompressed sequences
+		fcs      uint64
+	}
+
 	// Block is RLE, this is the size.
 	RLESize uint32
 	tmp     [4]byte
@@ -109,12 +118,7 @@ func (b *blockDec) String() string {
 func newBlockDec(lowMem bool) *blockDec {
 	b := blockDec{
 		lowMem: lowMem,
-		result:  make(chan decodeOutput, 1),
-		input:   make(chan struct{}, 1),
-		history: make(chan *history, 1),
 	}
-	b.decWG.Add(1)
-	go b.startDecoder()
 	return &b
 }
 
@@ -137,6 +141,12 @@ func (b *blockDec) reset(br byteBuffer, windowSize uint64) error {
 	case blockTypeReserved:
 		return ErrReservedBlockType
 	case blockTypeRLE:
+		if cSize > maxCompressedBlockSize || cSize > int(b.WindowSize) {
+			if debugDecoder {
+				printf("rle block too big: csize:%d block: %+v\n", uint64(cSize), b)
+			}
+			return ErrWindowSizeExceeded
+		}
 		b.RLESize = uint32(cSize)
 		if b.lowMem {
 			maxSize = cSize
@@ -158,6 +168,13 @@ func (b *blockDec) reset(br byteBuffer, windowSize uint64) error {
 			return ErrCompressedSizeTooBig
 		}
 	case blockTypeRaw:
+		if cSize > maxCompressedBlockSize || cSize > int(b.WindowSize) {
+			if debugDecoder {
+				printf("rle block too big: csize:%d block: %+v\n", uint64(cSize), b)
+			}
+			return ErrWindowSizeExceeded
+		}
+
 		b.RLESize = 0
 		// We do not need a destination for raw blocks.
 		maxSize = -1
@@ -192,85 +209,14 @@ func (b *blockDec) sendErr(err error) {
 	b.Last = true
 	b.Type = blockTypeReserved
 	b.err = err
-	b.input <- struct{}{}
 }
 
 // Close will release resources.
 // Closed blockDec cannot be reset.
 func (b *blockDec) Close() {
-	close(b.input)
-	close(b.history)
-	close(b.result)
-	b.decWG.Wait()
 }
 
-// decodeAsync will prepare decoding the block when it receives input.
+// decodeBuf
-// This will separate output and history.
-func (b *blockDec) startDecoder() {
-	defer b.decWG.Done()
-	for range b.input {
-		//println("blockDec: Got block input")
-		switch b.Type {
-		case blockTypeRLE:
-			if cap(b.dst) < int(b.RLESize) {
-				if b.lowMem {
-					b.dst = make([]byte, b.RLESize)
-				} else {
-					b.dst = make([]byte, maxBlockSize)
-				}
-			}
-			o := decodeOutput{
-				d:   b,
-				b:   b.dst[:b.RLESize],
-				err: nil,
-			}
-			v := b.data[0]
-			for i := range o.b {
-				o.b[i] = v
-			}
-			hist := <-b.history
-			hist.append(o.b)
-			b.result <- o
-		case blockTypeRaw:
-			o := decodeOutput{
-				d:   b,
-				b:   b.data,
-				err: nil,
-			}
-			hist := <-b.history
-			hist.append(o.b)
-			b.result <- o
-		case blockTypeCompressed:
-			b.dst = b.dst[:0]
-			err := b.decodeCompressed(nil)
-			o := decodeOutput{
-				d:   b,
-				b:   b.dst,
-				err: err,
-			}
-			if debugDecoder {
-				println("Decompressed to", len(b.dst), "bytes, error:", err)
-			}
-			b.result <- o
-		case blockTypeReserved:
-			// Used for returning errors.
-			<-b.history
-			b.result <- decodeOutput{
-				d:   b,
-				b:   nil,
-				err: b.err,
-			}
-		default:
-			panic("Invalid block type")
-		}
-		if debugDecoder {
-			println("blockDec: Finished block")
-		}
-	}
-}
-
-// decodeAsync will prepare decoding the block when it receives the history.
-// If history is provided, it will not fetch it from the channel.
 func (b *blockDec) decodeBuf(hist *history) error {
 	switch b.Type {
 	case blockTypeRLE:
@@ -293,14 +239,23 @@ func (b *blockDec) decodeBuf(hist *history) error {
 		return nil
 	case blockTypeCompressed:
 		saved := b.dst
+		// Append directly to history
+		if hist.ignoreBuffer == 0 {
 			b.dst = hist.b
 			hist.b = nil
+		} else {
+			b.dst = b.dst[:0]
+		}
 		err := b.decodeCompressed(hist)
 		if debugDecoder {
 			println("Decompressed to total", len(b.dst), "bytes, hash:", xxhash.Sum64(b.dst), "error:", err)
 		}
+		if hist.ignoreBuffer == 0 {
 			hist.b = b.dst
 			b.dst = saved
+		} else {
+			hist.appendKeep(b.dst)
+		}
 		return err
 	case blockTypeReserved:
 		// Used for returning errors.
@@ -310,30 +265,18 @@ func (b *blockDec) decodeBuf(hist *history) error {
 	}
 }
 
-// decodeCompressed will start decompressing a block.
+func (b *blockDec) decodeLiterals(in []byte, hist *history) (remain []byte, err error) {
-// If no history is supplied the decoder will decodeAsync as much as possible
-// before fetching from blockDec.history
-func (b *blockDec) decodeCompressed(hist *history) error {
-	in := b.data
-	delayedHistory := hist == nil
-
-	if delayedHistory {
-		// We must always grab history.
-		defer func() {
-			if hist == nil {
-				<-b.history
-			}
-		}()
-	}
 	// There must be at least one byte for Literals_Block_Type and one for Sequences_Section_Header
 	if len(in) < 2 {
-		return ErrBlockTooSmall
+		return in, ErrBlockTooSmall
 	}
+
 	litType := literalsBlockType(in[0] & 3)
 	var litRegenSize int
 	var litCompSize int
 	sizeFormat := (in[0] >> 2) & 3
 	var fourStreams bool
+	var literals []byte
 	switch litType {
 	case literalsBlockRaw, literalsBlockRLE:
 		switch sizeFormat {
@@ -349,7 +292,7 @@ func (b *blockDec) decodeCompressed(hist *history) error {
 			//  Regenerated_Size uses 20 bits (0-1048575). Literals_Section_Header uses 3 bytes.
 			if len(in) < 3 {
 				println("too small: litType:", litType, " sizeFormat", sizeFormat, len(in))
-				return ErrBlockTooSmall
+				return in, ErrBlockTooSmall
 			}
 			litRegenSize = int(in[0]>>4) + (int(in[1]) << 4) + (int(in[2]) << 12)
 			in = in[3:]
@@ -360,7 +303,7 @@ func (b *blockDec) decodeCompressed(hist *history) error {
 			// Both Regenerated_Size and Compressed_Size use 10 bits (0-1023).
 			if len(in) < 3 {
 				println("too small: litType:", litType, " sizeFormat", sizeFormat, len(in))
-				return ErrBlockTooSmall
+				return in, ErrBlockTooSmall
 			}
 			n := uint64(in[0]>>4) + (uint64(in[1]) << 4) + (uint64(in[2]) << 12)
 			litRegenSize = int(n & 1023)
@@ -371,7 +314,7 @@ func (b *blockDec) decodeCompressed(hist *history) error {
 			fourStreams = true
 			if len(in) < 4 {
 				println("too small: litType:", litType, " sizeFormat", sizeFormat, len(in))
-				return ErrBlockTooSmall
+				return in, ErrBlockTooSmall
 			}
 			n := uint64(in[0]>>4) + (uint64(in[1]) << 4) + (uint64(in[2]) << 12) + (uint64(in[3]) << 20)
 			litRegenSize = int(n & 16383)
@@ -381,7 +324,7 @@ func (b *blockDec) decodeCompressed(hist *history) error {
 			fourStreams = true
 			if len(in) < 5 {
 				println("too small: litType:", litType, " sizeFormat", sizeFormat, len(in))
-				return ErrBlockTooSmall
+				return in, ErrBlockTooSmall
 			}
 			n := uint64(in[0]>>4) + (uint64(in[1]) << 4) + (uint64(in[2]) << 12) + (uint64(in[3]) << 20) + (uint64(in[4]) << 28)
 			litRegenSize = int(n & 262143)
@@ -392,13 +335,15 @@ func (b *blockDec) decodeCompressed(hist *history) error {
 	if debugDecoder {
 		println("literals type:", litType, "litRegenSize:", litRegenSize, "litCompSize:", litCompSize, "sizeFormat:", sizeFormat, "4X:", fourStreams)
 	}
-	var literals []byte
+	if litRegenSize > int(b.WindowSize) || litRegenSize > maxCompressedBlockSize {
-	var huff *huff0.Scratch
+		return in, ErrWindowSizeExceeded
+	}
+
 	switch litType {
 	case literalsBlockRaw:
 		if len(in) < litRegenSize {
 			println("too small: litType:", litType, " sizeFormat", sizeFormat, "remain:", len(in), "want:", litRegenSize)
-			return ErrBlockTooSmall
+			return in, ErrBlockTooSmall
 		}
 		literals = in[:litRegenSize]
 		in = in[litRegenSize:]
@@ -406,7 +351,7 @@ func (b *blockDec) decodeCompressed(hist *history) error {
 	case literalsBlockRLE:
 		if len(in) < 1 {
 			println("too small: litType:", litType, " sizeFormat", sizeFormat, "remain:", len(in), "want:", 1)
-			return ErrBlockTooSmall
+			return in, ErrBlockTooSmall
 		}
 		if cap(b.literalBuf) < litRegenSize {
 			if b.lowMem {
@@ -417,7 +362,6 @@ func (b *blockDec) decodeCompressed(hist *history) error {
 					b.literalBuf = make([]byte, litRegenSize)
 				} else {
 					b.literalBuf = make([]byte, litRegenSize, maxCompressedLiteralSize)
-
 				}
 			}
 		}
@@ -433,7 +377,7 @@ func (b *blockDec) decodeCompressed(hist *history) error {
 	case literalsBlockTreeless:
 		if len(in) < litCompSize {
 			println("too small: litType:", litType, " sizeFormat", sizeFormat, "remain:", len(in), "want:", litCompSize)
-			return ErrBlockTooSmall
+			return in, ErrBlockTooSmall
 		}
 		// Store compressed literals, so we defer decoding until we get history.
 		literals = in[:litCompSize]
@@ -441,15 +385,10 @@ func (b *blockDec) decodeCompressed(hist *history) error {
 		if debugDecoder {
 			printf("Found %d compressed literals\n", litCompSize)
 		}
-	case literalsBlockCompressed:
+		huff := hist.huffTree
-		if len(in) < litCompSize {
+		if huff == nil {
-			println("too small: litType:", litType, " sizeFormat", sizeFormat, "remain:", len(in), "want:", litCompSize)
+			return in, errors.New("literal block was treeless, but no history was defined")
-			return ErrBlockTooSmall
 		}
-		literals = in[:litCompSize]
-		in = in[litCompSize:]
-		huff = huffDecoderPool.Get().(*huff0.Scratch)
-		var err error
 		// Ensure we have space to store it.
 		if cap(b.literalBuf) < litRegenSize {
 			if b.lowMem {
@@ -458,14 +397,53 @@ func (b *blockDec) decodeCompressed(hist *history) error {
 				b.literalBuf = make([]byte, 0, maxCompressedLiteralSize)
 			}
 		}
+		var err error
+		// Use our out buffer.
+		huff.MaxDecodedSize = maxCompressedBlockSize
+		if fourStreams {
+			literals, err = huff.Decoder().Decompress4X(b.literalBuf[:0:litRegenSize], literals)
+		} else {
+			literals, err = huff.Decoder().Decompress1X(b.literalBuf[:0:litRegenSize], literals)
+		}
+		// Make sure we don't leak our literals buffer
+		if err != nil {
+			println("decompressing literals:", err)
+			return in, err
+		}
+		if len(literals) != litRegenSize {
+			return in, fmt.Errorf("literal output size mismatch want %d, got %d", litRegenSize, len(literals))
+		}
+
+	case literalsBlockCompressed:
+		if len(in) < litCompSize {
+			println("too small: litType:", litType, " sizeFormat", sizeFormat, "remain:", len(in), "want:", litCompSize)
+			return in, ErrBlockTooSmall
+		}
+		literals = in[:litCompSize]
+		in = in[litCompSize:]
+		// Ensure we have space to store it.
+		if cap(b.literalBuf) < litRegenSize {
+			if b.lowMem {
+				b.literalBuf = make([]byte, 0, litRegenSize)
+			} else {
+				b.literalBuf = make([]byte, 0, maxCompressedBlockSize)
+			}
+		}
+		huff := hist.huffTree
+		if huff == nil || (hist.dict != nil && huff == hist.dict.litEnc) {
+			huff = huffDecoderPool.Get().(*huff0.Scratch)
 			if huff == nil {
 				huff = &huff0.Scratch{}
 			}
+		}
+		var err error
 		huff, literals, err = huff0.ReadTable(literals, huff)
 		if err != nil {
 			println("reading huffman table:", err)
-			return err
+			return in, err
 		}
+		hist.huffTree = huff
+		huff.MaxDecodedSize = maxCompressedBlockSize
 		// Use our out buffer.
 		if fourStreams {
 			literals, err = huff.Decoder().Decompress4X(b.literalBuf[:0:litRegenSize], literals)
@@ -474,24 +452,52 @@ func (b *blockDec) decodeCompressed(hist *history) error {
 		}
 		if err != nil {
 			println("decoding compressed literals:", err)
-			return err
+			return in, err
 		}
 		// Make sure we don't leak our literals buffer
 		if len(literals) != litRegenSize {
-			return fmt.Errorf("literal output size mismatch want %d, got %d", litRegenSize, len(literals))
+			return in, fmt.Errorf("literal output size mismatch want %d, got %d", litRegenSize, len(literals))
 		}
 		if debugDecoder {
 			printf("Decompressed %d literals into %d bytes\n", litCompSize, litRegenSize)
 		}
 	}
+	hist.decoders.literals = literals
+	return in, nil
+}
 
+// decodeCompressed will start decompressing a block.
+func (b *blockDec) decodeCompressed(hist *history) error {
+	in := b.data
+	in, err := b.decodeLiterals(in, hist)
+	if err != nil {
+		return err
+	}
+	err = b.prepareSequences(in, hist)
+	if err != nil {
+		return err
+	}
+	if hist.decoders.nSeqs == 0 {
+		b.dst = append(b.dst, hist.decoders.literals...)
+		return nil
+	}
+	err = hist.decoders.decodeSync(hist)
+	if err != nil {
+		return err
+	}
+	b.dst = hist.decoders.out
+	hist.recentOffsets = hist.decoders.prevOffset
+	return nil
+}
+
+func (b *blockDec) prepareSequences(in []byte, hist *history) (err error) {
 	// Decode Sequences
 	// https://github.com/facebook/zstd/blob/dev/doc/zstd_compression_format.md#sequences-section
 	if len(in) < 1 {
 		return ErrBlockTooSmall
 	}
+	var nSeqs int
 	seqHeader := in[0]
-	nSeqs := 0
 	switch {
 	case seqHeader == 0:
 		in = in[1:]
@@ -512,7 +518,8 @@ func (b *blockDec) decodeCompressed(hist *history) error {
 		in = in[3:]
 	}
 
-	var seqs = &sequenceDecs{}
+	var seqs = &hist.decoders
+	seqs.nSeqs = nSeqs
 	if nSeqs > 0 {
 		if len(in) < 1 {
 			return ErrBlockTooSmall
@@ -541,6 +548,9 @@ func (b *blockDec) decodeCompressed(hist *history) error {
 			}
 			switch mode {
 			case compModePredefined:
+				if seq.fse != nil && !seq.fse.preDefined {
+					fseDecoderPool.Put(seq.fse)
+				}
 				seq.fse = &fsePredef[i]
 			case compModeRLE:
 				if br.remain() < 1 {
@@ -548,34 +558,36 @@ func (b *blockDec) decodeCompressed(hist *history) error {
 				}
 				v := br.Uint8()
 				br.advance(1)
-				dec := fseDecoderPool.Get().(*fseDecoder)
+				if seq.fse == nil || seq.fse.preDefined {
+					seq.fse = fseDecoderPool.Get().(*fseDecoder)
+				}
 				symb, err := decSymbolValue(v, symbolTableX[i])
 				if err != nil {
 					printf("RLE Transform table (%v) error: %v", tableIndex(i), err)
 					return err
 				}
-				dec.setRLE(symb)
+				seq.fse.setRLE(symb)
-				seq.fse = dec
 				if debugDecoder {
 					printf("RLE set to %+v, code: %v", symb, v)
 				}
 			case compModeFSE:
 				println("Reading table for", tableIndex(i))
-				dec := fseDecoderPool.Get().(*fseDecoder)
+				if seq.fse == nil || seq.fse.preDefined {
-				err := dec.readNCount(&br, uint16(maxTableSymbol[i]))
+					seq.fse = fseDecoderPool.Get().(*fseDecoder)
+				}
+				err := seq.fse.readNCount(&br, uint16(maxTableSymbol[i]))
 				if err != nil {
 					println("Read table error:", err)
 					return err
 				}
-				err = dec.transform(symbolTableX[i])
+				err = seq.fse.transform(symbolTableX[i])
 				if err != nil {
 					println("Transform table error:", err)
 					return err
 				}
 				if debugDecoder {
-					println("Read table ok", "symbolLen:", dec.symbolLen)
+					println("Read table ok", "symbolLen:", seq.fse.symbolLen)
 				}
-				seq.fse = dec
 			case compModeRepeat:
 				seq.repeat = true
 			}
@@ -585,140 +597,88 @@ func (b *blockDec) decodeCompressed(hist *history) error {
 		}
 		in = br.unread()
 	}
-
-	// Wait for history.
-	// All time spent after this is critical since it is strictly sequential.
-	if hist == nil {
-		hist = <-b.history
-		if hist.error {
-			return ErrDecoderClosed
-		}
-	}
-
-	// Decode treeless literal block.
-	if litType == literalsBlockTreeless {
-		// TODO: We could send the history early WITHOUT the stream history.
-		//   This would allow decoding treeless literals before the byte history is available.
-		//   Silencia stats: Treeless 4393, with: 32775, total: 37168, 11% treeless.
-		//   So not much obvious gain here.
-
-		if hist.huffTree == nil {
-			return errors.New("literal block was treeless, but no history was defined")
-		}
-		// Ensure we have space to store it.
-		if cap(b.literalBuf) < litRegenSize {
-			if b.lowMem {
-				b.literalBuf = make([]byte, 0, litRegenSize)
-			} else {
-				b.literalBuf = make([]byte, 0, maxCompressedLiteralSize)
-			}
-		}
-		var err error
-		// Use our out buffer.
-		huff = hist.huffTree
-		if fourStreams {
-			literals, err = huff.Decoder().Decompress4X(b.literalBuf[:0:litRegenSize], literals)
-		} else {
-			literals, err = huff.Decoder().Decompress1X(b.literalBuf[:0:litRegenSize], literals)
-		}
-		// Make sure we don't leak our literals buffer
-		if err != nil {
-			println("decompressing literals:", err)
-			return err
-		}
-		if len(literals) != litRegenSize {
-			return fmt.Errorf("literal output size mismatch want %d, got %d", litRegenSize, len(literals))
-		}
-	} else {
-		if hist.huffTree != nil && huff != nil {
-			if hist.dict == nil || hist.dict.litEnc != hist.huffTree {
-				huffDecoderPool.Put(hist.huffTree)
-			}
-			hist.huffTree = nil
-		}
-	}
-	if huff != nil {
-		hist.huffTree = huff
-	}
 	if debugDecoder {
-		println("Final literals:", len(literals), "hash:", xxhash.Sum64(literals), "and", nSeqs, "sequences.")
+		println("Literals:", len(seqs.literals), "hash:", xxhash.Sum64(seqs.literals), "and", seqs.nSeqs, "sequences.")
 	}
 
 	if nSeqs == 0 {
-		// Decompressed content is defined entirely as Literals Section content.
+		if len(b.sequence) > 0 {
-		b.dst = append(b.dst, literals...)
+			b.sequence = b.sequence[:0]
-		if delayedHistory {
-			hist.append(literals)
 		}
 		return nil
 	}
-
+	br := seqs.br
-	seqs, err := seqs.mergeHistory(&hist.decoders)
+	if br == nil {
-	if err != nil {
+		br = &bitReader{}
-		return err
 	}
-	if debugDecoder {
-		println("History merged ok")
-	}
-	br := &bitReader{}
 	if err := br.init(in); err != nil {
 		return err
 	}
 
-	// TODO: Investigate if sending history without decoders are faster.
+	if err := seqs.initialize(br, hist, b.dst); err != nil {
-	//   This would allow the sequences to be decoded async and only have to construct stream history.
+		println("initializing sequences:", err)
-	//   If only recent offsets were not transferred, this would be an obvious win.
+		return err
-	// 	 Also, if first 3 sequences don't reference recent offsets, all sequences can be decoded.
+	}
+	return nil
+}
 
+func (b *blockDec) decodeSequences(hist *history) error {
+	if cap(b.sequence) < hist.decoders.nSeqs {
+		if b.lowMem {
+			b.sequence = make([]seqVals, 0, hist.decoders.nSeqs)
+		} else {
+			b.sequence = make([]seqVals, 0, 0x7F00+0xffff)
+		}
+	}
+	b.sequence = b.sequence[:hist.decoders.nSeqs]
+	if hist.decoders.nSeqs == 0 {
+		hist.decoders.seqSize = len(hist.decoders.literals)
+		return nil
+	}
+	hist.decoders.prevOffset = hist.recentOffsets
+	err := hist.decoders.decode(b.sequence)
+	hist.recentOffsets = hist.decoders.prevOffset
+	return err
+}
+
+func (b *blockDec) executeSequences(hist *history) error {
 	hbytes := hist.b
 	if len(hbytes) > hist.windowSize {
 		hbytes = hbytes[len(hbytes)-hist.windowSize:]
-		// We do not need history any more.
+		// We do not need history anymore.
 		if hist.dict != nil {
 			hist.dict.content = nil
 		}
 	}
-
+	hist.decoders.windowSize = hist.windowSize
-	if err := seqs.initialize(br, hist, literals, b.dst); err != nil {
+	hist.decoders.out = b.dst[:0]
-		println("initializing sequences:", err)
+	err := hist.decoders.execute(b.sequence, hbytes)
-		return err
-	}
-
-	err = seqs.decode(nSeqs, br, hbytes)
 	if err != nil {
 		return err
 	}
-	if !br.finished() {
+	return b.updateHistory(hist)
-		return fmt.Errorf("%d extra bits on block, should be 0", br.remain())
+}
-	}
 
-	err = br.close()
+func (b *blockDec) updateHistory(hist *history) error {
-	if err != nil {
-		printf("Closing sequences: %v, %+v\n", err, *br)
-	}
 	if len(b.data) > maxCompressedBlockSize {
 		return fmt.Errorf("compressed block size too large (%d)", len(b.data))
 	}
 	// Set output and release references.
-	b.dst = seqs.out
+	b.dst = hist.decoders.out
-	seqs.out, seqs.literals, seqs.hist = nil, nil, nil
+	hist.recentOffsets = hist.decoders.prevOffset
 
-	if !delayedHistory {
-		// If we don't have delayed history, no need to update.
-		hist.recentOffsets = seqs.prevOffset
-		return nil
-	}
 	if b.Last {
 		// if last block we don't care about history.
 		println("Last block, no history returned")
 		hist.b = hist.b[:0]
 		return nil
-	}
+	} else {
 		hist.append(b.dst)
-	hist.recentOffsets = seqs.prevOffset
 		if debugDecoder {
-		println("Finished block with literals:", len(literals), "and", nSeqs, "sequences.")
+			println("Finished block with ", len(b.sequence), "sequences. Added", len(b.dst), "to history, now length", len(hist.b))
 		}
+	}
+	hist.decoders.out, hist.decoders.literals = nil, nil
 
 	return nil
 }

vendor/github.com/klauspost/compress/zstd/bytebuf.go

@@ -113,6 +113,9 @@ func (r *readerWrapper) readBig(n int, dst []byte) ([]byte, error) {
 func (r *readerWrapper) readByte() (byte, error) {
 	n2, err := r.r.Read(r.tmp[:1])
 	if err != nil {
+		if err == io.EOF {
+			err = io.ErrUnexpectedEOF
+		}
 		return 0, err
 	}
 	if n2 != 1 {

vendor/github.com/klauspost/compress/zstd/decoder.go

@@ -5,9 +5,13 @@
 package zstd
 
 import (
-	"errors"
+	"bytes"
+	"context"
+	"encoding/binary"
 	"io"
 	"sync"
+
+	"github.com/klauspost/compress/zstd/internal/xxhash"
 )
 
 // Decoder provides decoding of zstandard streams.
@@ -22,12 +26,19 @@ type Decoder struct {
 	// Unreferenced decoders, ready for use.
 	decoders chan *blockDec
 
-	// Streams ready to be decoded.
-	stream chan decodeStream
-
 	// Current read position used for Reader functionality.
 	current decoderState
 
+	// sync stream decoding
+	syncStream struct {
+		decodedFrame uint64
+		br           readerWrapper
+		enabled      bool
+		inFrame      bool
+	}
+
+	frame *frameDec
+
 	// Custom dictionaries.
 	// Always uses copies.
 	dicts map[uint32]dict
@@ -46,7 +57,10 @@ type decoderState struct {
 	output chan decodeOutput
 
 	// cancel remaining output.
-	cancel chan struct{}
+	cancel context.CancelFunc
+
+	// crc of current frame
+	crc *xxhash.Digest
 
 	flushed bool
 }
@@ -81,7 +95,7 @@ func NewReader(r io.Reader, opts ...DOption) (*Decoder, error) {
 			return nil, err
 		}
 	}
-	d.current.output = make(chan decodeOutput, d.o.concurrent)
+	d.current.crc = xxhash.New()
 	d.current.flushed = true
 
 	if r == nil {
@@ -130,7 +144,7 @@ func (d *Decoder) Read(p []byte) (int, error) {
 				break
 			}
 			if !d.nextBlock(n == 0) {
-				return n, nil
+				return n, d.current.err
 			}
 		}
 	}
@@ -162,6 +176,7 @@ func (d *Decoder) Reset(r io.Reader) error {
 
 	d.drainOutput()
 
+	d.syncStream.br.r = nil
 	if r == nil {
 		d.current.err = ErrDecoderNilInput
 		if len(d.current.b) > 0 {
@@ -195,33 +210,39 @@ func (d *Decoder) Reset(r io.Reader) error {
 		}
 		return nil
 	}
-
-	if d.stream == nil {
-		d.stream = make(chan decodeStream, 1)
-		d.streamWg.Add(1)
-		go d.startStreamDecoder(d.stream)
-	}
-
 	// Remove current block.
+	d.stashDecoder()
 	d.current.decodeOutput = decodeOutput{}
 	d.current.err = nil
-	d.current.cancel = make(chan struct{})
 	d.current.flushed = false
 	d.current.d = nil
 
-	d.stream <- decodeStream{
+	// Ensure no-one else is still running...
-		r:      r,
+	d.streamWg.Wait()
-		output: d.current.output,
+	if d.frame == nil {
-		cancel: d.current.cancel,
+		d.frame = newFrameDec(d.o)
 	}
+
+	if d.o.concurrent == 1 {
+		return d.startSyncDecoder(r)
+	}
+
+	d.current.output = make(chan decodeOutput, d.o.concurrent)
+	ctx, cancel := context.WithCancel(context.Background())
+	d.current.cancel = cancel
+	d.streamWg.Add(1)
+	go d.startStreamDecoder(ctx, r, d.current.output)
+
 	return nil
 }
 
 // drainOutput will drain the output until errEndOfStream is sent.
 func (d *Decoder) drainOutput() {
 	if d.current.cancel != nil {
+		if debugDecoder {
 			println("cancelling current")
-		close(d.current.cancel)
+		}
+		d.current.cancel()
 		d.current.cancel = nil
 	}
 	if d.current.d != nil {
@@ -243,12 +264,9 @@ func (d *Decoder) drainOutput() {
 			}
 			d.decoders <- v.d
 		}
-		if v.err == errEndOfStream {
+	}
-			println("current flushed")
+	d.current.output = nil
 	d.current.flushed = true
-			return
-		}
-	}
 }
 
 // WriteTo writes data to w until there's no more data to write or when an error occurs.
@@ -287,7 +305,7 @@ func (d *Decoder) WriteTo(w io.Writer) (int64, error) {
 // DecodeAll can be used concurrently.
 // The Decoder concurrency limits will be respected.
 func (d *Decoder) DecodeAll(input, dst []byte) ([]byte, error) {
-	if d.current.err == ErrDecoderClosed {
+	if d.decoders == nil {
 		return dst, ErrDecoderClosed
 	}
 
@@ -300,6 +318,9 @@ func (d *Decoder) DecodeAll(input, dst []byte) ([]byte, error) {
 		}
 		frame.rawInput = nil
 		frame.bBuf = nil
+		if frame.history.decoders.br != nil {
+			frame.history.decoders.br.in = nil
+		}
 		d.decoders <- block
 	}()
 	frame.bBuf = input
@@ -307,27 +328,31 @@ func (d *Decoder) DecodeAll(input, dst []byte) ([]byte, error) {
 	for {
 		frame.history.reset()
 		err := frame.reset(&frame.bBuf)
+		if err != nil {
 			if err == io.EOF {
 				if debugDecoder {
 					println("frame reset return EOF")
 				}
 				return dst, nil
 			}
+			return dst, err
+		}
 		if frame.DictionaryID != nil {
 			dict, ok := d.dicts[*frame.DictionaryID]
 			if !ok {
 				return nil, ErrUnknownDictionary
 			}
+			if debugDecoder {
+				println("setting dict", frame.DictionaryID)
+			}
 			frame.history.setDict(&dict)
 		}
-		if err != nil {
+
-			return dst, err
-		}
 		if frame.FrameContentSize > d.o.maxDecodedSize-uint64(len(dst)) {
 			return dst, ErrDecoderSizeExceeded
 		}
 		if frame.FrameContentSize > 0 && frame.FrameContentSize < 1<<30 {
-			// Never preallocate moe than 1 GB up front.
+			// Never preallocate more than 1 GB up front.
 			if cap(dst)-len(dst) < int(frame.FrameContentSize) {
 				dst2 := make([]byte, len(dst), len(dst)+int(frame.FrameContentSize))
 				copy(dst2, dst)
@@ -368,6 +393,161 @@ func (d *Decoder) DecodeAll(input, dst []byte) ([]byte, error) {
 // If non-blocking mode is used the returned boolean will be false
 // if no data was available without blocking.
 func (d *Decoder) nextBlock(blocking bool) (ok bool) {
+	if d.current.err != nil {
+		// Keep error state.
+		return false
+	}
+	d.current.b = d.current.b[:0]
+
+	// SYNC:
+	if d.syncStream.enabled {
+		if !blocking {
+			return false
+		}
+		ok = d.nextBlockSync()
+		if !ok {
+			d.stashDecoder()
+		}
+		return ok
+	}
+
+	//ASYNC:
+	d.stashDecoder()
+	if blocking {
+		d.current.decodeOutput, ok = <-d.current.output
+	} else {
+		select {
+		case d.current.decodeOutput, ok = <-d.current.output:
+		default:
+			return false
+		}
+	}
+	if !ok {
+		// This should not happen, so signal error state...
+		d.current.err = io.ErrUnexpectedEOF
+		return false
+	}
+	next := d.current.decodeOutput
+	if next.d != nil && next.d.async.newHist != nil {
+		d.current.crc.Reset()
+	}
+	if debugDecoder {
+		var tmp [4]byte
+		binary.LittleEndian.PutUint32(tmp[:], uint32(xxhash.Sum64(next.b)))
+		println("got", len(d.current.b), "bytes, error:", d.current.err, "data crc:", tmp)
+	}
+
+	if len(next.b) > 0 {
+		n, err := d.current.crc.Write(next.b)
+		if err == nil {
+			if n != len(next.b) {
+				d.current.err = io.ErrShortWrite
+			}
+		}
+	}
+	if next.err == nil && next.d != nil && len(next.d.checkCRC) != 0 {
+		got := d.current.crc.Sum64()
+		var tmp [4]byte
+		binary.LittleEndian.PutUint32(tmp[:], uint32(got))
+		if !bytes.Equal(tmp[:], next.d.checkCRC) && !ignoreCRC {
+			if debugDecoder {
+				println("CRC Check Failed:", tmp[:], " (got) !=", next.d.checkCRC, "(on stream)")
+			}
+			d.current.err = ErrCRCMismatch
+		} else {
+			if debugDecoder {
+				println("CRC ok", tmp[:])
+			}
+		}
+	}
+
+	return true
+}
+
+func (d *Decoder) nextBlockSync() (ok bool) {
+	if d.current.d == nil {
+		d.current.d = <-d.decoders
+	}
+	for len(d.current.b) == 0 {
+		if !d.syncStream.inFrame {
+			d.frame.history.reset()
+			d.current.err = d.frame.reset(&d.syncStream.br)
+			if d.current.err != nil {
+				return false
+			}
+			if d.frame.DictionaryID != nil {
+				dict, ok := d.dicts[*d.frame.DictionaryID]
+				if !ok {
+					d.current.err = ErrUnknownDictionary
+					return false
+				} else {
+					d.frame.history.setDict(&dict)
+				}
+			}
+			if d.frame.WindowSize > d.o.maxDecodedSize || d.frame.WindowSize > d.o.maxWindowSize {
+				d.current.err = ErrDecoderSizeExceeded
+				return false
+			}
+
+			d.syncStream.decodedFrame = 0
+			d.syncStream.inFrame = true
+		}
+		d.current.err = d.frame.next(d.current.d)
+		if d.current.err != nil {
+			return false
+		}
+		d.frame.history.ensureBlock()
+		if debugDecoder {
+			println("History trimmed:", len(d.frame.history.b), "decoded already:", d.syncStream.decodedFrame)
+		}
+		histBefore := len(d.frame.history.b)
+		d.current.err = d.current.d.decodeBuf(&d.frame.history)
+
+		if d.current.err != nil {
+			println("error after:", d.current.err)
+			return false
+		}
+		d.current.b = d.frame.history.b[histBefore:]
+		if debugDecoder {
+			println("history after:", len(d.frame.history.b))
+		}
+
+		// Check frame size (before CRC)
+		d.syncStream.decodedFrame += uint64(len(d.current.b))
+		if d.frame.FrameContentSize > 0 && d.syncStream.decodedFrame > d.frame.FrameContentSize {
+			if debugDecoder {
+				printf("DecodedFrame (%d) > FrameContentSize (%d)\n", d.syncStream.decodedFrame, d.frame.FrameContentSize)
+			}
+			d.current.err = ErrFrameSizeExceeded
+			return false
+		}
+
+		// Check FCS
+		if d.current.d.Last && d.frame.FrameContentSize > 0 && d.syncStream.decodedFrame != d.frame.FrameContentSize {
+			if debugDecoder {
+				printf("DecodedFrame (%d) != FrameContentSize (%d)\n", d.syncStream.decodedFrame, d.frame.FrameContentSize)
+			}
+			d.current.err = ErrFrameSizeMismatch
+			return false
+		}
+
+		// Update/Check CRC
+		if d.frame.HasCheckSum {
+			d.frame.crc.Write(d.current.b)
+			if d.current.d.Last {
+				d.current.err = d.frame.checkCRC()
+				if d.current.err != nil {
+					println("CRC error:", d.current.err)
+					return false
+				}
+			}
+		}
+		d.syncStream.inFrame = !d.current.d.Last
+	}
+	return true
+}
+
+func (d *Decoder) stashDecoder() {
 	if d.current.d != nil {
 		if debugDecoder {
 			printf("re-adding current decoder %p", d.current.d)
@@ -375,24 +555,6 @@ func (d *Decoder) nextBlock(blocking bool) (ok bool) {
 		d.decoders <- d.current.d
 		d.current.d = nil
 	}
-	if d.current.err != nil {
-		// Keep error state.
-		return blocking
-	}
-
-	if blocking {
-		d.current.decodeOutput = <-d.current.output
-	} else {
-		select {
-		case d.current.decodeOutput = <-d.current.output:
-		default:
-			return false
-		}
-	}
-	if debugDecoder {
-		println("got", len(d.current.b), "bytes, error:", d.current.err)
-	}
-	return true
 }
 
 // Close will release all resources.
@@ -402,10 +564,10 @@ func (d *Decoder) Close() {
 		return
 	}
 	d.drainOutput()
-	if d.stream != nil {
+	if d.current.cancel != nil {
-		close(d.stream)
+		d.current.cancel()
 		d.streamWg.Wait()
-		d.stream = nil
+		d.current.cancel = nil
 	}
 	if d.decoders != nil {
 		close(d.decoders)
@@ -456,39 +618,229 @@ type decodeOutput struct {
 	err error
 }
 
-type decodeStream struct {
+func (d *Decoder) startSyncDecoder(r io.Reader) error {
-	r io.Reader
+	d.frame.history.reset()
-
+	d.syncStream.br = readerWrapper{r: r}
-	// Blocks ready to be written to output.
+	d.syncStream.inFrame = false
-	output chan decodeOutput
+	d.syncStream.enabled = true
-
+	d.syncStream.decodedFrame = 0
-	// cancel reading from the input
+	return nil
-	cancel chan struct{}
 }
 
-// errEndOfStream indicates that everything from the stream was read.
-var errEndOfStream = errors.New("end-of-stream")
-
 // Create Decoder:
-// Spawn n block decoders. These accept tasks to decode a block.
+// ASYNC:
-// Create goroutine that handles stream processing, this will send history to decoders as they are available.
+// Spawn 4 go routines.
-// Decoders update the history as they decode.
+// 0: Read frames and decode blocks.
-// When a block is returned:
+// 1: Decode block and literals. Receives hufftree and seqdecs, returns seqdecs and huff tree.
-// 		a) history is sent to the next decoder,
+// 2: Wait for recentOffsets if needed. Decode sequences, send recentOffsets.
-// 		b) content written to CRC.
+// 3: Wait for stream history, execute sequences, send stream history.
-// 		c) return data to WRITER.
+func (d *Decoder) startStreamDecoder(ctx context.Context, r io.Reader, output chan decodeOutput) {
-// 		d) wait for next block to return data.
-// Once WRITTEN, the decoders reused by the writer frame decoder for re-use.
-func (d *Decoder) startStreamDecoder(inStream chan decodeStream) {
 	defer d.streamWg.Done()
-	frame := newFrameDec(d.o)
+	br := readerWrapper{r: r}
-	for stream := range inStream {
+
-		if debugDecoder {
+	var seqPrepare = make(chan *blockDec, d.o.concurrent)
-			println("got new stream")
+	var seqDecode = make(chan *blockDec, d.o.concurrent)
+	var seqExecute = make(chan *blockDec, d.o.concurrent)
+
+	// Async 1: Prepare blocks...
+	go func() {
+		var hist history
+		var hasErr bool
+		for block := range seqPrepare {
+			if hasErr {
+				if block != nil {
+					seqDecode <- block
 				}
-		br := readerWrapper{r: stream.r}
+				continue
-	decodeStream:
+			}
+			if block.async.newHist != nil {
+				if debugDecoder {
+					println("Async 1: new history")
+				}
+				hist.reset()
+				if block.async.newHist.dict != nil {
+					hist.setDict(block.async.newHist.dict)
+				}
+			}
+			if block.err != nil || block.Type != blockTypeCompressed {
+				hasErr = block.err != nil
+				seqDecode <- block
+				continue
+			}
+
+			remain, err := block.decodeLiterals(block.data, &hist)
+			block.err = err
+			hasErr = block.err != nil
+			if err == nil {
+				block.async.literals = hist.decoders.literals
+				block.async.seqData = remain
+			} else if debugDecoder {
+				println("decodeLiterals error:", err)
+			}
+			seqDecode <- block
+		}
+		close(seqDecode)
+	}()
+
+	// Async 2: Decode sequences...
+	go func() {
+		var hist history
+		var hasErr bool
+
+		for block := range seqDecode {
+			if hasErr {
+				if block != nil {
+					seqExecute <- block
+				}
+				continue
+			}
+			if block.async.newHist != nil {
+				if debugDecoder {
+					println("Async 2: new history, recent:", block.async.newHist.recentOffsets)
+				}
+				hist.decoders = block.async.newHist.decoders
+				hist.recentOffsets = block.async.newHist.recentOffsets
+				if block.async.newHist.dict != nil {
+					hist.setDict(block.async.newHist.dict)
+				}
+			}
+			if block.err != nil || block.Type != blockTypeCompressed {
+				hasErr = block.err != nil
+				seqExecute <- block
+				continue
+			}
+
+			hist.decoders.literals = block.async.literals
+			block.err = block.prepareSequences(block.async.seqData, &hist)
+			if debugDecoder && block.err != nil {
+				println("prepareSequences returned:", block.err)
+			}
+			hasErr = block.err != nil
+			if block.err == nil {
+				block.err = block.decodeSequences(&hist)
+				if debugDecoder && block.err != nil {
+					println("decodeSequences returned:", block.err)
+				}
+				hasErr = block.err != nil
+				//				block.async.sequence = hist.decoders.seq[:hist.decoders.nSeqs]
+				block.async.seqSize = hist.decoders.seqSize
+			}
+			seqExecute <- block
+		}
+		close(seqExecute)
+	}()
+
+	var wg sync.WaitGroup
+	wg.Add(1)
+
+	// Async 3: Execute sequences...
+	frameHistCache := d.frame.history.b
+	go func() {
+		var hist history
+		var decodedFrame uint64
+		var fcs uint64
+		var hasErr bool
+		for block := range seqExecute {
+			out := decodeOutput{err: block.err, d: block}
+			if block.err != nil || hasErr {
+				hasErr = true
+				output <- out
+				continue
+			}
+			if block.async.newHist != nil {
+				if debugDecoder {
+					println("Async 3: new history")
+				}
+				hist.windowSize = block.async.newHist.windowSize
+				hist.allocFrameBuffer = block.async.newHist.allocFrameBuffer
+				if block.async.newHist.dict != nil {
+					hist.setDict(block.async.newHist.dict)
+				}
+
+				if cap(hist.b) < hist.allocFrameBuffer {
+					if cap(frameHistCache) >= hist.allocFrameBuffer {
+						hist.b = frameHistCache
+					} else {
+						hist.b = make([]byte, 0, hist.allocFrameBuffer)
+						println("Alloc history sized", hist.allocFrameBuffer)
+					}
+				}
+				hist.b = hist.b[:0]
+				fcs = block.async.fcs
+				decodedFrame = 0
+			}
+			do := decodeOutput{err: block.err, d: block}
+			switch block.Type {
+			case blockTypeRLE:
+				if debugDecoder {
+					println("add rle block length:", block.RLESize)
+				}
+
+				if cap(block.dst) < int(block.RLESize) {
+					if block.lowMem {
+						block.dst = make([]byte, block.RLESize)
+					} else {
+						block.dst = make([]byte, maxBlockSize)
+					}
+				}
+				block.dst = block.dst[:block.RLESize]
+				v := block.data[0]
+				for i := range block.dst {
+					block.dst[i] = v
+				}
+				hist.append(block.dst)
+				do.b = block.dst
+			case blockTypeRaw:
+				if debugDecoder {
+					println("add raw block length:", len(block.data))
+				}
+				hist.append(block.data)
+				do.b = block.data
+			case blockTypeCompressed:
+				if debugDecoder {
+					println("execute with history length:", len(hist.b), "window:", hist.windowSize)
+				}
+				hist.decoders.seqSize = block.async.seqSize
+				hist.decoders.literals = block.async.literals
+				do.err = block.executeSequences(&hist)
+				hasErr = do.err != nil
+				if debugDecoder && hasErr {
+					println("executeSequences returned:", do.err)
+				}
+				do.b = block.dst
+			}
+			if !hasErr {
+				decodedFrame += uint64(len(do.b))
+				if fcs > 0 && decodedFrame > fcs {
+					println("fcs exceeded", block.Last, fcs, decodedFrame)
+					do.err = ErrFrameSizeExceeded
+					hasErr = true
+				} else if block.Last && fcs > 0 && decodedFrame != fcs {
+					do.err = ErrFrameSizeMismatch
+					hasErr = true
+				} else {
+					if debugDecoder {
+						println("fcs ok", block.Last, fcs, decodedFrame)
+					}
+				}
+			}
+			output <- do
+		}
+		close(output)
+		frameHistCache = hist.b
+		wg.Done()
+		if debugDecoder {
+			println("decoder goroutines finished")
+		}
+	}()
+
+decodeStream:
 	for {
+		frame := d.frame
+		if debugDecoder {
+			println("New frame...")
+		}
+		var historySent bool
 		frame.history.reset()
 		err := frame.reset(&br)
 		if debugDecoder && err != nil {
@@ -502,54 +854,70 @@ func (d *Decoder) startStreamDecoder(inStream chan decodeStream) {
 				frame.history.setDict(&dict)
 			}
 		}
+		if err == nil && d.frame.WindowSize > d.o.maxWindowSize {
+			err = ErrDecoderSizeExceeded
+		}
 		if err != nil {
-				stream.output <- decodeOutput{
+			select {
-					err: err,
+			case <-ctx.Done():
+			case dec := <-d.decoders:
+				dec.sendErr(err)
+				seqPrepare <- dec
 			}
-				break
+			break decodeStream
-			}
-			if debugDecoder {
-				println("starting frame decoder")
 		}
 
-			// This goroutine will forward history between frames.
-			frame.frameDone.Add(1)
-			frame.initAsync()
-
-			go frame.startDecoder(stream.output)
-		decodeFrame:
 		// Go through all blocks of the frame.
 		for {
-				dec := <-d.decoders
+			var dec *blockDec
 			select {
-				case <-stream.cancel:
+			case <-ctx.Done():
-					if !frame.sendErr(dec, io.EOF) {
-						// To not let the decoder dangle, send it back.
-						stream.output <- decodeOutput{d: dec}
-					}
 				break decodeStream
-				default:
+			case dec = <-d.decoders:
+				// Once we have a decoder, we MUST return it.
 			}
 			err := frame.next(dec)
-				switch err {
+			if !historySent {
-				case io.EOF:
+				h := frame.history
-					// End of current frame, no error
+				if debugDecoder {
-					println("EOF on next block")
+					println("Alloc History:", h.allocFrameBuffer)
-					break decodeFrame
+				}
-				case nil:
+				dec.async.newHist = &h
-					continue
+				dec.async.fcs = frame.FrameContentSize
-				default:
+				historySent = true
-					println("block decoder returned", err)
+			} else {
+				dec.async.newHist = nil
+			}
+			if debugDecoder && err != nil {
+				println("next block returned error:", err)
+			}
+			dec.err = err
+			dec.checkCRC = nil
+			if dec.Last && frame.HasCheckSum && err == nil {
+				crc, err := frame.rawInput.readSmall(4)
+				if err != nil {
+					println("CRC missing?", err)
+					dec.err = err
+				}
+				var tmp [4]byte
+				copy(tmp[:], crc)
+				dec.checkCRC = tmp[:]
+				if debugDecoder {
+					println("found crc to check:", dec.checkCRC)
+				}
+			}
+			err = dec.err
+			last := dec.Last
+			seqPrepare <- dec
+			if err != nil {
 				break decodeStream
 			}
+			if last {
+				break
 			}
-			// All blocks have started decoding, check if there are more frames.
-			println("waiting for done")
-			frame.frameDone.Wait()
-			println("done waiting...")
 		}
-		frame.frameDone.Wait()
-		println("Sending EOS")
-		stream.output <- decodeOutput{err: errEndOfStream}
 	}
+	close(seqPrepare)
+	wg.Wait()
+	d.frame.history.b = frameHistCache
 }

vendor/github.com/klauspost/compress/zstd/decoder_options.go

@@ -28,6 +28,9 @@ func (o *decoderOptions) setDefault() {
 		concurrent:    runtime.GOMAXPROCS(0),
 		maxWindowSize: MaxWindowSize,
 	}
+	if o.concurrent > 4 {
+		o.concurrent = 4
+	}
 	o.maxDecodedSize = 1 << 63
 }
 
@@ -37,16 +40,25 @@ func WithDecoderLowmem(b bool) DOption {
 	return func(o *decoderOptions) error { o.lowMem = b; return nil }
 }
 
-// WithDecoderConcurrency will set the concurrency,
+// WithDecoderConcurrency sets the number of created decoders.
-// meaning the maximum number of decoders to run concurrently.
+// When decoding block with DecodeAll, this will limit the number
-// The value supplied must be at least 1.
+// of possible concurrently running decodes.
-// By default this will be set to GOMAXPROCS.
+// When decoding streams, this will limit the number of
+// inflight blocks.
+// When decoding streams and setting maximum to 1,
+// no async decoding will be done.
+// When a value of 0 is provided GOMAXPROCS will be used.
+// By default this will be set to 4 or GOMAXPROCS, whatever is lower.
 func WithDecoderConcurrency(n int) DOption {
 	return func(o *decoderOptions) error {
-		if n <= 0 {
+		if n < 0 {
 			return errors.New("concurrency must be at least 1")
 		}
+		if n == 0 {
+			o.concurrent = runtime.GOMAXPROCS(0)
+		} else {
 			o.concurrent = n
+		}
 		return nil
 	}
 }

vendor/github.com/klauspost/compress/zstd/encoder.go

@@ -98,23 +98,25 @@ func (e *Encoder) Reset(w io.Writer) {
 	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)
 		}
-	if s.encoder == nil {
+		s.current = s.current[:0]
-		s.encoder = e.o.encoder()
+		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.current = s.current[:0]
-	s.previous = s.previous[:0]
 	s.encoder.Reset(e.o.dict, false)
 	s.headerWritten = false
 	s.eofWritten = false
@@ -258,6 +260,46 @@ func (e *Encoder) nextBlock(final bool) error {
 		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))

vendor/github.com/klauspost/compress/zstd/encoder_options.go

@@ -76,6 +76,7 @@ func WithEncoderCRC(b bool) EOption {
 // WithEncoderConcurrency will set the concurrency,
 // meaning the maximum number of encoders to run concurrently.
 // The value supplied must be at least 1.
+// For streams, setting a value of 1 will disable async compression.
 // By default this will be set to GOMAXPROCS.
 func WithEncoderConcurrency(n int) EOption {
 	return func(o *encoderOptions) error {

vendor/github.com/klauspost/compress/zstd/framedec.go

@@ -8,23 +8,17 @@ import (
 	"bytes"
 	"encoding/hex"
 	"errors"
-	"hash"
 	"io"
-	"sync"
 
 	"github.com/klauspost/compress/zstd/internal/xxhash"
 )
 
 type frameDec struct {
 	o   decoderOptions
-	crc    hash.Hash64
+	crc *xxhash.Digest
-	offset int64
 
 	WindowSize uint64
 
-	// In order queue of blocks being decoded.
-	decoding chan *blockDec
-
 	// Frame history passed between blocks
 	history history
 
@@ -34,15 +28,10 @@ type frameDec struct {
 	bBuf byteBuf
 
 	FrameContentSize uint64
-	frameDone        sync.WaitGroup
 
 	DictionaryID  *uint32
 	HasCheckSum   bool
 	SingleSegment bool
-
-	// asyncRunning indicates whether the async routine processes input on 'decoding'.
-	asyncRunningMu sync.Mutex
-	asyncRunning   bool
 }
 
 const (
@@ -229,9 +218,10 @@ func (d *frameDec) reset(br byteBuffer) error {
 			d.FrameContentSize = uint64(d1) | (uint64(d2) << 32)
 		}
 		if debugDecoder {
-			println("field size bits:", v, "fcsSize:", fcsSize, "FrameContentSize:", d.FrameContentSize, hex.EncodeToString(b[:fcsSize]), "singleseg:", d.SingleSegment, "window:", d.WindowSize)
+			println("Read FCS:", d.FrameContentSize)
 		}
 	}
+
 	// Move this to shared.
 	d.HasCheckSum = fhd&(1<<2) != 0
 	if d.HasCheckSum {
@@ -264,10 +254,16 @@ func (d *frameDec) reset(br byteBuffer) error {
 	}
 	d.history.windowSize = int(d.WindowSize)
 	if d.o.lowMem && d.history.windowSize < maxBlockSize {
-		d.history.maxSize = d.history.windowSize * 2
+		d.history.allocFrameBuffer = d.history.windowSize * 2
+		// TODO: Maybe use FrameContent size
 	} else {
-		d.history.maxSize = d.history.windowSize + maxBlockSize
+		d.history.allocFrameBuffer = d.history.windowSize + maxBlockSize
 	}
+
+	if debugDecoder {
+		println("Frame: Dict:", d.DictionaryID, "FrameContentSize:", d.FrameContentSize, "singleseg:", d.SingleSegment, "window:", d.WindowSize, "crc:", d.HasCheckSum)
+	}
+
 	// history contains input - maybe we do something
 	d.rawInput = br
 	return nil
@@ -276,47 +272,16 @@ func (d *frameDec) reset(br byteBuffer) error {
 // next will start decoding the next block from stream.
 func (d *frameDec) next(block *blockDec) error {
 	if debugDecoder {
-		printf("decoding new block %p:%p", block, block.data)
+		println("decoding new block")
 	}
 	err := block.reset(d.rawInput, d.WindowSize)
 	if err != nil {
 		println("block error:", err)
 		// Signal the frame decoder we have a problem.
-		d.sendErr(block, err)
+		block.sendErr(err)
 		return err
 	}
-	block.input <- struct{}{}
-	if debugDecoder {
-		println("next block:", block)
-	}
-	d.asyncRunningMu.Lock()
-	defer d.asyncRunningMu.Unlock()
-	if !d.asyncRunning {
 	return nil
-	}
-	if block.Last {
-		// We indicate the frame is done by sending io.EOF
-		d.decoding <- block
-		return io.EOF
-	}
-	d.decoding <- block
-	return nil
-}
-
-// sendEOF will queue an error block on the frame.
-// This will cause the frame decoder to return when it encounters the block.
-// Returns true if the decoder was added.
-func (d *frameDec) sendErr(block *blockDec, err error) bool {
-	d.asyncRunningMu.Lock()
-	defer d.asyncRunningMu.Unlock()
-	if !d.asyncRunning {
-		return false
-	}
-
-	println("sending error", err.Error())
-	block.sendErr(err)
-	d.decoding <- block
-	return true
 }
 
 // checkCRC will check the checksum if the frame has one.
@@ -340,7 +305,7 @@ func (d *frameDec) checkCRC() error {
 		return err
 	}
 
-	if !bytes.Equal(tmp[:], want) {
+	if !bytes.Equal(tmp[:], want) && !ignoreCRC {
 		if debugDecoder {
 			println("CRC Check Failed:", tmp[:], "!=", want)
 		}
@@ -352,131 +317,13 @@ func (d *frameDec) checkCRC() error {
 	return nil
 }
 
-func (d *frameDec) initAsync() {
-	if !d.o.lowMem && !d.SingleSegment {
-		// set max extra size history to 2MB.
-		d.history.maxSize = d.history.windowSize + maxBlockSize
-	}
-	// re-alloc if more than one extra block size.
-	if d.o.lowMem && cap(d.history.b) > d.history.maxSize+maxBlockSize {
-		d.history.b = make([]byte, 0, d.history.maxSize)
-	}
-	if cap(d.history.b) < d.history.maxSize {
-		d.history.b = make([]byte, 0, d.history.maxSize)
-	}
-	if cap(d.decoding) < d.o.concurrent {
-		d.decoding = make(chan *blockDec, d.o.concurrent)
-	}
-	if debugDecoder {
-		h := d.history
-		printf("history init. len: %d, cap: %d", len(h.b), cap(h.b))
-	}
-	d.asyncRunningMu.Lock()
-	d.asyncRunning = true
-	d.asyncRunningMu.Unlock()
-}
-
-// startDecoder will start decoding blocks and write them to the writer.
-// The decoder will stop as soon as an error occurs or at end of frame.
-// When the frame has finished decoding the *bufio.Reader
-// containing the remaining input will be sent on frameDec.frameDone.
-func (d *frameDec) startDecoder(output chan decodeOutput) {
-	written := int64(0)
-
-	defer func() {
-		d.asyncRunningMu.Lock()
-		d.asyncRunning = false
-		d.asyncRunningMu.Unlock()
-
-		// Drain the currently decoding.
-		d.history.error = true
-	flushdone:
-		for {
-			select {
-			case b := <-d.decoding:
-				b.history <- &d.history
-				output <- <-b.result
-			default:
-				break flushdone
-			}
-		}
-		println("frame decoder done, signalling done")
-		d.frameDone.Done()
-	}()
-	// Get decoder for first block.
-	block := <-d.decoding
-	block.history <- &d.history
-	for {
-		var next *blockDec
-		// Get result
-		r := <-block.result
-		if r.err != nil {
-			println("Result contained error", r.err)
-			output <- r
-			return
-		}
-		if debugDecoder {
-			println("got result, from ", d.offset, "to", d.offset+int64(len(r.b)))
-			d.offset += int64(len(r.b))
-		}
-		if !block.Last {
-			// Send history to next block
-			select {
-			case next = <-d.decoding:
-				if debugDecoder {
-					println("Sending ", len(d.history.b), "bytes as history")
-				}
-				next.history <- &d.history
-			default:
-				// Wait until we have sent the block, so
-				// other decoders can potentially get the decoder.
-				next = nil
-			}
-		}
-
-		// Add checksum, async to decoding.
-		if d.HasCheckSum {
-			n, err := d.crc.Write(r.b)
-			if err != nil {
-				r.err = err
-				if n != len(r.b) {
-					r.err = io.ErrShortWrite
-				}
-				output <- r
-				return
-			}
-		}
-		written += int64(len(r.b))
-		if d.SingleSegment && uint64(written) > d.FrameContentSize {
-			println("runDecoder: single segment and", uint64(written), ">", d.FrameContentSize)
-			r.err = ErrFrameSizeExceeded
-			output <- r
-			return
-		}
-		if block.Last {
-			r.err = d.checkCRC()
-			output <- r
-			return
-		}
-		output <- r
-		if next == nil {
-			// There was no decoder available, we wait for one now that we have sent to the writer.
-			if debugDecoder {
-				println("Sending ", len(d.history.b), " bytes as history")
-			}
-			next = <-d.decoding
-			next.history <- &d.history
-		}
-		block = next
-	}
-}
-
 // runDecoder will create a sync decoder that will decode a block of data.
 func (d *frameDec) runDecoder(dst []byte, dec *blockDec) ([]byte, error) {
 	saved := d.history.b
 
 	// We use the history for output to avoid copying it.
 	d.history.b = dst
+	d.history.ignoreBuffer = len(dst)
 	// Store input length, so we only check new data.
 	crcStart := len(dst)
 	var err error
@@ -489,7 +336,7 @@ func (d *frameDec) runDecoder(dst []byte, dec *blockDec) ([]byte, error) {
 			println("next block:", dec)
 		}
 		err = dec.decodeBuf(&d.history)
-		if err != nil || dec.Last {
+		if err != nil {
 			break
 		}
 		if uint64(len(d.history.b)) > d.o.maxDecodedSize {
@@ -501,10 +348,23 @@ func (d *frameDec) runDecoder(dst []byte, dec *blockDec) ([]byte, error) {
 			err = ErrFrameSizeExceeded
 			break
 		}
+		if d.FrameContentSize > 0 && uint64(len(d.history.b)-crcStart) > d.FrameContentSize {
+			println("runDecoder: FrameContentSize exceeded", uint64(len(d.history.b)-crcStart), ">", d.FrameContentSize)
+			err = ErrFrameSizeExceeded
+			break
+		}
+		if dec.Last {
+			break
+		}
+		if debugDecoder && d.FrameContentSize > 0 {
+			println("runDecoder: FrameContentSize", uint64(len(d.history.b)-crcStart), "<=", d.FrameContentSize)
+		}
 	}
 	dst = d.history.b
 	if err == nil {
-		if d.HasCheckSum {
+		if d.FrameContentSize > 0 && uint64(len(d.history.b)-crcStart) != d.FrameContentSize {
+			err = ErrFrameSizeMismatch
+		} else if d.HasCheckSum {
 			var n int
 			n, err = d.crc.Write(dst[crcStart:])
 			if err == nil {

vendor/github.com/klauspost/compress/zstd/fuzz.go

@@ -0,0 +1,11 @@
+//go:build gofuzz
+// +build gofuzz
+
+// 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
+
+// ignoreCRC can be used for fuzz testing to ignore CRC values...
+const ignoreCRC = true

vendor/github.com/klauspost/compress/zstd/fuzz_none.go

@@ -0,0 +1,11 @@
+//go:build !gofuzz
+// +build !gofuzz
+
+// 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
+
+// ignoreCRC can be used for fuzz testing to ignore CRC values...
+const ignoreCRC = false

vendor/github.com/klauspost/compress/zstd/history.go

@@ -10,12 +10,22 @@ import (
 
 // history contains the information transferred between blocks.
 type history struct {
-	b             []byte
+	// Literal decompression
 	huffTree *huff0.Scratch
-	recentOffsets [3]int
+
+	// Sequence decompression
 	decoders      sequenceDecs
+	recentOffsets [3]int
+
+	// History buffer...
+	b []byte
+
+	// ignoreBuffer is meant to ignore a number of bytes
+	// when checking for matches in history
+	ignoreBuffer int
+
 	windowSize       int
-	maxSize       int
+	allocFrameBuffer int // needed?
 	error            bool
 	dict             *dict
 }
@@ -24,6 +34,7 @@ type history struct {
 // The history must already have been initialized to the desired size.
 func (h *history) reset() {
 	h.b = h.b[:0]
+	h.ignoreBuffer = 0
 	h.error = false
 	h.recentOffsets = [3]int{1, 4, 8}
 	if f := h.decoders.litLengths.fse; f != nil && !f.preDefined {
@@ -35,7 +46,7 @@ func (h *history) reset() {
 	if f := h.decoders.matchLengths.fse; f != nil && !f.preDefined {
 		fseDecoderPool.Put(f)
 	}
-	h.decoders = sequenceDecs{}
+	h.decoders = sequenceDecs{br: h.decoders.br}
 	if h.huffTree != nil {
 		if h.dict == nil || h.dict.litEnc != h.huffTree {
 			huffDecoderPool.Put(h.huffTree)
@@ -54,6 +65,7 @@ func (h *history) setDict(dict *dict) {
 	h.decoders.litLengths = dict.llDec
 	h.decoders.offsets = dict.ofDec
 	h.decoders.matchLengths = dict.mlDec
+	h.decoders.dict = dict.content
 	h.recentOffsets = dict.offsets
 	h.huffTree = dict.litEnc
 }
@@ -83,6 +95,24 @@ func (h *history) append(b []byte) {
 	copy(h.b[h.windowSize-len(b):], b)
 }
 
+// ensureBlock will ensure there is space for at least one block...
+func (h *history) ensureBlock() {
+	if cap(h.b) < h.allocFrameBuffer {
+		h.b = make([]byte, 0, h.allocFrameBuffer)
+		return
+	}
+
+	avail := cap(h.b) - len(h.b)
+	if avail >= h.windowSize || avail > maxCompressedBlockSize {
+		return
+	}
+	// Move data down so we only have window size left.
+	// We know we have less than window size in b at this point.
+	discard := len(h.b) - h.windowSize
+	copy(h.b, h.b[discard:])
+	h.b = h.b[:h.windowSize]
+}
+
 // append bytes to history without ever discarding anything.
 func (h *history) appendKeep(b []byte) {
 	h.b = append(h.b, b...)

vendor/github.com/klauspost/compress/zstd/seqdec.go

@@ -20,6 +20,10 @@ type seq struct {
 	llCode, mlCode, ofCode uint8
 }
 
+type seqVals struct {
+	ll, ml, mo int
+}
+
 func (s seq) String() string {
 	if s.offset <= 3 {
 		if s.offset == 0 {
@@ -61,16 +65,18 @@ type sequenceDecs struct {
 	offsets      sequenceDec
 	matchLengths sequenceDec
 	prevOffset   [3]int
-	hist         []byte
 	dict         []byte
 	literals     []byte
 	out          []byte
+	nSeqs        int
+	br           *bitReader
+	seqSize      int
 	windowSize   int
 	maxBits      uint8
 }
 
 // initialize all 3 decoders from the stream input.
-func (s *sequenceDecs) initialize(br *bitReader, hist *history, literals, out []byte) error {
+func (s *sequenceDecs) initialize(br *bitReader, hist *history, out []byte) error {
 	if err := s.litLengths.init(br); err != nil {
 		return errors.New("litLengths:" + err.Error())
 	}
@@ -80,8 +86,7 @@ func (s *sequenceDecs) initialize(br *bitReader, hist *history, literals, out []
 	if err := s.matchLengths.init(br); err != nil {
 		return errors.New("matchLengths:" + err.Error())
 	}
-	s.literals = literals
+	s.br = br
-	s.hist = hist.b
 	s.prevOffset = hist.recentOffsets
 	s.maxBits = s.litLengths.fse.maxBits + s.offsets.fse.maxBits + s.matchLengths.fse.maxBits
 	s.windowSize = hist.windowSize
@@ -94,11 +99,254 @@ func (s *sequenceDecs) initialize(br *bitReader, hist *history, literals, out []
 }
 
 // decode sequences from the stream with the provided history.
-func (s *sequenceDecs) decode(seqs int, br *bitReader, hist []byte) error {
+func (s *sequenceDecs) decode(seqs []seqVals) error {
+	br := s.br
+
+	// Grab full sizes tables, to avoid bounds checks.
+	llTable, mlTable, ofTable := s.litLengths.fse.dt[:maxTablesize], s.matchLengths.fse.dt[:maxTablesize], s.offsets.fse.dt[:maxTablesize]
+	llState, mlState, ofState := s.litLengths.state.state, s.matchLengths.state.state, s.offsets.state.state
+	s.seqSize = 0
+	litRemain := len(s.literals)
+
+	for i := range seqs {
+		var ll, mo, ml int
+		if br.off > 4+((maxOffsetBits+16+16)>>3) {
+			// inlined function:
+			// ll, mo, ml = s.nextFast(br, llState, mlState, ofState)
+
+			// Final will not read from stream.
+			var llB, mlB, moB uint8
+			ll, llB = llState.final()
+			ml, mlB = mlState.final()
+			mo, moB = ofState.final()
+
+			// extra bits are stored in reverse order.
+			br.fillFast()
+			mo += br.getBits(moB)
+			if s.maxBits > 32 {
+				br.fillFast()
+			}
+			ml += br.getBits(mlB)
+			ll += br.getBits(llB)
+
+			if moB > 1 {
+				s.prevOffset[2] = s.prevOffset[1]
+				s.prevOffset[1] = s.prevOffset[0]
+				s.prevOffset[0] = mo
+			} else {
+				// mo = s.adjustOffset(mo, ll, moB)
+				// Inlined for rather big speedup
+				if ll == 0 {
+					// There is an exception though, when current sequence's literals_length = 0.
+					// In this case, repeated offsets are shifted by one, so an offset_value of 1 means Repeated_Offset2,
+					// an offset_value of 2 means Repeated_Offset3, and an offset_value of 3 means Repeated_Offset1 - 1_byte.
+					mo++
+				}
+
+				if mo == 0 {
+					mo = s.prevOffset[0]
+				} else {
+					var temp int
+					if mo == 3 {
+						temp = s.prevOffset[0] - 1
+					} else {
+						temp = s.prevOffset[mo]
+					}
+
+					if temp == 0 {
+						// 0 is not valid; input is corrupted; force offset to 1
+						println("WARNING: temp was 0")
+						temp = 1
+					}
+
+					if mo != 1 {
+						s.prevOffset[2] = s.prevOffset[1]
+					}
+					s.prevOffset[1] = s.prevOffset[0]
+					s.prevOffset[0] = temp
+					mo = temp
+				}
+			}
+			br.fillFast()
+		} else {
+			if br.overread() {
+				if debugDecoder {
+					printf("reading sequence %d, exceeded available data\n", i)
+				}
+				return io.ErrUnexpectedEOF
+			}
+			ll, mo, ml = s.next(br, llState, mlState, ofState)
+			br.fill()
+		}
+
+		if debugSequences {
+			println("Seq", i, "Litlen:", ll, "mo:", mo, "(abs) ml:", ml)
+		}
+		// Evaluate.
+		// We might be doing this async, so do it early.
+		if mo == 0 && ml > 0 {
+			return fmt.Errorf("zero matchoff and matchlen (%d) > 0", ml)
+		}
+		if ml > maxMatchLen {
+			return fmt.Errorf("match len (%d) bigger than max allowed length", ml)
+		}
+		s.seqSize += ll + ml
+		if s.seqSize > maxBlockSize {
+			return fmt.Errorf("output (%d) bigger than max block size", s.seqSize)
+		}
+		litRemain -= ll
+		if litRemain < 0 {
+			return fmt.Errorf("unexpected literal count, want %d bytes, but only %d is available", ll, litRemain+ll)
+		}
+		seqs[i] = seqVals{
+			ll: ll,
+			ml: ml,
+			mo: mo,
+		}
+		if i == len(seqs)-1 {
+			// This is the last sequence, so we shouldn't update state.
+			break
+		}
+
+		// Manually inlined, ~ 5-20% faster
+		// Update all 3 states at once. Approx 20% faster.
+		nBits := llState.nbBits() + mlState.nbBits() + ofState.nbBits()
+		if nBits == 0 {
+			llState = llTable[llState.newState()&maxTableMask]
+			mlState = mlTable[mlState.newState()&maxTableMask]
+			ofState = ofTable[ofState.newState()&maxTableMask]
+		} else {
+			bits := br.get32BitsFast(nBits)
+			lowBits := uint16(bits >> ((ofState.nbBits() + mlState.nbBits()) & 31))
+			llState = llTable[(llState.newState()+lowBits)&maxTableMask]
+
+			lowBits = uint16(bits >> (ofState.nbBits() & 31))
+			lowBits &= bitMask[mlState.nbBits()&15]
+			mlState = mlTable[(mlState.newState()+lowBits)&maxTableMask]
+
+			lowBits = uint16(bits) & bitMask[ofState.nbBits()&15]
+			ofState = ofTable[(ofState.newState()+lowBits)&maxTableMask]
+		}
+	}
+	s.seqSize += litRemain
+	if s.seqSize > maxBlockSize {
+		return fmt.Errorf("output (%d) bigger than max block size", s.seqSize)
+	}
+	err := br.close()
+	if err != nil {
+		printf("Closing sequences: %v, %+v\n", err, *br)
+	}
+	return err
+}
+
+// execute will execute the decoded sequence with the provided history.
+// The sequence must be evaluated before being sent.
+func (s *sequenceDecs) execute(seqs []seqVals, hist []byte) error {
+	// Ensure we have enough output size...
+	if len(s.out)+s.seqSize > cap(s.out) {
+		addBytes := s.seqSize + len(s.out)
+		s.out = append(s.out, make([]byte, addBytes)...)
+		s.out = s.out[:len(s.out)-addBytes]
+	}
+
+	if debugDecoder {
+		printf("Execute %d seqs with hist %d, dict %d, literals: %d into %d bytes\n", len(seqs), len(hist), len(s.dict), len(s.literals), s.seqSize)
+	}
+
+	var t = len(s.out)
+	out := s.out[:t+s.seqSize]
+
+	for _, seq := range seqs {
+		// Add literals
+		copy(out[t:], s.literals[:seq.ll])
+		t += seq.ll
+		s.literals = s.literals[seq.ll:]
+
+		// Copy from dictionary...
+		if seq.mo > t+len(hist) || seq.mo > s.windowSize {
+			if len(s.dict) == 0 {
+				return fmt.Errorf("match offset (%d) bigger than current history (%d)", seq.mo, t+len(hist))
+			}
+
+			// we may be in dictionary.
+			dictO := len(s.dict) - (seq.mo - (t + len(hist)))
+			if dictO < 0 || dictO >= len(s.dict) {
+				return fmt.Errorf("match offset (%d) bigger than current history+dict (%d)", seq.mo, t+len(hist)+len(s.dict))
+			}
+			end := dictO + seq.ml
+			if end > len(s.dict) {
+				n := len(s.dict) - dictO
+				copy(out[t:], s.dict[dictO:])
+				t += n
+				seq.ml -= n
+			} else {
+				copy(out[t:], s.dict[dictO:end])
+				t += end - dictO
+				continue
+			}
+		}
+
+		// Copy from history.
+		if v := seq.mo - t; v > 0 {
+			// v is the start position in history from end.
+			start := len(hist) - v
+			if seq.ml > v {
+				// Some goes into current block.
+				// Copy remainder of history
+				copy(out[t:], hist[start:])
+				t += v
+				seq.ml -= v
+			} else {
+				copy(out[t:], hist[start:start+seq.ml])
+				t += seq.ml
+				continue
+			}
+		}
+		// We must be in current buffer now
+		if seq.ml > 0 {
+			start := t - seq.mo
+			if seq.ml <= t-start {
+				// No overlap
+				copy(out[t:], out[start:start+seq.ml])
+				t += seq.ml
+				continue
+			} else {
+				// Overlapping copy
+				// Extend destination slice and copy one byte at the time.
+				src := out[start : start+seq.ml]
+				dst := out[t:]
+				dst = dst[:len(src)]
+				t += len(src)
+				// Destination is the space we just added.
+				for i := range src {
+					dst[i] = src[i]
+				}
+			}
+		}
+	}
+	// Add final literals
+	copy(out[t:], s.literals)
+	if debugDecoder {
+		t += len(s.literals)
+		if t != len(out) {
+			panic(fmt.Errorf("length mismatch, want %d, got %d, ss: %d", len(out), t, s.seqSize))
+		}
+	}
+	s.out = out
+
+	return nil
+}
+
+// decode sequences from the stream with the provided history.
+func (s *sequenceDecs) decodeSync(history *history) error {
+	br := s.br
+	seqs := s.nSeqs
 	startSize := len(s.out)
 	// Grab full sizes tables, to avoid bounds checks.
 	llTable, mlTable, ofTable := s.litLengths.fse.dt[:maxTablesize], s.matchLengths.fse.dt[:maxTablesize], s.offsets.fse.dt[:maxTablesize]
 	llState, mlState, ofState := s.litLengths.state.state, s.matchLengths.state.state, s.offsets.state.state
+	hist := history.b[history.ignoreBuffer:]
+	out := s.out
 
 	for i := seqs - 1; i >= 0; i-- {
 		if br.overread() {
@@ -151,7 +399,7 @@ func (s *sequenceDecs) decode(seqs int, br *bitReader, hist []byte) error {
 
 					if temp == 0 {
 						// 0 is not valid; input is corrupted; force offset to 1
-						println("temp was 0")
+						println("WARNING: temp was 0")
 						temp = 1
 					}
 
@@ -176,51 +424,49 @@ func (s *sequenceDecs) decode(seqs int, br *bitReader, hist []byte) error {
 		if ll > len(s.literals) {
 			return fmt.Errorf("unexpected literal count, want %d bytes, but only %d is available", ll, len(s.literals))
 		}
-		size := ll + ml + len(s.out)
+		size := ll + ml + len(out)
 		if size-startSize > maxBlockSize {
 			return fmt.Errorf("output (%d) bigger than max block size", size)
 		}
-		if size > cap(s.out) {
+		if size > cap(out) {
 			// Not enough size, which can happen under high volume block streaming conditions
 			// but could be if destination slice is too small for sync operations.
 			// over-allocating here can create a large amount of GC pressure so we try to keep
 			// it as contained as possible
-			used := len(s.out) - startSize
+			used := len(out) - startSize
 			addBytes := 256 + ll + ml + used>>2
 			// Clamp to max block size.
 			if used+addBytes > maxBlockSize {
 				addBytes = maxBlockSize - used
 			}
-			s.out = append(s.out, make([]byte, addBytes)...)
+			out = append(out, make([]byte, addBytes)...)
-			s.out = s.out[:len(s.out)-addBytes]
+			out = out[:len(out)-addBytes]
 		}
 		if ml > maxMatchLen {
 			return fmt.Errorf("match len (%d) bigger than max allowed length", ml)
 		}
 
 		// Add literals
-		s.out = append(s.out, s.literals[:ll]...)
+		out = append(out, s.literals[:ll]...)
 		s.literals = s.literals[ll:]
-		out := s.out
 
 		if mo == 0 && ml > 0 {
 			return fmt.Errorf("zero matchoff and matchlen (%d) > 0", ml)
 		}
 
-		if mo > len(s.out)+len(hist) || mo > s.windowSize {
+		if mo > len(out)+len(hist) || mo > s.windowSize {
 			if len(s.dict) == 0 {
-				return fmt.Errorf("match offset (%d) bigger than current history (%d)", mo, len(s.out)+len(hist))
+				return fmt.Errorf("match offset (%d) bigger than current history (%d)", mo, len(out)+len(hist))
 			}
 
 			// we may be in dictionary.
-			dictO := len(s.dict) - (mo - (len(s.out) + len(hist)))
+			dictO := len(s.dict) - (mo - (len(out) + len(hist)))
 			if dictO < 0 || dictO >= len(s.dict) {
-				return fmt.Errorf("match offset (%d) bigger than current history (%d)", mo, len(s.out)+len(hist))
+				return fmt.Errorf("match offset (%d) bigger than current history (%d)", mo, len(out)+len(hist))
 			}
 			end := dictO + ml
 			if end > len(s.dict) {
 				out = append(out, s.dict[dictO:]...)
-				mo -= len(s.dict) - dictO
 				ml -= len(s.dict) - dictO
 			} else {
 				out = append(out, s.dict[dictO:end]...)
@@ -231,26 +477,25 @@ func (s *sequenceDecs) decode(seqs int, br *bitReader, hist []byte) error {
 
 		// Copy from history.
 		// TODO: Blocks without history could be made to ignore this completely.
-		if v := mo - len(s.out); v > 0 {
+		if v := mo - len(out); v > 0 {
 			// v is the start position in history from end.
-			start := len(s.hist) - v
+			start := len(hist) - v
 			if ml > v {
 				// Some goes into current block.
 				// Copy remainder of history
-				out = append(out, s.hist[start:]...)
+				out = append(out, hist[start:]...)
-				mo -= v
 				ml -= v
 			} else {
-				out = append(out, s.hist[start:start+ml]...)
+				out = append(out, hist[start:start+ml]...)
 				ml = 0
 			}
 		}
 		// We must be in current buffer now
 		if ml > 0 {
-			start := len(s.out) - mo
+			start := len(out) - mo
-			if ml <= len(s.out)-start {
+			if ml <= len(out)-start {
 				// No overlap
-				out = append(out, s.out[start:start+ml]...)
+				out = append(out, out[start:start+ml]...)
 			} else {
 				// Overlapping copy
 				// Extend destination slice and copy one byte at the time.
@@ -264,7 +509,6 @@ func (s *sequenceDecs) decode(seqs int, br *bitReader, hist []byte) error {
 				}
 			}
 		}
-		s.out = out
 		if i == 0 {
 			// This is the last sequence, so we shouldn't update state.
 			break
@@ -292,8 +536,8 @@ func (s *sequenceDecs) decode(seqs int, br *bitReader, hist []byte) error {
 	}
 
 	// Add final literals
-	s.out = append(s.out, s.literals...)
+	s.out = append(out, s.literals...)
-	return nil
+	return br.close()
 }
 
 // update states, at least 27 bits must be available.
@@ -457,36 +701,3 @@ func (s *sequenceDecs) adjustOffset(offset, litLen int, offsetB uint8) int {
 	s.prevOffset[0] = temp
 	return temp
 }
-
-// mergeHistory will merge history.
-func (s *sequenceDecs) mergeHistory(hist *sequenceDecs) (*sequenceDecs, error) {
-	for i := uint(0); i < 3; i++ {
-		var sNew, sHist *sequenceDec
-		switch i {
-		default:
-			// same as "case 0":
-			sNew = &s.litLengths
-			sHist = &hist.litLengths
-		case 1:
-			sNew = &s.offsets
-			sHist = &hist.offsets
-		case 2:
-			sNew = &s.matchLengths
-			sHist = &hist.matchLengths
-		}
-		if sNew.repeat {
-			if sHist.fse == nil {
-				return nil, fmt.Errorf("sequence stream %d, repeat requested, but no history", i)
-			}
-			continue
-		}
-		if sNew.fse == nil {
-			return nil, fmt.Errorf("sequence stream %d, no fse found", i)
-		}
-		if sHist.fse != nil && !sHist.fse.preDefined {
-			fseDecoderPool.Put(sHist.fse)
-		}
-		sHist.fse = sNew.fse
-	}
-	return hist, nil
-}

vendor/github.com/klauspost/compress/zstd/zstd.go

@@ -75,6 +75,10 @@ var (
 	// This is only returned if SingleSegment is specified on the frame.
 	ErrFrameSizeExceeded = errors.New("frame size exceeded")
 
+	// ErrFrameSizeMismatch is returned if the stated frame size does not match the expected size.
+	// This is only returned if SingleSegment is specified on the frame.
+	ErrFrameSizeMismatch = errors.New("frame size does not match size on stream")
+
 	// ErrCRCMismatch is returned if CRC mismatches.
 	ErrCRCMismatch = errors.New("CRC check failed")
 

vendor/modules.txt

@@ -138,7 +138,7 @@ github.com/gorilla/mux
 github.com/imdario/mergo
 # github.com/inconshreveable/mousetrap v1.0.0
 github.com/inconshreveable/mousetrap
-# github.com/klauspost/compress v1.14.3
+# github.com/klauspost/compress v1.15.0
 ## explicit
 github.com/klauspost/compress
 github.com/klauspost/compress/fse