1 files changed, 555 insertions, 0 deletions
diff --git a/vendor/github.com/klauspost/compress/zstd/decoder.go b/vendor/github.com/klauspost/compress/zstd/decoder.go
new file mode 100644
index 00000000..f430f58b
--- /dev/null
+++ b/vendor/github.com/klauspost/compress/zstd/decoder.go
@@ -0,0 +1,555 @@
+// Copyright 2019+ Klaus Post. All rights reserved.
+// License information can be found in the LICENSE file.
+// Based on work by Yann Collet, released under BSD License.
+
+package zstd
+
+import (
+	"errors"
+	"io"
+	"sync"
+)
+
+// Decoder provides decoding of zstandard streams.
+// The decoder has been designed to operate without allocations after a warmup.
+// This means that you should store the decoder for best performance.
+// To re-use a stream decoder, use the Reset(r io.Reader) error to switch to another stream.
+// A decoder can safely be re-used even if the previous stream failed.
+// To release the resources, you must call the Close() function on a decoder.
+type Decoder struct {
+	o decoderOptions
+
+	// 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
+
+	// Custom dictionaries.
+	// Always uses copies.
+	dicts map[uint32]dict
+
+	// streamWg is the waitgroup for all streams
+	streamWg sync.WaitGroup
+}
+
+// decoderState is used for maintaining state when the decoder
+// is used for streaming.
+type decoderState struct {
+	// current block being written to stream.
+	decodeOutput
+
+	// output in order to be written to stream.
+	output chan decodeOutput
+
+	// cancel remaining output.
+	cancel chan struct{}
+
+	flushed bool
+}
+
+var (
+	// Check the interfaces we want to support.
+	_ = io.WriterTo(&Decoder{})
+	_ = io.Reader(&Decoder{})
+)
+
+// NewReader creates a new decoder.
+// A nil Reader can be provided in which case Reset can be used to start a decode.
+//
+// A Decoder can be used in two modes:
+//
+// 1) As a stream, or
+// 2) For stateless decoding using DecodeAll.
+//
+// Only a single stream can be decoded concurrently, but the same decoder
+// can run multiple concurrent stateless decodes. It is even possible to
+// use stateless decodes while a stream is being decoded.
+//
+// The Reset function can be used to initiate a new stream, which is will considerably
+// reduce the allocations normally caused by NewReader.
+func NewReader(r io.Reader, opts ...DOption) (*Decoder, error) {
+	initPredefined()
+	var d Decoder
+	d.o.setDefault()
+	for _, o := range opts {
+		err := o(&d.o)
+		if err != nil {
+			return nil, err
+		}
+	}
+	d.current.output = make(chan decodeOutput, d.o.concurrent)
+	d.current.flushed = true
+
+	if r == nil {
+		d.current.err = ErrDecoderNilInput
+	}
+
+	// Transfer option dicts.
+	d.dicts = make(map[uint32]dict, len(d.o.dicts))
+	for _, dc := range d.o.dicts {
+		d.dicts[dc.id] = dc
+	}
+	d.o.dicts = nil
+
+	// Create decoders
+	d.decoders = make(chan *blockDec, d.o.concurrent)
+	for i := 0; i < d.o.concurrent; i++ {
+		dec := newBlockDec(d.o.lowMem)
+		dec.localFrame = newFrameDec(d.o)
+		d.decoders <- dec
+	}
+
+	if r == nil {
+		return &d, nil
+	}
+	return &d, d.Reset(r)
+}
+
+// Read bytes from the decompressed stream into p.
+// Returns the number of bytes written and any error that occurred.
+// When the stream is done, io.EOF will be returned.
+func (d *Decoder) Read(p []byte) (int, error) {
+	var n int
+	for {
+		if len(d.current.b) > 0 {
+			filled := copy(p, d.current.b)
+			p = p[filled:]
+			d.current.b = d.current.b[filled:]
+			n += filled
+		}
+		if len(p) == 0 {
+			break
+		}
+		if len(d.current.b) == 0 {
+			// We have an error and no more data
+			if d.current.err != nil {
+				break
+			}
+			if !d.nextBlock(n == 0) {
+				return n, nil
+			}
+		}
+	}
+	if len(d.current.b) > 0 {
+		if debugDecoder {
+			println("returning", n, "still bytes left:", len(d.current.b))
+		}
+		// Only return error at end of block
+		return n, nil
+	}
+	if d.current.err != nil {
+		d.drainOutput()
+	}
+	if debugDecoder {
+		println("returning", n, d.current.err, len(d.decoders))
+	}
+	return n, d.current.err
+}
+
+// Reset will reset the decoder the supplied stream after the current has finished processing.
+// Note that this functionality cannot be used after Close has been called.
+// Reset can be called with a nil reader to release references to the previous reader.
+// After being called with a nil reader, no other operations than Reset or DecodeAll or Close
+// should be used.
+func (d *Decoder) Reset(r io.Reader) error {
+	if d.current.err == ErrDecoderClosed {
+		return d.current.err
+	}
+
+	d.drainOutput()
+
+	if r == nil {
+		d.current.err = ErrDecoderNilInput
+		if len(d.current.b) > 0 {
+			d.current.b = d.current.b[:0]
+		}
+		d.current.flushed = true
+		return nil
+	}
+
+	// If bytes buffer and < 5MB, do sync decoding anyway.
+	if bb, ok := r.(byter); ok && bb.Len() < 5<<20 {
+		bb2 := bb
+		if debugDecoder {
+			println("*bytes.Buffer detected, doing sync decode, len:", bb.Len())
+		}
+		b := bb2.Bytes()
+		var dst []byte
+		if cap(d.current.b) > 0 {
+			dst = d.current.b
+		}
+
+		dst, err := d.DecodeAll(b, dst[:0])
+		if err == nil {
+			err = io.EOF
+		}
+		d.current.b = dst
+		d.current.err = err
+		d.current.flushed = true
+		if debugDecoder {
+			println("sync decode to", len(dst), "bytes, err:", err)
+		}
+		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.current.decodeOutput = decodeOutput{}
+	d.current.err = nil
+	d.current.cancel = make(chan struct{})
+	d.current.flushed = false
+	d.current.d = nil
+
+	d.stream <- decodeStream{
+		r:      r,
+		output: d.current.output,
+		cancel: d.current.cancel,
+	}
+	return nil
+}
+
+// drainOutput will drain the output until errEndOfStream is sent.
+func (d *Decoder) drainOutput() {
+	if d.current.cancel != nil {
+		println("cancelling current")
+		close(d.current.cancel)
+		d.current.cancel = nil
+	}
+	if d.current.d != nil {
+		if debugDecoder {
+			printf("re-adding current decoder %p, decoders: %d", d.current.d, len(d.decoders))
+		}
+		d.decoders <- d.current.d
+		d.current.d = nil
+		d.current.b = nil
+	}
+	if d.current.output == nil || d.current.flushed {
+		println("current already flushed")
+		return
+	}
+	for v := range d.current.output {
+		if v.d != nil {
+			if debugDecoder {
+				printf("re-adding decoder %p", v.d)
+			}
+			d.decoders <- v.d
+		}
+		if v.err == errEndOfStream {
+			println("current flushed")
+			d.current.flushed = true
+			return
+		}
+	}
+}
+
+// WriteTo writes data to w until there's no more data to write or when an error occurs.
+// The return value n is the number of bytes written.
+// Any error encountered during the write is also returned.
+func (d *Decoder) WriteTo(w io.Writer) (int64, error) {
+	var n int64
+	for {
+		if len(d.current.b) > 0 {
+			n2, err2 := w.Write(d.current.b)
+			n += int64(n2)
+			if err2 != nil && (d.current.err == nil || d.current.err == io.EOF) {
+				d.current.err = err2
+			} else if n2 != len(d.current.b) {
+				d.current.err = io.ErrShortWrite
+			}
+		}
+		if d.current.err != nil {
+			break
+		}
+		d.nextBlock(true)
+	}
+	err := d.current.err
+	if err != nil {
+		d.drainOutput()
+	}
+	if err == io.EOF {
+		err = nil
+	}
+	return n, err
+}
+
+// DecodeAll allows stateless decoding of a blob of bytes.
+// Output will be appended to dst, so if the destination size is known
+// you can pre-allocate the destination slice to avoid allocations.
+// 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 {
+		return dst, ErrDecoderClosed
+	}
+
+	// Grab a block decoder and frame decoder.
+	block := <-d.decoders
+	frame := block.localFrame
+	defer func() {
+		if debugDecoder {
+			printf("re-adding decoder: %p", block)
+		}
+		frame.rawInput = nil
+		frame.bBuf = nil
+		d.decoders <- block
+	}()
+	frame.bBuf = input
+
+	for {
+		frame.history.reset()
+		err := frame.reset(&frame.bBuf)
+		if err == io.EOF {
+			if debugDecoder {
+				println("frame reset return EOF")
+			}
+			return dst, nil
+		}
+		if frame.DictionaryID != nil {
+			dict, ok := d.dicts[*frame.DictionaryID]
+			if !ok {
+				return nil, ErrUnknownDictionary
+			}
+			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.
+			if cap(dst)-len(dst) < int(frame.FrameContentSize) {
+				dst2 := make([]byte, len(dst), len(dst)+int(frame.FrameContentSize))
+				copy(dst2, dst)
+				dst = dst2
+			}
+		}
+		if cap(dst) == 0 {
+			// Allocate len(input) * 2 by default if nothing is provided
+			// and we didn't get frame content size.
+			size := len(input) * 2
+			// Cap to 1 MB.
+			if size > 1<<20 {
+				size = 1 << 20
+			}
+			if uint64(size) > d.o.maxDecodedSize {
+				size = int(d.o.maxDecodedSize)
+			}
+			dst = make([]byte, 0, size)
+		}
+
+		dst, err = frame.runDecoder(dst, block)
+		if err != nil {
+			return dst, err
+		}
+		if len(frame.bBuf) == 0 {
+			if debugDecoder {
+				println("frame dbuf empty")
+			}
+			break
+		}
+	}
+	return dst, nil
+}
+
+// nextBlock returns the next block.
+// If an error occurs d.err will be set.
+// Optionally the function can block for new output.
+// 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.d != nil {
+		if debugDecoder {
+			printf("re-adding current decoder %p", d.current.d)
+		}
+		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.
+// It is NOT possible to reuse the decoder after this.
+func (d *Decoder) Close() {
+	if d.current.err == ErrDecoderClosed {
+		return
+	}
+	d.drainOutput()
+	if d.stream != nil {
+		close(d.stream)
+		d.streamWg.Wait()
+		d.stream = nil
+	}
+	if d.decoders != nil {
+		close(d.decoders)
+		for dec := range d.decoders {
+			dec.Close()
+		}
+		d.decoders = nil
+	}
+	if d.current.d != nil {
+		d.current.d.Close()
+		d.current.d = nil
+	}
+	d.current.err = ErrDecoderClosed
+}
+
+// IOReadCloser returns the decoder as an io.ReadCloser for convenience.
+// Any changes to the decoder will be reflected, so the returned ReadCloser
+// can be reused along with the decoder.
+// io.WriterTo is also supported by the returned ReadCloser.
+func (d *Decoder) IOReadCloser() io.ReadCloser {
+	return closeWrapper{d: d}
+}
+
+// closeWrapper wraps a function call as a closer.
+type closeWrapper struct {
+	d *Decoder
+}
+
+// WriteTo forwards WriteTo calls to the decoder.
+func (c closeWrapper) WriteTo(w io.Writer) (n int64, err error) {
+	return c.d.WriteTo(w)
+}
+
+// Read forwards read calls to the decoder.
+func (c closeWrapper) Read(p []byte) (n int, err error) {
+	return c.d.Read(p)
+}
+
+// Close closes the decoder.
+func (c closeWrapper) Close() error {
+	c.d.Close()
+	return nil
+}
+
+type decodeOutput struct {
+	d   *blockDec
+	b   []byte
+	err error
+}
+
+type decodeStream struct {
+	r io.Reader
+
+	// Blocks ready to be written to output.
+	output chan decodeOutput
+
+	// cancel reading from the input
+	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.
+// Create goroutine that handles stream processing, this will send history to decoders as they are available.
+// Decoders update the history as they decode.
+// When a block is returned:
+// 		a) history is sent to the next decoder,
+// 		b) content written to CRC.
+// 		c) return data to WRITER.
+// 		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)
+	for stream := range inStream {
+		if debugDecoder {
+			println("got new stream")
+		}
+		br := readerWrapper{r: stream.r}
+	decodeStream:
+		for {
+			frame.history.reset()
+			err := frame.reset(&br)
+			if debugDecoder && err != nil {
+				println("Frame decoder returned", err)
+			}
+			if err == nil && frame.DictionaryID != nil {
+				dict, ok := d.dicts[*frame.DictionaryID]
+				if !ok {
+					err = ErrUnknownDictionary
+				} else {
+					frame.history.setDict(&dict)
+				}
+			}
+			if err != nil {
+				stream.output <- decodeOutput{
+					err: err,
+				}
+				break
+			}
+			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
+				select {
+				case <-stream.cancel:
+					if !frame.sendErr(dec, io.EOF) {
+						// To not let the decoder dangle, send it back.
+						stream.output <- decodeOutput{d: dec}
+					}
+					break decodeStream
+				default:
+				}
+				err := frame.next(dec)
+				switch err {
+				case io.EOF:
+					// End of current frame, no error
+					println("EOF on next block")
+					break decodeFrame
+				case nil:
+					continue
+				default:
+					println("block decoder returned", err)
+					break decodeStream
+				}
+			}
+			// 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}
+	}
+}