From 9d6dce119949d340ebb42becae018a3c11148690 Mon Sep 17 00:00:00 2001 From: Daniel J Walsh Date: Thu, 1 Aug 2019 03:46:14 -0400 Subject: github.com/containers/storage v1.12.13 Signed-off-by: Daniel J Walsh --- .../github.com/klauspost/compress/zstd/decoder.go | 437 +++++++++++++++++++++ 1 file changed, 437 insertions(+) create mode 100644 vendor/github.com/klauspost/compress/zstd/decoder.go (limited to 'vendor/github.com/klauspost/compress/zstd/decoder.go') 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 000000000..f06bff6f6 --- /dev/null +++ b/vendor/github.com/klauspost/compress/zstd/decoder.go @@ -0,0 +1,437 @@ +// 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 ( + "bytes" + "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 + + // Unreferenced decoders, ready for use. + frames chan *frameDec + + // Streams ready to be decoded. + stream chan decodeStream + + // Current read position used for Reader functionality. + current decoderState + + // Custom dictionaries + dicts map[uint32]struct{} + + // 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 or DecodeBuffer. +// +// 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) { + 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 + + // Create decoders + d.decoders = make(chan *blockDec, d.o.concurrent) + d.frames = make(chan *frameDec, d.o.concurrent) + for i := 0; i < d.o.concurrent; i++ { + d.frames <- newFrameDec(d.o) + d.decoders <- newBlockDec(d.o.lowMem) + } + + 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) { + if d.stream == nil { + return 0, errors.New("no input has been initialized") + } + 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 + } + d.nextBlock() + } + } + if len(d.current.b) > 0 { + // Only return error at end of block + return n, nil + } + if d.current.err != nil { + d.drainOutput() + } + if debug { + 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. +func (d *Decoder) Reset(r io.Reader) error { + if d.current.err == ErrDecoderClosed { + return d.current.err + } + if r == nil { + return errors.New("nil Reader sent as input") + } + + if d.stream == nil { + d.stream = make(chan decodeStream, 1) + d.streamWg.Add(1) + go d.startStreamDecoder(d.stream) + } + + d.drainOutput() + + // If bytes buffer and < 1MB, do sync decoding anyway. + if bb, ok := r.(*bytes.Buffer); ok && bb.Len() < 1<<20 { + b := bb.Bytes() + dst, err := d.DecodeAll(b, nil) + if err == nil { + err = io.EOF + } + d.current.b = dst + d.current.err = err + d.current.flushed = true + return nil + } + + // 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 { + println("re-adding current decoder", 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 { + select { + case v := <-d.current.output: + if v.d != nil { + println("got decoder", 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) { + if d.stream == nil { + return 0, errors.New("no input has been initialized") + } + 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 = err2 + break + } + } + if d.current.err != nil { + break + } + d.nextBlock() + } + 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 + } + //println(len(d.frames), len(d.decoders), d.current) + block, frame := <-d.decoders, <-d.frames + defer func() { + d.decoders <- block + frame.rawInput = nil + d.frames <- frame + }() + if cap(dst) == 0 { + // Allocate 1MB by default. + dst = make([]byte, 0, 1<<20) + } + br := byteBuf(input) + for { + err := frame.reset(&br) + if err == io.EOF { + return dst, nil + } + 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 uint64(cap(dst)) < frame.FrameContentSize { + dst2 := make([]byte, len(dst), len(dst)+int(frame.FrameContentSize)) + copy(dst2, dst) + dst = dst2 + } + } + dst, err = frame.runDecoder(dst, block) + if err != nil { + return dst, err + } + if len(br) == 0 { + break + } + } + return dst, nil +} + +// nextBlock returns the next block. +// If an error occurs d.err will be set. +func (d *Decoder) nextBlock() { + if d.current.d != nil { + d.decoders <- d.current.d + d.current.d = nil + } + if d.current.err != nil { + // Keep error state. + return + } + d.current.decodeOutput = <-d.current.output + if debug { + println("got", len(d.current.b), "bytes, error:", d.current.err) + } +} + +// 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 +} + +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 { + br := readerWrapper{r: stream.r} + decodeStream: + for { + err := frame.reset(&br) + if debug && err != nil { + println("Frame decoder returned", err) + } + if err != nil { + stream.output <- decodeOutput{ + err: err, + } + break + } + if debug { + 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} + } +} -- cgit v1.2.3-54-g00ecf