From 8c12c6939aab9106db14ec2d11d983bc5b29fb2c Mon Sep 17 00:00:00 2001 From: Niall Sheridan Date: Sun, 7 Jul 2019 21:33:44 +0100 Subject: Switch to modules --- vendor/github.com/golang/snappy/encode.go | 285 ------------------------------ 1 file changed, 285 deletions(-) delete mode 100644 vendor/github.com/golang/snappy/encode.go (limited to 'vendor/github.com/golang/snappy/encode.go') diff --git a/vendor/github.com/golang/snappy/encode.go b/vendor/github.com/golang/snappy/encode.go deleted file mode 100644 index 8d393e9..0000000 --- a/vendor/github.com/golang/snappy/encode.go +++ /dev/null @@ -1,285 +0,0 @@ -// Copyright 2011 The Snappy-Go Authors. All rights reserved. -// Use of this source code is governed by a BSD-style -// license that can be found in the LICENSE file. - -package snappy - -import ( - "encoding/binary" - "errors" - "io" -) - -// Encode returns the encoded form of src. The returned slice may be a sub- -// slice of dst if dst was large enough to hold the entire encoded block. -// Otherwise, a newly allocated slice will be returned. -// -// The dst and src must not overlap. It is valid to pass a nil dst. -func Encode(dst, src []byte) []byte { - if n := MaxEncodedLen(len(src)); n < 0 { - panic(ErrTooLarge) - } else if len(dst) < n { - dst = make([]byte, n) - } - - // The block starts with the varint-encoded length of the decompressed bytes. - d := binary.PutUvarint(dst, uint64(len(src))) - - for len(src) > 0 { - p := src - src = nil - if len(p) > maxBlockSize { - p, src = p[:maxBlockSize], p[maxBlockSize:] - } - if len(p) < minNonLiteralBlockSize { - d += emitLiteral(dst[d:], p) - } else { - d += encodeBlock(dst[d:], p) - } - } - return dst[:d] -} - -// inputMargin is the minimum number of extra input bytes to keep, inside -// encodeBlock's inner loop. On some architectures, this margin lets us -// implement a fast path for emitLiteral, where the copy of short (<= 16 byte) -// literals can be implemented as a single load to and store from a 16-byte -// register. That literal's actual length can be as short as 1 byte, so this -// can copy up to 15 bytes too much, but that's OK as subsequent iterations of -// the encoding loop will fix up the copy overrun, and this inputMargin ensures -// that we don't overrun the dst and src buffers. -const inputMargin = 16 - 1 - -// minNonLiteralBlockSize is the minimum size of the input to encodeBlock that -// could be encoded with a copy tag. This is the minimum with respect to the -// algorithm used by encodeBlock, not a minimum enforced by the file format. -// -// The encoded output must start with at least a 1 byte literal, as there are -// no previous bytes to copy. A minimal (1 byte) copy after that, generated -// from an emitCopy call in encodeBlock's main loop, would require at least -// another inputMargin bytes, for the reason above: we want any emitLiteral -// calls inside encodeBlock's main loop to use the fast path if possible, which -// requires being able to overrun by inputMargin bytes. Thus, -// minNonLiteralBlockSize equals 1 + 1 + inputMargin. -// -// The C++ code doesn't use this exact threshold, but it could, as discussed at -// https://groups.google.com/d/topic/snappy-compression/oGbhsdIJSJ8/discussion -// The difference between Go (2+inputMargin) and C++ (inputMargin) is purely an -// optimization. It should not affect the encoded form. This is tested by -// TestSameEncodingAsCppShortCopies. -const minNonLiteralBlockSize = 1 + 1 + inputMargin - -// MaxEncodedLen returns the maximum length of a snappy block, given its -// uncompressed length. -// -// It will return a negative value if srcLen is too large to encode. -func MaxEncodedLen(srcLen int) int { - n := uint64(srcLen) - if n > 0xffffffff { - return -1 - } - // Compressed data can be defined as: - // compressed := item* literal* - // item := literal* copy - // - // The trailing literal sequence has a space blowup of at most 62/60 - // since a literal of length 60 needs one tag byte + one extra byte - // for length information. - // - // Item blowup is trickier to measure. Suppose the "copy" op copies - // 4 bytes of data. Because of a special check in the encoding code, - // we produce a 4-byte copy only if the offset is < 65536. Therefore - // the copy op takes 3 bytes to encode, and this type of item leads - // to at most the 62/60 blowup for representing literals. - // - // Suppose the "copy" op copies 5 bytes of data. If the offset is big - // enough, it will take 5 bytes to encode the copy op. Therefore the - // worst case here is a one-byte literal followed by a five-byte copy. - // That is, 6 bytes of input turn into 7 bytes of "compressed" data. - // - // This last factor dominates the blowup, so the final estimate is: - n = 32 + n + n/6 - if n > 0xffffffff { - return -1 - } - return int(n) -} - -var errClosed = errors.New("snappy: Writer is closed") - -// NewWriter returns a new Writer that compresses to w. -// -// The Writer returned does not buffer writes. There is no need to Flush or -// Close such a Writer. -// -// Deprecated: the Writer returned is not suitable for many small writes, only -// for few large writes. Use NewBufferedWriter instead, which is efficient -// regardless of the frequency and shape of the writes, and remember to Close -// that Writer when done. -func NewWriter(w io.Writer) *Writer { - return &Writer{ - w: w, - obuf: make([]byte, obufLen), - } -} - -// NewBufferedWriter returns a new Writer that compresses to w, using the -// framing format described at -// https://github.com/google/snappy/blob/master/framing_format.txt -// -// The Writer returned buffers writes. Users must call Close to guarantee all -// data has been forwarded to the underlying io.Writer. They may also call -// Flush zero or more times before calling Close. -func NewBufferedWriter(w io.Writer) *Writer { - return &Writer{ - w: w, - ibuf: make([]byte, 0, maxBlockSize), - obuf: make([]byte, obufLen), - } -} - -// Writer is an io.Writer that can write Snappy-compressed bytes. -type Writer struct { - w io.Writer - err error - - // ibuf is a buffer for the incoming (uncompressed) bytes. - // - // Its use is optional. For backwards compatibility, Writers created by the - // NewWriter function have ibuf == nil, do not buffer incoming bytes, and - // therefore do not need to be Flush'ed or Close'd. - ibuf []byte - - // obuf is a buffer for the outgoing (compressed) bytes. - obuf []byte - - // wroteStreamHeader is whether we have written the stream header. - wroteStreamHeader bool -} - -// Reset discards the writer's state and switches the Snappy writer to write to -// w. This permits reusing a Writer rather than allocating a new one. -func (w *Writer) Reset(writer io.Writer) { - w.w = writer - w.err = nil - if w.ibuf != nil { - w.ibuf = w.ibuf[:0] - } - w.wroteStreamHeader = false -} - -// Write satisfies the io.Writer interface. -func (w *Writer) Write(p []byte) (nRet int, errRet error) { - if w.ibuf == nil { - // Do not buffer incoming bytes. This does not perform or compress well - // if the caller of Writer.Write writes many small slices. This - // behavior is therefore deprecated, but still supported for backwards - // compatibility with code that doesn't explicitly Flush or Close. - return w.write(p) - } - - // The remainder of this method is based on bufio.Writer.Write from the - // standard library. - - for len(p) > (cap(w.ibuf)-len(w.ibuf)) && w.err == nil { - var n int - if len(w.ibuf) == 0 { - // Large write, empty buffer. - // Write directly from p to avoid copy. - n, _ = w.write(p) - } else { - n = copy(w.ibuf[len(w.ibuf):cap(w.ibuf)], p) - w.ibuf = w.ibuf[:len(w.ibuf)+n] - w.Flush() - } - nRet += n - p = p[n:] - } - if w.err != nil { - return nRet, w.err - } - n := copy(w.ibuf[len(w.ibuf):cap(w.ibuf)], p) - w.ibuf = w.ibuf[:len(w.ibuf)+n] - nRet += n - return nRet, nil -} - -func (w *Writer) write(p []byte) (nRet int, errRet error) { - if w.err != nil { - return 0, w.err - } - for len(p) > 0 { - obufStart := len(magicChunk) - if !w.wroteStreamHeader { - w.wroteStreamHeader = true - copy(w.obuf, magicChunk) - obufStart = 0 - } - - var uncompressed []byte - if len(p) > maxBlockSize { - uncompressed, p = p[:maxBlockSize], p[maxBlockSize:] - } else { - uncompressed, p = p, nil - } - checksum := crc(uncompressed) - - // Compress the buffer, discarding the result if the improvement - // isn't at least 12.5%. - compressed := Encode(w.obuf[obufHeaderLen:], uncompressed) - chunkType := uint8(chunkTypeCompressedData) - chunkLen := 4 + len(compressed) - obufEnd := obufHeaderLen + len(compressed) - if len(compressed) >= len(uncompressed)-len(uncompressed)/8 { - chunkType = chunkTypeUncompressedData - chunkLen = 4 + len(uncompressed) - obufEnd = obufHeaderLen - } - - // Fill in the per-chunk header that comes before the body. - w.obuf[len(magicChunk)+0] = chunkType - w.obuf[len(magicChunk)+1] = uint8(chunkLen >> 0) - w.obuf[len(magicChunk)+2] = uint8(chunkLen >> 8) - w.obuf[len(magicChunk)+3] = uint8(chunkLen >> 16) - w.obuf[len(magicChunk)+4] = uint8(checksum >> 0) - w.obuf[len(magicChunk)+5] = uint8(checksum >> 8) - w.obuf[len(magicChunk)+6] = uint8(checksum >> 16) - w.obuf[len(magicChunk)+7] = uint8(checksum >> 24) - - if _, err := w.w.Write(w.obuf[obufStart:obufEnd]); err != nil { - w.err = err - return nRet, err - } - if chunkType == chunkTypeUncompressedData { - if _, err := w.w.Write(uncompressed); err != nil { - w.err = err - return nRet, err - } - } - nRet += len(uncompressed) - } - return nRet, nil -} - -// Flush flushes the Writer to its underlying io.Writer. -func (w *Writer) Flush() error { - if w.err != nil { - return w.err - } - if len(w.ibuf) == 0 { - return nil - } - w.write(w.ibuf) - w.ibuf = w.ibuf[:0] - return w.err -} - -// Close calls Flush and then closes the Writer. -func (w *Writer) Close() error { - w.Flush() - ret := w.err - if w.err == nil { - w.err = errClosed - } - return ret -} -- cgit v1.2.3