plugeth/vendor/github.com/syndtr/goleveldb/leveldb/journal/journal.go
Péter Szilágyi 289b30715d Godeps, vendor: convert dependency management to trash (#3198)
This commit converts the dependency management from Godeps to the vendor
folder, also switching the tool from godep to trash. Since the upstream tool
lacks a few features proposed via a few PRs, until those PRs are merged in
(if), use github.com/karalabe/trash.

You can update dependencies via trash --update.

All dependencies have been updated to their latest version.

Parts of the build system are reworked to drop old notions of Godeps and
invocation of the go vet command so that it doesn't run against the vendor
folder, as that will just blow up during vetting.

The conversion drops OpenCL (and hence GPU mining support) from ethash and our
codebase. The short reasoning is that there's noone to maintain and having
opencl libs in our deps messes up builds as go install ./... tries to build
them, failing with unsatisfied link errors for the C OpenCL deps.

golang.org/x/net/context is not vendored in. We expect it to be fetched by the
user (i.e. using go get). To keep ci.go builds reproducible the package is
"vendored" in build/_vendor.
2016-10-28 19:05:01 +02:00

525 lines
13 KiB
Go

// Copyright 2011 The LevelDB-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.
// Taken from: https://code.google.com/p/leveldb-go/source/browse/leveldb/record/record.go?r=1d5ccbe03246da926391ee12d1c6caae054ff4b0
// License, authors and contributors informations can be found at bellow URLs respectively:
// https://code.google.com/p/leveldb-go/source/browse/LICENSE
// https://code.google.com/p/leveldb-go/source/browse/AUTHORS
// https://code.google.com/p/leveldb-go/source/browse/CONTRIBUTORS
// Package journal reads and writes sequences of journals. Each journal is a stream
// of bytes that completes before the next journal starts.
//
// When reading, call Next to obtain an io.Reader for the next journal. Next will
// return io.EOF when there are no more journals. It is valid to call Next
// without reading the current journal to exhaustion.
//
// When writing, call Next to obtain an io.Writer for the next journal. Calling
// Next finishes the current journal. Call Close to finish the final journal.
//
// Optionally, call Flush to finish the current journal and flush the underlying
// writer without starting a new journal. To start a new journal after flushing,
// call Next.
//
// Neither Readers or Writers are safe to use concurrently.
//
// Example code:
// func read(r io.Reader) ([]string, error) {
// var ss []string
// journals := journal.NewReader(r, nil, true, true)
// for {
// j, err := journals.Next()
// if err == io.EOF {
// break
// }
// if err != nil {
// return nil, err
// }
// s, err := ioutil.ReadAll(j)
// if err != nil {
// return nil, err
// }
// ss = append(ss, string(s))
// }
// return ss, nil
// }
//
// func write(w io.Writer, ss []string) error {
// journals := journal.NewWriter(w)
// for _, s := range ss {
// j, err := journals.Next()
// if err != nil {
// return err
// }
// if _, err := j.Write([]byte(s)), err != nil {
// return err
// }
// }
// return journals.Close()
// }
//
// The wire format is that the stream is divided into 32KiB blocks, and each
// block contains a number of tightly packed chunks. Chunks cannot cross block
// boundaries. The last block may be shorter than 32 KiB. Any unused bytes in a
// block must be zero.
//
// A journal maps to one or more chunks. Each chunk has a 7 byte header (a 4
// byte checksum, a 2 byte little-endian uint16 length, and a 1 byte chunk type)
// followed by a payload. The checksum is over the chunk type and the payload.
//
// There are four chunk types: whether the chunk is the full journal, or the
// first, middle or last chunk of a multi-chunk journal. A multi-chunk journal
// has one first chunk, zero or more middle chunks, and one last chunk.
//
// The wire format allows for limited recovery in the face of data corruption:
// on a format error (such as a checksum mismatch), the reader moves to the
// next block and looks for the next full or first chunk.
package journal
import (
"encoding/binary"
"fmt"
"io"
"github.com/syndtr/goleveldb/leveldb/errors"
"github.com/syndtr/goleveldb/leveldb/storage"
"github.com/syndtr/goleveldb/leveldb/util"
)
// These constants are part of the wire format and should not be changed.
const (
fullChunkType = 1
firstChunkType = 2
middleChunkType = 3
lastChunkType = 4
)
const (
blockSize = 32 * 1024
headerSize = 7
)
type flusher interface {
Flush() error
}
// ErrCorrupted is the error type that generated by corrupted block or chunk.
type ErrCorrupted struct {
Size int
Reason string
}
func (e *ErrCorrupted) Error() string {
return fmt.Sprintf("leveldb/journal: block/chunk corrupted: %s (%d bytes)", e.Reason, e.Size)
}
// Dropper is the interface that wrap simple Drop method. The Drop
// method will be called when the journal reader dropping a block or chunk.
type Dropper interface {
Drop(err error)
}
// Reader reads journals from an underlying io.Reader.
type Reader struct {
// r is the underlying reader.
r io.Reader
// the dropper.
dropper Dropper
// strict flag.
strict bool
// checksum flag.
checksum bool
// seq is the sequence number of the current journal.
seq int
// buf[i:j] is the unread portion of the current chunk's payload.
// The low bound, i, excludes the chunk header.
i, j int
// n is the number of bytes of buf that are valid. Once reading has started,
// only the final block can have n < blockSize.
n int
// last is whether the current chunk is the last chunk of the journal.
last bool
// err is any accumulated error.
err error
// buf is the buffer.
buf [blockSize]byte
}
// NewReader returns a new reader. The dropper may be nil, and if
// strict is true then corrupted or invalid chunk will halt the journal
// reader entirely.
func NewReader(r io.Reader, dropper Dropper, strict, checksum bool) *Reader {
return &Reader{
r: r,
dropper: dropper,
strict: strict,
checksum: checksum,
last: true,
}
}
var errSkip = errors.New("leveldb/journal: skipped")
func (r *Reader) corrupt(n int, reason string, skip bool) error {
if r.dropper != nil {
r.dropper.Drop(&ErrCorrupted{n, reason})
}
if r.strict && !skip {
r.err = errors.NewErrCorrupted(storage.FileDesc{}, &ErrCorrupted{n, reason})
return r.err
}
return errSkip
}
// nextChunk sets r.buf[r.i:r.j] to hold the next chunk's payload, reading the
// next block into the buffer if necessary.
func (r *Reader) nextChunk(first bool) error {
for {
if r.j+headerSize <= r.n {
checksum := binary.LittleEndian.Uint32(r.buf[r.j+0 : r.j+4])
length := binary.LittleEndian.Uint16(r.buf[r.j+4 : r.j+6])
chunkType := r.buf[r.j+6]
unprocBlock := r.n - r.j
if checksum == 0 && length == 0 && chunkType == 0 {
// Drop entire block.
r.i = r.n
r.j = r.n
return r.corrupt(unprocBlock, "zero header", false)
}
if chunkType < fullChunkType || chunkType > lastChunkType {
// Drop entire block.
r.i = r.n
r.j = r.n
return r.corrupt(unprocBlock, fmt.Sprintf("invalid chunk type %#x", chunkType), false)
}
r.i = r.j + headerSize
r.j = r.j + headerSize + int(length)
if r.j > r.n {
// Drop entire block.
r.i = r.n
r.j = r.n
return r.corrupt(unprocBlock, "chunk length overflows block", false)
} else if r.checksum && checksum != util.NewCRC(r.buf[r.i-1:r.j]).Value() {
// Drop entire block.
r.i = r.n
r.j = r.n
return r.corrupt(unprocBlock, "checksum mismatch", false)
}
if first && chunkType != fullChunkType && chunkType != firstChunkType {
chunkLength := (r.j - r.i) + headerSize
r.i = r.j
// Report the error, but skip it.
return r.corrupt(chunkLength, "orphan chunk", true)
}
r.last = chunkType == fullChunkType || chunkType == lastChunkType
return nil
}
// The last block.
if r.n < blockSize && r.n > 0 {
if !first {
return r.corrupt(0, "missing chunk part", false)
}
r.err = io.EOF
return r.err
}
// Read block.
n, err := io.ReadFull(r.r, r.buf[:])
if err != nil && err != io.EOF && err != io.ErrUnexpectedEOF {
return err
}
if n == 0 {
if !first {
return r.corrupt(0, "missing chunk part", false)
}
r.err = io.EOF
return r.err
}
r.i, r.j, r.n = 0, 0, n
}
}
// Next returns a reader for the next journal. It returns io.EOF if there are no
// more journals. The reader returned becomes stale after the next Next call,
// and should no longer be used. If strict is false, the reader will returns
// io.ErrUnexpectedEOF error when found corrupted journal.
func (r *Reader) Next() (io.Reader, error) {
r.seq++
if r.err != nil {
return nil, r.err
}
r.i = r.j
for {
if err := r.nextChunk(true); err == nil {
break
} else if err != errSkip {
return nil, err
}
}
return &singleReader{r, r.seq, nil}, nil
}
// Reset resets the journal reader, allows reuse of the journal reader. Reset returns
// last accumulated error.
func (r *Reader) Reset(reader io.Reader, dropper Dropper, strict, checksum bool) error {
r.seq++
err := r.err
r.r = reader
r.dropper = dropper
r.strict = strict
r.checksum = checksum
r.i = 0
r.j = 0
r.n = 0
r.last = true
r.err = nil
return err
}
type singleReader struct {
r *Reader
seq int
err error
}
func (x *singleReader) Read(p []byte) (int, error) {
r := x.r
if r.seq != x.seq {
return 0, errors.New("leveldb/journal: stale reader")
}
if x.err != nil {
return 0, x.err
}
if r.err != nil {
return 0, r.err
}
for r.i == r.j {
if r.last {
return 0, io.EOF
}
x.err = r.nextChunk(false)
if x.err != nil {
if x.err == errSkip {
x.err = io.ErrUnexpectedEOF
}
return 0, x.err
}
}
n := copy(p, r.buf[r.i:r.j])
r.i += n
return n, nil
}
func (x *singleReader) ReadByte() (byte, error) {
r := x.r
if r.seq != x.seq {
return 0, errors.New("leveldb/journal: stale reader")
}
if x.err != nil {
return 0, x.err
}
if r.err != nil {
return 0, r.err
}
for r.i == r.j {
if r.last {
return 0, io.EOF
}
x.err = r.nextChunk(false)
if x.err != nil {
if x.err == errSkip {
x.err = io.ErrUnexpectedEOF
}
return 0, x.err
}
}
c := r.buf[r.i]
r.i++
return c, nil
}
// Writer writes journals to an underlying io.Writer.
type Writer struct {
// w is the underlying writer.
w io.Writer
// seq is the sequence number of the current journal.
seq int
// f is w as a flusher.
f flusher
// buf[i:j] is the bytes that will become the current chunk.
// The low bound, i, includes the chunk header.
i, j int
// buf[:written] has already been written to w.
// written is zero unless Flush has been called.
written int
// first is whether the current chunk is the first chunk of the journal.
first bool
// pending is whether a chunk is buffered but not yet written.
pending bool
// err is any accumulated error.
err error
// buf is the buffer.
buf [blockSize]byte
}
// NewWriter returns a new Writer.
func NewWriter(w io.Writer) *Writer {
f, _ := w.(flusher)
return &Writer{
w: w,
f: f,
}
}
// fillHeader fills in the header for the pending chunk.
func (w *Writer) fillHeader(last bool) {
if w.i+headerSize > w.j || w.j > blockSize {
panic("leveldb/journal: bad writer state")
}
if last {
if w.first {
w.buf[w.i+6] = fullChunkType
} else {
w.buf[w.i+6] = lastChunkType
}
} else {
if w.first {
w.buf[w.i+6] = firstChunkType
} else {
w.buf[w.i+6] = middleChunkType
}
}
binary.LittleEndian.PutUint32(w.buf[w.i+0:w.i+4], util.NewCRC(w.buf[w.i+6:w.j]).Value())
binary.LittleEndian.PutUint16(w.buf[w.i+4:w.i+6], uint16(w.j-w.i-headerSize))
}
// writeBlock writes the buffered block to the underlying writer, and reserves
// space for the next chunk's header.
func (w *Writer) writeBlock() {
_, w.err = w.w.Write(w.buf[w.written:])
w.i = 0
w.j = headerSize
w.written = 0
}
// writePending finishes the current journal and writes the buffer to the
// underlying writer.
func (w *Writer) writePending() {
if w.err != nil {
return
}
if w.pending {
w.fillHeader(true)
w.pending = false
}
_, w.err = w.w.Write(w.buf[w.written:w.j])
w.written = w.j
}
// Close finishes the current journal and closes the writer.
func (w *Writer) Close() error {
w.seq++
w.writePending()
if w.err != nil {
return w.err
}
w.err = errors.New("leveldb/journal: closed Writer")
return nil
}
// Flush finishes the current journal, writes to the underlying writer, and
// flushes it if that writer implements interface{ Flush() error }.
func (w *Writer) Flush() error {
w.seq++
w.writePending()
if w.err != nil {
return w.err
}
if w.f != nil {
w.err = w.f.Flush()
return w.err
}
return nil
}
// Reset resets the journal writer, allows reuse of the journal writer. Reset
// will also closes the journal writer if not already.
func (w *Writer) Reset(writer io.Writer) (err error) {
w.seq++
if w.err == nil {
w.writePending()
err = w.err
}
w.w = writer
w.f, _ = writer.(flusher)
w.i = 0
w.j = 0
w.written = 0
w.first = false
w.pending = false
w.err = nil
return
}
// Next returns a writer for the next journal. The writer returned becomes stale
// after the next Close, Flush or Next call, and should no longer be used.
func (w *Writer) Next() (io.Writer, error) {
w.seq++
if w.err != nil {
return nil, w.err
}
if w.pending {
w.fillHeader(true)
}
w.i = w.j
w.j = w.j + headerSize
// Check if there is room in the block for the header.
if w.j > blockSize {
// Fill in the rest of the block with zeroes.
for k := w.i; k < blockSize; k++ {
w.buf[k] = 0
}
w.writeBlock()
if w.err != nil {
return nil, w.err
}
}
w.first = true
w.pending = true
return singleWriter{w, w.seq}, nil
}
type singleWriter struct {
w *Writer
seq int
}
func (x singleWriter) Write(p []byte) (int, error) {
w := x.w
if w.seq != x.seq {
return 0, errors.New("leveldb/journal: stale writer")
}
if w.err != nil {
return 0, w.err
}
n0 := len(p)
for len(p) > 0 {
// Write a block, if it is full.
if w.j == blockSize {
w.fillHeader(false)
w.writeBlock()
if w.err != nil {
return 0, w.err
}
w.first = false
}
// Copy bytes into the buffer.
n := copy(w.buf[w.j:], p)
w.j += n
p = p[n:]
}
return n0, nil
}