diff options
Diffstat (limited to 'vendor/github.com/syndtr/goleveldb/leveldb/journal/journal.go')
| -rw-r--r-- | vendor/github.com/syndtr/goleveldb/leveldb/journal/journal.go | 524 |
1 files changed, 524 insertions, 0 deletions
diff --git a/vendor/github.com/syndtr/goleveldb/leveldb/journal/journal.go b/vendor/github.com/syndtr/goleveldb/leveldb/journal/journal.go new file mode 100644 index 0000000..d094c3d --- /dev/null +++ b/vendor/github.com/syndtr/goleveldb/leveldb/journal/journal.go @@ -0,0 +1,524 @@ +// 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 +} |