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Copy pathbitrot-streaming.go
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204 lines (190 loc) · 6.14 KB
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// Copyright (c) 2015-2021 MinIO, Inc.
//
// This file is part of MinIO Object Storage stack
//
// This program is free software: you can redistribute it and/or modify
// it under the terms of the GNU Affero General Public License as published by
// the Free Software Foundation, either version 3 of the License, or
// (at your option) any later version.
//
// This program is distributed in the hope that it will be useful
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
// GNU Affero General Public License for more details.
//
// You should have received a copy of the GNU Affero General Public License
// along with this program. If not, see <http://www.gnu.org/licenses/>.
package cmd
import (
"bytes"
"context"
"encoding/hex"
"fmt"
"hash"
"io"
"sync"
xhttp "github.com/minio/minio/internal/http"
"github.com/minio/minio/internal/ioutil"
"github.com/minio/minio/internal/logger"
)
// Calculates bitrot in chunks and writes the hash into the stream.
type streamingBitrotWriter struct {
iow io.WriteCloser
closeWithErr func(err error) error
h hash.Hash
shardSize int64
canClose *sync.WaitGroup
}
func (b *streamingBitrotWriter) Write(p []byte) (int, error) {
if len(p) == 0 {
return 0, nil
}
b.h.Reset()
b.h.Write(p)
hashBytes := b.h.Sum(nil)
_, err := b.iow.Write(hashBytes)
if err != nil {
b.closeWithErr(err)
return 0, err
}
n, err := b.iow.Write(p)
if err != nil {
b.closeWithErr(err)
return n, err
}
if n != len(p) {
err = io.ErrShortWrite
b.closeWithErr(err)
}
return n, err
}
func (b *streamingBitrotWriter) Close() error {
err := b.iow.Close()
// Wait for all data to be written before returning else it causes race conditions.
// Race condition is because of io.PipeWriter implementation. i.e consider the following
// sequent of operations:
// 1) pipe.Write()
// 2) pipe.Close()
// Now pipe.Close() can return before the data is read on the other end of the pipe and written to the disk
// Hence an immediate Read() on the file can return incorrect data.
if b.canClose != nil {
b.canClose.Wait()
}
return err
}
// newStreamingBitrotWriterBuffer returns streaming bitrot writer implementation.
// The output is written to the supplied writer w.
func newStreamingBitrotWriterBuffer(w io.Writer, algo BitrotAlgorithm, shardSize int64) io.Writer {
return &streamingBitrotWriter{iow: ioutil.NopCloser(w), h: algo.New(), shardSize: shardSize, canClose: nil, closeWithErr: func(err error) error {
// Similar to CloseWithError on pipes we always return nil.
return nil
}}
}
// Returns streaming bitrot writer implementation.
func newStreamingBitrotWriter(disk StorageAPI, volume, filePath string, length int64, algo BitrotAlgorithm, shardSize int64) io.Writer {
r, w := io.Pipe()
h := algo.New()
bw := &streamingBitrotWriter{iow: w, closeWithErr: w.CloseWithError, h: h, shardSize: shardSize, canClose: &sync.WaitGroup{}}
bw.canClose.Add(1)
go func() {
totalFileSize := int64(-1) // For compressed objects length will be unknown (represented by length=-1)
if length != -1 {
bitrotSumsTotalSize := ceilFrac(length, shardSize) * int64(h.Size()) // Size used for storing bitrot checksums.
totalFileSize = bitrotSumsTotalSize + length
}
r.CloseWithError(disk.CreateFile(context.TODO(), volume, filePath, totalFileSize, r))
bw.canClose.Done()
}()
return bw
}
// ReadAt() implementation which verifies the bitrot hash available as part of the stream.
type streamingBitrotReader struct {
disk StorageAPI
data []byte
rc io.Reader
volume string
filePath string
tillOffset int64
currOffset int64
h hash.Hash
shardSize int64
hashBytes []byte
}
func (b *streamingBitrotReader) Close() error {
if b.rc == nil {
return nil
}
if closer, ok := b.rc.(io.Closer); ok {
// drain the body for connection re-use at network layer.
xhttp.DrainBody(struct {
io.Reader
io.Closer
}{
Reader: b.rc,
Closer: closeWrapper(func() error { return nil }),
})
return closer.Close()
}
return nil
}
func (b *streamingBitrotReader) ReadAt(buf []byte, offset int64) (int, error) {
var err error
if offset%b.shardSize != 0 {
// Offset should always be aligned to b.shardSize
// Can never happen unless there are programmer bugs
return 0, errUnexpected
}
if b.rc == nil {
// For the first ReadAt() call we need to open the stream for reading.
b.currOffset = offset
streamOffset := (offset/b.shardSize)*int64(b.h.Size()) + offset
if len(b.data) == 0 && b.tillOffset != streamOffset {
b.rc, err = b.disk.ReadFileStream(context.TODO(), b.volume, b.filePath, streamOffset, b.tillOffset-streamOffset)
if err != nil {
logger.LogIf(GlobalContext,
fmt.Errorf("Error(%w) reading erasure shards at (%s: %s/%s), will attempt to reconstruct if we have quorum",
err, b.disk, b.volume, b.filePath))
}
} else {
b.rc = io.NewSectionReader(bytes.NewReader(b.data), streamOffset, b.tillOffset-streamOffset)
}
if err != nil {
return 0, err
}
}
if offset != b.currOffset {
// Can never happen unless there are programmer bugs
return 0, errUnexpected
}
b.h.Reset()
_, err = io.ReadFull(b.rc, b.hashBytes)
if err != nil {
return 0, err
}
_, err = io.ReadFull(b.rc, buf)
if err != nil {
return 0, err
}
b.h.Write(buf)
if !bytes.Equal(b.h.Sum(nil), b.hashBytes) {
logger.LogIf(GlobalContext, fmt.Errorf("Disk: %s -> %s/%s - content hash does not match - expected %s, got %s",
b.disk, b.volume, b.filePath, hex.EncodeToString(b.hashBytes), hex.EncodeToString(b.h.Sum(nil))))
return 0, errFileCorrupt
}
b.currOffset += int64(len(buf))
return len(buf), nil
}
// Returns streaming bitrot reader implementation.
func newStreamingBitrotReader(disk StorageAPI, data []byte, volume, filePath string, tillOffset int64, algo BitrotAlgorithm, shardSize int64) *streamingBitrotReader {
h := algo.New()
return &streamingBitrotReader{
disk: disk,
data: data,
volume: volume,
filePath: filePath,
tillOffset: ceilFrac(tillOffset, shardSize)*int64(h.Size()) + tillOffset,
h: h,
shardSize: shardSize,
hashBytes: make([]byte, h.Size()),
}
}