minio/cmd/erasure-encode.go
2019-01-17 18:28:18 +05:30

110 lines
2.7 KiB
Go

/*
* Minio Cloud Storage, (C) 2016 Minio, Inc.
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package cmd
import (
"context"
"io"
"sync"
"github.com/minio/minio/cmd/logger"
)
// Writes in parallel to writers
type parallelWriter struct {
writers []io.Writer
writeQuorum int
errs []error
}
// Write writes data to writers in parallel.
func (p *parallelWriter) Write(ctx context.Context, blocks [][]byte) error {
var wg sync.WaitGroup
for i := range p.writers {
if p.writers[i] == nil {
p.errs[i] = errDiskNotFound
continue
}
wg.Add(1)
go func(i int) {
defer wg.Done()
_, p.errs[i] = p.writers[i].Write(blocks[i])
if p.errs[i] != nil {
p.writers[i] = nil
}
}(i)
}
wg.Wait()
// If nilCount >= p.writeQuorum, we return nil. This is because HealFile() uses
// CreateFile with p.writeQuorum=1 to accommodate healing of single disk.
// i.e if we do no return here in such a case, reduceWriteQuorumErrs() would
// return a quorum error to HealFile().
nilCount := 0
for _, err := range p.errs {
if err == nil {
nilCount++
}
}
if nilCount >= p.writeQuorum {
return nil
}
return reduceWriteQuorumErrs(ctx, p.errs, objectOpIgnoredErrs, p.writeQuorum)
}
// Encode reads from the reader, erasure-encodes the data and writes to the writers.
func (e *Erasure) Encode(ctx context.Context, src io.Reader, writers []io.Writer, buf []byte, quorum int) (total int64, err error) {
writer := &parallelWriter{
writers: writers,
writeQuorum: quorum,
errs: make([]error, len(writers)),
}
for {
var blocks [][]byte
n, err := io.ReadFull(src, buf)
if err != nil && err != io.EOF && err != io.ErrUnexpectedEOF {
logger.LogIf(ctx, err)
return 0, err
}
eof := err == io.EOF || err == io.ErrUnexpectedEOF
if n == 0 && total != 0 {
// Reached EOF, nothing more to be done.
break
}
// We take care of the situation where if n == 0 and total == 0 by creating empty data and parity files.
blocks, err = e.EncodeData(ctx, buf[:n])
if err != nil {
logger.LogIf(ctx, err)
return 0, err
}
if err = writer.Write(ctx, blocks); err != nil {
logger.LogIf(ctx, err)
return 0, err
}
total += int64(n)
if eof {
break
}
}
return total, nil
}