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minio/erasure-healfile.go

84 lines
2.5 KiB

/*
* 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 main
import "encoding/hex"
// Heals the erasure coded file. reedsolomon.Reconstruct() is used to reconstruct the missing parts.
func erasureHealFile(latestDisks []StorageAPI, outDatedDisks []StorageAPI, volume, path, healBucket, healPath string, size int64, blockSize int64, dataBlocks int, parityBlocks int, algo string) (checkSums []string, err error) {
var offset int64
remainingSize := size
// Hash for bitrot protection.
hashWriters := newHashWriters(len(outDatedDisks), bitRotAlgo)
for remainingSize > 0 {
curBlockSize := blockSize
if remainingSize < curBlockSize {
curBlockSize = remainingSize
}
// Calculate the block size that needs to be read from each disk.
curEncBlockSize := getChunkSize(curBlockSize, dataBlocks)
// Memory for reading data from disks and reconstructing missing data using erasure coding.
enBlocks := make([][]byte, len(latestDisks))
// Read data from the latest disks.
// FIXME: no need to read from all the disks. dataBlocks+1 is enough.
for index, disk := range latestDisks {
if disk == nil {
continue
}
enBlocks[index] = make([]byte, curEncBlockSize)
_, err := disk.ReadFile(volume, path, offset, enBlocks[index])
if err != nil {
enBlocks[index] = nil
}
}
// Reconstruct missing data.
err := decodeData(enBlocks, dataBlocks, parityBlocks)
if err != nil {
return nil, err
}
// Write to the healPath file.
for index, disk := range outDatedDisks {
if disk == nil {
continue
}
err := disk.AppendFile(healBucket, healPath, enBlocks[index])
if err != nil {
return nil, err
}
hashWriters[index].Write(enBlocks[index])
}
remainingSize -= curBlockSize
offset += curEncBlockSize
}
// Checksums for the bit rot.
checkSums = make([]string, len(outDatedDisks))
for index, disk := range outDatedDisks {
if disk == nil {
continue
}
checkSums[index] = hex.EncodeToString(hashWriters[index].Sum(nil))
}
return checkSums, nil
}