minio/cmd/erasure.go
Andreas Auernhammer 85fcee1919 erasure: simplify XL backend operations (#4649) (#4758)
This change provides new implementations of the XL backend operations:
 - create file
 - read   file
 - heal   file
Further this change adds table based tests for all three operations.

This affects also the bitrot algorithm integration. Algorithms are now
integrated in an idiomatic way (like crypto.Hash).
Fixes #4696
Fixes #4649
Fixes #4359
2017-08-14 18:08:42 -07:00

116 lines
3.7 KiB
Go

/*
* Minio Cloud Storage, (C) 2017 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 (
"crypto/subtle"
"hash"
"github.com/klauspost/reedsolomon"
)
// OfflineDisk represents an unavailable disk.
var OfflineDisk StorageAPI // zero value is nil
// ErasureFileInfo contains information about an erasure file operation (create, read, heal).
type ErasureFileInfo struct {
Size int64
Algorithm BitrotAlgorithm
Checksums [][]byte
}
// ErasureStorage represents an array of disks.
// The disks contain erasure coded and bitrot-protected data.
type ErasureStorage struct {
disks []StorageAPI
erasure reedsolomon.Encoder
dataBlocks, parityBlocks int
}
// NewErasureStorage creates a new ErasureStorage. The storage erasure codes and protects all data written to
// the disks.
func NewErasureStorage(disks []StorageAPI, dataBlocks, parityBlocks int) (s ErasureStorage, err error) {
erasure, err := reedsolomon.New(dataBlocks, parityBlocks)
if err != nil {
return s, traceErrorf("failed to create erasure coding: %v", err)
}
s = ErasureStorage{
disks: make([]StorageAPI, len(disks)),
erasure: erasure,
dataBlocks: dataBlocks,
parityBlocks: parityBlocks,
}
copy(s.disks, disks)
return
}
// ErasureEncode encodes the given data and returns the erasure-coded data.
// It returns an error if the erasure coding failed.
func (s *ErasureStorage) ErasureEncode(data []byte) ([][]byte, error) {
encoded, err := s.erasure.Split(data)
if err != nil {
return nil, traceErrorf("failed to split data: %v", err)
}
if err = s.erasure.Encode(encoded); err != nil {
return nil, traceErrorf("failed to encode data: %v", err)
}
return encoded, nil
}
// ErasureDecodeDataBlocks decodes the given erasure-coded data.
// It only decodes the data blocks but does not verify them.
// It returns an error if the decoding failed.
func (s *ErasureStorage) ErasureDecodeDataBlocks(data [][]byte) error {
if err := s.erasure.ReconstructData(data); err != nil {
return traceErrorf("failed to reconstruct data: %v", err)
}
return nil
}
// ErasureDecodeDataAndParityBlocks decodes the given erasure-coded data and verifies it.
// It returns an error if the decoding failed.
func (s *ErasureStorage) ErasureDecodeDataAndParityBlocks(data [][]byte) error {
if err := s.erasure.Reconstruct(data); err != nil {
return traceErrorf("failed to reconstruct data: %v", err)
}
return nil
}
// NewBitrotVerifier returns a new BitrotVerifier implementing the given algorithm.
func NewBitrotVerifier(algorithm BitrotAlgorithm, checksum []byte) *BitrotVerifier {
return &BitrotVerifier{algorithm.New(), algorithm, checksum, false}
}
// BitrotVerifier can be used to verify protected data.
type BitrotVerifier struct {
hash.Hash
algorithm BitrotAlgorithm
sum []byte
verified bool
}
// Verify returns true iff the computed checksum of the verifier matches the the checksum provided when the verifier
// was created.
func (v *BitrotVerifier) Verify() bool {
v.verified = true
return subtle.ConstantTimeCompare(v.Sum(nil), v.sum) == 1
}
// IsVerified returns true iff Verify was called at least once.
func (v *BitrotVerifier) IsVerified() bool { return v.verified }