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			100 lines
		
	
	
		
			2.9 KiB
		
	
	
	
		
			Go
		
	
	
	
	
	
			
		
		
	
	
			100 lines
		
	
	
		
			2.9 KiB
		
	
	
	
		
			Go
		
	
	
	
	
	
/*
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 * Minio Cloud Storage, (C) 2017 Minio, Inc.
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 *
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 * Licensed under the Apache License, Version 2.0 (the "License");
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 * you may not use this file except in compliance with the License.
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 * You may obtain a copy of the License at
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 *
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 *     http://www.apache.org/licenses/LICENSE-2.0
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 *
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 * Unless required by applicable law or agreed to in writing, software
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 * distributed under the License is distributed on an "AS IS" BASIS,
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 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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 * See the License for the specific language governing permissions and
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 * limitations under the License.
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 */
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package cmd
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import (
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	"context"
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	"github.com/klauspost/reedsolomon"
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	"github.com/minio/minio/cmd/logger"
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)
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// OfflineDisk represents an unavailable disk.
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var OfflineDisk StorageAPI // zero value is nil
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// ErasureStorage - erasure encoding details.
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type ErasureStorage struct {
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	erasure                  reedsolomon.Encoder
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	dataBlocks, parityBlocks int
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	blockSize                int64
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}
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// NewErasureStorage creates a new ErasureStorage.
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func NewErasureStorage(ctx context.Context, dataBlocks, parityBlocks int, blockSize int64) (s ErasureStorage, err error) {
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	shardsize := int(ceilFrac(blockSize, int64(dataBlocks)))
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	erasure, err := reedsolomon.New(dataBlocks, parityBlocks, reedsolomon.WithAutoGoroutines(shardsize))
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	if err != nil {
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		logger.LogIf(ctx, err)
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		return s, err
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	}
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	s = ErasureStorage{
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		erasure:      erasure,
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		dataBlocks:   dataBlocks,
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		parityBlocks: parityBlocks,
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		blockSize:    blockSize,
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	}
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	return
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}
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// ErasureEncode encodes the given data and returns the erasure-coded data.
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// It returns an error if the erasure coding failed.
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func (s *ErasureStorage) ErasureEncode(ctx context.Context, data []byte) ([][]byte, error) {
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	if len(data) == 0 {
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		return make([][]byte, s.dataBlocks+s.parityBlocks), nil
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	}
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	encoded, err := s.erasure.Split(data)
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	if err != nil {
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		logger.LogIf(ctx, err)
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		return nil, err
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	}
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	if err = s.erasure.Encode(encoded); err != nil {
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		logger.LogIf(ctx, err)
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		return nil, err
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	}
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	return encoded, nil
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}
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// ErasureDecodeDataBlocks decodes the given erasure-coded data.
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// It only decodes the data blocks but does not verify them.
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// It returns an error if the decoding failed.
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func (s *ErasureStorage) ErasureDecodeDataBlocks(data [][]byte) error {
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	needsReconstruction := false
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	for _, b := range data[:s.dataBlocks] {
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		if b == nil {
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			needsReconstruction = true
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			break
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		}
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	}
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	if !needsReconstruction {
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		return nil
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	}
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	if err := s.erasure.ReconstructData(data); err != nil {
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		return err
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	}
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	return nil
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}
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// ErasureDecodeDataAndParityBlocks decodes the given erasure-coded data and verifies it.
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// It returns an error if the decoding failed.
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func (s *ErasureStorage) ErasureDecodeDataAndParityBlocks(ctx context.Context, data [][]byte) error {
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	if err := s.erasure.Reconstruct(data); err != nil {
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		logger.LogIf(ctx, err)
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		return err
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	}
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	return nil
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}
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