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use dep instead of glide
This commit is contained in:
596
vendor/github.com/klauspost/reedsolomon/reedsolomon.go
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vendored
596
vendor/github.com/klauspost/reedsolomon/reedsolomon.go
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vendored
@@ -1,596 +0,0 @@
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/**
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* Reed-Solomon Coding over 8-bit values.
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*
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* Copyright 2015, Klaus Post
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* Copyright 2015, Backblaze, Inc.
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*/
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// Package reedsolomon enables Erasure Coding in Go
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//
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// For usage and examples, see https://github.com/klauspost/reedsolomon
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//
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package reedsolomon
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import (
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"bytes"
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"errors"
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"io"
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"sync"
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)
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// Encoder is an interface to encode Reed-Salomon parity sets for your data.
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type Encoder interface {
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// Encodes parity for a set of data shards.
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// Input is 'shards' containing data shards followed by parity shards.
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// The number of shards must match the number given to New().
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// Each shard is a byte array, and they must all be the same size.
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// The parity shards will always be overwritten and the data shards
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// will remain the same, so it is safe for you to read from the
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// data shards while this is running.
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Encode(shards [][]byte) error
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// Verify returns true if the parity shards contain correct data.
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// The data is the same format as Encode. No data is modified, so
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// you are allowed to read from data while this is running.
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Verify(shards [][]byte) (bool, error)
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// Reconstruct will recreate the missing shards if possible.
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//
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// Given a list of shards, some of which contain data, fills in the
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// ones that don't have data.
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//
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// The length of the array must be equal to the total number of shards.
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// You indicate that a shard is missing by setting it to nil.
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//
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// If there are too few shards to reconstruct the missing
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// ones, ErrTooFewShards will be returned.
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//
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// The reconstructed shard set is complete, but integrity is not verified.
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// Use the Verify function to check if data set is ok.
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Reconstruct(shards [][]byte) error
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// Split a data slice into the number of shards given to the encoder,
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// and create empty parity shards.
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//
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// The data will be split into equally sized shards.
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// If the data size isn't dividable by the number of shards,
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// the last shard will contain extra zeros.
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//
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// There must be at least 1 byte otherwise ErrShortData will be
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// returned.
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//
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// The data will not be copied, except for the last shard, so you
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// should not modify the data of the input slice afterwards.
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Split(data []byte) ([][]byte, error)
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// Join the shards and write the data segment to dst.
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//
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// Only the data shards are considered.
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// You must supply the exact output size you want.
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// If there are to few shards given, ErrTooFewShards will be returned.
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// If the total data size is less than outSize, ErrShortData will be returned.
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Join(dst io.Writer, shards [][]byte, outSize int) error
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}
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// reedSolomon contains a matrix for a specific
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// distribution of datashards and parity shards.
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// Construct if using New()
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type reedSolomon struct {
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DataShards int // Number of data shards, should not be modified.
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ParityShards int // Number of parity shards, should not be modified.
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Shards int // Total number of shards. Calculated, and should not be modified.
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m matrix
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tree inversionTree
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parity [][]byte
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o options
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}
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// ErrInvShardNum will be returned by New, if you attempt to create
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// an Encoder where either data or parity shards is zero or less.
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var ErrInvShardNum = errors.New("cannot create Encoder with zero or less data/parity shards")
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// ErrMaxShardNum will be returned by New, if you attempt to create
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// an Encoder where data and parity shards cannot be bigger than
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// Galois field GF(2^8) - 1.
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var ErrMaxShardNum = errors.New("cannot create Encoder with 255 or more data+parity shards")
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// New creates a new encoder and initializes it to
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// the number of data shards and parity shards that
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// you want to use. You can reuse this encoder.
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// Note that the maximum number of data shards is 256.
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// If no options are supplied, default options are used.
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func New(dataShards, parityShards int, opts ...Option) (Encoder, error) {
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r := reedSolomon{
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DataShards: dataShards,
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ParityShards: parityShards,
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Shards: dataShards + parityShards,
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o: defaultOptions,
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}
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for _, opt := range opts {
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opt(&r.o)
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}
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if dataShards <= 0 || parityShards <= 0 {
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return nil, ErrInvShardNum
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}
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if dataShards+parityShards > 255 {
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return nil, ErrMaxShardNum
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}
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// Start with a Vandermonde matrix. This matrix would work,
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// in theory, but doesn't have the property that the data
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// shards are unchanged after encoding.
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vm, err := vandermonde(r.Shards, dataShards)
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if err != nil {
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return nil, err
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}
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// Multiply by the inverse of the top square of the matrix.
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// This will make the top square be the identity matrix, but
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// preserve the property that any square subset of rows is
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// invertible.
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top, _ := vm.SubMatrix(0, 0, dataShards, dataShards)
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top, _ = top.Invert()
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r.m, _ = vm.Multiply(top)
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// Inverted matrices are cached in a tree keyed by the indices
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// of the invalid rows of the data to reconstruct.
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// The inversion root node will have the identity matrix as
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// its inversion matrix because it implies there are no errors
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// with the original data.
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r.tree = newInversionTree(dataShards, parityShards)
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r.parity = make([][]byte, parityShards)
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for i := range r.parity {
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r.parity[i] = r.m[dataShards+i]
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}
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return &r, err
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}
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// ErrTooFewShards is returned if too few shards where given to
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// Encode/Verify/Reconstruct. It will also be returned from Reconstruct
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// if there were too few shards to reconstruct the missing data.
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var ErrTooFewShards = errors.New("too few shards given")
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// Encodes parity for a set of data shards.
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// An array 'shards' containing data shards followed by parity shards.
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// The number of shards must match the number given to New.
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// Each shard is a byte array, and they must all be the same size.
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// The parity shards will always be overwritten and the data shards
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// will remain the same.
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func (r reedSolomon) Encode(shards [][]byte) error {
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if len(shards) != r.Shards {
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return ErrTooFewShards
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}
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err := checkShards(shards, false)
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if err != nil {
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return err
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}
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// Get the slice of output buffers.
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output := shards[r.DataShards:]
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// Do the coding.
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r.codeSomeShards(r.parity, shards[0:r.DataShards], output, r.ParityShards, len(shards[0]))
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return nil
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}
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// Verify returns true if the parity shards contain the right data.
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// The data is the same format as Encode. No data is modified.
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func (r reedSolomon) Verify(shards [][]byte) (bool, error) {
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if len(shards) != r.Shards {
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return false, ErrTooFewShards
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}
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err := checkShards(shards, false)
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if err != nil {
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return false, err
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}
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// Slice of buffers being checked.
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toCheck := shards[r.DataShards:]
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// Do the checking.
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return r.checkSomeShards(r.parity, shards[0:r.DataShards], toCheck, r.ParityShards, len(shards[0])), nil
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}
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// Multiplies a subset of rows from a coding matrix by a full set of
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// input shards to produce some output shards.
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// 'matrixRows' is The rows from the matrix to use.
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// 'inputs' An array of byte arrays, each of which is one input shard.
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// The number of inputs used is determined by the length of each matrix row.
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// outputs Byte arrays where the computed shards are stored.
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// The number of outputs computed, and the
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// number of matrix rows used, is determined by
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// outputCount, which is the number of outputs to compute.
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func (r reedSolomon) codeSomeShards(matrixRows, inputs, outputs [][]byte, outputCount, byteCount int) {
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if r.o.maxGoroutines > 1 && byteCount > r.o.minSplitSize {
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r.codeSomeShardsP(matrixRows, inputs, outputs, outputCount, byteCount)
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return
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}
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for c := 0; c < r.DataShards; c++ {
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in := inputs[c]
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for iRow := 0; iRow < outputCount; iRow++ {
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if c == 0 {
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galMulSlice(matrixRows[iRow][c], in, outputs[iRow], r.o.useSSSE3, r.o.useAVX2)
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} else {
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galMulSliceXor(matrixRows[iRow][c], in, outputs[iRow], r.o.useSSSE3, r.o.useAVX2)
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}
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}
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}
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}
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// Perform the same as codeSomeShards, but split the workload into
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// several goroutines.
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func (r reedSolomon) codeSomeShardsP(matrixRows, inputs, outputs [][]byte, outputCount, byteCount int) {
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var wg sync.WaitGroup
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do := byteCount / r.o.maxGoroutines
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if do < r.o.minSplitSize {
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do = r.o.minSplitSize
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}
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start := 0
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for start < byteCount {
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if start+do > byteCount {
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do = byteCount - start
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}
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wg.Add(1)
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go func(start, stop int) {
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for c := 0; c < r.DataShards; c++ {
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in := inputs[c]
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for iRow := 0; iRow < outputCount; iRow++ {
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if c == 0 {
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galMulSlice(matrixRows[iRow][c], in[start:stop], outputs[iRow][start:stop], r.o.useSSSE3, r.o.useAVX2)
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} else {
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galMulSliceXor(matrixRows[iRow][c], in[start:stop], outputs[iRow][start:stop], r.o.useSSSE3, r.o.useAVX2)
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}
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}
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}
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wg.Done()
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}(start, start+do)
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start += do
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}
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wg.Wait()
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}
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// checkSomeShards is mostly the same as codeSomeShards,
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// except this will check values and return
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// as soon as a difference is found.
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func (r reedSolomon) checkSomeShards(matrixRows, inputs, toCheck [][]byte, outputCount, byteCount int) bool {
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if r.o.maxGoroutines > 1 && byteCount > r.o.minSplitSize {
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return r.checkSomeShardsP(matrixRows, inputs, toCheck, outputCount, byteCount)
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}
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outputs := make([][]byte, len(toCheck))
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for i := range outputs {
|
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outputs[i] = make([]byte, byteCount)
|
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}
|
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for c := 0; c < r.DataShards; c++ {
|
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in := inputs[c]
|
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for iRow := 0; iRow < outputCount; iRow++ {
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galMulSliceXor(matrixRows[iRow][c], in, outputs[iRow], r.o.useSSSE3, r.o.useAVX2)
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}
|
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}
|
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|
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for i, calc := range outputs {
|
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if !bytes.Equal(calc, toCheck[i]) {
|
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return false
|
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}
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}
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return true
|
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}
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|
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func (r reedSolomon) checkSomeShardsP(matrixRows, inputs, toCheck [][]byte, outputCount, byteCount int) bool {
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same := true
|
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var mu sync.RWMutex // For above
|
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|
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var wg sync.WaitGroup
|
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do := byteCount / r.o.maxGoroutines
|
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if do < r.o.minSplitSize {
|
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do = r.o.minSplitSize
|
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}
|
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start := 0
|
||||
for start < byteCount {
|
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if start+do > byteCount {
|
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do = byteCount - start
|
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}
|
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wg.Add(1)
|
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go func(start, do int) {
|
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defer wg.Done()
|
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outputs := make([][]byte, len(toCheck))
|
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for i := range outputs {
|
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outputs[i] = make([]byte, do)
|
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}
|
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for c := 0; c < r.DataShards; c++ {
|
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mu.RLock()
|
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if !same {
|
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mu.RUnlock()
|
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return
|
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}
|
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mu.RUnlock()
|
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in := inputs[c][start : start+do]
|
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for iRow := 0; iRow < outputCount; iRow++ {
|
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galMulSliceXor(matrixRows[iRow][c], in, outputs[iRow], r.o.useSSSE3, r.o.useAVX2)
|
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}
|
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}
|
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|
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for i, calc := range outputs {
|
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if !bytes.Equal(calc, toCheck[i][start:start+do]) {
|
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mu.Lock()
|
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same = false
|
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mu.Unlock()
|
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return
|
||||
}
|
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}
|
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}(start, do)
|
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start += do
|
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}
|
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wg.Wait()
|
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return same
|
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}
|
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|
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// ErrShardNoData will be returned if there are no shards,
|
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// or if the length of all shards is zero.
|
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var ErrShardNoData = errors.New("no shard data")
|
||||
|
||||
// ErrShardSize is returned if shard length isn't the same for all
|
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// shards.
|
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var ErrShardSize = errors.New("shard sizes does not match")
|
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|
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// checkShards will check if shards are the same size
|
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// or 0, if allowed. An error is returned if this fails.
|
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// An error is also returned if all shards are size 0.
|
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func checkShards(shards [][]byte, nilok bool) error {
|
||||
size := shardSize(shards)
|
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if size == 0 {
|
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return ErrShardNoData
|
||||
}
|
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for _, shard := range shards {
|
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if len(shard) != size {
|
||||
if len(shard) != 0 || !nilok {
|
||||
return ErrShardSize
|
||||
}
|
||||
}
|
||||
}
|
||||
return nil
|
||||
}
|
||||
|
||||
// shardSize return the size of a single shard.
|
||||
// The first non-zero size is returned,
|
||||
// or 0 if all shards are size 0.
|
||||
func shardSize(shards [][]byte) int {
|
||||
for _, shard := range shards {
|
||||
if len(shard) != 0 {
|
||||
return len(shard)
|
||||
}
|
||||
}
|
||||
return 0
|
||||
}
|
||||
|
||||
// Reconstruct will recreate the missing shards, if possible.
|
||||
//
|
||||
// Given a list of shards, some of which contain data, fills in the
|
||||
// ones that don't have data.
|
||||
//
|
||||
// The length of the array must be equal to Shards.
|
||||
// You indicate that a shard is missing by setting it to nil.
|
||||
//
|
||||
// If there are too few shards to reconstruct the missing
|
||||
// ones, ErrTooFewShards will be returned.
|
||||
//
|
||||
// The reconstructed shard set is complete, but integrity is not verified.
|
||||
// Use the Verify function to check if data set is ok.
|
||||
func (r reedSolomon) Reconstruct(shards [][]byte) error {
|
||||
if len(shards) != r.Shards {
|
||||
return ErrTooFewShards
|
||||
}
|
||||
// Check arguments.
|
||||
err := checkShards(shards, true)
|
||||
if err != nil {
|
||||
return err
|
||||
}
|
||||
|
||||
shardSize := shardSize(shards)
|
||||
|
||||
// Quick check: are all of the shards present? If so, there's
|
||||
// nothing to do.
|
||||
numberPresent := 0
|
||||
for i := 0; i < r.Shards; i++ {
|
||||
if len(shards[i]) != 0 {
|
||||
numberPresent++
|
||||
}
|
||||
}
|
||||
if numberPresent == r.Shards {
|
||||
// Cool. All of the shards data data. We don't
|
||||
// need to do anything.
|
||||
return nil
|
||||
}
|
||||
|
||||
// More complete sanity check
|
||||
if numberPresent < r.DataShards {
|
||||
return ErrTooFewShards
|
||||
}
|
||||
|
||||
// Pull out an array holding just the shards that
|
||||
// correspond to the rows of the submatrix. These shards
|
||||
// will be the input to the decoding process that re-creates
|
||||
// the missing data shards.
|
||||
//
|
||||
// Also, create an array of indices of the valid rows we do have
|
||||
// and the invalid rows we don't have up until we have enough valid rows.
|
||||
subShards := make([][]byte, r.DataShards)
|
||||
validIndices := make([]int, r.DataShards)
|
||||
invalidIndices := make([]int, 0)
|
||||
subMatrixRow := 0
|
||||
for matrixRow := 0; matrixRow < r.Shards && subMatrixRow < r.DataShards; matrixRow++ {
|
||||
if len(shards[matrixRow]) != 0 {
|
||||
subShards[subMatrixRow] = shards[matrixRow]
|
||||
validIndices[subMatrixRow] = matrixRow
|
||||
subMatrixRow++
|
||||
} else {
|
||||
invalidIndices = append(invalidIndices, matrixRow)
|
||||
}
|
||||
}
|
||||
|
||||
// Attempt to get the cached inverted matrix out of the tree
|
||||
// based on the indices of the invalid rows.
|
||||
dataDecodeMatrix := r.tree.GetInvertedMatrix(invalidIndices)
|
||||
|
||||
// If the inverted matrix isn't cached in the tree yet we must
|
||||
// construct it ourselves and insert it into the tree for the
|
||||
// future. In this way the inversion tree is lazily loaded.
|
||||
if dataDecodeMatrix == nil {
|
||||
// Pull out the rows of the matrix that correspond to the
|
||||
// shards that we have and build a square matrix. This
|
||||
// matrix could be used to generate the shards that we have
|
||||
// from the original data.
|
||||
subMatrix, _ := newMatrix(r.DataShards, r.DataShards)
|
||||
for subMatrixRow, validIndex := range validIndices {
|
||||
for c := 0; c < r.DataShards; c++ {
|
||||
subMatrix[subMatrixRow][c] = r.m[validIndex][c]
|
||||
}
|
||||
}
|
||||
// Invert the matrix, so we can go from the encoded shards
|
||||
// back to the original data. Then pull out the row that
|
||||
// generates the shard that we want to decode. Note that
|
||||
// since this matrix maps back to the original data, it can
|
||||
// be used to create a data shard, but not a parity shard.
|
||||
dataDecodeMatrix, err = subMatrix.Invert()
|
||||
if err != nil {
|
||||
return err
|
||||
}
|
||||
|
||||
// Cache the inverted matrix in the tree for future use keyed on the
|
||||
// indices of the invalid rows.
|
||||
err = r.tree.InsertInvertedMatrix(invalidIndices, dataDecodeMatrix, r.Shards)
|
||||
if err != nil {
|
||||
return err
|
||||
}
|
||||
}
|
||||
|
||||
// Re-create any data shards that were missing.
|
||||
//
|
||||
// The input to the coding is all of the shards we actually
|
||||
// have, and the output is the missing data shards. The computation
|
||||
// is done using the special decode matrix we just built.
|
||||
outputs := make([][]byte, r.ParityShards)
|
||||
matrixRows := make([][]byte, r.ParityShards)
|
||||
outputCount := 0
|
||||
|
||||
for iShard := 0; iShard < r.DataShards; iShard++ {
|
||||
if len(shards[iShard]) == 0 {
|
||||
shards[iShard] = make([]byte, shardSize)
|
||||
outputs[outputCount] = shards[iShard]
|
||||
matrixRows[outputCount] = dataDecodeMatrix[iShard]
|
||||
outputCount++
|
||||
}
|
||||
}
|
||||
r.codeSomeShards(matrixRows, subShards, outputs[:outputCount], outputCount, shardSize)
|
||||
|
||||
// Now that we have all of the data shards intact, we can
|
||||
// compute any of the parity that is missing.
|
||||
//
|
||||
// The input to the coding is ALL of the data shards, including
|
||||
// any that we just calculated. The output is whichever of the
|
||||
// data shards were missing.
|
||||
outputCount = 0
|
||||
for iShard := r.DataShards; iShard < r.Shards; iShard++ {
|
||||
if len(shards[iShard]) == 0 {
|
||||
shards[iShard] = make([]byte, shardSize)
|
||||
outputs[outputCount] = shards[iShard]
|
||||
matrixRows[outputCount] = r.parity[iShard-r.DataShards]
|
||||
outputCount++
|
||||
}
|
||||
}
|
||||
r.codeSomeShards(matrixRows, shards[:r.DataShards], outputs[:outputCount], outputCount, shardSize)
|
||||
return nil
|
||||
}
|
||||
|
||||
// ErrShortData will be returned by Split(), if there isn't enough data
|
||||
// to fill the number of shards.
|
||||
var ErrShortData = errors.New("not enough data to fill the number of requested shards")
|
||||
|
||||
// Split a data slice into the number of shards given to the encoder,
|
||||
// and create empty parity shards.
|
||||
//
|
||||
// The data will be split into equally sized shards.
|
||||
// If the data size isn't divisible by the number of shards,
|
||||
// the last shard will contain extra zeros.
|
||||
//
|
||||
// There must be at least 1 byte otherwise ErrShortData will be
|
||||
// returned.
|
||||
//
|
||||
// The data will not be copied, except for the last shard, so you
|
||||
// should not modify the data of the input slice afterwards.
|
||||
func (r reedSolomon) Split(data []byte) ([][]byte, error) {
|
||||
if len(data) == 0 {
|
||||
return nil, ErrShortData
|
||||
}
|
||||
// Calculate number of bytes per shard.
|
||||
perShard := (len(data) + r.DataShards - 1) / r.DataShards
|
||||
|
||||
// Pad data to r.Shards*perShard.
|
||||
padding := make([]byte, (r.Shards*perShard)-len(data))
|
||||
data = append(data, padding...)
|
||||
|
||||
// Split into equal-length shards.
|
||||
dst := make([][]byte, r.Shards)
|
||||
for i := range dst {
|
||||
dst[i] = data[:perShard]
|
||||
data = data[perShard:]
|
||||
}
|
||||
|
||||
return dst, nil
|
||||
}
|
||||
|
||||
// ErrReconstructRequired is returned if too few data shards are intact and a
|
||||
// reconstruction is required before you can successfully join the shards.
|
||||
var ErrReconstructRequired = errors.New("reconstruction required as one or more required data shards are nil")
|
||||
|
||||
// Join the shards and write the data segment to dst.
|
||||
//
|
||||
// Only the data shards are considered.
|
||||
// You must supply the exact output size you want.
|
||||
//
|
||||
// If there are to few shards given, ErrTooFewShards will be returned.
|
||||
// If the total data size is less than outSize, ErrShortData will be returned.
|
||||
// If one or more required data shards are nil, ErrReconstructRequired will be returned.
|
||||
func (r reedSolomon) Join(dst io.Writer, shards [][]byte, outSize int) error {
|
||||
// Do we have enough shards?
|
||||
if len(shards) < r.DataShards {
|
||||
return ErrTooFewShards
|
||||
}
|
||||
shards = shards[:r.DataShards]
|
||||
|
||||
// Do we have enough data?
|
||||
size := 0
|
||||
for _, shard := range shards {
|
||||
if shard == nil {
|
||||
return ErrReconstructRequired
|
||||
}
|
||||
size += len(shard)
|
||||
|
||||
// Do we have enough data already?
|
||||
if size >= outSize {
|
||||
break
|
||||
}
|
||||
}
|
||||
if size < outSize {
|
||||
return ErrShortData
|
||||
}
|
||||
|
||||
// Copy data to dst
|
||||
write := outSize
|
||||
for _, shard := range shards {
|
||||
if write < len(shard) {
|
||||
_, err := dst.Write(shard[:write])
|
||||
return err
|
||||
}
|
||||
n, err := dst.Write(shard)
|
||||
if err != nil {
|
||||
return err
|
||||
}
|
||||
write -= n
|
||||
}
|
||||
return nil
|
||||
}
|
Reference in New Issue
Block a user