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minio/pkg/erasure/doc.go

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2.4 KiB

// Package erasure is a Go wrapper for the Intel Intelligent Storage
// Acceleration Library (Intel ISA-L). Intel ISA-L is a CPU optimized
// implementation of erasure coding algorithms.
//
// For more information on Intel ISA-L, please visit:
// https://01.org/intel%C2%AE-storage-acceleration-library-open-source-version
//
// Usage:
//
// Encode encodes a block of data. The input is the original data. The output
// is a 2 tuple containing (k + m) chunks of erasure encoded data and the
// length of the original object.
//
// Decode decodes 2 tuple data containing (k + m) chunks back into its original form.
// Additionally original block length should also be provided as input.
//
// Decoded data is exactly similar in length and content as the original data.
//
// Encoding data may be performed in 3 steps.
//
// 1. Create a parse set of encoder parameters
// 2. Create a new encoder
// 3. Encode data
//
// Decoding data is also performed in 3 steps.
//
// 1. Create a parse set of encoder parameters for validation
// 2. Create a new encoder
// 3. Decode data
//
// Erasure parameters contain three configurable elements:
// ValidateParams(k, m, technique int) (ErasureParams, error)
// k - Number of rows in matrix
// m - Number of colums in matrix
// technique - Matrix type, can be either Cauchy (recommended) or Vandermonde
// constraints: k + m < Galois Field (2^8)
//
// Choosing right parity and matrix technique is left for application to decide.
//
// But here are the few points to keep in mind
//
// Matrix Type:
// - Vandermonde is most commonly used method for choosing coefficients in erasure
// encoding but does not guarantee invertable for every sub matrix.
// - Whereas Cauchy is our recommended method for choosing coefficients in erasure coding.
// Since any sub-matrix of a Cauchy matrix is invertable.
//
// Total blocks:
// - Data blocks and Parity blocks should not be greater than 'Galois Field' (2^8)
//
// Example
//
// Creating and using an encoder
// var bytes []byte
// params := erasure.ValidateParams(10, 5)
// encoder := erasure.NewErasure(params)
// encodedData, length := encoder.Encode(bytes)
//
// Creating and using a decoder
// var encodedData [][]byte
// var length int
// params := erasure.ValidateParams(10, 5)
// encoder := erasure.NewErasure(params)
// originalData, err := encoder.Decode(encodedData, length)
//
package erasure