example_test.go

// The MIT License (MIT)
//
// Copyright (C) 2016-2017 Vivint, Inc.
//
// Permission is hereby granted, free of charge, to any person obtaining a copy
// of this software and associated documentation files (the "Software"), to deal
// in the Software without restriction, including without limitation the rights
// to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
// copies of the Software, and to permit persons to whom the Software is
// furnished to do so, subject to the following conditions:
//
// The above copyright notice and this permission notice shall be included in all
// copies or substantial portions of the Software.
//
// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
// OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
// SOFTWARE.

package infectious_test

import (
	"fmt"
	"testing"

	"github.com/vivint/infectious"
)

func Example(t *testing.T) {
	const (
		required = 8
		total    = 14
	)

	// Create a *FEC, which will require required pieces for reconstruction at
	// minimum, and generate total total pieces.
	f, err := infectious.NewFEC(required, total)
	if err != nil {
		panic(err)
	}

	// Prepare to receive the shares of encoded data.
	shares := make([]infectious.Share, total)
	output := func(s infectious.Share) {
		// the memory in s gets reused, so we need to make a deep copy
		shares[s.Number] = s.DeepCopy()
	}

	// the data to encode must be padded to a multiple of required, hence the
	// underscores.
	err = f.Encode([]byte("hello, world! __"), output)
	if err != nil {
		panic(err)
	}

	// we now have total shares.
	for _, share := range shares {
		fmt.Printf("%d: %#v\n", share.Number, string(share.Data))
	}

	// Let's reconstitute with two pieces missing and one piece corrupted.
	shares = shares[2:]     // drop the first two pieces
	shares[2].Data[1] = '!' // mutate some data

	result, err := f.Decode(nil, shares)
	if err != nil {
		panic(err)
	}

	// we have the original data!
	fmt.Printf("got: %#v\n", string(result))
}