The go-delta from mktip

go-delta's Introduction

go-delta - A Go package and utility to generate and apply binary delta updates.

Suggestions:

Works best on text files, database dumps and any other files with lots of repeating patterns and few changes between updates.
Generating deltas of compressed files is not recommended because a small change in the source data can lead to lots of changes in the compressed result, so generating a delta update may give you only minimal size reduction.
Don't compress bytes returned by Delta.Bytes() because they are already compressed using ZLib compression.
Every delta update adds about 156 bytes for the source and target hashes and various lengths, so it is not recommended for very miniscule updates.

Demonstration:

package main

import (
    "fmt"
    "github.com/balacode/go-delta"
)

func main() {
    fmt.Print("Binary delta update demo:\n\n")

    // The original data (20 bytes):
    var source = []byte("quick brown fox, lazy dog, and five boxing wizards")
    fmt.Print("The original is:", "\n", string(source), "\n\n")

    // The updated data containing the original and new content (82 bytes):
    var target = []byte(
        "The quick brown fox jumps over the lazy dog. " +
        "The five boxing wizards jump quickly.",
    )
    fmt.Print("The update is:", "\n", string(target), "\n\n")

    var dbytes []byte
    {
    	// Use Make() to generate a compressed patch from source and target
    	var d = delta.Make(source, target)
    	
    	// Convert the delta to a slice of bytes (e.g. for writing to a file)
    	dbytes = d.Bytes()
    }

    // Create a Delta from the byte slice
    var d = delta.Load(dbytes)

    // Apply the patch to source to get the target
    // The size of the patch is much shorter than target.
    var target2, err = d.Apply(source)
    if err != nil {
        fmt.Println(err)
    }
    fmt.Print("Patched:", "\n", string(target2), "\n\n")
} //                                                                        main

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