README.md

DeltaQ

Fast and portable delta encoding for .NET in 100% safe, managed code.

DeltaQ is available for use as a library in .NET and .NET Framework, and as a cross-platform command-line tool, dq, which can be used to perform delta operations (similar to bsdiff or xdelta).

Support

Discussion and technical support is available on Discord.

Installing

dq command-line tool

> dotnet tool install DeltaQ.CommandLine -g

DeltaQ library

> dotnet add package DeltaQ

Usage

dq command-line tool

Create a binary delta (diff) with BsDiff

dq bsdiff <oldfile> <newfile> <deltafile>

Here's an example of dq creating a bsdiff delta for patching file app_v1.exe into app_v2.exe:

> ls -sh
total 32M
16M app_v1.exe  17M app_v2.exe

> dq bsdiff app_v1.exe app_v2.exe v1_to_v2.delta
Generating BsDiff delta between
Old file: "app_v1.exe"
New file: "app_v2.exe"

Delta file: "v1_to_v2.delta"
Delta size: 4.28 MB (13.49%)

Apply a binary delta (patch) with BsDiff

dq bspatch <oldfile> <deltafile> <newfile>

Instead of distributing the large app_v2.exe when it's time to upgrade, dq can recreate it by applying the much smaller delta file v1_to_v2.delta to the original app_v1.exe:

> dq bspatch app_v1.exe v1_to_v2.delta generated_app_v2.exe
Applying BsDiff delta between
Old file:   "app_v1.exe"
Delta file: "v1_to_v2.delta"

New file: "generated_app_v2.exe"

> sha256sum app_v2.exe generated_app_v2.exe
fab165a6e604dc7f9265d13013b6fb06319faec4eaa251a8a6d74a7e30e38dc6  app_v2.exe
fab165a6e604dc7f9265d13013b6fb06319faec4eaa251a8a6d74a7e30e38dc6  generated_app_v2.exe

DeltaQ library

The DeltaQ package contains all currently supported delta encoding and suffix sorting providers, for use in your own .NET projects.

Example: bsdiff and bspatch files

using System.IO;
using DeltaQ.BsDiff;
using DeltaQ.SuffixSorting;
using DeltaQ.SuffixSorting.LibDivSufSort;

void MakeDelta() {
    var oldData = File.ReadAllBytes("oldfile.txt");
    var newData = File.ReadAllBytes("newfile.txt");
    using var outStream = File.Create("old_to_new.delta");
    ISuffixSort suffixSorter = new LibDivSufSort();

    Diff.Create(oldData, newData, outStream, suffixSorter);
}

void UseDelta() {
    var oldData = File.ReadAllBytes("oldfile.txt");
    var deltaData = File.ReadAllBytes("old_to_new.delta");
    using var outStream = File.Create("generated_newfile.txt");

    Patch.Apply(oldData, deltaData, outStream);
}

Example: Suffix sorting with LibDivSufSort

using DeltaQ.SuffixSorting;
using DeltaQ.SuffixSorting.LibDivSufSort;

ISuffixSort suffixSorter = new LibDivSufSort();

ReadOnlySpan<byte> text = new byte[] { 1, 2, 3, 4 };
using var ownedSuffixArray = suffixSorter.Sort(text);
ReadOnlySpan<int> sortedSuffixes = ownedSuffixArray.Memory.Span;