RaptorQ

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stable release: v0.1.9
current release: v1.0.0-prealpha
CURRENTLY BREAKING APIs, stick with the stable release
UPDATE: almost finished the brakage, things should be stable enough

RaptorQ is a Forward Error Correction algorithm designed to deliver your data efficiently and without retransmissions for lost packets.

After sending K packets of your data as-is, RaptorQ generates as many repair symbols as you need. Once the receiver has at least K symbols, be it the source symbols, repair symbols or any combination of the two, it can reconstruct the whole input it was meant to receive.

This is called a Fountain code, and RaptorQ is the latest and most efficient code in this category.

libRaptorQ implements RFC6330, which specifies the RaptorQ algorithm.

libRaptorQ is entirely written in C++11, and uses eigen to handle matrix manipulation.

Currently it's only been tested under Linux, but should work well under *BSD and MacOSX, too.

Windows should work too, provided you use a complier that understands C++11
(hint: you might have some problems with VisualC++, but that's not a C++ compiler anyway)

Developers

See the CONTRIBUTING file.

The Source Code

Although things seems to work, no stable release has been released yet.

This means you can only check this out with git.

to check out the repository:

$ git clone https://github.com/LucaFulchir/libRaptorQ.git

you can also get it from our main server:

$ git clone https://www.fenrirproject.org/Luker/libRaptorQ.git

GPG source check

Once you have cloned it, it's always a good thing to check the repository gpg signatures, so you can import my key with:

2016 key:
$ gpg --keyserver pgp.mit.edu --recv-key F61F6137
2015 key:
$ gpg --keyserver pgp.mit.edu --recv-key D42DDF0A

please check the full fingerprint, it should be like this:

 $ gpg2 --fingerprint F61F6137
 pub   rsa2048/F61F6137 2016-01-11 [expires: 2017-01-25]
       Key fingerprint = 95EB 6FA4 03D7 29A7 13C2  FC9F F85A DA1C F61F 6137
 uid         [ultimate] Luca Fulchir (2016 key) <luker@fenrirproject.org>
 full 2015 fingerprint:
 Key fingerprint = AB35 E45F 5CA5 E35B 8B55  818F 0157 D133 D42D DF0A

Now you have the source, and the key, it's enough to check the signature of the last commit:

$ git log -n 1 --show-signature

The important part is that you get something like this:

 gpg: Signature made Mon 11 Jan 2016 14:19:21 CET using RSA key ID F61F6137
 gpg: Good signature from "Luca Fulchir (2016 key) <luker@fenrirproject.org>"
 [unknown]
 gpg: WARNING: This key is not certified with a trusted signature!
 gpg:          There is no indication that the signature belongs to the owner.
 Primary key fingerprint: 95EB 6FA4 03D7 29A7 13C2  FC9F F85A DA1C F61F 6137
 Author: Luca Fulchir <luker@fenrirproject.org>

And as long as you got the right key, and you find the "gpg: Goog signature", you can be sure you have the right code.

TDB: The repository is using the maintainer private key for now, it will start using a dedicated key in the (near) future.

Install

Dependencies

libRaptorQ depends from Eigen3 and LZ4
In case your system does not have Eigen3, Eigenv3.2.8 is included in the source files, so you do not need it.
LZ4 is included as a git submodule, so if you do not have it, run:
git submodule init
git submodule update
To get the library, which will be statically linked and NOT INSTALLED on your system.

Building

The build system uses CMake. So enter the source directory and we'll create a directory and build everything there:

$ mkdir build
$ cd build

$ cmake -DCMAKE_BUILD_TYPE=Release ../

$ make -j 4

Optional targets are available:
$ make tests examples docs
where:

• tests: benchmarks, rfc tests.
• examples: C/C++ examples
• docs: LATEX documentation.

or simply:
$ make -j 4 everything

finally, install everything
$ make install

libRaptorQ uses deterministic (reproducible) builds, so if you compile it twice, or on two different computers (but with the same compiler), the hash of the resulting libraries will be the same.

There are combinations of compiler and LTO/Profiling that break deterministic builds, so check the cmake warnings.

You can customize the CMake build with the following variables:

PROFILING   ON/OFF: Default:ON. Activate or deactivate profiling.
                Profiling compiles everything, then runs a test to see
                which code paths are more used. Then it recompiles everything
                but optimizing for for those code paths.
                Only for gcc/clang.
LTO         ON/OFF: Default:ON. Activate or deactivate Link time Optimization
                Makes the library smaller and better optimized.
                Only for gcc/clang.
CLANG_STDLIB ON/OFF: Default:OFF. use clang's libc++
                Note: only clang can use its standard library
USE_LZ4     ON/OFF: use the lz4 compression for caching precomputations.
                Default: ON
CLI         ON/OFF Build Command Line Interface tools.
CMAKE_C_COMPILER    gcc, clang...
CMAKE_CXX_COMPILER  choose between g++ or clang++.
RQ_LINKER   gold/ld/bsd Choose your linker. Default:autodetect.
CMAKE_BUILD_TYPE    Debug,MinSizeRel,Release,RelWithDebInfo
CMAKE_INSTALL_PREFIX Default: /usr/local

Using libRaptorQ

C and C++11 interfaces are available.

You can compile a PDF of the documentation by doing:
$ make docs

Or you can simply visit the wiki for the full up-to-date documentation.