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diff --git a/third_party/nix/README.md b/third_party/nix/README.md deleted file mode 100644 index 4bb5896831..0000000000 --- a/third_party/nix/README.md +++ /dev/null @@ -1,179 +0,0 @@ -Tvix, also known as TVL's fork of Nix -------------------------------------- - -Nix is a new take on package management that is fairly unique. Because -of its purity aspects, a lot of issues found in traditional package -managers don't appear with Nix. - -To find out more about the tool, usage and installation instructions, -please read the manual, which is available on the Nix website at -<http://nixos.org/nix/manual>. - -This repository is [TVL's](https://tvl.fyi)'s fork of Nix, which we lovingly -refer to as Tvix. - -## Fork background - -Nix is a fantastic project with over a decade of demonstrated -real-world usage, but also with quite a few problems. - -First of all, the project consists of two main components: The Nix -package collection ("[nixpkgs][]") and the package manager itself. - -The package collection is an enormous effort with hundreds of -thousands of commits, encoding expert knowledge about lots of -different software and ways of building and managing it. It is a very -valuable piece of software. - -The package manager however is an old C++ project with severe code -quality issues, little to no documentation, no consistent style and no -unit test coverage. - -Its codebase is larger than it needs to be (often due to custom -reimplementations of basic functionality) and is mostly ad-hoc -structured, making it difficult to correctly implement large-scale -improvements. - -In addition, the upstream Nix project is diverging from the opinions -of some community members via the introduction of concepts such as Nix -flakes. - -To counteract these things we have decided to fork Nix. - -## Fork goals - -The things listed here are explicitly in-scope for work on the fork. -This list is not exhaustive, and it is very likely that many other -smaller things will be discovered along the way. - -### nixpkgs compatibility - -This fork will maintain compatibility with nixpkgs as much as -possible. If at any point we do need to diverge, we will do it in a -way that is backwards compatible. - -### Code quality improvements - -Code quality encompasses several different issues. - -One goal is to slowly bring the codebase in line with the [Google C++ -style guide][google-style]. Apart from the trivial reformatting (which -is already done), this means slowly chipping away at incorrectly -structured type hierarchies, usage of exceptions, usage of raw -pointers, global mutability and so on. - -Another goal is to reduce the amount of code in Nix by removing custom -reimplementations of basic functionality (such as string splitting or -reading files). - -For functionality that is not part of the C++17 standard library, -[Abseil][] will be the primary external library used. - -### Explicit RPC mechanisms - -Nix currently uses homegrown mechanisms of interacting with other Nix -binaries, for example for remote builds or interaction between the CLI -and the Nix daemon. - -This will be replaced with [gRPC][]. - -### New sandboxing mechanism - -Nix implements its own sandboxing mechanism. This was probably the -correct decision at the time, but is not necessary anymore because -Linux containers have become massively popular and lots of new tooling -is now available. - -The goal is to replace the custom sandboxing implementation with -pluggable [OCI runtimes][oci], which will make it possible to use -arbitrary container runtimes such as [gVisor][] or [systemd-nspawn][] - -### Pluggable Nix store backends - -The current Nix store implementation will be removed from Nix' core -and instead be refactored into a gRPC API that can be implemented by -different backends. - -### Builds as graph reductions - -A Nix derivation that should be instantiated describes a build graph. -This graph will become a first-class citizen, making it possible to -distribute different parts of the computation to different nodes. - -Implementing this properly will also allow us to improve the -implementation of import-from-derivation by explicitly moving through -different graph reduction stages. - -## Fork non-goals - -To set expectations, there are some explicit non-goals, too. - -* Merging these changes back into upstream is not a goal, and maybe - not even feasible. The core work has not even started yet and just - basic cleanup has already created a diff of over 40 000 lines. - - This would likely also turn into a political effort, which we have - no interest in. - -* Improved performance is not an (initial) goal. Nix performance is - very unevenly distributed across the codebase (some things have seen - a lot of ad-hoc optimisation, others are written like inefficient - toy implementations) and we simply don't know what effect the - cleanup will have. - - Once the codebase is in a better state we will be able to start - optimising it again while retaining readability, but this is not a - goal until a later point in time. - -* Compatibility with new upstream features is not a goal. Specifically - we do not want Nix flakes, but other changes upstream makes will be - considered for inclusion. - -* Support for non-Linux systems. Currently Nix support Mac OS and - potentially other systems, but this support will be dropped. - - Once we have OCI-compatible sandboxes and a store protocol it will - be possible to reintroduce these with less friction. - -## Building - -To build the project, set up an out-of-tree cmake directory and run cmake in -nix-shell. - -``` -mkdir ~/build/tvix -cd ~/build/tvix - -nix-shell $DEPOT_PATH -A third_party.nix.build-shell - -# Disable clang-tidy for quicker builds -cmake $DEPOT_PATH/third_party/nix/ -DCLANG_TIDY_PATH="" -make -j16 -l12 - -# Run tests -make test -``` - -## Contributing to the fork - -The TVL depot's default [contribution guidelines][contributing] apply. - -In addition, please make sure that submitted code builds and is -formatted with `clang-format`, using the configuration found in this -folder. - -## License - -Nix is released under the LGPL v2.1 - -This product includes software developed by the OpenSSL Project for -use in the [OpenSSL Toolkit](http://www.OpenSSL.org/). - -[nixpkgs]: https://github.com/NixOS/nixpkgs -[google-style]: https://google.github.io/styleguide/cppguide.html -[Abseil]: https://abseil.io/ -[gRPC]: https://grpc.io/ -[oci]: https://www.opencontainers.org/ -[gVisor]: https://gvisor.dev/ -[systemd-nspawn]: https://www.freedesktop.org/software/systemd/man/systemd-nspawn.html -[contributing]: https://cs.tvl.fyi/depot/-/blob/docs/CONTRIBUTING.md |