bf286a54bc
This type carries the information required for calculating a
span (i.e. the chunk and offset), instead of the span itself. The span
is then only calculated in cases where it is required (when throwing
errors).
This reduces the eval time for
`builtins.length (builtins.attrNames (import <nixpkgs> {}))` by *one
third*!
The data structure in chunks that carries span information reduces
in-memory size by trading off the speed of retrieving span
information. This is because the span information is only actually
required when throwing errors (or emitting warnings).
However, somewhere along the way we grew a dependency on carrying span
information in thunks (for correctly reporting error chains). Hitting
the code paths for span retrieval was expensive, and carrying the
spans in a different way would still be less cache-efficient. This
change is the best tradeoff I could come up with.
Refs: b/229.
Change-Id: I27d4c4b5c5f9be90ac47f2db61941e123a78a77b
Reviewed-on: https://cl.tvl.fyi/c/depot/+/7558
Reviewed-by: grfn <grfn@gws.fyi>
Tested-by: BuildkiteCI
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|---|---|---|
| .. | ||
| .vscode | ||
| cli | ||
| docs | ||
| eval | ||
| nar | ||
| nix_cli | ||
| proto | ||
| store | ||
| verify-lang-tests | ||
| .gitignore | ||
| Cargo.lock | ||
| Cargo.nix | ||
| Cargo.toml | ||
| crate-hashes.json | ||
| default.nix | ||
| LICENSE | ||
| OWNERS | ||
| README.md | ||
Tvix
For more information about Tvix, contact one of the project owners. We are interested in people who would like to help us review designs, brainstorm and describe requirements that we may not yet have considered.
Rust projects
Some parts of Tvix are written in Rust. To simplify the dependency
management on the Nix side of these builds, we use crate2nix in a
single Rust workspace in //tvix to maintain the Nix build
configuration.
When making changes to Cargo dependency configuration in any of the
Rust projects under //tvix, be sure to run crate2nix generate in
//tvix itself and commit the changes to the generated Cargo.nix
file.
crate2nix is available via direnv inside of depot, or can be built
from the third_party.nixpkgs.crate2nix attribute of depot. Make sure
to build it from depot to avoid generating files with a different
version that might have different output.
License structure
All code implemented for Tvix is licensed under the GPL-3.0, with the exception of the protocol buffer definitions used for communication between services which are available under a more permissive license (MIT).
The idea behind this structure is that any direct usage of our code (e.g. linking to it, embedding the evaluator, etc.) will fall under the terms of the GPL3, but users are free to implement their own components speaking these protocols under the terms of the MIT license.