It's in no release yet, but this is the current rev in master.
Change-Id: I9e4bc2fde26e85c4182bd66b3e566c2d957072ed
Reviewed-on: https://cl.tvl.fyi/c/depot/+/9469
Autosubmit: flokli <flokli@flokli.de>
Reviewed-by: raitobezarius <tvl@lahfa.xyz>
Tested-by: BuildkiteCI
This adds support for listening on UNIX domain sockets via the
tokio-listener crate. The crate will automatically determine whether to
start a TCP or UNIX domain socket server based on the listen address.
Unfortunately, it's not compatible with tonic right out of the box so I
added some wrapper types to implement the necessary traits to make
things work. We should investigate upstreaming a `tonic` option to the
tokio-listener crate which implements the relevant `tonic` traits.
Example:
```
$ tvix-store daemon -l /run/tvix-store.sock
INFO tvix_store: tvix-store listening on /run/tvix-store.sock
$ tvix-store mount -l /mnt/tvix --blob-service-addr grpc+unix:///run/tvix-store.sock --directory-service-addr grpc+unix:///run/tvix-store.sock --path-info-service-addr grpc+unix:///run/tvix-store.sock
$ ls /mnt/tvix
```
Change-Id: I91c4a4b0c5a177b3b90e6c01a4e5d263130e6bdb
Reviewed-on: https://cl.tvl.fyi/c/depot/+/9429
Tested-by: BuildkiteCI
Reviewed-by: flokli <flokli@flokli.de>
Reviewed-by: raitobezarius <tvl@lahfa.xyz>
This adds a virtiofs daemon implementation which hooks into the existing
tvix-store filesystem implementation that is used for FUSE.
This allows adding the filesystem to a microvm without having to set up
FUSE inside the guest.
Change-Id: If80c36c9657f2289853e8d9a364bf4f1f7b7559c
Reviewed-on: https://cl.tvl.fyi/c/depot/+/9344
Autosubmit: Connor Brewster <cbrewster@hey.com>
Tested-by: BuildkiteCI
Reviewed-by: flokli <flokli@flokli.de>
We don't use this here, except in a test, where we don't really use
it either.
Change-Id: Ia6c45fccf663fe328942b1e1a2cd1c3a1b7f9ae5
Reviewed-on: https://cl.tvl.fyi/c/depot/+/9376
Autosubmit: flokli <flokli@flokli.de>
Reviewed-by: Connor Brewster <cbrewster@hey.com>
Tested-by: BuildkiteCI
This splits the pure content-addressed layers from tvix-store into a
`castore` crate, and only leaves PathInfo related things, as well as the
CLI entrypoint in the tvix-store crate.
Notable changes:
- `fixtures` and `utils` had to be moved out of the `test` cfg, so they
can be imported from tvix-store.
- Some ad-hoc fixtures in the test were moved to proper fixtures in the
same step.
- The protos are now created by a (more static) recipe in the protos/
directory.
The (now two) golang targets are commented out, as it's not possible to
update them properly in the same CL. This will be done by a followup CL
once this is merged (and whitby deployed)
Bug: https://b.tvl.fyi/issues/301
Change-Id: I8d675d4bf1fb697eb7d479747c1b1e3635718107
Reviewed-on: https://cl.tvl.fyi/c/depot/+/9370
Reviewed-by: tazjin <tazjin@tvl.su>
Reviewed-by: flokli <flokli@flokli.de>
Autosubmit: flokli <flokli@flokli.de>
Tested-by: BuildkiteCI
Reviewed-by: Connor Brewster <cbrewster@hey.com>
We've decided to asyncify all of the services to reduce some of the
pains going back and for between sync<->async. The end goal will be for
all the tvix-store internals to be async and then expose a sync
interface for things like tvix eval io.
Change-Id: I97c71f8db1d05a38bd8f625df5087d565705d52d
Reviewed-on: https://cl.tvl.fyi/c/depot/+/9369
Autosubmit: Connor Brewster <cbrewster@hey.com>
Tested-by: BuildkiteCI
Reviewed-by: flokli <flokli@flokli.de>
This switches the FUSE implementation from fuser to fuse-backend-rs.
fuse-backend-rs is designed to work with both FUSE and virtiofs.
Virtiofs support will make it possible to plug the tvix-store into a
microvm and have `/nix/store` access without having to setup FUSE inside
the guest.
Additionally fuse-backend-rs has nice support for running multiple FUSE
threads and has some async support.
The goal of this commit is to mechanically switch over to
fuse-backend-rs with minimal changes. I did have to add some locks here
and there because fuse-backend-rs uses `&self` on all methods whereas
fuser uses `&mut self`. `&self` is required for concurrent access to the
FUSE server, so this makes sense.
We can consider switching to concurrent maps and use some other
techniques to reduce lock contention and critical section size.
Issue: https://b.tvl.fyi/issues/305
Change-Id: Icde5a58c6eef98f8984c1e04e980b756dfb76b47
Reviewed-on: https://cl.tvl.fyi/c/depot/+/9341
Tested-by: BuildkiteCI
Reviewed-by: flokli <flokli@flokli.de>
We previously kept the trait of a BlobService sync.
This however had some annoying consequences:
- It became more and more complicated to track when we're in a context
with an async runtime in the context or not, producing bugs like
https://b.tvl.fyi/issues/304
- The sync trait shielded away async clients from async worloads,
requiring manual block_on code inside the gRPC client code, and
spawn_blocking calls in consumers of the trait, even if they were
async (like the gRPC server)
- We had to write our own custom glue code (SyncReadIntoAsyncRead)
to convert a sync io::Read into a tokio::io::AsyncRead, which already
existed in tokio internally, but upstream ia hesitant to expose.
This now makes the BlobService trait async (via the async_trait macro,
like we already do in various gRPC parts), and replaces the sync readers
and writers with their async counterparts.
Tests interacting with a BlobService now need to have an async runtime
available, the easiest way for this is to mark the test functions
with the tokio::test macro, allowing us to directly .await in the test
function.
In places where we don't have an async runtime available from context
(like tvix-cli), we can pass one down explicitly.
Now that we don't provide a sync interface anymore, the (sync) FUSE
library now holds a pointer to a tokio runtime handle, and needs to at
least have 2 threads available when talking to a blob service (which is
why some of the tests now use the multi_thread flavor).
The FUSE tests got a bit more verbose, as we couldn't use the
setup_and_mount function accepting a callback anymore. We can hopefully
move some of the test fixture setup to rstest in the future to make this
less repetitive.
Co-Authored-By: Connor Brewster <cbrewster@hey.com>
Change-Id: Ia0501b606e32c852d0108de9c9016b21c94a3c05
Reviewed-on: https://cl.tvl.fyi/c/depot/+/9329
Reviewed-by: Connor Brewster <cbrewster@hey.com>
Tested-by: BuildkiteCI
Reviewed-by: raitobezarius <tvl@lahfa.xyz>
This enables the tokio `signal` feature, and registers a ctrl_c signal
handler, which will use the unmount handle to unmount in case a ctrl-c
signal is received.
This avoids having disconnected mountpoints when Ctrl-C'ing a
`tvix-store mount` invocation.
In case the filesystem is unmounted externally (via `umount /path/to/
mountpoint`), the future is waiting for the signal is never resolved and
the task is stopped.
Change-Id: I149f705a6cb50188177f2a6c6a5fcd77218e2a3f
Reviewed-on: https://cl.tvl.fyi/c/depot/+/9218
Reviewed-by: tazjin <tazjin@tvl.su>
Autosubmit: flokli <flokli@flokli.de>
Tested-by: BuildkiteCI
https://github.com/BurntSushi/walkdir/pull/170 got merged, meaning we
don't need to keep our own logic in here anymore.
Our test cases already cover this.
Change-Id: Ied3043ee651c8aafa10271c1e1ca5d460fb6c0b8
Reviewed-on: https://cl.tvl.fyi/c/depot/+/9269
Autosubmit: flokli <flokli@flokli.de>
Tested-by: BuildkiteCI
Reviewed-by: tazjin <tazjin@tvl.su>
This trait is eval-specific, there's no point in dealing with these
things in tvix-store.
This implements the EvalIO interface for a Tvix store.
The proper place for this glue code (for now) is tvix-cli, which knows
about both tvix-store and tvix-eval.
There's one annoyance with this move: The `tvix-store import` subcommand
previously also used the TvixStoreIO implementation (because it
conveniently did what we wanted).
Some of this code had to be duplicated, mostly logic to calculate the
NAR-based output path and create the PathInfo object.
Some, but potentially more of this can be extracted into helper
functions in a shared crate, and then be used from both TvixStoreIO in
tvix-cli as well as the tvix-store CLI entrypoint.
Change-Id: Ia7515e83c1b54f95baf810fbd8414c5521382d40
Reviewed-on: https://cl.tvl.fyi/c/depot/+/9212
Tested-by: BuildkiteCI
Reviewed-by: tazjin <tazjin@tvl.su>
Autosubmit: flokli <flokli@flokli.de>
Derivations can have non-unicode strings in their env values, so the
ATerm representations are not necessarily String anymore, but Vec<u8>.
Change-Id: Ic23839471eb7f68d9c3c30667c878830946b6607
Reviewed-on: https://cl.tvl.fyi/c/depot/+/8990
Tested-by: BuildkiteCI
Reviewed-by: raitobezarius <tvl@lahfa.xyz>
Autosubmit: flokli <flokli@flokli.de>
The change allows applications that use tvix_serde for parsing
nix-based configuration to extend the language with domain-specific
set of features.
Change-Id: Ia86612308a167c456ecf03e93fe0fbae55b876a6
Reviewed-on: https://cl.tvl.fyi/c/depot/+/8848
Reviewed-by: tazjin <tazjin@tvl.su>
Tested-by: BuildkiteCI
This allows constructing blob stores with a URL syntax at runtime,
by passing the --blob-service-addr arg.
We probably still want to have some builder pattern here, to allow
additional schemes to be registered.
Change-Id: Ie588ff7a7c6fb64c9474dfbd2e4bc5f168dfd778
Reviewed-on: https://cl.tvl.fyi/c/depot/+/8742
Reviewed-by: tazjin <tazjin@tvl.su>
Tested-by: BuildkiteCI
This brings in fuse (via the `fuser` crate), and adds pkg-config and
libfuse to the dev shell, so `cargo build` can link against it.
Change-Id: I0d11607490e27d946bdf92b0b9e45f9ab644ba74
Reviewed-on: https://cl.tvl.fyi/c/depot/+/8664
Autosubmit: flokli <flokli@flokli.de>
Reviewed-by: tazjin <tazjin@tvl.su>
Tested-by: BuildkiteCI
This switches tvix-cli over from using `NixCompatIO` to `TvixStoreIO`.
For now, we simply instantiate in-memory services instead of getting
fancy with constructors inside tvix-store, but long-term, we might want
to support some URI syntax, to make this configurable at runtime.
nixpkgs eval tests might be fine (and fast!) with a purely in-memory
backend, but other usages might involve talking to a local tvix-store
over gRPC (using the gRPC client, either unix domain socket or even
further away remote), or running tvix-store in "embedded" mode (using
another client than the gRPC client).
Change-Id: I509afd3dc5ce3f2d52b0fb7067748fab820e26ab
Reviewed-on: https://cl.tvl.fyi/c/depot/+/8572
Autosubmit: flokli <flokli@flokli.de>
Reviewed-by: tazjin <tazjin@tvl.su>
Tested-by: BuildkiteCI
Make it cleaner that StorePath only does encode the first path component
after the STORE_DIR prefix. Also, move some of the comments around a
bit, so it makes more sense what's using what.
Change-Id: Ibb57373a13526e30c58ad561ca50e1336b091d94
Reviewed-on: https://cl.tvl.fyi/c/depot/+/8566
Reviewed-by: tazjin <tazjin@tvl.su>
Tested-by: BuildkiteCI
Autosubmit: flokli <flokli@flokli.de>
It's okay if these calls mutate some internal state inside an
implementation.
Change-Id: I12bb11bde0310778c3da1275696bf7de058863a3
Reviewed-on: https://cl.tvl.fyi/c/depot/+/8571
Tested-by: BuildkiteCI
Reviewed-by: tazjin <tazjin@tvl.su>
Whether chunking is involved or not, is an implementation detail of each
Blobstore. Consumers of a whole blob shouldn't need to worry about that.
It currently is not visible in the gRPC interface either. It
shouldn't bleed into everything.
Let the BlobService trait provide `open_read` and `open_write` methods,
which return handles providing io::Read or io::Write, and leave the
details up to the implementation.
This means, our custom BlobReader module can go away, and all the
chunking bits in there, too.
In the future, we might still want to add more chunking-aware syncing,
but as a syncing strategy some stores can expose, not as a fundamental
protocol component.
This currently needs "SyncReadIntoAsyncRead", taken and vendored in from
https://github.com/tokio-rs/tokio/pull/5669.
It provides a AsyncRead for a sync Read, which is necessary to connect
our (sync) BlobReader interface to a GRPC server implementation.
As an alternative, we could also make the BlobReader itself async, and
let consumers of the trait (EvalIO) deal with the async-ness, but this
is less of a change for now.
In terms of vendoring, I initially tried to move our tokio crate to
these commits, but ended up in version incompatibilities, so let's
vendor it in for now.
Change-Id: I5969ebbc4c0e1ceece47981be3b9e7cfb3f59ad0
Reviewed-on: https://cl.tvl.fyi/c/depot/+/8551
Tested-by: BuildkiteCI
Reviewed-by: tazjin <tazjin@tvl.su>
This provides a GRPCDirectoryService struct implementing
DirectoryService, allowing a client to Directory objects from a (remote)
tvix-store.
Remote in this case is anything outside the current process, be it
another process, or an endpoint on the network.
To keep the sync interface in the `DirectoryService` trait, a handle to
some tokio runtime needs to be passed into the constructor, and the two
methods use `self.tokio_handle.spawn` to start an async function, and
`self.tokio_handle.block_on` to wait for its completion.
The client handle, called `grpc_client` itself is easy to clone, and
treats concurrent requests internally. This means, even though we keep
the `DirectoryService` trait sync, there's nothing preventing it from
being used concurrently, let's say from multiple threads.
There's still two limitations for now:
1) The trait doesn't make use of the `recursive` request, which
currently leads to a N+1 query problem. This can be fixed
by `GRPCDirectoryService` having a reference to another
`DirectoryService` acting as the local side.
I want to wait for general store composition code to pop up before
manually coding this here.
2) It's currently only possible to put() leaf directory nodes, as the
request normally requires uploading a whole closure. We might want
to add another batch function to upload a whole closure, and/or do
this batching in certain cases. This still needs some more thinking.
Change-Id: I7ffec791610b72c0960cf5307cefbb12ec946dc9
Reviewed-on: https://cl.tvl.fyi/c/depot/+/8336
Tested-by: BuildkiteCI
Autosubmit: flokli <flokli@flokli.de>
Reviewed-by: tazjin <tazjin@tvl.su>
Apparently, having multiple packages with the same path is a bad thing:
```
The bin target `tvix-store` in package `tvix-store-bin v0.1.0 (/home/flokli/tvl/tvix/store)` has the same output filename as the lib target `tvix_store` in package `tvix-store-bin v0.1.0 (/home/flokli/tvl/tvix/store)`.
Colliding filename is: /home/flokli/tvl/tvix/target/doc/tvix_store/index.html
The output filenames should be unique.
This is a known bug where multiple crates with the same name use
the same path; see <https://github.com/rust-lang/cargo/issues/6313>.
```
Change-Id: Ic785c0349070783baf5e8fd23f5fb60603a3c995
Reviewed-on: https://cl.tvl.fyi/c/depot/+/8308
Tested-by: BuildkiteCI
Reviewed-by: tazjin <tazjin@tvl.su>
* We no longer need backtrace-on-stack-overflow, as we no longer
overflow the stack with the recent eval refactorings. This was weird
voodoo anyways, introduced earlier to debug some cases where stack
overflows occured.
* default features of genawaiter crate are not needed, as we don't use
their proc macros
Change-Id: I346fc5a18d7f117ee805909a8be8f535b96be76c
Reviewed-on: https://cl.tvl.fyi/c/depot/+/8263
Reviewed-by: flokli <flokli@flokli.de>
Tested-by: BuildkiteCI
Reviewed-by: raitobezarius <tvl@lahfa.xyz>
This was the last piece of code using BlobWriter.
We can also use `read_all_and_chunk`, it's just requires a bit more
plumbing:
- The data coming from the client (stream) needs to be mapped (we
extract the .data field).
- The stream needs to be turned into an (async) reader
- The reader needs to be made sync, and that code using the sync reader
needs to be in a `task::spawn_blocking`.
Change-Id: I4e374e1a9f47d5a0933f59a8f5c121185a5f3e95
Reviewed-on: https://cl.tvl.fyi/c/depot/+/8260
Autosubmit: flokli <flokli@flokli.de>
Reviewed-by: raitobezarius <tvl@lahfa.xyz>
Tested-by: BuildkiteCI
Reviewed-by: tazjin <tazjin@tvl.su>
This removes the use of Box::new, switching fastcdc to version 3.0.2
with https://github.com/nlfiedler/fastcdc-rs/issues/25 fixed.
Change-Id: I64f388b9e0a7f358e25a8bb7ca0e4df1d3bb01c4
Reviewed-on: https://cl.tvl.fyi/c/depot/+/8249
Tested-by: BuildkiteCI
Reviewed-by: raitobezarius <tvl@lahfa.xyz>
Reviewed-by: tazjin <tazjin@tvl.su>
Autosubmit: flokli <flokli@flokli.de>
Look at the data that's written to us, and upload all chunks but the
rest in parallel, using rayon. This required moving `upload_chunk`
outside the struct, and accepting a ChunkService to use for upload
(which it was previously getting from `self.chunk_service`).
This doesn't speed up things too much for now, because things are still
mostly linear.
Change-Id: Id785b5705c3392214d2da1a5b6a182bcf5048c8d
Reviewed-on: https://cl.tvl.fyi/c/depot/+/8195
Autosubmit: flokli <flokli@flokli.de>
Tested-by: BuildkiteCI
Reviewed-by: raitobezarius <tvl@lahfa.xyz>
This imports the contents at a given Path into the tvix store.
It doesn't register the contents at a Path in the store itself, that's up
to the PathInfoService.
Change-Id: I2c493532d65b90f199ddb7dfc90249f5c2957dee
Reviewed-on: https://cl.tvl.fyi/c/depot/+/8159
Reviewed-by: raitobezarius <tvl@lahfa.xyz>
Tested-by: BuildkiteCI
This switches away from the less canonical "ronomon" version to the
implementation as described in the
[paper](https://ieeexplore.ieee.org/document/9055082) by Wen Xia, et
al., in 2020.
That version uses 64-bit hash values and tends to be faster than both
the ronomon and v2016 versions, and produces the same chunking as the
2016 version.
As per https://docs.rs/fastcdc/latest/fastcdc/#implementations-1, it's
the recommended choice.
The crate also gained support for streaming version of chunkers:
https://docs.rs/fastcdc/latest/fastcdc/#large-data, which might be
useful.
Change-Id: Ieabec3da54eb2b73c045cb54e51f7a216f63641e
Reviewed-on: https://cl.tvl.fyi/c/depot/+/8134
Reviewed-by: raitobezarius <tvl@lahfa.xyz>
Tested-by: BuildkiteCI
This adds a NARCalculationService trait, which will take a root node,
and provide a proto::CalculateNarResponse in return.
It also adds a NonCachingNARCalculationService implementation, that will
simply always render the NAR in memory to calculate the size and sha256,
without any caching.
Change-Id: Id1ffb18559212fa6001f70f2634bbc3dfd0aa343
Reviewed-on: https://cl.tvl.fyi/c/depot/+/8096
Reviewed-by: raitobezarius <tvl@lahfa.xyz>
Tested-by: BuildkiteCI
This module contains the request/response types for generators
requesting actions from the VM.
For most of these, an async helper function is added that will be used
inside of generator functions to make use of these requests/responses
instead of constructing them directly.
Change-Id: I1e085f88adaf784a34867957a0e82532d3a83d7c
Reviewed-on: https://cl.tvl.fyi/c/depot/+/8148
Tested-by: BuildkiteCI
Reviewed-by: raitobezarius <tvl@lahfa.xyz>
Our fork fixes a small bug (https://github.com/jneem/wu-manber/pull/1)
but it's not clear whether upstream will accept patches, so for now
lets point this directly at our fork.
Change-Id: Iccdcedae3e9a8b783241431787c952561d032694
Reviewed-on: https://cl.tvl.fyi/c/depot/+/8031
Reviewed-by: tazjin <tazjin@tvl.su>
Autosubmit: tazjin <tazjin@tvl.su>
Tested-by: BuildkiteCI
Switch out the string-scanning algorithm used in the reference scanner.
The construction of aho-corasick automata made up the vast majority of
runtime when evaluating nixpkgs previously. While the actual scanning
with a constructed automaton is relatively fast, we almost never scan
for the same set of strings twice and the cost is not worth it.
An algorithm that better matches our needs is the Wu-Manber multiple
string match algorithm, which works efficiently on *long* and *random*
strings of the *same length*, which describes store paths (up to their
hash component).
This switches the refscanner crate to a Rust implementation[0][1] of
this algorithm.
This has several implications:
1. This crate does not provide a way to scan streams. I'm not sure if
this is an inherent problem with the algorithm (probably not, but
it would need buffering). Either way, related functions and
tests (which were actually unused) have been removed.
2. All strings need to be of the same length. For this reason, we
truncate the known paths after their hash part (they are still
unique, of course).
3. Passing an empty set of matches, or a match that is shorter than
the length of a store path, causes the crate to panic. We safeguard
against this by completely skipping the refscanning if there are no
known paths (i.e. when evaluating the first derivation of an eval),
and by bailing out of scanning a string that is shorter than a
store path.
On the upside, this reduces overall runtime to less 1/5 of what it was
before when evaluating `pkgs.stdenv.drvPath`.
[0]: Frankly, it's a random, research-grade MIT-licensed
crate that I found on Github:
https://github.com/jneem/wu-manber
[1]: We probably want to rewrite or at least fork the above crate, and
add things like a three-byte wide scanner. Evaluating large
portions of nixpkgs can easily lead to more than 65k derivations
being scanned for.
Change-Id: I08926778e1e5d5a87fc9ac26e0437aed8bbd9eb0
Reviewed-on: https://cl.tvl.fyi/c/depot/+/8017
Tested-by: BuildkiteCI
Reviewed-by: flokli <flokli@flokli.de>
Put this in its src/derivation.
Change-Id: Ic047ab1c2da555a833ee454e10ef60c77537b617
Reviewed-on: https://cl.tvl.fyi/c/depot/+/7967
Reviewed-by: tazjin <tazjin@tvl.su>
Tested-by: BuildkiteCI
Autosubmit: flokli <flokli@flokli.de>
Move nixbase32 and store_path into this.
This allows //tvix/cli to not pull in //tvix/store for now.
Change-Id: Id3a32867205d95794bc0d33b21d4cb3d9bafd02a
Reviewed-on: https://cl.tvl.fyi/c/depot/+/7964
Tested-by: BuildkiteCI
Reviewed-by: tazjin <tazjin@tvl.su>
This helper function only was created because
populate_output_configuration was hard to test before cl/7939.
With that out of the way, we can pull it in.
Change-Id: I64b36c0eb34343290a8d84a03b0d29392a821fc7
Reviewed-on: https://cl.tvl.fyi/c/depot/+/7961
Autosubmit: flokli <flokli@flokli.de>
Tested-by: BuildkiteCI
Reviewed-by: tazjin <tazjin@tvl.su>
This is much less code, and makes it much easier to read.
Change-Id: I9028f226105f905c2cc2cabd33907ff493e26225
Reviewed-on: https://cl.tvl.fyi/c/depot/+/7938
Reviewed-by: tazjin <tazjin@tvl.su>
Tested-by: BuildkiteCI
Autosubmit: flokli <flokli@flokli.de>
Instead of being called with `md5`, `sha1`, `sha256` or `sha512`,
`fetchurl.nix` (from corepkgs / `<nix`) can also be called with a `hash`
attribute, being an SRI hash.
In that case, `builtin.derivation` is called with `outputHashAlgo` being
an empty string, and `outputHash` being an SRI hash string.
In other cases, an SRI hash is passed as outputHash, but outputHashAlgo
is set too.
Nix does modify these values in (single, fixed) output specification it
serializes to ATerm, but keeps it unharmed in `env`.
Move this into a construct_output_hash helper function, that can be
tested better in isolation.
Change-Id: Id9d716a119664c44ea7747540399966752e20187
Reviewed-on: https://cl.tvl.fyi/c/depot/+/7933
Reviewed-by: tazjin <tazjin@tvl.su>
Autosubmit: flokli <flokli@flokli.de>
Tested-by: BuildkiteCI
This allows parsing TOML from Tvix. We can enable the eval-okay-fromTOML
testcase from nix_tests. It uses the `toml` crate, and the serde
integration it brings with it.
Change-Id: Ic6f95aacf2aeb890116629b409752deac49dd655
Reviewed-on: https://cl.tvl.fyi/c/depot/+/7920
Autosubmit: flokli <flokli@flokli.de>
Reviewed-by: tazjin <tazjin@tvl.su>
Tested-by: BuildkiteCI
Apparently our naive implementation of float formatting, which simply
used {:.5}, and trimmed trailing "0" strings not sufficient.
It wrongly trimmed numbers with zeroes but no decimal point, like
`10000` got trimmed to `1`.
Nix uses `std::to_string` on the double, which according to
https://en.cppreference.com/w/cpp/string/basic_string/to_string
is equivalent to `std::sprintf(buf, "%f", value)`.
https://en.cppreference.com/w/cpp/io/c/fprintf mentions this is treated
like this:
> Precision specifies the exact number of digits to appear after
> the decimal point character. The default precision is 6. In the
> alternative implementation decimal point character is written even if
> no digits follow it. For infinity and not-a-number conversion style
> see notes.
This doesn't seem to be the case though, and Nix uses scientific
notation in some cases.
There's a whole bunch of strategies to determine which is a more compact
notation, and which notation should be used for a given number.
https://github.com/rust-lang/rust/issues/24556 provides some pointers
into various rabbit holes for those interested.
This gist seems to be that currently a different formatting is not
exposed in rust directly, at least not for public consumption.
There is the
[lexical-core](https://github.com/Alexhuszagh/rust-lexical) crate
though, which provides a way to format floats with various strategies
and formats.
Change our implementation of `TotalDisplay` for the `Value::Float` case
to use that. We still need to do some post-processing, because Nix
always adds the sign in scientific notation (and there's no way to
configure lexical-core to do that), and lexical-core in some cases keeps
the trailing zeros.
Even with all that in place, there as a difference in `eval-okay-
fromjson.nix` (from tvix-tests), which I couldn't get to work. I updated
the fixture to a less problematic number.
With this, the testsuite passes again, and does for the upcoming CL
introducing builtins.fromTOML, and enabling the nix testsuite bits for
it, too.
Change-Id: Ie6fba5619e1d9fd7ce669a51594658b029057acc
Reviewed-on: https://cl.tvl.fyi/c/depot/+/7922
Tested-by: BuildkiteCI
Autosubmit: flokli <flokli@flokli.de>
Reviewed-by: tazjin <tazjin@tvl.su>
