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 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>
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>
This should make no difference in Nix builds, but allows running tests
locally again with `cargo test` for //tvix/eval.
Change-Id: I97d61840143d5c14db61d5862781bf635f9a28e7
Reviewed-on: https://cl.tvl.fyi/c/depot/+/7590
Reviewed-by: grfn <grfn@gws.fyi>
Tested-by: BuildkiteCI
Reviewed-by: flokli <flokli@flokli.de>
