feat(tvix/store/pathinfoservice): implement NixHTTPPathInfoService r/7038

NixHTTPPathInfoService acts as a bridge in between the Nix HTTP Binary
cache protocol provided by Nix binary caches such as cache.nixos.org,
and the Tvix Store Model.
It implements the [PathInfoService] trait in an interesting way: Every
[PathInfoService::get] fetches the .narinfo and referred NAR file,
inserting components into a [BlobService] and [DirectoryService], then
returning a [PathInfo] struct with the root.
Due to this being quite a costly operation, clients are expected to
layer this service with store composition, so they're only ingested
once.
The client is expected to be (indirectly) using the same [BlobService]
and [DirectoryService], so able to fetch referred Directories and Blobs.
[PathInfoService::put] and [PathInfoService::nar] are not implemented
and return an error if called.

This behaves very similar to the nar-bridge-pathinfo code in nar-bridge,
except it's now in Rust.

Change-Id: Ia03d4fed9d0657965d100299af97cd917a03f2f0
Reviewed-on: https://cl.tvl.fyi/c/depot/+/10069
Tested-by: BuildkiteCI
Autosubmit: flokli <flokli@flokli.de>
Reviewed-by: raitobezarius <tvl@lahfa.xyz>

1 files changed, 2 insertions, 0 deletions

diff --git a/tvix/store/src/pathinfoservice/mod.rs b/tvix/store/src/pathinfoservice/mod.rs
index 3fde10179b..5faa0900a0 100644
--- a/tvix/store/src/pathinfoservice/mod.rs
+++ b/tvix/store/src/pathinfoservice/mod.rs
@@ -1,6 +1,7 @@
 mod from_addr;
 mod grpc;
 mod memory;
+mod nix_http;
 mod sled;
 
 use futures::Stream;
@@ -14,6 +15,7 @@ use crate::proto::PathInfo;
 pub use self::from_addr::from_addr;
 pub use self::grpc::GRPCPathInfoService;
 pub use self::memory::MemoryPathInfoService;
+pub use self::nix_http::NixHTTPPathInfoService;
 pub use self::sled::SledPathInfoService;
 
 /// The base trait all PathInfo services need to implement.