refactor(tvix/store): drop calculate_nar from PathInfoService r/8103

This shouldn't be part of the PathInfoService trait.

Pretty much none of the PathInfoServices do implement it, and requiring
them to implement it means they also cannot make use of this calculation
already being done by other PathInfoServices.

Move it out into its own NarCalculationService trait, defined somewhere
at tvix_store::nar, and have everyone who wants to trigger nar
calculation use nar_calculation_service directly, which now is an
additional field in TvixStoreIO for example.

It being moved outside the PathInfoService trait doesn't prohibit
specific implementations to implement it (like the GRPC client for the
`PathInfoService` does.

This is currently wired together in a bit of a hacky fashion - as of
now, everything uses the naive implementation that traverses blob and
directoryservice, rather than composing it properly. I want to leave
that up to a later CL, dealing with other parts of store composition
too.

Change-Id: I18d07ea4301d4a07651b8218bc5fe95e4e307208
Reviewed-on: https://cl.tvl.fyi/c/depot/+/11619
Reviewed-by: Connor Brewster <cbrewster@hey.com>
Autosubmit: flokli <flokli@flokli.de>
Tested-by: BuildkiteCI

1 files changed, 15 insertions, 7 deletions

diff --git a/tvix/glue/src/fetchers/mod.rs b/tvix/glue/src/fetchers/mod.rs
index 342dfd84e879..1b2e1ee20cc0 100644
--- a/tvix/glue/src/fetchers/mod.rs
+++ b/tvix/glue/src/fetchers/mod.rs
@@ -14,7 +14,7 @@ use tvix_castore::{
     directoryservice::DirectoryService,
     proto::{node::Node, FileNode},
 };
-use tvix_store::{pathinfoservice::PathInfoService, proto::PathInfo};
+use tvix_store::{nar::NarCalculationService, pathinfoservice::PathInfoService, proto::PathInfo};
 use url::Url;
 
 use crate::builtins::FetcherError;
@@ -106,20 +106,27 @@ impl Fetch {
 }
 
 /// Knows how to fetch a given [Fetch].
-pub struct Fetcher<BS, DS, PS> {
+pub struct Fetcher<BS, DS, PS, NS> {
     http_client: reqwest::Client,
     blob_service: BS,
     directory_service: DS,
     path_info_service: PS,
+    nar_calculation_service: NS,
 }
 
-impl<BS, DS, PS> Fetcher<BS, DS, PS> {
-    pub fn new(blob_service: BS, directory_service: DS, path_info_service: PS) -> Self {
+impl<BS, DS, PS, NS> Fetcher<BS, DS, PS, NS> {
+    pub fn new(
+        blob_service: BS,
+        directory_service: DS,
+        path_info_service: PS,
+        nar_calculation_service: NS,
+    ) -> Self {
         Self {
             http_client: reqwest::Client::new(),
             blob_service,
             directory_service,
             path_info_service,
+            nar_calculation_service,
         }
     }
 
@@ -170,11 +177,12 @@ async fn hash<D: Digest + std::io::Write>(
     Ok((hasher.finalize(), bytes_copied))
 }
 
-impl<BS, DS, PS> Fetcher<BS, DS, PS>
+impl<BS, DS, PS, NS> Fetcher<BS, DS, PS, NS>
 where
     BS: BlobService + Clone + 'static,
     DS: DirectoryService + Clone,
     PS: PathInfoService,
+    NS: NarCalculationService,
 {
     /// Ingest the data from a specified [Fetch].
     /// On success, return the root node, a content digest and length.
@@ -257,7 +265,7 @@ where
                 // Even if no expected NAR sha256 has been provided, we need
                 // the actual one later.
                 let (nar_size, actual_nar_sha256) = self
-                    .path_info_service
+                    .nar_calculation_service
                     .calculate_nar(&node)
                     .await
                     .map_err(|e| {
@@ -309,7 +317,7 @@ where
         // the [PathInfo].
         let (nar_size, nar_sha256) = match &ca_hash {
             CAHash::Flat(_nix_hash) => self
-                .path_info_service
+                .nar_calculation_service
                 .calculate_nar(&node)
                 .await
                 .map_err(|e| FetcherError::Io(e.into()))?,