refactor(tvix/store/directorysvc): move from Vec<u8> to B3Digest r/6177

This introduces a new struct, B3Digest, which internally holds a
Vec<u8>, but only allows construction with 32 bytes.

It also implements display, which will print the base64 representation.
This should reduce some boilerplate when parsing Vec<u8>.

Change-Id: Ia91aa40cb691916773abc8f93e6ed79a5fd34863
Reviewed-on: https://cl.tvl.fyi/c/depot/+/8592
Reviewed-by: tazjin <tazjin@tvl.su>
Autosubmit: flokli <flokli@flokli.de>
Tested-by: BuildkiteCI

1 files changed, 2 insertions, 8 deletions

diff --git a/tvix/store/src/nar/non_caching_calculation_service.rs b/tvix/store/src/nar/non_caching_calculation_service.rs
index ff6eb4d5d057..8a080cb4df5e 100644
--- a/tvix/store/src/nar/non_caching_calculation_service.rs
+++ b/tvix/store/src/nar/non_caching_calculation_service.rs
@@ -26,18 +26,12 @@ impl<BS: BlobService, DS: DirectoryService> NonCachingNARCalculationService<BS,
 impl<BS: BlobService, DS: DirectoryService> NARCalculationService
     for NonCachingNARCalculationService<BS, DS>
 {
-    fn calculate_nar(
-        &self,
-        root_node: &proto::node::Node,
-    ) -> Result<proto::CalculateNarResponse, RenderError> {
+    fn calculate_nar(&self, root_node: &proto::node::Node) -> Result<(u64, [u8; 32]), RenderError> {
         let h = Sha256::new();
         let mut cw = CountWrite::from(h);
 
         self.nar_renderer.write_nar(&mut cw, root_node)?;
 
-        Ok(proto::CalculateNarResponse {
-            nar_size: cw.count() as u64,
-            nar_sha256: cw.into_inner().finalize().to_vec(),
-        })
+        Ok((cw.count(), cw.into_inner().finalize().into()))
     }
 }