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, 6 insertions, 9 deletions

diff --git a/tvix/store/src/nar/mod.rs b/tvix/store/src/nar/mod.rs
index d6a2f0889a5f..2bfb541733be 100644
--- a/tvix/store/src/nar/mod.rs
+++ b/tvix/store/src/nar/mod.rs
@@ -1,4 +1,4 @@
-use crate::proto;
+use crate::{proto, B3Digest};
 use data_encoding::BASE64;
 use thiserror::Error;
 
@@ -14,14 +14,14 @@ pub enum RenderError {
     #[error("failure talking to a backing store client: {0}")]
     StoreError(crate::Error),
 
-    #[error("unable to find directory {}, referred from {}", BASE64.encode(.0), .1)]
-    DirectoryNotFound(Vec<u8>, String),
+    #[error("unable to find directory {}, referred from {}", .0, .1)]
+    DirectoryNotFound(B3Digest, String),
 
     #[error("unable to find blob {}, referred from {}", BASE64.encode(.0), .1)]
-    BlobNotFound(Vec<u8>, String),
+    BlobNotFound([u8; 32], String),
 
     #[error("unexpected size in metadata for blob {}, referred from {} returned, expected {}, got {}", BASE64.encode(.0), .1, .2, .3)]
-    UnexpectedBlobMeta(Vec<u8>, String, u32, u32),
+    UnexpectedBlobMeta([u8; 32], String, u32, u32),
 
     #[error("failure using the NAR writer: {0}")]
     NARWriterError(std::io::Error),
@@ -29,8 +29,5 @@ pub enum RenderError {
 
 /// The base trait for something calculating NARs, and returning their size and sha256.
 pub trait NARCalculationService {
-    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>;
 }