refactor(tvix/store): use strictly typed PathInfo struct r/8787

This switches the PathInfoService trait from using the proto-derived
PathInfo struct to a more restrictive struct, and updates all
implementations to use it.

It removes a lot of the previous conversion and checks, as invalid
states became nonrepresentable, and validations are expressed on the
type level.

PathInfoService implementations consuming protobuf need to convert and
do the verification internally, and can only return the strongly typed
variant.

The nix_compat::narinfo::NarInfo conversions for the proto PathInfo
are removed, we only keep a version showing a NarInfo representation for
the strong struct.

Converting back to a PathInfo requires the root node now, but is
otherwise trivial, so left to the users.

Co-Authored-By: Florian Klink <flokli@flokli.de>
Change-Id: I6fdfdb44063efebb44a8f0097b6b81a828717e03
Reviewed-on: https://cl.tvl.fyi/c/depot/+/12588
Reviewed-by: flokli <flokli@flokli.de>
Tested-by: BuildkiteCI

1 files changed, 10 insertions, 20 deletions

diff --git a/tvix/store/src/pathinfoservice/bigtable.rs b/tvix/store/src/pathinfoservice/bigtable.rs
index 15128986ff56..3d8db8e5044a 100644
--- a/tvix/store/src/pathinfoservice/bigtable.rs
+++ b/tvix/store/src/pathinfoservice/bigtable.rs
@@ -1,6 +1,5 @@
-use super::PathInfoService;
+use super::{PathInfo, PathInfoService};
 use crate::proto;
-use crate::proto::PathInfo;
 use async_stream::try_stream;
 use bigtable_rs::{bigtable, google::bigtable::v2 as bigtable_v2};
 use bytes::Bytes;
@@ -232,14 +231,13 @@ impl PathInfoService for BigtablePathInfoService {
         }
 
         // Try to parse the value into a PathInfo message
-        let path_info = proto::PathInfo::decode(Bytes::from(cell.value))
+        let path_info_proto = proto::PathInfo::decode(Bytes::from(cell.value))
             .map_err(|e| Error::StorageError(format!("unable to decode pathinfo proto: {}", e)))?;
 
-        let store_path = path_info
-            .validate()
-            .map_err(|e| Error::StorageError(format!("invalid PathInfo: {}", e)))?;
+        let path_info = PathInfo::try_from(path_info_proto)
+            .map_err(|e| Error::StorageError(format!("Invalid path info: {e}")))?;
 
-        if store_path.digest() != &digest {
+        if path_info.store_path.digest() != &digest {
             return Err(Error::StorageError("PathInfo has unexpected digest".into()));
         }
 
@@ -248,14 +246,10 @@ impl PathInfoService for BigtablePathInfoService {
 
     #[instrument(level = "trace", skip_all, fields(path_info.root_node = ?path_info.node))]
     async fn put(&self, path_info: PathInfo) -> Result<PathInfo, Error> {
-        let store_path = path_info
-            .validate()
-            .map_err(|e| Error::InvalidRequest(format!("pathinfo failed validation: {}", e)))?;
-
         let mut client = self.client.clone();
-        let path_info_key = derive_pathinfo_key(store_path.digest());
+        let path_info_key = derive_pathinfo_key(path_info.store_path.digest());
 
-        let data = path_info.encode_to_vec();
+        let data = proto::PathInfo::from(path_info.clone()).encode_to_vec();
         if data.len() as u64 > CELL_SIZE_LIMIT {
             return Err(Error::StorageError(
                 "PathInfo exceeds cell limit on Bigtable".into(),
@@ -340,16 +334,12 @@ impl PathInfoService for BigtablePathInfoService {
                 }
 
                 // Try to parse the value into a PathInfo message.
-                let path_info = proto::PathInfo::decode(Bytes::from(cell.value))
+                let path_info_proto = proto::PathInfo::decode(Bytes::from(cell.value))
                     .map_err(|e| Error::StorageError(format!("unable to decode pathinfo proto: {}", e)))?;
 
-                // Validate the containing PathInfo, ensure its StorePath digest
-                // matches row key.
-                let store_path = path_info
-                    .validate()
-                    .map_err(|e| Error::StorageError(format!("invalid PathInfo: {}", e)))?;
+                let path_info = PathInfo::try_from(path_info_proto).map_err(|e| Error::StorageError(format!("Invalid path info: {e}")))?;
 
-                let exp_path_info_key = derive_pathinfo_key(store_path.digest());
+                let exp_path_info_key = derive_pathinfo_key(path_info.store_path.digest());
 
                 if exp_path_info_key.as_bytes() != row_key.as_slice() {
                     Err(Error::StorageError("PathInfo has unexpected digest".into()))?