refactor(tvix/castore): use Directory struct separate from proto one

This uses our own data type to deal with Directories in the castore model.

It makes some undesired states unrepresentable, removing the need for conversions and checking in various places:

 - In the protobuf, blake3 digests could have a wrong length, as proto doesn't know fixed-size fields. We now use `B3Digest`, which makes cloning cheaper, and removes the need to do size-checking everywhere.
 - In the protobuf, we had three different lists for `files`, `symlinks` and `directories`. This was mostly a protobuf size optimization, but made interacting with them a bit awkward. This has now been replaced with a list of enums, and convenience iterators to get various nodes, and add new ones.

Change-Id: I7b92691bb06d77ff3f58a5ccea94a22c16f84f04
Reviewed-on: https://cl.tvl.fyi/c/depot/+/12057
Tested-by: BuildkiteCI
Reviewed-by: flokli <flokli@flokli.de>

tvix/store/src/pathinfoservice/fs/mod.rs

@@ -1,10 +1,10 @@
 use futures::stream::BoxStream;
 use futures::StreamExt;
 use tonic::async_trait;
+use tvix_castore::directoryservice::Node;
 use tvix_castore::fs::{RootNodes, TvixStoreFs};
-use tvix_castore::proto as castorepb;
-use tvix_castore::Error;
 use tvix_castore::{blobservice::BlobService, directoryservice::DirectoryService};
+use tvix_castore::{Error, ValidateNodeError};
 
 use super::PathInfoService;
 
@@ -48,7 +48,7 @@ impl<T> RootNodes for RootNodesWrapper<T>
 where
     T: AsRef<dyn PathInfoService> + Send + Sync,
 {
-    async fn get_by_basename(&self, name: &[u8]) -> Result<Option<castorepb::node::Node>, Error> {
+    async fn get_by_basename(&self, name: &[u8]) -> Result<Option<Node>, Error> {
         let Ok(store_path) = nix_compat::store_path::StorePath::from_bytes(name) else {
             return Ok(None);
         };
@@ -61,20 +61,23 @@ where
             .map(|path_info| {
                 path_info
                     .node
+                    .as_ref()
                     .expect("missing root node")
-                    .node
-                    .expect("empty node")
-            }))
+                    .try_into()
+                    .map_err(|e: ValidateNodeError| Error::StorageError(e.to_string()))
+            })
+            .transpose()?)
     }
 
-    fn list(&self) -> BoxStream<Result<castorepb::node::Node, Error>> {
+    fn list(&self) -> BoxStream<Result<Node, Error>> {
         Box::pin(self.0.as_ref().list().map(|result| {
-            result.map(|path_info| {
+            result.and_then(|path_info| {
                 path_info
                     .node
+                    .as_ref()
                     .expect("missing root node")
-                    .node
-                    .expect("empty node")
+                    .try_into()
+                    .map_err(|e: ValidateNodeError| Error::StorageError(e.to_string()))
             })
         }))
     }

tvix/store/src/pathinfoservice/grpc.rs

@@ -11,7 +11,8 @@ use tonic::{async_trait, Code};
 use tracing::{instrument, Span};
 use tracing_indicatif::span_ext::IndicatifSpanExt;
 use tvix_castore::composition::{CompositionContext, ServiceBuilder};
-use tvix_castore::{proto as castorepb, Error};
+use tvix_castore::directoryservice::Node;
+use tvix_castore::Error;
 
 /// Connects to a (remote) tvix-store PathInfoService over gRPC.
 #[derive(Clone)]
@@ -123,10 +124,7 @@ where
     T::Future: Send,
 {
     #[instrument(level = "trace", skip_all, fields(root_node = ?root_node, indicatif.pb_show=1))]
-    async fn calculate_nar(
-        &self,
-        root_node: &castorepb::node::Node,
-    ) -> Result<(u64, [u8; 32]), Error> {
+    async fn calculate_nar(&self, root_node: &Node) -> Result<(u64, [u8; 32]), Error> {
         let span = Span::current();
         span.pb_set_message("Waiting for NAR calculation");
         span.pb_start();
@@ -134,8 +132,8 @@ where
         let path_info = self
             .grpc_client
             .clone()
-            .calculate_nar(castorepb::Node {
-                node: Some(root_node.clone()),
+            .calculate_nar(tvix_castore::proto::Node {
+                node: Some(root_node.into()),
             })
             .await
             .map_err(|e| Error::StorageError(e.to_string()))?

tvix/store/src/pathinfoservice/lru.rs

@@ -109,7 +109,10 @@ mod test {
             let root_node = p.node.as_mut().unwrap();
             if let castorepb::Node { node: Some(node) } = root_node {
                 let n = node.to_owned();
-                *node = n.rename("11111111111111111111111111111111-dummy2".into());
+                *node = (&tvix_castore::directoryservice::Node::try_from(&n)
+                    .unwrap()
+                    .rename("11111111111111111111111111111111-dummy2".into()))
+                    .into();
             } else {
                 unreachable!()
             }

tvix/store/src/pathinfoservice/nix_http.rs

@@ -230,7 +230,7 @@ where
         Ok(Some(PathInfo {
             node: Some(castorepb::Node {
                 // set the name of the root node to the digest-name of the store path.
-                node: Some(root_node.rename(narinfo.store_path.to_string().to_owned().into())),
+                node: Some((&root_node.rename(narinfo.store_path.to_string().into())).into()),
             }),
             references: pathinfo.references,
             narinfo: pathinfo.narinfo,