refactor(tvix/castore): remove `name` from Nodes r/8504

Nodes only have names if they're contained inside a Directory, or if
they're a root node and have something else possibly giving them a name
externally.

This removes all `name` fields in the three different Nodes, and instead
maintains it inside a BTreeMap inside the Directory.

It also removes the NamedNode trait (they don't have a get_name()), as
well as Node::rename(self, name), and all [Partial]Ord implementations
for Node (as they don't have names to use for sorting).

The `nodes()`, `directories()`, `files()` iterators inside a `Directory`
now return a tuple of Name and Node, as does the RootNodesProvider.

The different {Directory,File,Symlink}Node struct constructors got
simpler, and the {Directory,File}Node ones became infallible - as
there's no more possibility to represent invalid state.

The proto structs stayed the same - there's now from_name_and_node and
into_name_and_node to convert back and forth between the two `Node`
structs.

Some further cleanups:

The error types for Node validation were renamed. Everything related to
names is now in the DirectoryError (not yet happy about the naming)

There's some leftover cleanups to do:
 - There should be a from_(sorted_)iter and into_iter in Directory, so
   we can construct and deconstruct in one go.
   That should also enable us to implement conversions from and to the
   proto representation that moves, rather than clones.

 - The BuildRequest and PathInfo structs are still proto-based, so we
   still do a bunch of conversions back and forth there (and have some
   ugly expect there). There's not much point for error handling here,
   this will be moved to stricter types in a followup CL.

Change-Id: I7369a8e3a426f44419c349077cb4fcab2044ebb6
Reviewed-on: https://cl.tvl.fyi/c/depot/+/12205
Tested-by: BuildkiteCI
Reviewed-by: yuka <yuka@yuka.dev>
Autosubmit: flokli <flokli@flokli.de>
Reviewed-by: benjaminedwardwebb <benjaminedwardwebb@gmail.com>
Reviewed-by: Connor Brewster <cbrewster@hey.com>

3 files changed, 27 insertions, 22 deletions

diff --git a/tvix/nar-bridge/src/lib.rs b/tvix/nar-bridge/src/lib.rs
index 2f3dd82439b1..56b7e19a3cb0 100644
--- a/tvix/nar-bridge/src/lib.rs
+++ b/tvix/nar-bridge/src/lib.rs
@@ -7,7 +7,7 @@ use std::num::NonZeroUsize;
 use std::sync::Arc;
 use tvix_castore::blobservice::BlobService;
 use tvix_castore::directoryservice::DirectoryService;
-use tvix_castore::proto::node::Node;
+use tvix_castore::Node;
 use tvix_store::pathinfoservice::PathInfoService;
 
 mod nar;
diff --git a/tvix/nar-bridge/src/nar.rs b/tvix/nar-bridge/src/nar.rs
index acbcfa2817bc..f65c8f0be2ab 100644
--- a/tvix/nar-bridge/src/nar.rs
+++ b/tvix/nar-bridge/src/nar.rs
@@ -52,14 +52,15 @@ pub async fn get(
             StatusCode::NOT_FOUND
         })?;
 
-    let root_node: tvix_castore::Node = (&root_node).try_into().map_err(|e| {
+    let (root_name, root_node) = root_node.into_name_and_node().map_err(|e| {
         warn!(err=%e, "root node validation failed");
         StatusCode::BAD_REQUEST
     })?;
 
-    // validate the node, but add a dummy node name, as we only send unnamed
-    // nodes
-    let root_node = root_node.rename("00000000000000000000000000000000-dummy".into());
+    if !root_name.is_empty() {
+        warn!("root node has name, which it shouldn't");
+        return Err(StatusCode::BAD_REQUEST);
+    }
 
     let (w, r) = tokio::io::duplex(1024 * 8);
 
@@ -125,7 +126,7 @@ pub async fn put(
 
     // store mapping of narhash to root node into root_nodes.
     // we need it later to populate the root node when accepting the PathInfo.
-    root_nodes.write().put(nar_hash_actual, (&root_node).into());
+    root_nodes.write().put(nar_hash_actual, root_node);
 
     Ok("")
 }
diff --git a/tvix/nar-bridge/src/narinfo.rs b/tvix/nar-bridge/src/narinfo.rs
index fc19bdc871cd..f97ee970819d 100644
--- a/tvix/nar-bridge/src/narinfo.rs
+++ b/tvix/nar-bridge/src/narinfo.rs
@@ -1,8 +1,9 @@
 use axum::http::StatusCode;
 use bytes::Bytes;
 use nix_compat::{narinfo::NarInfo, nixbase32};
+use prost::Message;
 use tracing::{instrument, warn, Span};
-use tvix_castore::proto::{self as castorepb, node::Node};
+use tvix_castore::proto::{self as castorepb};
 use tvix_store::proto::PathInfo;
 
 use crate::AppState;
@@ -67,17 +68,21 @@ pub async fn get(
     })?;
 
     // encode the (unnamed) root node in the NAR url itself.
-    let root_node =
-        tvix_castore::Node::try_from(path_info.node.as_ref().expect("root node must not be none"))
-            .unwrap() // PathInfo is validated
-            .rename("".into());
-
-    let mut buf = Vec::new();
-    Node::encode(&(&root_node).into(), &mut buf);
+    // We strip the name from the proto node before sending it out.
+    // It's not needed to render the NAR, it'll make the URL shorter, and it
+    // will make caching these requests easier.
+    let (_, root_node) = path_info
+        .node
+        .as_ref()
+        .expect("invalid pathinfo")
+        .to_owned()
+        .into_name_and_node()
+        .expect("invalid pathinfo");
 
     let url = format!(
         "nar/tvix-castore/{}?narsize={}",
-        data_encoding::BASE64URL_NOPAD.encode(&buf),
+        data_encoding::BASE64URL_NOPAD
+            .encode(&castorepb::Node::from_name_and_node("".into(), root_node).encode_to_vec()),
         narinfo.nar_size,
     );
 
@@ -125,19 +130,18 @@ pub async fn put(
 
     // Lookup root node with peek, as we don't want to update the LRU list.
     // We need to be careful to not hold the RwLock across the await point.
-    let maybe_root_node: Option<tvix_castore::Node> = root_nodes
-        .read()
-        .peek(&narinfo.nar_hash)
-        .and_then(|v| v.try_into().ok());
+    let maybe_root_node: Option<tvix_castore::Node> =
+        root_nodes.read().peek(&narinfo.nar_hash).cloned();
 
     match maybe_root_node {
         Some(root_node) => {
             // Set the root node from the lookup.
             // We need to rename the node to the narinfo storepath basename, as
             // that's where it's stored in PathInfo.
-            pathinfo.node = Some(castorepb::Node {
-                node: Some((&root_node.rename(narinfo.store_path.to_string().into())).into()),
-            });
+            pathinfo.node = Some(castorepb::Node::from_name_and_node(
+                narinfo.store_path.to_string().into(),
+                root_node,
+            ));
 
             // Persist the PathInfo.
             path_info_service.put(pathinfo).await.map_err(|e| {