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>

1 files changed, 24 insertions, 22 deletions

diff --git a/tvix/castore/src/errors.rs b/tvix/castore/src/errors.rs
index 083f43036845..e03cfa5a5207 100644
--- a/tvix/castore/src/errors.rs
+++ b/tvix/castore/src/errors.rs
@@ -13,33 +13,12 @@ pub enum Error {
     StorageError(String),
 }
 
-/// Errors that can occur during the validation of [Directory] messages.
-#[derive(Debug, thiserror::Error, PartialEq)]
-pub enum ValidateDirectoryError {
-    /// Elements are not in sorted order
-    #[error("{:?} is not sorted", .0.as_bstr())]
-    WrongSorting(Vec<u8>),
-    /// Multiple elements with the same name encountered
-    #[error("{:?} is a duplicate name", .0.as_bstr())]
-    DuplicateName(Vec<u8>),
-    /// Invalid node
-    #[error("invalid node with name {:?}: {:?}", .0.as_bstr(), .1.to_string())]
-    InvalidNode(Vec<u8>, ValidateNodeError),
-    #[error("Total size exceeds u32::MAX")]
-    SizeOverflow,
-}
-
-/// Errors that occur during Node validation
+/// Errors that occur during construction of [crate::Node]
 #[derive(Debug, thiserror::Error, PartialEq)]
 pub enum ValidateNodeError {
-    #[error("No node set")]
-    NoNodeSet,
     /// Invalid digest length encountered
     #[error("invalid digest length: {0}")]
     InvalidDigestLen(usize),
-    /// Invalid name encountered
-    #[error("Invalid name: {}", .0.as_bstr())]
-    InvalidName(bytes::Bytes),
     /// Invalid symlink target
     #[error("Invalid symlink target: {}", .0.as_bstr())]
     InvalidSymlinkTarget(bytes::Bytes),
@@ -53,6 +32,29 @@ impl From<crate::digests::Error> for ValidateNodeError {
     }
 }
 
+/// Errors that can occur when populating [crate::Directory] messages,
+/// or parsing [crate::proto::Directory]
+#[derive(Debug, thiserror::Error, PartialEq)]
+pub enum DirectoryError {
+    /// Multiple elements with the same name encountered
+    #[error("{:?} is a duplicate name", .0.as_bstr())]
+    DuplicateName(Vec<u8>),
+    /// Node failed validation
+    #[error("invalid node with name {:?}: {:?}", .0.as_bstr(), .1.to_string())]
+    InvalidNode(bytes::Bytes, ValidateNodeError),
+    #[error("Total size exceeds u32::MAX")]
+    SizeOverflow,
+    /// Invalid name encountered
+    #[error("Invalid name: {}", .0.as_bstr())]
+    InvalidName(bytes::Bytes),
+    /// Elements are not in sorted order. Can only happen on protos
+    #[error("{:?} is not sorted", .0.as_bstr())]
+    WrongSorting(bytes::Bytes),
+    /// This can only happen if there's an unknown node type (on protos)
+    #[error("No node set")]
+    NoNodeSet,
+}
+
 impl From<JoinError> for Error {
     fn from(value: JoinError) -> Self {
         Error::StorageError(value.to_string())