1 files changed, 76 insertions, 0 deletions
diff --git a/tvix/castore/src/directoryservice/mod.rs b/tvix/castore/src/directoryservice/mod.rs
new file mode 100644
index 000000000000..db3d5767eadd
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+++ b/tvix/castore/src/directoryservice/mod.rs
@@ -0,0 +1,76 @@
+use crate::{proto, B3Digest, Error};
+use futures::stream::BoxStream;
+use tonic::async_trait;
+
+mod from_addr;
+mod grpc;
+mod memory;
+mod sled;
+mod traverse;
+mod utils;
+
+pub use self::from_addr::from_addr;
+pub use self::grpc::GRPCDirectoryService;
+pub use self::memory::MemoryDirectoryService;
+pub use self::sled::SledDirectoryService;
+pub use self::traverse::descend_to;
+
+/// The base trait all Directory services need to implement.
+/// This is a simple get and put of [crate::proto::Directory], returning their
+/// digest.
+#[async_trait]
+pub trait DirectoryService: Send + Sync {
+    /// Looks up a single Directory message by its digest.
+    /// The returned Directory message *must* be valid.
+    /// In case the directory is not found, Ok(None) is returned.
+    async fn get(&self, digest: &B3Digest) -> Result<Option<proto::Directory>, Error>;
+    /// Uploads a single Directory message, and returns the calculated
+    /// digest, or an error. An error *must* also be returned if the message is
+    /// not valid.
+    async fn put(&self, directory: proto::Directory) -> Result<B3Digest, Error>;
+
+    /// Looks up a closure of [proto::Directory].
+    /// Ideally this would be a `impl Stream<Item = Result<proto::Directory, Error>>`,
+    /// and we'd be able to add a default implementation for it here, but
+    /// we can't have that yet.
+    ///
+    /// This returns a pinned, boxed stream. The pinning allows for it to be polled easily,
+    /// and the box allows different underlying stream implementations to be returned since
+    /// Rust doesn't support this as a generic in traits yet. This is the same thing that
+    /// [async_trait] generates, but for streams instead of futures.
+    ///
+    /// The individual Directory messages *must* be valid.
+    fn get_recursive(
+        &self,
+        root_directory_digest: &B3Digest,
+    ) -> BoxStream<Result<proto::Directory, Error>>;
+
+    /// Allows persisting a closure of [proto::Directory], which is a graph of
+    /// connected Directory messages.
+    fn put_multiple_start(&self) -> Box<dyn DirectoryPutter>;
+}
+
+/// Provides a handle to put a closure of connected [proto::Directory] elements.
+///
+/// The consumer can periodically call [DirectoryPutter::put], starting from the
+/// leaves. Once the root is reached, [DirectoryPutter::close] can be called to
+/// retrieve the root digest (or an error).
+///
+/// DirectoryPutters might be created without a single [DirectoryPutter::put],
+/// and then dropped without calling [DirectoryPutter::close],
+/// for example when ingesting a path that ends up not pointing to a directory,
+/// but a single file or symlink.
+#[async_trait]
+pub trait DirectoryPutter: Send {
+    /// Put a individual [proto::Directory] into the store.
+    /// Error semantics and behaviour is up to the specific implementation of
+    /// this trait.
+    /// Due to bursting, the returned error might refer to an object previously
+    /// sent via `put`.
+    async fn put(&mut self, directory: proto::Directory) -> Result<(), Error>;
+
+    /// Close the stream, and wait for any errors.
+    /// If there's been any invalid Directory message uploaded, and error *must*
+    /// be returned.
+    async fn close(&mut self) -> Result<B3Digest, Error>;
+}