feat(tvix/eval): implement `builtins.filterSource` r/7578

We add a new set of builtins called `import_builtins`, which
will contain import-related builtins, such as `builtins.path` and
`builtins.filterSource`. Both can import paths into the store, with
various knobs to alter the result, e.g. filtering, renaming, expected
hashes.

We introduce `filtered_ingest` which will drive the filtered ingestion
via the Nix function via the generator machinery, and then we register
the root node to the path info service inside the store.

`builtins.filterSource` is very simple, `builtins.path` is a more
complicated model requiring the same logic albeit more sophisticated
with name customization, file ingestion method and expected SHA-256.

Change-Id: I1083f37808b35f7b37818c8ffb9543d9682b2de2
Reviewed-on: https://cl.tvl.fyi/c/depot/+/10654
Autosubmit: raitobezarius <tvl@lahfa.xyz>
Tested-by: BuildkiteCI
Reviewed-by: flokli <flokli@flokli.de>

1 files changed, 148 insertions, 0 deletions

diff --git a/tvix/glue/src/builtins/import.rs b/tvix/glue/src/builtins/import.rs
new file mode 100644
index 0000000000..536585102d
--- /dev/null
+++ b/tvix/glue/src/builtins/import.rs
@@ -0,0 +1,148 @@
+//! Implements builtins used to import paths in the store.
+
+use futures::pin_mut;
+use std::path::Path;
+use tvix_eval::{
+    builtin_macros::builtins,
+    generators::{self, GenCo},
+    ErrorKind, Value,
+};
+
+use std::rc::Rc;
+
+async fn filtered_ingest(
+    state: Rc<TvixStoreIO>,
+    co: GenCo,
+    path: &Path,
+    filter: Option<&Value>,
+) -> Result<tvix_castore::proto::node::Node, ErrorKind> {
+    let mut entries_per_depths: Vec<Vec<walkdir::DirEntry>> = vec![Vec::new()];
+    let mut it = walkdir::WalkDir::new(path)
+        .follow_links(false)
+        .follow_root_links(false)
+        .contents_first(false)
+        .sort_by_file_name()
+        .into_iter();
+
+    // Skip root node.
+    entries_per_depths[0].push(
+        it.next()
+            .ok_or_else(|| ErrorKind::IO {
+                path: Some(path.to_path_buf()),
+                error: std::io::Error::new(std::io::ErrorKind::NotFound, "No root node emitted")
+                    .into(),
+            })?
+            .map_err(|err| ErrorKind::IO {
+                path: Some(path.to_path_buf()),
+                error: std::io::Error::from(err).into(),
+            })?,
+    );
+
+    while let Some(entry) = it.next() {
+        // Entry could be a NotFound, if the root path specified does not exist.
+        let entry = entry.map_err(|err| ErrorKind::IO {
+            path: err.path().map(|p| p.to_path_buf()),
+            error: std::io::Error::from(err).into(),
+        })?;
+
+        // As per Nix documentation `:doc builtins.filterSource`.
+        let file_type = if entry.file_type().is_dir() {
+            "directory"
+        } else if entry.file_type().is_file() {
+            "regular"
+        } else if entry.file_type().is_symlink() {
+            "symlink"
+        } else {
+            "unknown"
+        };
+
+        let should_keep: bool = if let Some(filter) = filter {
+            generators::request_force(
+                &co,
+                generators::request_call_with(
+                    &co,
+                    filter.clone(),
+                    [
+                        Value::String(Box::new(entry.path().as_os_str().as_encoded_bytes().into())),
+                        Value::String(Box::new(file_type.into())),
+                    ],
+                )
+                .await,
+            )
+            .await
+            .as_bool()?
+        } else {
+            true
+        };
+
+        if !should_keep {
+            if file_type == "directory" {
+                it.skip_current_dir();
+            }
+            continue;
+        }
+
+        if entry.depth() >= entries_per_depths.len() {
+            debug_assert!(
+                entry.depth() == entries_per_depths.len(),
+                "Received unexpected entry with depth {} during descent, previously at {}",
+                entry.depth(),
+                entries_per_depths.len()
+            );
+
+            entries_per_depths.push(vec![entry]);
+        } else {
+            entries_per_depths[entry.depth()].push(entry);
+        }
+
+        // FUTUREWORK: determine when it's the right moment to flush a level to the ingester.
+    }
+
+    let entries_stream = tvix_castore::import::leveled_entries_to_stream(entries_per_depths);
+
+    pin_mut!(entries_stream);
+
+    state
+        .ingest_entries_sync(entries_stream)
+        .map_err(|err| ErrorKind::IO {
+            path: Some(path.to_path_buf()),
+            error: err.into(),
+        })
+}
+
+#[builtins(state = "Rc<TvixStoreIO>")]
+mod import_builtins {
+    use std::rc::Rc;
+
+    use super::*;
+
+    use tvix_eval::generators::Gen;
+    use tvix_eval::{generators::GenCo, ErrorKind, Value};
+
+    use crate::tvix_store_io::TvixStoreIO;
+
+    #[builtin("filterSource")]
+    async fn builtin_filter_source(
+        state: Rc<TvixStoreIO>,
+        co: GenCo,
+        #[lazy] filter: Value,
+        path: Value,
+    ) -> Result<Value, ErrorKind> {
+        let p = path.to_path()?;
+        let root_node = filtered_ingest(state.clone(), co, &p, Some(&filter)).await?;
+        let name = tvix_store::import::path_to_name(&p)?;
+
+        Ok(state
+            .register_node_in_path_info_service_sync(name, &p, root_node)
+            .map_err(|err| ErrorKind::IO {
+                path: Some(p.to_path_buf()),
+                error: err.into(),
+            })?
+            .to_absolute_path()
+            .into())
+    }
+}
+
+pub use import_builtins::builtins as import_builtins;
+
+use crate::tvix_store_io::TvixStoreIO;