1 files changed, 37 insertions, 0 deletions
diff --git a/tvix/store/src/nar/non_caching_calculation_service.rs b/tvix/store/src/nar/non_caching_calculation_service.rs
new file mode 100644
index 000000000000..8a080cb4df5e
--- /dev/null
+++ b/tvix/store/src/nar/non_caching_calculation_service.rs
@@ -0,0 +1,37 @@
+use count_write::CountWrite;
+use sha2::{Digest, Sha256};
+
+use crate::blobservice::BlobService;
+use crate::directoryservice::DirectoryService;
+use crate::proto;
+
+use super::renderer::NARRenderer;
+use super::{NARCalculationService, RenderError};
+
+/// A NAR calculation service which simply renders the whole NAR whenever
+/// we ask for the calculation.
+#[derive(Clone)]
+pub struct NonCachingNARCalculationService<BS: BlobService, DS: DirectoryService> {
+    nar_renderer: NARRenderer<BS, DS>,
+}
+
+impl<BS: BlobService, DS: DirectoryService> NonCachingNARCalculationService<BS, DS> {
+    pub fn new(blob_service: BS, directory_service: DS) -> Self {
+        Self {
+            nar_renderer: NARRenderer::new(blob_service, directory_service),
+        }
+    }
+}
+
+impl<BS: BlobService, DS: DirectoryService> NARCalculationService
+    for NonCachingNARCalculationService<BS, DS>
+{
+    fn calculate_nar(&self, root_node: &proto::node::Node) -> Result<(u64, [u8; 32]), RenderError> {
+        let h = Sha256::new();
+        let mut cw = CountWrite::from(h);
+
+        self.nar_renderer.write_nar(&mut cw, root_node)?;
+
+        Ok((cw.count(), cw.into_inner().finalize().into()))
+    }
+}