feat(tvix/store/utils): detect gRPC NAR calculation service

We were currently always using SimpleRenderer, which would mean the
client would download every blob locally to calculate the checksum,
which of course is very slow.

Detect this special case and create a second instance (and client) for
now.

Change-Id: If39a862a5311e71c8073ac4e663f6c5dd437072e
Reviewed-on: https://cl.tvl.fyi/c/depot/+/11848
Reviewed-by: Simon Hauser <simon.hauser@helsinki-systems.de>
Tested-by: BuildkiteCI

tvix/store/src/utils.rs

@@ -9,6 +9,7 @@ use tvix_castore::{
     blobservice::{self, BlobService},
     directoryservice::{self, DirectoryService},
 };
+use url::Url;
 
 use crate::nar::{NarCalculationService, SimpleRenderer};
 use crate::pathinfoservice::{self, PathInfoService};
@@ -31,6 +32,7 @@ pub async fn construct_services(
         directoryservice::from_addr(directory_service_addr.as_ref())
             .await?
             .into();
+
     let path_info_service = pathinfoservice::from_addr(
         path_info_service_addr.as_ref(),
         blob_service.clone(),
@@ -38,11 +40,30 @@ pub async fn construct_services(
     )
     .await?;
 
-    // TODO: grpc client also implements NarCalculationService
+    // HACK: The grpc client also implements NarCalculationService, and we
-    let nar_calculation_service = Box::new(SimpleRenderer::new(
+    // really want to use it (otherwise we'd need to fetch everything again for hashing).
-        blob_service.clone(),
+    // Until we revamped store composition and config, detect this special case here.
-        directory_service.clone(),
+    let nar_calculation_service: Box<dyn NarCalculationService> = {
-    )) as Box<dyn NarCalculationService>;
+        use crate::pathinfoservice::GRPCPathInfoService;
+        use crate::proto::path_info_service_client::PathInfoServiceClient;
+
+        let url = Url::parse(path_info_service_addr.as_ref())
+            .map_err(|e| io::Error::other(e.to_string()))?;
+
+        if url.scheme().starts_with("grpc+") {
+            let client = PathInfoServiceClient::new(
+                tvix_castore::tonic::channel_from_url(&url)
+                    .await
+                    .map_err(|e| io::Error::other(e.to_string()))?,
+            );
+            Box::new(GRPCPathInfoService::from_client(client))
+        } else {
+            Box::new(SimpleRenderer::new(
+                blob_service.clone(),
+                directory_service.clone(),
+            )) as Box<dyn NarCalculationService>
+        }
+    };
 
     Ok((
         blob_service,