feat(tvix/store/pathinfosvc): provide listing r/6555

This provides an additional method in the PathInfoService trait, as
well as an RPC method on the gRPC layer to list all PathInfo objects in
a PathInfoService.

Change-Id: I7378f6bbd334bd6ac4e9be92505bd099a1c2b19a
Reviewed-on: https://cl.tvl.fyi/c/depot/+/9216
Reviewed-by: tazjin <tazjin@tvl.su>
Autosubmit: flokli <flokli@flokli.de>
Tested-by: BuildkiteCI

9 files changed, 310 insertions, 41 deletions

diff --git a/tvix/store/protos/rpc_pathinfo.pb.go b/tvix/store/protos/rpc_pathinfo.pb.go
index bc4da2a127f9..293cb5a7c321 100644
--- a/tvix/store/protos/rpc_pathinfo.pb.go
+++ b/tvix/store/protos/rpc_pathinfo.pb.go
@@ -96,6 +96,46 @@ type GetPathInfoRequest_ByOutputHash struct {
 
 func (*GetPathInfoRequest_ByOutputHash) isGetPathInfoRequest_ByWhat() {}
 
+// The parameters that can be used to lookup (multiple) PathInfo objects.
+// Currently no filtering is possible, all objects are returned.
+type ListPathInfoRequest struct {
+	state         protoimpl.MessageState
+	sizeCache     protoimpl.SizeCache
+	unknownFields protoimpl.UnknownFields
+}
+
+func (x *ListPathInfoRequest) Reset() {
+	*x = ListPathInfoRequest{}
+	if protoimpl.UnsafeEnabled {
+		mi := &file_tvix_store_protos_rpc_pathinfo_proto_msgTypes[1]
+		ms := protoimpl.X.MessageStateOf(protoimpl.Pointer(x))
+		ms.StoreMessageInfo(mi)
+	}
+}
+
+func (x *ListPathInfoRequest) String() string {
+	return protoimpl.X.MessageStringOf(x)
+}
+
+func (*ListPathInfoRequest) ProtoMessage() {}
+
+func (x *ListPathInfoRequest) ProtoReflect() protoreflect.Message {
+	mi := &file_tvix_store_protos_rpc_pathinfo_proto_msgTypes[1]
+	if protoimpl.UnsafeEnabled && x != nil {
+		ms := protoimpl.X.MessageStateOf(protoimpl.Pointer(x))
+		if ms.LoadMessageInfo() == nil {
+			ms.StoreMessageInfo(mi)
+		}
+		return ms
+	}
+	return mi.MessageOf(x)
+}
+
+// Deprecated: Use ListPathInfoRequest.ProtoReflect.Descriptor instead.
+func (*ListPathInfoRequest) Descriptor() ([]byte, []int) {
+	return file_tvix_store_protos_rpc_pathinfo_proto_rawDescGZIP(), []int{1}
+}
+
 // CalculateNARResponse is the response returned by the CalculateNAR request.
 //
 // It contains the size of the NAR representation (in bytes), and the sha56
@@ -114,7 +154,7 @@ type CalculateNARResponse struct {
 func (x *CalculateNARResponse) Reset() {
 	*x = CalculateNARResponse{}
 	if protoimpl.UnsafeEnabled {
-		mi := &file_tvix_store_protos_rpc_pathinfo_proto_msgTypes[1]
+		mi := &file_tvix_store_protos_rpc_pathinfo_proto_msgTypes[2]
 		ms := protoimpl.X.MessageStateOf(protoimpl.Pointer(x))
 		ms.StoreMessageInfo(mi)
 	}
@@ -127,7 +167,7 @@ func (x *CalculateNARResponse) String() string {
 func (*CalculateNARResponse) ProtoMessage() {}
 
 func (x *CalculateNARResponse) ProtoReflect() protoreflect.Message {
-	mi := &file_tvix_store_protos_rpc_pathinfo_proto_msgTypes[1]
+	mi := &file_tvix_store_protos_rpc_pathinfo_proto_msgTypes[2]
 	if protoimpl.UnsafeEnabled && x != nil {
 		ms := protoimpl.X.MessageStateOf(protoimpl.Pointer(x))
 		if ms.LoadMessageInfo() == nil {
@@ -140,7 +180,7 @@ func (x *CalculateNARResponse) ProtoReflect() protoreflect.Message {
 
 // Deprecated: Use CalculateNARResponse.ProtoReflect.Descriptor instead.
 func (*CalculateNARResponse) Descriptor() ([]byte, []int) {
-	return file_tvix_store_protos_rpc_pathinfo_proto_rawDescGZIP(), []int{1}
+	return file_tvix_store_protos_rpc_pathinfo_proto_rawDescGZIP(), []int{2}
 }
 
 func (x *CalculateNARResponse) GetNarSize() uint64 {
@@ -170,28 +210,34 @@ var file_tvix_store_protos_rpc_pathinfo_proto_rawDesc = []byte{
 	0x0e, 0x62, 0x79, 0x5f, 0x6f, 0x75, 0x74, 0x70, 0x75, 0x74, 0x5f, 0x68, 0x61, 0x73, 0x68, 0x18,
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 }
 
 var (
@@ -206,22 +252,25 @@ func file_tvix_store_protos_rpc_pathinfo_proto_rawDescGZIP() []byte {
 	return file_tvix_store_protos_rpc_pathinfo_proto_rawDescData
 }
 
-var file_tvix_store_protos_rpc_pathinfo_proto_msgTypes = make([]protoimpl.MessageInfo, 2)
+var file_tvix_store_protos_rpc_pathinfo_proto_msgTypes = make([]protoimpl.MessageInfo, 3)
 var file_tvix_store_protos_rpc_pathinfo_proto_goTypes = []interface{}{
 	(*GetPathInfoRequest)(nil),   // 0: tvix.store.v1.GetPathInfoRequest
-	(*CalculateNARResponse)(nil), // 1: tvix.store.v1.CalculateNARResponse
-	(*PathInfo)(nil),             // 2: tvix.store.v1.PathInfo
-	(*Node)(nil),                 // 3: tvix.store.v1.Node
+	(*ListPathInfoRequest)(nil),  // 1: tvix.store.v1.ListPathInfoRequest
+	(*CalculateNARResponse)(nil), // 2: tvix.store.v1.CalculateNARResponse
+	(*PathInfo)(nil),             // 3: tvix.store.v1.PathInfo
+	(*Node)(nil),                 // 4: tvix.store.v1.Node
 }
 var file_tvix_store_protos_rpc_pathinfo_proto_depIdxs = []int32{
 	0, // 0: tvix.store.v1.PathInfoService.Get:input_type -> tvix.store.v1.GetPathInfoRequest
-	2, // 1: tvix.store.v1.PathInfoService.Put:input_type -> tvix.store.v1.PathInfo
-	3, // 2: tvix.store.v1.PathInfoService.CalculateNAR:input_type -> tvix.store.v1.Node
-	2, // 3: tvix.store.v1.PathInfoService.Get:output_type -> tvix.store.v1.PathInfo
-	2, // 4: tvix.store.v1.PathInfoService.Put:output_type -> tvix.store.v1.PathInfo
-	1, // 5: tvix.store.v1.PathInfoService.CalculateNAR:output_type -> tvix.store.v1.CalculateNARResponse
-	3, // [3:6] is the sub-list for method output_type
-	0, // [0:3] is the sub-list for method input_type
+	3, // 1: tvix.store.v1.PathInfoService.Put:input_type -> tvix.store.v1.PathInfo
+	4, // 2: tvix.store.v1.PathInfoService.CalculateNAR:input_type -> tvix.store.v1.Node
+	1, // 3: tvix.store.v1.PathInfoService.List:input_type -> tvix.store.v1.ListPathInfoRequest
+	3, // 4: tvix.store.v1.PathInfoService.Get:output_type -> tvix.store.v1.PathInfo
+	3, // 5: tvix.store.v1.PathInfoService.Put:output_type -> tvix.store.v1.PathInfo
+	2, // 6: tvix.store.v1.PathInfoService.CalculateNAR:output_type -> tvix.store.v1.CalculateNARResponse
+	3, // 7: tvix.store.v1.PathInfoService.List:output_type -> tvix.store.v1.PathInfo
+	4, // [4:8] is the sub-list for method output_type
+	0, // [0:4] is the sub-list for method input_type
 	0, // [0:0] is the sub-list for extension type_name
 	0, // [0:0] is the sub-list for extension extendee
 	0, // [0:0] is the sub-list for field type_name
@@ -247,6 +296,18 @@ func file_tvix_store_protos_rpc_pathinfo_proto_init() {
 			}
 		}
 		file_tvix_store_protos_rpc_pathinfo_proto_msgTypes[1].Exporter = func(v interface{}, i int) interface{} {
+			switch v := v.(*ListPathInfoRequest); i {
+			case 0:
+				return &v.state
+			case 1:
+				return &v.sizeCache
+			case 2:
+				return &v.unknownFields
+			default:
+				return nil
+			}
+		}
+		file_tvix_store_protos_rpc_pathinfo_proto_msgTypes[2].Exporter = func(v interface{}, i int) interface{} {
 			switch v := v.(*CalculateNARResponse); i {
 			case 0:
 				return &v.state
@@ -268,7 +329,7 @@ func file_tvix_store_protos_rpc_pathinfo_proto_init() {
 			GoPackagePath: reflect.TypeOf(x{}).PkgPath(),
 			RawDescriptor: file_tvix_store_protos_rpc_pathinfo_proto_rawDesc,
 			NumEnums:      0,
-			NumMessages:   2,
+			NumMessages:   3,
 			NumExtensions: 0,
 			NumServices:   1,
 		},
diff --git a/tvix/store/protos/rpc_pathinfo.proto b/tvix/store/protos/rpc_pathinfo.proto
index fecf682d168d..e1d6cd774144 100644
--- a/tvix/store/protos/rpc_pathinfo.proto
+++ b/tvix/store/protos/rpc_pathinfo.proto
@@ -41,6 +41,10 @@ service PathInfoService {
     // It can also be used to calculate arbitrary NAR hashes of output paths,
     // in case a legacy Nix Binary Cache frontend is provided.
     rpc CalculateNAR(Node) returns (CalculateNARResponse);
+
+    // Return a stream of PathInfo messages matching the criteria specified in
+    // ListPathInfoRequest.
+    rpc List(ListPathInfoRequest) returns (stream PathInfo);
 }
 
 // The parameters that can be used to lookup a (single) PathInfo object.
@@ -55,6 +59,10 @@ message GetPathInfoRequest {
     };
 }
 
+// The parameters that can be used to lookup (multiple) PathInfo objects.
+// Currently no filtering is possible, all objects are returned.
+message ListPathInfoRequest { }
+
 // CalculateNARResponse is the response returned by the CalculateNAR request.
 //
 // It contains the size of the NAR representation (in bytes), and the sha56
diff --git a/tvix/store/protos/rpc_pathinfo_grpc.pb.go b/tvix/store/protos/rpc_pathinfo_grpc.pb.go
index bf83a9b7d98b..d7b6711c0310 100644
--- a/tvix/store/protos/rpc_pathinfo_grpc.pb.go
+++ b/tvix/store/protos/rpc_pathinfo_grpc.pb.go
@@ -25,6 +25,7 @@ const (
 	PathInfoService_Get_FullMethodName          = "/tvix.store.v1.PathInfoService/Get"
 	PathInfoService_Put_FullMethodName          = "/tvix.store.v1.PathInfoService/Put"
 	PathInfoService_CalculateNAR_FullMethodName = "/tvix.store.v1.PathInfoService/CalculateNAR"
+	PathInfoService_List_FullMethodName         = "/tvix.store.v1.PathInfoService/List"
 )
 
 // PathInfoServiceClient is the client API for PathInfoService service.
@@ -60,6 +61,9 @@ type PathInfoServiceClient interface {
 	// It can also be used to calculate arbitrary NAR hashes of output paths,
 	// in case a legacy Nix Binary Cache frontend is provided.
 	CalculateNAR(ctx context.Context, in *Node, opts ...grpc.CallOption) (*CalculateNARResponse, error)
+	// Return a stream of PathInfo messages matching the criteria specified in
+	// ListPathInfoRequest.
+	List(ctx context.Context, in *ListPathInfoRequest, opts ...grpc.CallOption) (PathInfoService_ListClient, error)
 }
 
 type pathInfoServiceClient struct {
@@ -97,6 +101,38 @@ func (c *pathInfoServiceClient) CalculateNAR(ctx context.Context, in *Node, opts
 	return out, nil
 }
 
+func (c *pathInfoServiceClient) List(ctx context.Context, in *ListPathInfoRequest, opts ...grpc.CallOption) (PathInfoService_ListClient, error) {
+	stream, err := c.cc.NewStream(ctx, &PathInfoService_ServiceDesc.Streams[0], PathInfoService_List_FullMethodName, opts...)
+	if err != nil {
+		return nil, err
+	}
+	x := &pathInfoServiceListClient{stream}
+	if err := x.ClientStream.SendMsg(in); err != nil {
+		return nil, err
+	}
+	if err := x.ClientStream.CloseSend(); err != nil {
+		return nil, err
+	}
+	return x, nil
+}
+
+type PathInfoService_ListClient interface {
+	Recv() (*PathInfo, error)
+	grpc.ClientStream
+}
+
+type pathInfoServiceListClient struct {
+	grpc.ClientStream
+}
+
+func (x *pathInfoServiceListClient) Recv() (*PathInfo, error) {
+	m := new(PathInfo)
+	if err := x.ClientStream.RecvMsg(m); err != nil {
+		return nil, err
+	}
+	return m, nil
+}
+
 // PathInfoServiceServer is the server API for PathInfoService service.
 // All implementations must embed UnimplementedPathInfoServiceServer
 // for forward compatibility
@@ -130,6 +166,9 @@ type PathInfoServiceServer interface {
 	// It can also be used to calculate arbitrary NAR hashes of output paths,
 	// in case a legacy Nix Binary Cache frontend is provided.
 	CalculateNAR(context.Context, *Node) (*CalculateNARResponse, error)
+	// Return a stream of PathInfo messages matching the criteria specified in
+	// ListPathInfoRequest.
+	List(*ListPathInfoRequest, PathInfoService_ListServer) error
 	mustEmbedUnimplementedPathInfoServiceServer()
 }
 
@@ -146,6 +185,9 @@ func (UnimplementedPathInfoServiceServer) Put(context.Context, *PathInfo) (*Path
 func (UnimplementedPathInfoServiceServer) CalculateNAR(context.Context, *Node) (*CalculateNARResponse, error) {
 	return nil, status.Errorf(codes.Unimplemented, "method CalculateNAR not implemented")
 }
+func (UnimplementedPathInfoServiceServer) List(*ListPathInfoRequest, PathInfoService_ListServer) error {
+	return status.Errorf(codes.Unimplemented, "method List not implemented")
+}
 func (UnimplementedPathInfoServiceServer) mustEmbedUnimplementedPathInfoServiceServer() {}
 
 // UnsafePathInfoServiceServer may be embedded to opt out of forward compatibility for this service.
@@ -213,6 +255,27 @@ func _PathInfoService_CalculateNAR_Handler(srv interface{}, ctx context.Context,
 	return interceptor(ctx, in, info, handler)
 }
 
+func _PathInfoService_List_Handler(srv interface{}, stream grpc.ServerStream) error {
+	m := new(ListPathInfoRequest)
+	if err := stream.RecvMsg(m); err != nil {
+		return err
+	}
+	return srv.(PathInfoServiceServer).List(m, &pathInfoServiceListServer{stream})
+}
+
+type PathInfoService_ListServer interface {
+	Send(*PathInfo) error
+	grpc.ServerStream
+}
+
+type pathInfoServiceListServer struct {
+	grpc.ServerStream
+}
+
+func (x *pathInfoServiceListServer) Send(m *PathInfo) error {
+	return x.ServerStream.SendMsg(m)
+}
+
 // PathInfoService_ServiceDesc is the grpc.ServiceDesc for PathInfoService service.
 // It's only intended for direct use with grpc.RegisterService,
 // and not to be introspected or modified (even as a copy)
@@ -233,6 +296,12 @@ var PathInfoService_ServiceDesc = grpc.ServiceDesc{
 			Handler:    _PathInfoService_CalculateNAR_Handler,
 		},
 	},
-	Streams:  []grpc.StreamDesc{},
+	Streams: []grpc.StreamDesc{
+		{
+			StreamName:    "List",
+			Handler:       _PathInfoService_List_Handler,
+			ServerStreams: true,
+		},
+	},
 	Metadata: "tvix/store/protos/rpc_pathinfo.proto",
 }
diff --git a/tvix/store/src/pathinfoservice/grpc.rs b/tvix/store/src/pathinfoservice/grpc.rs
index c98a89c4b8e7..2bd766697bd1 100644
--- a/tvix/store/src/pathinfoservice/grpc.rs
+++ b/tvix/store/src/pathinfoservice/grpc.rs
@@ -1,8 +1,12 @@
 use super::PathInfoService;
-use crate::{blobservice::BlobService, directoryservice::DirectoryService, proto};
+use crate::{
+    blobservice::BlobService,
+    directoryservice::DirectoryService,
+    proto::{self, ListPathInfoRequest},
+};
 use std::sync::Arc;
 use tokio::net::UnixStream;
-use tonic::{transport::Channel, Code, Status};
+use tonic::{transport::Channel, Code, Status, Streaming};
 
 /// Connects to a (remote) tvix-store PathInfoService over gRPC.
 #[derive(Clone)]
@@ -160,6 +164,62 @@ impl PathInfoService for GRPCPathInfoService {
 
         Ok((resp.nar_size, nar_sha256))
     }
+
+    fn list(&self) -> Box<dyn Iterator<Item = Result<proto::PathInfo, crate::Error>> + Send> {
+        // Get a new handle to the gRPC client.
+        let mut grpc_client = self.grpc_client.clone();
+
+        let task: tokio::task::JoinHandle<Result<_, Status>> =
+            self.tokio_handle.spawn(async move {
+                let s = grpc_client
+                    .list(ListPathInfoRequest::default())
+                    .await?
+                    .into_inner();
+
+                Ok(s)
+            });
+
+        let stream = self.tokio_handle.block_on(task).unwrap().unwrap();
+
+        Box::new(StreamIterator::new(self.tokio_handle.clone(), stream))
+    }
+}
+
+pub struct StreamIterator {
+    tokio_handle: tokio::runtime::Handle,
+    stream: Streaming<proto::PathInfo>,
+}
+
+impl StreamIterator {
+    pub fn new(tokio_handle: tokio::runtime::Handle, stream: Streaming<proto::PathInfo>) -> Self {
+        Self {
+            tokio_handle,
+            stream,
+        }
+    }
+}
+
+impl Iterator for StreamIterator {
+    type Item = Result<proto::PathInfo, crate::Error>;
+
+    fn next(&mut self) -> Option<Self::Item> {
+        match self.tokio_handle.block_on(self.stream.message()) {
+            Ok(o) => match o {
+                Some(pathinfo) => {
+                    // validate the pathinfo
+                    if let Err(e) = pathinfo.validate() {
+                        return Some(Err(crate::Error::StorageError(format!(
+                            "pathinfo {:?} failed validation: {}",
+                            pathinfo, e
+                        ))));
+                    }
+                    Some(Ok(pathinfo))
+                }
+                None => None,
+            },
+            Err(e) => Some(Err(crate::Error::StorageError(e.to_string()))),
+        }
+    }
 }
 
 #[cfg(test)]
diff --git a/tvix/store/src/pathinfoservice/memory.rs b/tvix/store/src/pathinfoservice/memory.rs
index f7abb2180ef7..aba1216c6e96 100644
--- a/tvix/store/src/pathinfoservice/memory.rs
+++ b/tvix/store/src/pathinfoservice/memory.rs
@@ -85,6 +85,18 @@ impl PathInfoService for MemoryPathInfoService {
         )
         .map_err(|e| Error::StorageError(e.to_string()))
     }
+
+    fn list(&self) -> Box<dyn Iterator<Item = Result<proto::PathInfo, Error>> + Send + '_> {
+        let db = self.db.read().unwrap();
+
+        // Copy all elements into a list.
+        // This is a bit ugly, because we can't have db escape the lifetime
+        // of this function, but elements need to be returned owned anyways, and this in-
+        // memory impl is only for testing purposes anyways.
+        let items: Vec<_> = db.iter().map(|(_k, v)| Ok(v.clone())).collect();
+
+        Box::new(items.into_iter())
+    }
 }
 
 #[cfg(test)]
diff --git a/tvix/store/src/pathinfoservice/mod.rs b/tvix/store/src/pathinfoservice/mod.rs
index 191e8dbd602e..51d3e51115eb 100644
--- a/tvix/store/src/pathinfoservice/mod.rs
+++ b/tvix/store/src/pathinfoservice/mod.rs
@@ -39,4 +39,8 @@ pub trait PathInfoService: Send + Sync {
     /// This can be used to calculate NAR-based output paths,
     /// and implementations are encouraged to cache it.
     fn calculate_nar(&self, root_node: &proto::node::Node) -> Result<(u64, [u8; 32]), Error>;
+
+    /// Iterate over all PathInfo objects in the store.
+    /// Implementations can decide to disallow listing.
+    fn list(&self) -> Box<dyn Iterator<Item = Result<proto::PathInfo, Error>> + Send + '_>;
 }
diff --git a/tvix/store/src/pathinfoservice/sled.rs b/tvix/store/src/pathinfoservice/sled.rs
index 2448b073c622..4f327626d19d 100644
--- a/tvix/store/src/pathinfoservice/sled.rs
+++ b/tvix/store/src/pathinfoservice/sled.rs
@@ -136,6 +136,31 @@ impl PathInfoService for SledPathInfoService {
         )
         .map_err(|e| Error::StorageError(e.to_string()))
     }
+
+    fn list(&self) -> Box<dyn Iterator<Item = Result<proto::PathInfo, Error>> + Send> {
+        Box::new(self.db.iter().values().map(|v| match v {
+            Ok(data) => {
+                // we retrieved some bytes
+                match proto::PathInfo::decode(&*data) {
+                    Ok(path_info) => Ok(path_info),
+                    Err(e) => {
+                        warn!("failed to decode stored PathInfo: {}", e);
+                        Err(Error::StorageError(format!(
+                            "failed to decode stored PathInfo: {}",
+                            e
+                        )))
+                    }
+                }
+            }
+            Err(e) => {
+                warn!("failed to retrieve PathInfo: {}", e);
+                Err(Error::StorageError(format!(
+                    "failed to retrieve PathInfo: {}",
+                    e
+                )))
+            }
+        }))
+    }
 }
 
 #[cfg(test)]
diff --git a/tvix/store/src/proto/grpc_pathinfoservice_wrapper.rs b/tvix/store/src/proto/grpc_pathinfoservice_wrapper.rs
index bbf235f8ace9..16a2fd51d0df 100644
--- a/tvix/store/src/proto/grpc_pathinfoservice_wrapper.rs
+++ b/tvix/store/src/proto/grpc_pathinfoservice_wrapper.rs
@@ -2,11 +2,14 @@ use crate::nar::RenderError;
 use crate::pathinfoservice::PathInfoService;
 use crate::proto;
 use std::sync::Arc;
+use tokio::task;
+use tokio_stream::wrappers::ReceiverStream;
 use tonic::{async_trait, Request, Response, Result, Status};
-use tracing::{instrument, warn};
+use tracing::{debug, instrument, warn};
 
 pub struct GRPCPathInfoServiceWrapper {
     path_info_service: Arc<dyn PathInfoService>,
+    // FUTUREWORK: allow exposing without allowing listing
 }
 
 impl From<Arc<dyn PathInfoService>> for GRPCPathInfoServiceWrapper {
@@ -19,6 +22,8 @@ impl From<Arc<dyn PathInfoService>> for GRPCPathInfoServiceWrapper {
 
 #[async_trait]
 impl proto::path_info_service_server::PathInfoService for GRPCPathInfoServiceWrapper {
+    type ListStream = ReceiverStream<tonic::Result<proto::PathInfo, Status>>;
+
     #[instrument(skip(self))]
     async fn get(
         &self,
@@ -78,6 +83,29 @@ impl proto::path_info_service_server::PathInfoService for GRPCPathInfoServiceWra
             }
         }
     }
+
+    #[instrument(skip(self))]
+    async fn list(
+        &self,
+        _request: Request<proto::ListPathInfoRequest>,
+    ) -> Result<Response<Self::ListStream>, Status> {
+        let (tx, rx) = tokio::sync::mpsc::channel(5);
+
+        let path_info_service = self.path_info_service.clone();
+
+        let _task = task::spawn(async move {
+            for e in path_info_service.list() {
+                let res = e.map_err(|e| Status::internal(e.to_string()));
+                if tx.send(res).await.is_err() {
+                    debug!("receiver dropped");
+                    break;
+                }
+            }
+        });
+
+        let receiver_stream = ReceiverStream::new(rx);
+        Ok(Response::new(receiver_stream))
+    }
 }
 
 impl From<RenderError> for tonic::Status {
diff --git a/tvix/store/src/proto/tests/grpc_pathinfoservice.rs b/tvix/store/src/proto/tests/grpc_pathinfoservice.rs
index 95d97bb12890..114e89cacc10 100644
--- a/tvix/store/src/proto/tests/grpc_pathinfoservice.rs
+++ b/tvix/store/src/proto/tests/grpc_pathinfoservice.rs
@@ -9,6 +9,7 @@ use crate::tests::utils::gen_blob_service;
 use crate::tests::utils::gen_directory_service;
 use crate::tests::utils::gen_pathinfo_service;
 use std::sync::Arc;
+use tokio_stream::wrappers::ReceiverStream;
 use tonic::Request;
 
 /// generates a GRPCPathInfoService out of blob, directory and pathinfo services.
@@ -16,7 +17,8 @@ use tonic::Request;
 /// We only interact with it via the PathInfo GRPC interface.
 /// It uses the NonCachingNARCalculationService NARCalculationService to
 /// calculate NARs.
-fn gen_grpc_service() -> Arc<dyn GRPCPathInfoService> {
+fn gen_grpc_service(
+) -> Arc<dyn GRPCPathInfoService<ListStream = ReceiverStream<Result<PathInfo, tonic::Status>>>> {
     let blob_service = gen_blob_service();
     let directory_service = gen_directory_service();
     Arc::new(GRPCPathInfoServiceWrapper::from(gen_pathinfo_service(