refactor(tvix/nar-bridge): have Export return root node r/6780

… and nar size / sha256 digest.

Instead of producing sparse PathInfo messages when NARs are sent to
nar-bridge, the nar-bridge http server now keeps a lookup table
(narsha256) -> (rootNode, narSize)

This removes a whole bunch of noise, because we don't need to keep
sparse fields around.

A convenience function
`GenPathInfo(rootNode *castorev1pb.Node, narInfo *narinfo.NarInfo)` is
added, which is used to produce PathInfo messages, either when receiving
a NAR file over http and uploading it to a remote PathInfoService, or to
synthesize the PathInfoMessage to return to the client, if nar-bridge is
acting as a PathInfoService for a remove Nix HTTP Binary cache.

Change-Id: Ibba1ab6238a050816c4fab29cb21ae88877d8613
Reviewed-on: https://cl.tvl.fyi/c/depot/+/9651
Tested-by: BuildkiteCI
Reviewed-by: Brian McGee <brian@bmcgee.ie>

1 files changed, 10 insertions, 4 deletions

diff --git a/tvix/nar-bridge/pkg/http/server.go b/tvix/nar-bridge/pkg/http/server.go
index e8eb229ab41a..aa8037e2ba38 100644
--- a/tvix/nar-bridge/pkg/http/server.go
+++ b/tvix/nar-bridge/pkg/http/server.go
@@ -25,11 +25,17 @@ type Server struct {
 	// When uploading NAR files to a HTTP binary cache, the .nar
 	// files are uploaded before the .narinfo files.
 	// We need *both* to be able to fully construct a PathInfo object.
-	// Keep a in-memory map of narhash(es) (in SRI) to sparse PathInfo.
+	// Keep a in-memory map of narhash(es) (in SRI) to (unnamed) root node and nar
+	// size.
 	// This is necessary until we can ask a PathInfoService for a node with a given
 	// narSha256.
-	narHashToPathInfoMu sync.Mutex
-	narHashToPathInfo   map[string]*storev1pb.PathInfo
+	narDbMu sync.Mutex
+	narDb   map[string]*narData
+}
+
+type narData struct {
+	rootNode *castorev1pb.Node
+	narSize  uint64
 }
 
 func New(
@@ -64,7 +70,7 @@ func New(
 		directoryServiceClient: directoryServiceClient,
 		blobServiceClient:      blobServiceClient,
 		pathInfoServiceClient:  pathInfoServiceClient,
-		narHashToPathInfo:      make(map[string]*storev1pb.PathInfo),
+		narDb:                  make(map[string]*narData),
 	}
 
 	registerNarPut(s)