serve service: Respond with digest for blob and tree checks

...to be able to interrogate remotes irrespective of protocol.

When serve endpoint is active, it will provide the correct digest
with which to interrogate the remote endpoint. Otherwise, for a
compatible remote check the file mappings for the correct digest.

The serve service proto file is updated accordingly.

1 files changed, 43 insertions, 9 deletions

diff --git a/src/buildtool/serve_api/serve_service/source_tree.cpp b/src/buildtool/serve_api/serve_service/source_tree.cpp
index a6514c46..0e629d8d 100644
--- a/src/buildtool/serve_api/serve_service/source_tree.cpp
+++ b/src/buildtool/serve_api/serve_service/source_tree.cpp
@@ -1339,6 +1339,17 @@ auto SourceTreeService::ServeContent(
     const ::justbuild::just_serve::ServeContentRequest* request,
     ServeContentResponse* response) -> ::grpc::Status {
     auto const& content{request->content()};
+    auto const digest = ArtifactDigestFactory::Create(
+        native_context_->storage_config->hash_function.GetType(),
+        content,
+        /*size is unknown*/ 0,
+        /*is_tree=*/false);
+    if (not digest) {
+        logger_->Emit(LogLevel::Error, "Failed to create digest object");
+        response->set_status(ServeContentResponse::INTERNAL_ERROR);
+        return ::grpc::Status::OK;
+    }
+
     // acquire locks
     auto repo_lock = RepositoryGarbageCollector::SharedLock(
         *native_context_->storage_config);
@@ -1362,6 +1373,10 @@ auto SourceTreeService::ServeContent(
         auto const status =
             SyncGitEntryToCas<ObjectType::File, ServeContentResponse>(
                 content, native_context_->storage_config->GitRoot());
+        if (status == ServeContentResponse::OK) {
+            *(response->mutable_digest()) =
+                ArtifactDigestFactory::ToBazel(*digest);
+        }
         response->set_status(status);
         return ::grpc::Status::OK;
     }
@@ -1381,6 +1396,10 @@ auto SourceTreeService::ServeContent(
             auto const status =
                 SyncGitEntryToCas<ObjectType::File, ServeContentResponse>(
                     content, path);
+            if (status == ServeContentResponse::OK) {
+                *(response->mutable_digest()) =
+                    ArtifactDigestFactory::ToBazel(*digest);
+            }
             response->set_status(status);
             return ::grpc::Status::OK;
         }
@@ -1396,11 +1415,6 @@ auto SourceTreeService::ServeContent(
     }
 
     // check also in the local CAS
-    auto const digest = ArtifactDigestFactory::Create(
-        native_context_->storage_config->hash_function.GetType(),
-        content,
-        0,
-        /*is_tree=*/false);
     if (digest and apis_.local->IsAvailable(*digest)) {
         if (not apis_.local->RetrieveToCas(
                 {Artifact::ObjectInfo{.digest = *digest,
@@ -1413,6 +1427,7 @@ auto SourceTreeService::ServeContent(
             return ::grpc::Status::OK;
         }
         // success!
+        *(response->mutable_digest()) = ArtifactDigestFactory::ToBazel(*digest);
         response->set_status(ServeContentResponse::OK);
         return ::grpc::Status::OK;
     }
@@ -1426,6 +1441,18 @@ auto SourceTreeService::ServeTree(
     const ::justbuild::just_serve::ServeTreeRequest* request,
     ServeTreeResponse* response) -> ::grpc::Status {
     auto const& tree_id{request->tree()};
+    auto const hash_type =
+        native_context_->storage_config->hash_function.GetType();
+    auto const digest = ArtifactDigestFactory::Create(hash_type,
+                                                      tree_id,
+                                                      /*size is unknown*/ 0,
+                                                      /*is_tree=*/true);
+    if (not digest) {
+        logger_->Emit(LogLevel::Error, "Failed to create digest object");
+        response->set_status(ServeTreeResponse::INTERNAL_ERROR);
+        return ::grpc::Status::OK;
+    }
+
     // acquire locks
     auto repo_lock = RepositoryGarbageCollector::SharedLock(
         *native_context_->storage_config);
@@ -1454,9 +1481,14 @@ auto SourceTreeService::ServeTree(
         return ::grpc::Status::OK;
     }
     if (*has_tree) {
+        // upload tree to remote CAS
         auto const status =
             SyncGitEntryToCas<ObjectType::Tree, ServeTreeResponse>(
                 tree_id, native_context_->storage_config->GitRoot());
+        if (status == ServeTreeResponse::OK) {
+            *(response->mutable_digest()) =
+                ArtifactDigestFactory::ToBazel(*digest);
+        }
         response->set_status(status);
         return ::grpc::Status::OK;
     }
@@ -1472,18 +1504,19 @@ auto SourceTreeService::ServeTree(
             return ::grpc::Status::OK;
         }
         if (*has_tree) {
+            // upload blob to remote CAS
             auto const status =
                 SyncGitEntryToCas<ObjectType::Tree, ServeTreeResponse>(tree_id,
                                                                        path);
+            if (status == ServeTreeResponse::OK) {
+                *(response->mutable_digest()) =
+                    ArtifactDigestFactory::ToBazel(*digest);
+            }
             response->set_status(status);
             return ::grpc::Status::OK;
         }
     }
     // check also in the local CAS
-    auto const hash_type =
-        native_context_->storage_config->hash_function.GetType();
-    auto const digest =
-        ArtifactDigestFactory::Create(hash_type, tree_id, 0, /*is_tree=*/true);
     if (digest and apis_.local->IsAvailable(*digest)) {
         // upload tree to remote CAS; only possible in native mode
         if (not ProtocolTraits::IsNative(hash_type)) {
@@ -1505,6 +1538,7 @@ auto SourceTreeService::ServeTree(
             return ::grpc::Status::OK;
         }
         // success!
+        *(response->mutable_digest()) = ArtifactDigestFactory::ToBazel(*digest);
         response->set_status(ServeTreeResponse::OK);
         return ::grpc::Status::OK;
     }