internal/lsp/cache: only clone metadata if something changed

We with immutable metadata, we don't need to clone if nothing was invalidated. Benchmark (didChange in k8s): 65ms->45ms For golang/go#45686 Change-Id: I6b5e764c53a35784fd8c7b43bc26361f4ee8d928 Reviewed-on: https://go-review.googlesource.com/c/tools/+/340853 Run-TryBot: Robert Findley <[email protected]> Reviewed-by: Alan Donovan <[email protected]> gopls-CI: kokoro <[email protected]> TryBot-Result: Gopher Robot <[email protected]>
golang · Jun 16, 2022 · dffd645 · dffd645
1 parent 4ba3d22
commit dffd645
Showing 1 changed file with 9 additions and 2 deletions.
diff --git a/internal/lsp/cache/snapshot.go b/internal/lsp/cache/snapshot.go
@@ -2016,8 +2016,15 @@ func (s *snapshot) clone(ctx, bgCtx context.Context, changes map[span.URI]*fileC
 		}
 	}
 
-	result.meta = s.meta.Clone(metadataUpdates)
-	result.workspacePackages = computeWorkspacePackages(result.meta)
+	if len(metadataUpdates) > 0 {
+		result.meta = s.meta.Clone(metadataUpdates)
+		result.workspacePackages = computeWorkspacePackages(result.meta)
+	} else {
+		// No metadata changes. Since metadata is only updated by cloning, it is
+		// safe to re-use the existing metadata here.
+		result.meta = s.meta
+		result.workspacePackages = s.workspacePackages
+	}
 
 	// Inherit all of the go.mod-related handles.
 	for _, v := range result.modTidyHandles {