internal/lsp: skip packages load for auxilary go.mod changes

This change will skip packages.load calls when a go.mod file changes if that go.mod file is not the go.mod file associated with the view.

Change-Id: I23a214a89203dd58417f3e2f69725ce3b669a5ca
Reviewed-on: https://go-review.googlesource.com/c/tools/+/217238
Reviewed-by: Rebecca Stambler <rstambler@golang.org>
Run-TryBot: Rohan Challa <rohan@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>

internal/lsp/cache/snapshot.go

@@ -752,7 +752,8 @@ func (s *snapshot) shouldLoad(ctx context.Context, originalFH, currentFH source.
 	}
 	// If a go.mod file's contents have changed, always invalidate metadata.
 	if kind := originalFH.Identity().Kind; kind == source.Mod {
-		return true
+		modfile, _ := s.view.ModFiles()
+		return originalFH.Identity().URI == modfile
 	}
 	// Get the original and current parsed files in order to check package name and imports.
 	original, _, _, originalErr := s.view.session.cache.ParseGoHandle(originalFH, source.ParseHeader).Parse(ctx)

internal/lsp/text_synchronization.go

@@ -147,11 +147,15 @@ func (s *Server) didModifyFiles(ctx context.Context, modifications []source.File
 			if err != nil {
 				return nil, err
 			}
-			// If a modification comes in for a go.mod file,
-			// and the view was never properly initialized,
-			// try to recreate the associated view.
+			// If a modification comes in for the view's go.mod file and the view
+			// was never properly initialized, or the view does not have
+			// a go.mod file, try to recreate the associated view.
 			switch fh.Identity().Kind {
 			case source.Mod:
+				modfile, _ := snapshot.View().ModFiles()
+				if modfile != "" || fh.Identity().URI != modfile {
+					continue
+				}
 				newSnapshot, err := snapshot.View().Rebuild(ctx)
 				if err != nil {
 					return nil, err