internal/lsp/cache: improve ModTidyHandle cache key

This change alters the key that is used to cache go.mod diagnostic changes, in particular it replaces using the snapshot ID with a string of all the imports used in the module and the hashed contents of the go.mod file. This reduces the number of times that we run "go mod tidy" to only when we detect import changes or the go.mod file is changed.

Change-Id: Icf49db34f44a4ae4772fff6dfb8b9a6955a8e2d6
Reviewed-on: https://go-review.googlesource.com/c/tools/+/218238
Reviewed-by: Rebecca Stambler <rstambler@golang.org>
Run-TryBot: Rebecca Stambler <rstambler@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>

internal/lsp/cache/check.go

@@ -13,6 +13,7 @@ import (
 	"go/types"
 	"path"
 	"sort"
+	"strings"
 	"sync"
 
 	"golang.org/x/tools/go/packages"
@@ -209,6 +210,28 @@ func (ph *packageHandle) MissingDependencies() []string {
 	return md
 }
 
+func hashImports(ctx context.Context, wsPackages []source.PackageHandle) (string, error) {
+	results := make(map[string]bool)
+	var imports []string
+	for _, ph := range wsPackages {
+		// Check package since we do not always invalidate the metadata.
+		pkg, err := ph.Check(ctx)
+		if err != nil {
+			return "", err
+		}
+		for _, path := range pkg.Imports() {
+			imp := path.PkgPath()
+			if _, ok := results[imp]; !ok {
+				results[imp] = true
+				imports = append(imports, imp)
+			}
+		}
+	}
+	sort.Strings(imports)
+	hashed := strings.Join(imports, ",")
+	return hashContents([]byte(hashed)), nil
+}
+
 func (ph *packageHandle) Cached() (source.Package, error) {
 	return ph.cached()
 }

internal/lsp/cache/mod_tidy.go

@@ -29,9 +29,10 @@ const ModTidyError = "go mod tidy"
 const SyntaxError = "syntax"
 
 type parseModKey struct {
-	view       string
-	snapshotID uint64
-	cfg        string
+	view    string
+	imports string
+	gomod   string
+	cfg     string
 }
 
 type modTidyHandle struct {
@@ -90,16 +91,28 @@ func (mth *modTidyHandle) Tidy(ctx context.Context) (*modfile.File, *protocol.Co
 	return data.origParsedFile, data.origMapper, data.missingDeps, data.parseErrors, data.err
 }
 
-func (s *snapshot) ModTidyHandle(ctx context.Context, realfh source.FileHandle) source.ModTidyHandle {
+func (s *snapshot) ModTidyHandle(ctx context.Context, realfh source.FileHandle) (source.ModTidyHandle, error) {
 	realURI, tempURI := s.view.ModFiles()
 	cfg := s.View().Config(ctx)
 	options := s.View().Options()
 	folder := s.View().Folder().Filename()
 
+	wsPackages, err := s.WorkspacePackages(ctx)
+	if ctx.Err() != nil {
+		return nil, ctx.Err()
+	}
+	if err != nil {
+		return nil, err
+	}
+	imports, err := hashImports(ctx, wsPackages)
+	if err != nil {
+		return nil, err
+	}
 	key := parseModKey{
-		view:       folder,
-		snapshotID: s.ID(),
-		cfg:        hashConfig(cfg),
+		view:    folder,
+		imports: imports,
+		gomod:   realfh.Identity().Identifier,
+		cfg:     hashConfig(cfg),
 	}
 	h := s.view.session.cache.store.Bind(key, func(ctx context.Context) interface{} {
 		data := &modTidyData{}
@@ -194,7 +207,7 @@ func (s *snapshot) ModTidyHandle(ctx context.Context, realfh source.FileHandle)
 		handle: h,
 		file:   realfh,
 		cfg:    cfg,
-	}
+	}, nil
 }
 
 // extractModParseErrors processes the raw errors returned by modfile.Parse,

internal/lsp/mod/diagnostics.go

@@ -35,7 +35,11 @@ func Diagnostics(ctx context.Context, snapshot source.Snapshot) (map[source.File
 	if err != nil {
 		return nil, nil, err
 	}
-	_, _, missingDeps, parseErrors, err := snapshot.ModTidyHandle(ctx, realfh).Tidy(ctx)
+	mth, err := snapshot.ModTidyHandle(ctx, realfh)
+	if err != nil {
+		return nil, nil, err
+	}
+	_, _, missingDeps, parseErrors, err := mth.Tidy(ctx)
 	if err != nil {
 		return nil, nil, err
 	}
@@ -61,7 +65,11 @@ func Diagnostics(ctx context.Context, snapshot source.Snapshot) (map[source.File
 }
 
 func SuggestedFixes(ctx context.Context, snapshot source.Snapshot, realfh source.FileHandle, diags []protocol.Diagnostic) []protocol.CodeAction {
-	_, _, _, parseErrors, err := snapshot.ModTidyHandle(ctx, realfh).Tidy(ctx)
+	mth, err := snapshot.ModTidyHandle(ctx, realfh)
+	if err != nil {
+		return nil
+	}
+	_, _, _, parseErrors, err := mth.Tidy(ctx)
 	if err != nil {
 		return nil
 	}
@@ -126,7 +134,11 @@ func SuggestedGoFixes(ctx context.Context, snapshot source.Snapshot, gofh source
 	if err != nil {
 		return nil, err
 	}
-	realFile, realMapper, missingDeps, _, err := snapshot.ModTidyHandle(ctx, realfh).Tidy(ctx)
+	mth, err := snapshot.ModTidyHandle(ctx, realfh)
+	if err != nil {
+		return nil, err
+	}
+	realFile, realMapper, missingDeps, _, err := mth.Tidy(ctx)
 	if err != nil {
 		return nil, err
 	}

internal/lsp/source/view.go

@@ -39,7 +39,7 @@ type Snapshot interface {
 
 	// ModTidyHandle returns a ModTidyHandle for the given go.mod file handle.
 	// This function can have no data or error if there is no modfile detected.
-	ModTidyHandle(ctx context.Context, fh FileHandle) ModTidyHandle
+	ModTidyHandle(ctx context.Context, fh FileHandle) (ModTidyHandle, error)
 
 	// PackageHandles returns the PackageHandles for the packages that this file
 	// belongs to.