diff --git a/internal/lsp/cache/check.go b/internal/lsp/cache/check.go
index 2f8020869a..46ade5cbfc 100644
--- a/internal/lsp/cache/check.go
+++ b/internal/lsp/cache/check.go
@@ -23,9 +23,9 @@ import (
 )
 
 type importer struct {
-	view   *view
-	ctx    context.Context
-	config *packages.Config
+	snapshot *snapshot
+	ctx      context.Context
+	config   *packages.Config
 
 	// seen maintains the set of previously imported packages.
 	// If we have seen a package that is already in this map, we have a circular import.
@@ -62,7 +62,7 @@ type checkPackageHandle struct {
 	config *packages.Config
 }
 
-func (cph *checkPackageHandle) mode() source.ParseMode {
+func (cph *checkPackageHandle) Mode() source.ParseMode {
 	if len(cph.files) == 0 {
 		return -1
 	}
@@ -83,19 +83,15 @@ type checkPackageData struct {
 	err error
 }
 
-func (pkg *pkg) GetImport(ctx context.Context, pkgPath string) (source.Package, error) {
-	if imp := pkg.imports[packagePath(pkgPath)]; imp != nil {
-		return imp, nil
-	}
-	// Don't return a nil pointer because that still satisfies the interface.
-	return nil, errors.Errorf("no imported package for %s", pkgPath)
-}
-
 // checkPackageHandle returns a source.CheckPackageHandle for a given package and config.
-func (imp *importer) checkPackageHandle(ctx context.Context, m *metadata) (*checkPackageHandle, error) {
+func (imp *importer) checkPackageHandle(ctx context.Context, id packageID, s *snapshot) (*checkPackageHandle, error) {
+	m := s.getMetadata(id)
+	if m == nil {
+		return nil, errors.Errorf("no metadata for %s", id)
+	}
 	phs, err := imp.parseGoHandles(ctx, m)
 	if err != nil {
-		log.Error(ctx, "no ParseGoHandles", err, telemetry.Package.Of(m.id))
+		log.Error(ctx, "no ParseGoHandles", err, telemetry.Package.Of(id))
 		return nil, err
 	}
 	cph := &checkPackageHandle{
@@ -104,12 +100,19 @@ func (imp *importer) checkPackageHandle(ctx context.Context, m *metadata) (*chec
 		config:  imp.config,
 		imports: make(map[packagePath]*checkPackageHandle),
 	}
-	h := imp.view.session.cache.store.Bind(cph.key(), func(ctx context.Context) interface{} {
+	h := imp.snapshot.view.session.cache.store.Bind(cph.key(), func(ctx context.Context) interface{} {
 		data := &checkPackageData{}
 		data.pkg, data.err = imp.typeCheck(ctx, cph, m)
 		return data
 	})
+
 	cph.handle = h
+
+	// Cache the CheckPackageHandle in the snapshot.
+	for _, ph := range cph.files {
+		uri := ph.File().Identity().URI
+		s.addPackage(uri, cph)
+	}
 	return cph, nil
 }
 
@@ -190,16 +193,16 @@ func (cph *checkPackageHandle) key() checkPackageKey {
 func (imp *importer) parseGoHandles(ctx context.Context, m *metadata) ([]source.ParseGoHandle, error) {
 	phs := make([]source.ParseGoHandle, 0, len(m.files))
 	for _, uri := range m.files {
-		f, err := imp.view.GetFile(ctx, uri)
+		f, err := imp.snapshot.view.GetFile(ctx, uri)
 		if err != nil {
 			return nil, err
 		}
-		fh := f.Handle(ctx)
+		fh := imp.snapshot.Handle(ctx, f)
 		mode := source.ParseExported
 		if imp.topLevelPackageID == m.id {
 			mode = source.ParseFull
 		}
-		phs = append(phs, imp.view.session.cache.ParseGoHandle(fh, mode))
+		phs = append(phs, imp.snapshot.view.session.cache.ParseGoHandle(fh, mode))
 	}
 	return phs, nil
 }
@@ -236,7 +239,7 @@ func (imp *importer) typeCheck(ctx context.Context, cph *checkPackageHandle, m *
 	defer done()
 
 	pkg := &pkg{
-		view:       imp.view,
+		view:       imp.snapshot.view,
 		id:         m.id,
 		pkgPath:    m.pkgPath,
 		files:      cph.Files(),
@@ -259,13 +262,17 @@ func (imp *importer) typeCheck(ctx context.Context, cph *checkPackageHandle, m *
 	}
 	// Set imports of package to correspond to cached packages.
 	cimp := imp.child(ctx, pkg, cph)
-	for _, child := range m.children {
-		childHandle, err := cimp.checkPackageHandle(ctx, child)
-		if err != nil {
-			log.Error(ctx, "no check package handle", err, telemetry.Package.Of(child.id))
+	for _, depID := range m.deps {
+		dep := imp.snapshot.getMetadata(depID)
+		if dep == nil {
 			continue
 		}
-		cph.imports[child.pkgPath] = childHandle
+		depHandle, err := cimp.checkPackageHandle(ctx, depID, imp.snapshot)
+		if err != nil {
+			log.Error(ctx, "no check package handle", err, telemetry.Package.Of(depID))
+			continue
+		}
+		cph.imports[dep.pkgPath] = depHandle
 	}
 	var (
 		files       = make([]*ast.File, len(pkg.files))
@@ -284,7 +291,7 @@ func (imp *importer) typeCheck(ctx context.Context, cph *checkPackageHandle, m *
 
 	for _, err := range parseErrors {
 		if err != nil {
-			imp.view.session.cache.appendPkgError(pkg, err)
+			imp.snapshot.view.session.cache.appendPkgError(pkg, err)
 		}
 	}
 
@@ -308,11 +315,11 @@ func (imp *importer) typeCheck(ctx context.Context, cph *checkPackageHandle, m *
 
 	cfg := &types.Config{
 		Error: func(err error) {
-			imp.view.session.cache.appendPkgError(pkg, err)
+			imp.snapshot.view.session.cache.appendPkgError(pkg, err)
 		},
 		Importer: cimp,
 	}
-	check := types.NewChecker(cfg, imp.view.session.cache.FileSet(), pkg.types, pkg.typesInfo)
+	check := types.NewChecker(cfg, imp.snapshot.view.session.cache.FileSet(), pkg.types, pkg.typesInfo)
 
 	// Type checking errors are handled via the config, so ignore them here.
 	_ = check.Files(files)
@@ -328,7 +335,7 @@ func (imp *importer) child(ctx context.Context, pkg *pkg, cph *checkPackageHandl
 	}
 	seen[pkg.id] = struct{}{}
 	return &importer{
-		view:                     imp.view,
+		snapshot:                 imp.snapshot,
 		ctx:                      ctx,
 		config:                   imp.config,
 		seen:                     seen,
diff --git a/internal/lsp/cache/file.go b/internal/lsp/cache/file.go
index a9748d5336..a40e0244dc 100644
--- a/internal/lsp/cache/file.go
+++ b/internal/lsp/cache/file.go
@@ -5,11 +5,9 @@
 package cache
 
 import (
-	"context"
 	"go/token"
 	"path/filepath"
 	"strings"
-	"sync"
 
 	"golang.org/x/tools/internal/lsp/source"
 	"golang.org/x/tools/internal/span"
@@ -31,9 +29,6 @@ type fileBase struct {
 	kind  source.FileKind
 
 	view *view
-
-	handleMu sync.Mutex
-	handle   source.FileHandle
 }
 
 func basename(filename string) string {
@@ -44,6 +39,10 @@ func (f *fileBase) URI() span.URI {
 	return f.uris[0]
 }
 
+func (f *fileBase) Kind() source.FileKind {
+	return f.kind
+}
+
 func (f *fileBase) filename() string {
 	return f.fname
 }
@@ -53,17 +52,6 @@ func (f *fileBase) View() source.View {
 	return f.view
 }
 
-// Content returns a handle for the contents of the file.
-func (f *fileBase) Handle(ctx context.Context) source.FileHandle {
-	f.handleMu.Lock()
-	defer f.handleMu.Unlock()
-
-	if f.handle == nil {
-		f.handle = f.view.session.GetFile(f.URI(), f.kind)
-	}
-	return f.handle
-}
-
 func (f *fileBase) FileSet() *token.FileSet {
 	return f.view.Session().Cache().FileSet()
 }
diff --git a/internal/lsp/cache/gofile.go b/internal/lsp/cache/gofile.go
index 1102cec943..e3ed8ec739 100644
--- a/internal/lsp/cache/gofile.go
+++ b/internal/lsp/cache/gofile.go
@@ -6,8 +6,6 @@ package cache
 
 import (
 	"context"
-	"go/ast"
-	"sync"
 
 	"golang.org/x/tools/internal/lsp/source"
 	"golang.org/x/tools/internal/lsp/telemetry"
@@ -15,68 +13,112 @@ import (
 	errors "golang.org/x/xerrors"
 )
 
-// goFile holds all of the information we know about a Go file.
-type goFile struct {
-	fileBase
+func (v *view) CheckPackageHandles(ctx context.Context, f source.File) (source.Snapshot, []source.CheckPackageHandle, error) {
+	// Get the snapshot that will be used for type-checking.
+	s := v.getSnapshot()
 
-	// mu protects all mutable state of the Go file,
-	// which can be modified during type-checking.
-	mu sync.Mutex
-
-	imports []*ast.ImportSpec
+	cphs, err := s.checkPackageHandles(ctx, f)
+	if err != nil {
+		return nil, nil, err
+	}
+	return s, cphs, nil
 }
 
-type packageKey struct {
-	id   packageID
-	mode source.ParseMode
-}
-
-func (f *goFile) CheckPackageHandles(ctx context.Context) (results []source.CheckPackageHandle, err error) {
+func (s *snapshot) checkPackageHandles(ctx context.Context, f source.File) ([]source.CheckPackageHandle, error) {
 	ctx = telemetry.File.With(ctx, f.URI())
-	fh := f.Handle(ctx)
 
-	var dirty bool
-	meta, pkgs := f.view.getSnapshot(f.URI())
-	if len(meta) == 0 {
-		dirty = true
-	}
-	for _, m := range meta {
-		if len(m.missingDeps) != 0 {
-			dirty = true
-		}
-	}
-	for _, cph := range pkgs {
-		// If we're explicitly checking if a file needs to be type-checked,
-		// we need it to be fully parsed.
-		if cph.mode() != source.ParseFull {
-			continue
-		}
-		// Check if there is a fully-parsed package to which this file belongs.
-		for _, file := range cph.Files() {
-			if file.File().Identity() == fh.Identity() {
-				results = append(results, cph)
-			}
-		}
-	}
-	if dirty || len(results) == 0 {
-		cphs, err := f.view.loadParseTypecheck(ctx, f, fh)
+	fh := s.Handle(ctx, f)
+
+	// Determine if we need to type-check the package.
+	m, cphs, load, check := s.shouldCheck(fh)
+	cfg := s.view.Config(ctx)
+
+	// We may need to re-load package metadata.
+	// We only need to this if it has been invalidated, and is therefore unvailable.
+	if load {
+		var err error
+		m, err = s.load(ctx, f.URI(), cfg)
 		if err != nil {
 			return nil, err
 		}
-		if cphs == nil {
-			return results, nil
+		// If load has explicitly returned nil metadata and no error,
+		// it means that we should not re-type-check the packages.
+		if m == nil {
+			return cphs, nil
 		}
-		results = cphs
 	}
-	if len(results) == 0 {
+	if check {
+		var results []source.CheckPackageHandle
+		for _, m := range m {
+			imp := &importer{
+				config:            cfg,
+				seen:              make(map[packageID]struct{}),
+				topLevelPackageID: m.id,
+				snapshot:          s,
+			}
+			cph, err := imp.checkPackageHandle(ctx, m.id, s)
+			if err != nil {
+				return nil, err
+			}
+			results = append(results, cph)
+		}
+		cphs = results
+	}
+	if len(cphs) == 0 {
 		return nil, errors.Errorf("no CheckPackageHandles for %s", f.URI())
 	}
-	return results, nil
+	return cphs, nil
 }
 
-func (v *view) GetActiveReverseDeps(ctx context.Context, uri span.URI) (results []source.CheckPackageHandle) {
+func (s *snapshot) shouldCheck(fh source.FileHandle) (m []*metadata, cphs []source.CheckPackageHandle, load, check bool) {
+	// Get the metadata for the given file.
+	m = s.getMetadataForURI(fh.Identity().URI)
+
+	// If there is no metadata for the package, we definitely need to type-check again.
+	if len(m) == 0 {
+		return nil, nil, true, true
+	}
+
+	// If the metadata for the package had missing dependencies,
+	// we _may_ need to re-check. If the missing dependencies haven't changed
+	// since previous load, we will not check again.
+	for _, m := range m {
+		if len(m.missingDeps) != 0 {
+			load = true
+			check = true
+		}
+	}
+	// We expect to see a checked package for each package ID,
+	// and it should be parsed in full mode.
 	var (
-		rdeps = v.reverseDependencies(ctx, uri)
+		expected   = len(m)
+		cachedCPHs = s.getPackages(fh.Identity().URI)
+	)
+	if len(cachedCPHs) < expected {
+		return m, nil, load, true
+	}
+	for _, cph := range cachedCPHs {
+		// The package may have been checked in the exported mode.
+		if cph.Mode() != source.ParseFull {
+			continue
+		}
+		// Confirm that the file belongs to this package.
+		for _, file := range cph.Files() {
+			if file.File().Identity() == fh.Identity() {
+				cphs = append(cphs, cph)
+			}
+		}
+	}
+	if len(cphs) < expected {
+		return m, nil, load, true
+	}
+	return m, cphs, load, check
+}
+
+func (v *view) GetActiveReverseDeps(ctx context.Context, f source.File) (results []source.CheckPackageHandle) {
+	var (
+		s     = v.getSnapshot()
+		rdeps = transitiveReverseDependencies(ctx, f.URI(), s)
 		files = v.openFiles(ctx, rdeps)
 		seen  = make(map[span.URI]struct{})
 	)
@@ -84,11 +126,7 @@ func (v *view) GetActiveReverseDeps(ctx context.Context, uri span.URI) (results
 		if _, ok := seen[f.URI()]; ok {
 			continue
 		}
-		gof, ok := f.(source.GoFile)
-		if !ok {
-			continue
-		}
-		cphs, err := gof.CheckPackageHandles(ctx)
+		cphs, err := s.checkPackageHandles(ctx, f)
 		if err != nil {
 			continue
 		}
@@ -100,3 +138,28 @@ func (v *view) GetActiveReverseDeps(ctx context.Context, uri span.URI) (results
 	}
 	return results
 }
+
+func transitiveReverseDependencies(ctx context.Context, uri span.URI, s *snapshot) (result []span.URI) {
+	var (
+		seen         = make(map[packageID]struct{})
+		uris         = make(map[span.URI]struct{})
+		topLevelURIs = make(map[span.URI]struct{})
+	)
+
+	metadata := s.getMetadataForURI(uri)
+
+	for _, m := range metadata {
+		for _, uri := range m.files {
+			topLevelURIs[uri] = struct{}{}
+		}
+		s.reverseDependencies(m.id, uris, seen)
+	}
+	// Filter out the URIs that belong to the original package.
+	for uri := range uris {
+		if _, ok := topLevelURIs[uri]; ok {
+			continue
+		}
+		result = append(result, uri)
+	}
+	return result
+}
diff --git a/internal/lsp/cache/load.go b/internal/lsp/cache/load.go
index 9d99eff9f8..f175b5f215 100644
--- a/internal/lsp/cache/load.go
+++ b/internal/lsp/cache/load.go
@@ -7,7 +7,7 @@ package cache
 import (
 	"context"
 	"fmt"
-	"go/ast"
+	"go/types"
 
 	"golang.org/x/tools/go/packages"
 	"golang.org/x/tools/internal/lsp/source"
@@ -19,122 +19,37 @@ import (
 	errors "golang.org/x/xerrors"
 )
 
-func (v *view) loadParseTypecheck(ctx context.Context, f *goFile, fh source.FileHandle) ([]source.CheckPackageHandle, error) {
-	ctx, done := trace.StartSpan(ctx, "cache.view.loadParseTypeCheck", telemetry.URI.Of(f.URI()))
-	defer done()
-
-	meta, err := v.load(ctx, f, fh)
-	if err != nil {
-		return nil, err
-	}
-	// If load has explicitly returns nil metadata and no error,
-	// it means that we should not re-typecheck the packages.
-	if meta == nil {
-		return nil, nil
-	}
-	var (
-		cphs    []*checkPackageHandle
-		results []source.CheckPackageHandle
-	)
-	for _, m := range meta {
-		imp := &importer{
-			view:              v,
-			config:            v.Config(ctx),
-			seen:              make(map[packageID]struct{}),
-			topLevelPackageID: m.id,
-		}
-		cph, err := imp.checkPackageHandle(ctx, m)
-		if err != nil {
-			return nil, err
-		}
-		for _, ph := range cph.files {
-			if err := v.cachePerFile(ctx, ph); err != nil {
-				return nil, err
-			}
-		}
-		cphs = append(cphs, cph)
-		results = append(results, cph)
-	}
-	// Cache the package type information for the top-level package.
-	v.updatePackages(cphs)
-	return results, nil
+type packageKey struct {
+	mode source.ParseMode
+	id   packageID
 }
 
-func (v *view) cachePerFile(ctx context.Context, ph source.ParseGoHandle) error {
-	file, _, _, err := ph.Parse(ctx)
-	if err != nil {
-		return err
-	}
-	f, err := v.GetFile(ctx, ph.File().Identity().URI)
-	if err != nil {
-		return err
-	}
-	gof, ok := f.(*goFile)
-	if !ok {
-		return errors.Errorf("%s is not a Go file", ph.File().Identity().URI)
-	}
-	gof.mu.Lock()
-	gof.imports = file.Imports
-	gof.mu.Unlock()
-	return nil
+type metadata struct {
+	id          packageID
+	pkgPath     packagePath
+	name        string
+	files       []span.URI
+	typesSizes  types.Sizes
+	errors      []packages.Error
+	deps        []packageID
+	missingDeps map[packagePath]struct{}
 }
 
-func (view *view) load(ctx context.Context, f *goFile, fh source.FileHandle) ([]*metadata, error) {
-	ctx, done := trace.StartSpan(ctx, "cache.view.load", telemetry.URI.Of(f.URI()))
+func (s *snapshot) load(ctx context.Context, uri span.URI, cfg *packages.Config) ([]*metadata, error) {
+	ctx, done := trace.StartSpan(ctx, "cache.view.load", telemetry.URI.Of(uri))
 	defer done()
 
-	// Get the metadata for the file.
-	meta, err := view.checkMetadata(ctx, f, fh)
-	if err != nil {
-		return nil, err
-	}
-	if len(meta) == 0 {
-		return nil, fmt.Errorf("no package metadata found for %s", f.URI())
-	}
-	return meta, nil
-}
-
-// checkMetadata determines if we should run go/packages.Load for this file.
-// If yes, update the metadata for the file and its package.
-func (v *view) checkMetadata(ctx context.Context, f *goFile, fh source.FileHandle) ([]*metadata, error) {
-	var shouldRunGopackages bool
-
-	m := v.getMetadata(fh.Identity().URI)
-	if len(m) == 0 {
-		shouldRunGopackages = true
-	}
-	// Get file content in case we don't already have it.
-	parsed, _, _, err := v.session.cache.ParseGoHandle(fh, source.ParseHeader).Parse(ctx)
-	if err != nil {
-		return nil, err
-	}
-	// Check if we need to re-run go/packages before loading the package.
-	shouldRunGopackages = shouldRunGopackages || v.shouldRunGopackages(ctx, f, parsed, m)
-
-	// The package metadata is correct as-is, so just return it.
-	if !shouldRunGopackages {
-		return m, nil
-	}
-
-	// Don't bother running go/packages if the context has been canceled.
-	if ctx.Err() != nil {
-		return nil, ctx.Err()
-	}
-
-	ctx, done := trace.StartSpan(ctx, "packages.Load", telemetry.File.Of(f.filename()))
-	defer done()
-
-	pkgs, err := packages.Load(v.Config(ctx), fmt.Sprintf("file=%s", f.filename()))
+	pkgs, err := packages.Load(cfg, fmt.Sprintf("file=%s", uri.Filename()))
 	log.Print(ctx, "go/packages.Load", tag.Of("packages", len(pkgs)))
 
 	if len(pkgs) == 0 {
 		if err == nil {
-			err = errors.Errorf("go/packages.Load: no packages found for %s", f.filename())
+			err = errors.Errorf("go/packages.Load: no packages found for %s", uri)
 		}
 		// Return this error as a diagnostic to the user.
 		return nil, err
 	}
-	m, prevMissingImports, err := v.updateMetadata(ctx, f.URI(), pkgs)
+	m, prevMissingImports, err := s.updateMetadata(ctx, uri, pkgs)
 	if err != nil {
 		return nil, err
 	}
@@ -145,36 +60,6 @@ func (v *view) checkMetadata(ctx context.Context, f *goFile, fh source.FileHandl
 	return meta, nil
 }
 
-// shouldRunGopackages reparses a file's package and import declarations to
-// determine if they have changed.
-// It assumes that the caller holds the lock on the f.mu lock.
-func (v *view) shouldRunGopackages(ctx context.Context, f *goFile, file *ast.File, metadata []*metadata) bool {
-	f.mu.Lock()
-	defer f.mu.Unlock()
-
-	// Check if the package's name has changed, by checking if this is a filename
-	// we already know about, and if so, check if its package name has changed.
-	for _, m := range metadata {
-		for _, uri := range m.files {
-			if span.CompareURI(uri, f.URI()) == 0 {
-				if m.name != file.Name.Name {
-					return true
-				}
-			}
-		}
-	}
-	// If the package's imports have changed, re-run `go list`.
-	if len(f.imports) != len(file.Imports) {
-		return true
-	}
-	for i, importSpec := range f.imports {
-		if importSpec.Path.Value != file.Imports[i].Path.Value {
-			return true
-		}
-	}
-	return false
-}
-
 func validateMetadata(ctx context.Context, metadata []*metadata, prevMissingImports map[packageID]map[packagePath]struct{}) ([]*metadata, error) {
 	// If we saw incorrect metadata for this package previously, don't both rechecking it.
 	for _, m := range metadata {
@@ -207,3 +92,123 @@ func sameSet(x, y map[packagePath]struct{}) bool {
 	}
 	return true
 }
+
+// shouldLoad reparses a file's package and import declarations to
+// determine if they have changed.
+func (c *cache) shouldLoad(ctx context.Context, s *snapshot, originalFH, currentFH source.FileHandle) bool {
+	if originalFH == nil {
+		return true
+	}
+
+	// Get the original parsed file in order to check package name and imports.
+	original, _, _, err := c.ParseGoHandle(originalFH, source.ParseHeader).Parse(ctx)
+	if err != nil {
+		return false
+	}
+
+	// Get the current parsed file in order to check package name and imports.
+	current, _, _, err := c.ParseGoHandle(currentFH, source.ParseHeader).Parse(ctx)
+	if err != nil {
+		return false
+	}
+
+	// Check if the package's metadata has changed. The cases handled are:
+	//
+	//    1. A package's name has changed
+	//    2. A file's imports have changed
+	//
+	if original.Name.Name != current.Name.Name {
+		return true
+	}
+	// If the package's imports have changed, re-run `go list`.
+	if len(original.Imports) != len(current.Imports) {
+		return true
+	}
+	for i, importSpec := range original.Imports {
+		// TODO: Handle the case where the imports have just been re-ordered.
+		if importSpec.Path.Value != current.Imports[i].Path.Value {
+			return true
+		}
+	}
+	return false
+}
+
+func (s *snapshot) updateMetadata(ctx context.Context, uri span.URI, pkgs []*packages.Package) ([]*metadata, map[packageID]map[packagePath]struct{}, error) {
+	// Clear metadata since we are re-running go/packages.
+	prevMissingImports := make(map[packageID]map[packagePath]struct{})
+	m := s.getMetadataForURI(uri)
+
+	for _, m := range m {
+		if len(m.missingDeps) > 0 {
+			prevMissingImports[m.id] = m.missingDeps
+		}
+	}
+
+	var results []*metadata
+	for _, pkg := range pkgs {
+		log.Print(ctx, "go/packages.Load", tag.Of("package", pkg.PkgPath), tag.Of("files", pkg.CompiledGoFiles))
+
+		// Set the metadata for this package.
+		if err := s.updateImports(ctx, packagePath(pkg.PkgPath), pkg); err != nil {
+			return nil, nil, err
+		}
+		m := s.getMetadata(packageID(pkg.ID))
+		if m != nil {
+			results = append(results, m)
+		}
+	}
+
+	// Rebuild the import graph when the metadata is updated.
+	s.clearAndRebuildImportGraph()
+
+	if len(results) == 0 {
+		return nil, nil, errors.Errorf("no metadata for %s", uri)
+	}
+	return results, prevMissingImports, nil
+}
+
+func (s *snapshot) updateImports(ctx context.Context, pkgPath packagePath, pkg *packages.Package) error {
+	// Recreate the metadata rather than reusing it to avoid locking.
+	m := &metadata{
+		id:         packageID(pkg.ID),
+		pkgPath:    pkgPath,
+		name:       pkg.Name,
+		typesSizes: pkg.TypesSizes,
+		errors:     pkg.Errors,
+	}
+	for _, filename := range pkg.CompiledGoFiles {
+		uri := span.FileURI(filename)
+		m.files = append(m.files, uri)
+
+		s.addID(uri, m.id)
+	}
+
+	// Add the metadata to the cache.
+	s.setMetadata(m)
+
+	for importPath, importPkg := range pkg.Imports {
+		importPkgPath := packagePath(importPath)
+		importID := packageID(importPkg.ID)
+
+		if importPkgPath == pkgPath {
+			return errors.Errorf("cycle detected in %s", importPath)
+		}
+		m.deps = append(m.deps, importID)
+
+		// Don't remember any imports with significant errors.
+		if importPkgPath != "unsafe" && len(importPkg.CompiledGoFiles) == 0 {
+			if m.missingDeps == nil {
+				m.missingDeps = make(map[packagePath]struct{})
+			}
+			m.missingDeps[importPkgPath] = struct{}{}
+			continue
+		}
+		dep := s.getMetadata(importID)
+		if dep == nil {
+			if err := s.updateImports(ctx, importPkgPath, importPkg); err != nil {
+				log.Error(ctx, "error in dependency", err)
+			}
+		}
+	}
+	return nil
+}
diff --git a/internal/lsp/cache/pkg.go b/internal/lsp/cache/pkg.go
index e0fc01ad92..32b8521811 100644
--- a/internal/lsp/cache/pkg.go
+++ b/internal/lsp/cache/pkg.go
@@ -191,6 +191,14 @@ func (pkg *pkg) IsIllTyped() bool {
 	return pkg.types == nil || pkg.typesInfo == nil || pkg.typesSizes == nil
 }
 
+func (pkg *pkg) GetImport(ctx context.Context, pkgPath string) (source.Package, error) {
+	if imp := pkg.imports[packagePath(pkgPath)]; imp != nil {
+		return imp, nil
+	}
+	// Don't return a nil pointer because that still satisfies the interface.
+	return nil, errors.Errorf("no imported package for %s", pkgPath)
+}
+
 func (pkg *pkg) SetDiagnostics(a *analysis.Analyzer, diags []source.Diagnostic) {
 	pkg.diagMu.Lock()
 	defer pkg.diagMu.Unlock()
diff --git a/internal/lsp/cache/session.go b/internal/lsp/cache/session.go
index 6cd4a61f54..4e175b5a6a 100644
--- a/internal/lsp/cache/session.go
+++ b/internal/lsp/cache/session.go
@@ -102,10 +102,12 @@ func (s *session) NewView(ctx context.Context, name string, folder span.URI, opt
 			packages: make(map[span.URI]map[packageKey]*checkPackageHandle),
 			ids:      make(map[span.URI][]packageID),
 			metadata: make(map[packageID]*metadata),
+			files:    make(map[span.URI]source.FileHandle),
 		},
 		ignoredURIs: make(map[span.URI]struct{}),
 		builtin:     &builtinPkg{},
 	}
+	v.snapshot.view = v
 	v.analyzers = UpdateAnalyzers(v, defaultAnalyzers)
 	// Preemptively build the builtin package,
 	// so we immediately add builtin.go to the list of ignored files.
diff --git a/internal/lsp/cache/snapshot.go b/internal/lsp/cache/snapshot.go
index a998fa7fdd..972cad193b 100644
--- a/internal/lsp/cache/snapshot.go
+++ b/internal/lsp/cache/snapshot.go
@@ -2,286 +2,171 @@ package cache
 
 import (
 	"context"
-	"go/types"
+	"sync"
 
-	"golang.org/x/tools/go/packages"
+	"golang.org/x/tools/internal/lsp/source"
 	"golang.org/x/tools/internal/span"
-	"golang.org/x/tools/internal/telemetry/log"
-	"golang.org/x/tools/internal/telemetry/tag"
-	errors "golang.org/x/xerrors"
 )
 
 type snapshot struct {
-	id uint64
+	id   uint64
+	view *view
 
-	packages map[span.URI]map[packageKey]*checkPackageHandle
-	ids      map[span.URI][]packageID
+	mu sync.Mutex
+
+	// ids maps file URIs to package IDs.
+	// It may be invalidated on calls to go/packages.
+	ids map[span.URI][]packageID
+
+	// metadata maps file IDs to their associated metadata.
+	// It may invalidated on calls to go/packages.
 	metadata map[packageID]*metadata
+
+	// importedBy maps package IDs to the list of packages that import them.
+	importedBy map[packageID][]packageID
+
+	// files maps file URIs to their corresponding FileHandles.
+	// It may invalidated when a file's content changes.
+	files map[span.URI]source.FileHandle
+
+	// packages maps a file URI to a set of CheckPackageHandles to which that file belongs.
+	// It may be invalidated when a file's content changes.
+	packages map[span.URI]map[packageKey]*checkPackageHandle
 }
 
-type metadata struct {
-	id          packageID
-	pkgPath     packagePath
-	name        string
-	files       []span.URI
-	typesSizes  types.Sizes
-	parents     map[packageID]bool
-	children    map[packageID]*metadata
-	errors      []packages.Error
-	missingDeps map[packagePath]struct{}
-}
+func (s *snapshot) getImportedBy(id packageID) []packageID {
+	s.mu.Lock()
+	defer s.mu.Unlock()
 
-func (v *view) getSnapshot(uri span.URI) ([]*metadata, []*checkPackageHandle) {
-	v.snapshotMu.Lock()
-	defer v.snapshotMu.Unlock()
-
-	var m []*metadata
-	for _, id := range v.snapshot.ids[uri] {
-		m = append(m, v.snapshot.metadata[id])
+	// If we haven't rebuilt the import graph since creating the snapshot.
+	if len(s.importedBy) == 0 {
+		s.rebuildImportGraph()
 	}
-	var cphs []*checkPackageHandle
-	for _, cph := range v.snapshot.packages[uri] {
+
+	return s.importedBy[id]
+}
+
+func (s *snapshot) addPackage(uri span.URI, cph *checkPackageHandle) {
+	s.mu.Lock()
+	defer s.mu.Unlock()
+
+	pkgs, ok := s.packages[uri]
+	if !ok {
+		pkgs = make(map[packageKey]*checkPackageHandle)
+		s.packages[uri] = pkgs
+	}
+	// TODO: Check that there isn't already something set here.
+	// This can't be done until we fix the cache keys for CheckPackageHandles.
+	pkgs[packageKey{
+		id:   cph.m.id,
+		mode: cph.Mode(),
+	}] = cph
+}
+
+func (s *snapshot) getPackages(uri span.URI) (cphs []source.CheckPackageHandle) {
+	s.mu.Lock()
+	defer s.mu.Unlock()
+
+	for _, cph := range s.packages[uri] {
 		cphs = append(cphs, cph)
 	}
-	return m, cphs
+	return cphs
 }
 
-func (v *view) getMetadata(uri span.URI) []*metadata {
-	v.snapshotMu.Lock()
-	defer v.snapshotMu.Unlock()
+func (s *snapshot) getMetadataForURI(uri span.URI) (metadata []*metadata) {
+	s.mu.Lock()
+	defer s.mu.Unlock()
 
-	var m []*metadata
-	for _, id := range v.snapshot.ids[uri] {
-		m = append(m, v.snapshot.metadata[id])
-	}
-	return m
-}
-
-func (v *view) getPackages(uri span.URI) map[packageKey]*checkPackageHandle {
-	v.snapshotMu.Lock()
-	defer v.snapshotMu.Unlock()
-
-	return v.snapshot.packages[uri]
-}
-
-func (v *view) updateMetadata(ctx context.Context, uri span.URI, pkgs []*packages.Package) ([]*metadata, map[packageID]map[packagePath]struct{}, error) {
-	v.snapshotMu.Lock()
-	defer v.snapshotMu.Unlock()
-
-	// Clear metadata since we are re-running go/packages.
-	prevMissingImports := make(map[packageID]map[packagePath]struct{})
-	for _, id := range v.snapshot.ids[uri] {
-		if m, ok := v.snapshot.metadata[id]; ok && len(m.missingDeps) > 0 {
-			prevMissingImports[id] = m.missingDeps
+	for _, id := range s.ids[uri] {
+		if m, ok := s.metadata[id]; ok {
+			metadata = append(metadata, m)
 		}
 	}
-	without := make(map[span.URI]struct{})
-	for _, id := range v.snapshot.ids[uri] {
-		v.remove(id, without, map[packageID]struct{}{})
-	}
-	v.snapshot = v.snapshot.cloneMetadata(without)
-
-	var results []*metadata
-	for _, pkg := range pkgs {
-		log.Print(ctx, "go/packages.Load", tag.Of("package", pkg.PkgPath), tag.Of("files", pkg.CompiledGoFiles))
-
-		// Build the import graph for this package.
-		if err := v.updateImportGraph(ctx, &importGraph{
-			pkgPath: packagePath(pkg.PkgPath),
-			pkg:     pkg,
-			parent:  nil,
-		}); err != nil {
-			return nil, nil, err
-		}
-		results = append(results, v.snapshot.metadata[packageID(pkg.ID)])
-	}
-	if len(results) == 0 {
-		return nil, nil, errors.Errorf("no metadata for %s", uri)
-	}
-	return results, prevMissingImports, nil
+	return metadata
 }
 
-type importGraph struct {
-	pkgPath packagePath
-	pkg     *packages.Package
-	parent  *metadata
+func (s *snapshot) setMetadata(m *metadata) {
+	s.mu.Lock()
+	defer s.mu.Unlock()
+
+	s.metadata[m.id] = m
 }
 
-func (v *view) updateImportGraph(ctx context.Context, g *importGraph) error {
-	// Recreate the metadata rather than reusing it to avoid locking.
-	m := &metadata{
-		id:         packageID(g.pkg.ID),
-		pkgPath:    g.pkgPath,
-		name:       g.pkg.Name,
-		typesSizes: g.pkg.TypesSizes,
-		errors:     g.pkg.Errors,
-	}
-	for _, filename := range g.pkg.CompiledGoFiles {
-		uri := span.FileURI(filename)
-		v.snapshot.ids[uri] = append(v.snapshot.ids[uri], m.id)
-		m.files = append(m.files, uri)
-	}
-	// Preserve the import graph.
-	if original, ok := v.snapshot.metadata[m.id]; ok {
-		m.children = original.children
-		m.parents = original.parents
-	}
-	if m.children == nil {
-		m.children = make(map[packageID]*metadata)
-	}
-	if m.parents == nil {
-		m.parents = make(map[packageID]bool)
-	}
+func (s *snapshot) getMetadata(id packageID) *metadata {
+	s.mu.Lock()
+	defer s.mu.Unlock()
 
-	// Add the metadata to the cache.
-	v.snapshot.metadata[m.id] = m
-
-	// Connect the import graph.
-	if g.parent != nil {
-		m.parents[g.parent.id] = true
-		g.parent.children[m.id] = m
-	}
-	for importPath, importPkg := range g.pkg.Imports {
-		importPkgPath := packagePath(importPath)
-		if importPkgPath == g.pkgPath {
-			return errors.Errorf("cycle detected in %s", importPath)
-		}
-		// Don't remember any imports with significant errors.
-		if importPkgPath != "unsafe" && len(importPkg.CompiledGoFiles) == 0 {
-			if m.missingDeps == nil {
-				m.missingDeps = make(map[packagePath]struct{})
-			}
-			m.missingDeps[importPkgPath] = struct{}{}
-			continue
-		}
-		if _, ok := m.children[packageID(importPkg.ID)]; !ok {
-			if err := v.updateImportGraph(ctx, &importGraph{
-				pkgPath: importPkgPath,
-				pkg:     importPkg,
-				parent:  m,
-			}); err != nil {
-				log.Error(ctx, "error in dependency", err)
-			}
-		}
-	}
-	// Clear out any imports that have been removed since the package was last loaded.
-	for importID := range m.children {
-		child, ok := v.snapshot.metadata[importID]
-		if !ok {
-			continue
-		}
-		importPath := string(child.pkgPath)
-		if _, ok := g.pkg.Imports[importPath]; ok {
-			continue
-		}
-		delete(m.children, importID)
-		delete(child.parents, m.id)
-	}
-	return nil
+	return s.metadata[id]
 }
 
-func (v *view) updatePackages(cphs []*checkPackageHandle) {
-	v.snapshotMu.Lock()
-	defer v.snapshotMu.Unlock()
+func (s *snapshot) addID(uri span.URI, id packageID) {
+	s.mu.Lock()
+	defer s.mu.Unlock()
 
-	for _, cph := range cphs {
-		for _, ph := range cph.files {
-			uri := ph.File().Identity().URI
-			if _, ok := v.snapshot.packages[uri]; !ok {
-				v.snapshot.packages[uri] = make(map[packageKey]*checkPackageHandle)
-			}
-			v.snapshot.packages[uri][packageKey{
-				id:   cph.m.id,
-				mode: ph.Mode(),
-			}] = cph
-		}
-	}
+	s.ids[uri] = append(s.ids[uri], id)
 }
 
-// invalidateContent invalidates the content of a Go file,
-// including any position and type information that depends on it.
-func (v *view) invalidateContent(ctx context.Context, f *goFile) {
-	f.handleMu.Lock()
-	defer f.handleMu.Unlock()
+func (s *snapshot) getIDs(uri span.URI) []packageID {
+	s.mu.Lock()
+	defer s.mu.Unlock()
 
-	without := make(map[span.URI]struct{})
-
-	// Remove the package and all of its reverse dependencies from the cache.
-	v.snapshotMu.Lock()
-	defer v.snapshotMu.Unlock()
-
-	for _, id := range v.snapshot.ids[f.URI()] {
-		f.view.remove(id, without, map[packageID]struct{}{})
-	}
-	v.snapshot = v.snapshot.clonePackages(without)
-	f.handle = nil
+	return s.ids[uri]
 }
 
-// invalidateMeta invalidates package metadata for all files in f's
-// package. This forces f's package's metadata to be reloaded next
-// time the package is checked.
-func (v *view) invalidateMetadata(uri span.URI) {
-	v.snapshotMu.Lock()
-	defer v.snapshotMu.Unlock()
+func (s *snapshot) getFile(uri span.URI) source.FileHandle {
+	s.mu.Lock()
+	defer s.mu.Unlock()
 
-	without := make(map[span.URI]struct{})
-
-	for _, id := range v.snapshot.ids[uri] {
-		v.remove(id, without, map[packageID]struct{}{})
-	}
-	v.snapshot = v.snapshot.cloneMetadata(without)
+	return s.files[uri]
 }
 
-// remove invalidates a package and its reverse dependencies in the view's
-// package cache. It is assumed that the caller has locked both the mutexes
-// of both the mcache and the pcache.
-func (v *view) remove(id packageID, toDelete map[span.URI]struct{}, seen map[packageID]struct{}) {
-	if _, ok := seen[id]; ok {
-		return
-	}
-	m, ok := v.snapshot.metadata[id]
-	if !ok {
-		return
-	}
-	seen[id] = struct{}{}
-	for parentID := range m.parents {
-		v.remove(parentID, toDelete, seen)
-	}
-	for _, uri := range m.files {
-		toDelete[uri] = struct{}{}
+func (s *snapshot) Handle(ctx context.Context, f source.File) source.FileHandle {
+	s.mu.Lock()
+	defer s.mu.Unlock()
+
+	if _, ok := s.files[f.URI()]; !ok {
+		s.files[f.URI()] = s.view.session.GetFile(f.URI(), f.Kind())
 	}
+	return s.files[f.URI()]
 }
 
-func (s *snapshot) clonePackages(without map[span.URI]struct{}) *snapshot {
+func (s *snapshot) clone(withoutURI span.URI, withoutTypes, withoutMetadata map[span.URI]struct{}) *snapshot {
+	s.mu.Lock()
+	defer s.mu.Unlock()
+
 	result := &snapshot{
-		id:       s.id + 1,
-		packages: make(map[span.URI]map[packageKey]*checkPackageHandle),
-		ids:      s.ids,
-		metadata: s.metadata,
+		id:         s.id + 1,
+		view:       s.view,
+		packages:   make(map[span.URI]map[packageKey]*checkPackageHandle),
+		ids:        make(map[span.URI][]packageID),
+		metadata:   make(map[packageID]*metadata),
+		importedBy: make(map[packageID][]packageID),
+		files:      make(map[span.URI]source.FileHandle),
+	}
+	// Copy all of the FileHandles except for the one that was invalidated.
+	for k, v := range s.files {
+		if k == withoutURI {
+			continue
+		}
+		result.files[k] = v
 	}
 	for k, v := range s.packages {
-		if _, ok := without[k]; ok {
-			continue
+		if withoutTypes != nil {
+			if _, ok := withoutTypes[k]; ok {
+				continue
+			}
 		}
 		result.packages[k] = v
 	}
-	return result
-}
-
-func (s *snapshot) cloneMetadata(without map[span.URI]struct{}) *snapshot {
-	result := &snapshot{
-		id:       s.id + 1,
-		packages: s.packages,
-		ids:      make(map[span.URI][]packageID),
-		metadata: make(map[packageID]*metadata),
-	}
 	withoutIDs := make(map[packageID]struct{})
 	for k, ids := range s.ids {
-		if _, ok := without[k]; ok {
-			for _, id := range ids {
-				withoutIDs[id] = struct{}{}
+		if withoutMetadata != nil {
+			if _, ok := withoutMetadata[k]; ok {
+				for _, id := range ids {
+					withoutIDs[id] = struct{}{}
+				}
+				continue
 			}
-			continue
 		}
 		result.ids[k] = ids
 	}
@@ -294,34 +179,91 @@ func (s *snapshot) cloneMetadata(without map[span.URI]struct{}) *snapshot {
 	return result
 }
 
-func (v *view) reverseDependencies(ctx context.Context, uri span.URI) map[span.URI]struct{} {
-	seen := make(map[packageID]struct{})
-	uris := make(map[span.URI]struct{})
+// invalidateContent invalidates the content of a Go file,
+// including any position and type information that depends on it.
+func (v *view) invalidateContent(ctx context.Context, uri span.URI, kind source.FileKind) {
+	withoutTypes := make(map[span.URI]struct{})
+	withoutMetadata := make(map[span.URI]struct{})
 
+	// This should be the only time we hold the view's snapshot lock for any period of time.
 	v.snapshotMu.Lock()
 	defer v.snapshotMu.Unlock()
 
-	for _, id := range v.snapshot.ids[uri] {
-		v.rdeps(id, seen, uris, id)
+	ids := v.snapshot.getIDs(uri)
+
+	// Remove the package and all of its reverse dependencies from the cache.
+	for _, id := range ids {
+		v.snapshot.reverseDependencies(id, withoutTypes, map[packageID]struct{}{})
 	}
-	return uris
+
+	// Get the original FileHandle for the URI, if it exists.
+	originalFH := v.snapshot.getFile(uri)
+
+	// Get the current FileHandle for the URI.
+	currentFH := v.session.GetFile(uri, kind)
+
+	// Check if the file's package name or imports have changed,
+	// and if so, invalidate metadata.
+	if v.session.cache.shouldLoad(ctx, v.snapshot, originalFH, currentFH) {
+		withoutMetadata = withoutTypes
+
+		// TODO: If a package's name has changed,
+		// we should invalidate the metadata for the new package name (if it exists).
+	}
+
+	v.snapshot = v.snapshot.clone(uri, withoutTypes, withoutMetadata)
 }
 
-func (v *view) rdeps(topID packageID, seen map[packageID]struct{}, results map[span.URI]struct{}, id packageID) {
+// invalidateMetadata invalidates package metadata for all files in f's
+// package. This forces f's package's metadata to be reloaded next
+// time the package is checked.
+//
+// TODO: This function shouldn't be necessary.
+// We should be able to handle its use cases more efficiently.
+func (v *view) invalidateMetadata(uri span.URI) {
+	v.snapshotMu.Lock()
+	defer v.snapshotMu.Unlock()
+
+	withoutMetadata := make(map[span.URI]struct{})
+	for _, id := range v.snapshot.getIDs(uri) {
+		v.snapshot.reverseDependencies(id, withoutMetadata, map[packageID]struct{}{})
+	}
+	v.snapshot = v.snapshot.clone(uri, nil, withoutMetadata)
+}
+
+// reverseDependencies populates the uris map with file URIs belonging to the
+// provided package and its transitive reverse dependencies.
+func (s *snapshot) reverseDependencies(id packageID, uris map[span.URI]struct{}, seen map[packageID]struct{}) {
 	if _, ok := seen[id]; ok {
 		return
 	}
-	seen[id] = struct{}{}
-	m, ok := v.snapshot.metadata[id]
-	if !ok {
+	m := s.getMetadata(id)
+	if m == nil {
 		return
 	}
-	if id != topID {
-		for _, uri := range m.files {
-			results[uri] = struct{}{}
-		}
+	seen[id] = struct{}{}
+	importedBy := s.getImportedBy(id)
+	for _, parentID := range importedBy {
+		s.reverseDependencies(parentID, uris, seen)
 	}
-	for parentID := range m.parents {
-		v.rdeps(topID, seen, results, parentID)
+	for _, uri := range m.files {
+		uris[uri] = struct{}{}
+	}
+}
+
+func (s *snapshot) clearAndRebuildImportGraph() {
+	s.mu.Lock()
+	defer s.mu.Unlock()
+
+	// Completely invalidate the original map.
+	s.importedBy = make(map[packageID][]packageID)
+	s.rebuildImportGraph()
+}
+
+func (s *snapshot) rebuildImportGraph() {
+	for id, m := range s.metadata {
+		for _, importID := range m.deps {
+			s.importedBy[importID] = append(s.importedBy[importID], id)
+		}
 	}
 }
diff --git a/internal/lsp/cache/view.go b/internal/lsp/cache/view.go
index 34cebd4d6d..f9279dcc32 100644
--- a/internal/lsp/cache/view.go
+++ b/internal/lsp/cache/view.go
@@ -288,6 +288,17 @@ func (v *view) BuiltinPackage() source.BuiltinPackage {
 	return v.builtin
 }
 
+func (v *view) Snapshot() source.Snapshot {
+	return v.getSnapshot()
+}
+
+func (v *view) getSnapshot() *snapshot {
+	v.snapshotMu.Lock()
+	defer v.snapshotMu.Unlock()
+
+	return v.snapshot
+}
+
 // SetContent sets the overlay contents for a file.
 func (v *view) SetContent(ctx context.Context, uri span.URI, content []byte) (bool, error) {
 	v.mu.Lock()
@@ -298,11 +309,12 @@ func (v *view) SetContent(ctx context.Context, uri span.URI, content []byte) (bo
 	v.cancel()
 	v.backgroundCtx, v.cancel = context.WithCancel(v.baseCtx)
 
-	if !v.Ignore(uri) {
-		kind := source.DetectLanguage("", uri.Filename())
-		return v.session.SetOverlay(uri, kind, content), nil
+	if v.Ignore(uri) {
+		return false, nil
 	}
-	return false, nil
+
+	kind := source.DetectLanguage("", uri.Filename())
+	return v.session.SetOverlay(uri, kind, content), nil
 }
 
 // FindFile returns the file if the given URI is already a part of the view.
@@ -329,46 +341,20 @@ func (v *view) GetFile(ctx context.Context, uri span.URI) (source.File, error) {
 
 // getFile is the unlocked internal implementation of GetFile.
 func (v *view) getFile(ctx context.Context, uri span.URI, kind source.FileKind) (viewFile, error) {
-	if f, err := v.findFile(uri); err != nil {
+	f, err := v.findFile(uri)
+	if err != nil {
 		return nil, err
 	} else if f != nil {
 		return f, nil
 	}
-	var f viewFile
-	switch kind {
-	case source.Mod:
-		f = &modFile{
-			fileBase: fileBase{
-				view:  v,
-				fname: uri.Filename(),
-				kind:  source.Mod,
-			},
-		}
-	case source.Sum:
-		f = &sumFile{
-			fileBase: fileBase{
-				view:  v,
-				fname: uri.Filename(),
-				kind:  source.Sum,
-			},
-		}
-	default:
-		// Assume that all other files are Go files, regardless of extension.
-		f = &goFile{
-			fileBase: fileBase{
-				view:  v,
-				fname: uri.Filename(),
-				kind:  source.Go,
-			},
-		}
-		v.session.filesWatchMap.Watch(uri, func() {
-			gof, ok := f.(*goFile)
-			if !ok {
-				return
-			}
-			v.invalidateContent(ctx, gof)
-		})
+	f = &fileBase{
+		view:  v,
+		fname: uri.Filename(),
+		kind:  source.Go,
 	}
+	v.session.filesWatchMap.Watch(uri, func() {
+		v.invalidateContent(ctx, uri, kind)
+	})
 	v.mapFile(uri, f)
 	return f, nil
 }
@@ -425,11 +411,11 @@ func (v *view) mapFile(uri span.URI, f viewFile) {
 	}
 }
 
-func (v *view) openFiles(ctx context.Context, uris map[span.URI]struct{}) (results []source.File) {
+func (v *view) openFiles(ctx context.Context, uris []span.URI) (results []source.File) {
 	v.mu.Lock()
 	defer v.mu.Unlock()
 
-	for uri := range uris {
+	for _, uri := range uris {
 		// Call unlocked version of getFile since we hold the lock on the view.
 		if f, err := v.getFile(ctx, uri, source.Go); err == nil && v.session.IsOpen(uri) {
 			results = append(results, f)
diff --git a/internal/lsp/code_action.go b/internal/lsp/code_action.go
index 0e6523cc0d..ea7bff628c 100644
--- a/internal/lsp/code_action.go
+++ b/internal/lsp/code_action.go
@@ -27,8 +27,10 @@ func (s *Server) codeAction(ctx context.Context, params *protocol.CodeActionPara
 		return nil, err
 	}
 
+	fh := view.Snapshot().Handle(ctx, f)
+
 	// Determine the supported actions for this file kind.
-	fileKind := f.Handle(ctx).Identity().Kind
+	fileKind := fh.Identity().Kind
 	supportedCodeActions, ok := view.Options().SupportedCodeActions[fileKind]
 	if !ok {
 		return nil, fmt.Errorf("no supported code actions for %v file kind", fileKind)
@@ -67,17 +69,13 @@ func (s *Server) codeAction(ctx context.Context, params *protocol.CodeActionPara
 			},
 		})
 	case source.Go:
-		gof, ok := f.(source.GoFile)
-		if !ok {
-			return nil, errors.Errorf("%s is not a Go file", f.URI())
-		}
-		edits, editsPerFix, err := source.AllImportsFixes(ctx, view, gof)
+		edits, editsPerFix, err := source.AllImportsFixes(ctx, view, f)
 		if err != nil {
 			return nil, err
 		}
 		if diagnostics := params.Context.Diagnostics; wanted[protocol.QuickFix] && len(diagnostics) > 0 {
 			// First, add the quick fixes reported by go/analysis.
-			qf, err := quickFixes(ctx, view, gof, diagnostics)
+			qf, err := quickFixes(ctx, view, f, diagnostics)
 			if err != nil {
 				log.Error(ctx, "quick fixes failed", err, telemetry.File.Of(uri))
 			}
@@ -207,9 +205,9 @@ func importDiagnostics(fix *imports.ImportFix, diagnostics []protocol.Diagnostic
 	return results
 }
 
-func quickFixes(ctx context.Context, view source.View, gof source.GoFile, diagnostics []protocol.Diagnostic) ([]protocol.CodeAction, error) {
+func quickFixes(ctx context.Context, view source.View, f source.File, diagnostics []protocol.Diagnostic) ([]protocol.CodeAction, error) {
 	var codeActions []protocol.CodeAction
-	cphs, err := gof.CheckPackageHandles(ctx)
+	_, cphs, err := view.CheckPackageHandles(ctx, f)
 	if err != nil {
 		return nil, err
 	}
diff --git a/internal/lsp/command.go b/internal/lsp/command.go
index d6c4a03f4d..72e8647532 100644
--- a/internal/lsp/command.go
+++ b/internal/lsp/command.go
@@ -22,7 +22,8 @@ func (s *Server) executeCommand(ctx context.Context, params *protocol.ExecuteCom
 		if err != nil {
 			return nil, err
 		}
-		if _, ok := f.(source.ModFile); !ok {
+		fh := view.Snapshot().Handle(ctx, f)
+		if fh.Identity().Kind != source.Mod {
 			return nil, errors.Errorf("%s is not a mod file", uri)
 		}
 		// Run go.mod tidy on the view.
diff --git a/internal/lsp/completion.go b/internal/lsp/completion.go
index 7b64a99392..0f6b7f4ea4 100644
--- a/internal/lsp/completion.go
+++ b/internal/lsp/completion.go
@@ -20,7 +20,7 @@ func (s *Server) completion(ctx context.Context, params *protocol.CompletionPara
 	uri := span.NewURI(params.TextDocument.URI)
 	view := s.session.ViewOf(uri)
 	options := view.Options()
-	f, err := getGoFile(ctx, view, uri)
+	f, err := view.GetFile(ctx, uri)
 	if err != nil {
 		return nil, err
 	}
diff --git a/internal/lsp/definition.go b/internal/lsp/definition.go
index 8e49cd3119..f8f18df9ef 100644
--- a/internal/lsp/definition.go
+++ b/internal/lsp/definition.go
@@ -15,7 +15,7 @@ import (
 func (s *Server) definition(ctx context.Context, params *protocol.DefinitionParams) ([]protocol.Location, error) {
 	uri := span.NewURI(params.TextDocument.URI)
 	view := s.session.ViewOf(uri)
-	f, err := getGoFile(ctx, view, uri)
+	f, err := view.GetFile(ctx, uri)
 	if err != nil {
 		return nil, err
 	}
@@ -38,7 +38,7 @@ func (s *Server) definition(ctx context.Context, params *protocol.DefinitionPara
 func (s *Server) typeDefinition(ctx context.Context, params *protocol.TypeDefinitionParams) ([]protocol.Location, error) {
 	uri := span.NewURI(params.TextDocument.URI)
 	view := s.session.ViewOf(uri)
-	f, err := getGoFile(ctx, view, uri)
+	f, err := view.GetFile(ctx, uri)
 	if err != nil {
 		return nil, err
 	}
diff --git a/internal/lsp/diagnostics.go b/internal/lsp/diagnostics.go
index 4f137b6cce..6b602cd3d1 100644
--- a/internal/lsp/diagnostics.go
+++ b/internal/lsp/diagnostics.go
@@ -14,7 +14,6 @@ import (
 	"golang.org/x/tools/internal/span"
 	"golang.org/x/tools/internal/telemetry/log"
 	"golang.org/x/tools/internal/telemetry/trace"
-	errors "golang.org/x/xerrors"
 )
 
 func (s *Server) diagnostics(view source.View, uri span.URI) error {
@@ -28,12 +27,7 @@ func (s *Server) diagnostics(view source.View, uri span.URI) error {
 	if err != nil {
 		return err
 	}
-	// For non-Go files, don't return any diagnostics.
-	gof, ok := f.(source.GoFile)
-	if !ok {
-		return errors.Errorf("%s is not a Go file", f.URI())
-	}
-	reports, warningMsg, err := source.Diagnostics(ctx, view, gof, view.Options().DisabledAnalyses)
+	reports, warningMsg, err := source.Diagnostics(ctx, view, f, view.Options().DisabledAnalyses)
 	if err != nil {
 		return err
 	}
diff --git a/internal/lsp/folding_range.go b/internal/lsp/folding_range.go
index 49de6033c8..d0eecc49a2 100644
--- a/internal/lsp/folding_range.go
+++ b/internal/lsp/folding_range.go
@@ -11,7 +11,7 @@ import (
 func (s *Server) foldingRange(ctx context.Context, params *protocol.FoldingRangeParams) ([]protocol.FoldingRange, error) {
 	uri := span.NewURI(params.TextDocument.URI)
 	view := s.session.ViewOf(uri)
-	f, err := getGoFile(ctx, view, uri)
+	f, err := view.GetFile(ctx, uri)
 	if err != nil {
 		return nil, err
 	}
diff --git a/internal/lsp/hover.go b/internal/lsp/hover.go
index c79ba6e0c7..ae51f46596 100644
--- a/internal/lsp/hover.go
+++ b/internal/lsp/hover.go
@@ -18,7 +18,7 @@ import (
 func (s *Server) hover(ctx context.Context, params *protocol.HoverParams) (*protocol.Hover, error) {
 	uri := span.NewURI(params.TextDocument.URI)
 	view := s.session.ViewOf(uri)
-	f, err := getGoFile(ctx, view, uri)
+	f, err := view.GetFile(ctx, uri)
 	if err != nil {
 		return nil, err
 	}
diff --git a/internal/lsp/link.go b/internal/lsp/link.go
index cea01ab955..4c79bdc707 100644
--- a/internal/lsp/link.go
+++ b/internal/lsp/link.go
@@ -23,11 +23,11 @@ import (
 func (s *Server) documentLink(ctx context.Context, params *protocol.DocumentLinkParams) ([]protocol.DocumentLink, error) {
 	uri := span.NewURI(params.TextDocument.URI)
 	view := s.session.ViewOf(uri)
-	f, err := getGoFile(ctx, view, uri)
+	f, err := view.GetFile(ctx, uri)
 	if err != nil {
 		return nil, err
 	}
-	fh := f.Handle(ctx)
+	fh := view.Snapshot().Handle(ctx, f)
 	file, m, _, err := view.Session().Cache().ParseGoHandle(fh, source.ParseFull).Parse(ctx)
 	if err != nil {
 		return nil, err
diff --git a/internal/lsp/lsp_test.go b/internal/lsp/lsp_test.go
index 691621d71f..4b2856cf65 100644
--- a/internal/lsp/lsp_test.go
+++ b/internal/lsp/lsp_test.go
@@ -76,11 +76,7 @@ func (r *runner) Diagnostics(t *testing.T, uri span.URI, want []source.Diagnosti
 	if err != nil {
 		t.Fatalf("no file for %s: %v", f, err)
 	}
-	gof, ok := f.(source.GoFile)
-	if !ok {
-		t.Fatalf("%s is not a Go file: %v", uri, err)
-	}
-	results, _, err := source.Diagnostics(r.ctx, v, gof, nil)
+	results, _, err := source.Diagnostics(r.ctx, v, f, nil)
 	if err != nil {
 		t.Fatal(err)
 	}
@@ -323,7 +319,7 @@ func (r *runner) SuggestedFix(t *testing.T, spn span.Span) {
 	uri := spn.URI()
 	filename := uri.Filename()
 	view := r.server.session.ViewOf(uri)
-	f, err := getGoFile(r.ctx, view, uri)
+	f, err := view.GetFile(r.ctx, uri)
 	if err != nil {
 		t.Fatal(err)
 	}
diff --git a/internal/lsp/references.go b/internal/lsp/references.go
index 25977774ca..6930a6c174 100644
--- a/internal/lsp/references.go
+++ b/internal/lsp/references.go
@@ -17,7 +17,7 @@ import (
 func (s *Server) references(ctx context.Context, params *protocol.ReferenceParams) ([]protocol.Location, error) {
 	uri := span.NewURI(params.TextDocument.URI)
 	view := s.session.ViewOf(uri)
-	f, err := getGoFile(ctx, view, uri)
+	f, err := view.GetFile(ctx, uri)
 	if err != nil {
 		return nil, err
 	}
diff --git a/internal/lsp/rename.go b/internal/lsp/rename.go
index d4b4d0876a..9ce36729a1 100644
--- a/internal/lsp/rename.go
+++ b/internal/lsp/rename.go
@@ -15,7 +15,7 @@ import (
 func (s *Server) rename(ctx context.Context, params *protocol.RenameParams) (*protocol.WorkspaceEdit, error) {
 	uri := span.NewURI(params.TextDocument.URI)
 	view := s.session.ViewOf(uri)
-	f, err := getGoFile(ctx, view, uri)
+	f, err := view.GetFile(ctx, uri)
 	if err != nil {
 		return nil, err
 	}
@@ -38,7 +38,7 @@ func (s *Server) rename(ctx context.Context, params *protocol.RenameParams) (*pr
 func (s *Server) prepareRename(ctx context.Context, params *protocol.PrepareRenameParams) (*protocol.Range, error) {
 	uri := span.NewURI(params.TextDocument.URI)
 	view := s.session.ViewOf(uri)
-	f, err := getGoFile(ctx, view, uri)
+	f, err := view.GetFile(ctx, uri)
 	if err != nil {
 		return nil, err
 	}
diff --git a/internal/lsp/server.go b/internal/lsp/server.go
index 7b514fc547..fe096522f6 100644
--- a/internal/lsp/server.go
+++ b/internal/lsp/server.go
@@ -2,6 +2,7 @@
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
+// Package lsp implements LSP for gopls.
 package lsp
 
 import (
diff --git a/internal/lsp/signature_help.go b/internal/lsp/signature_help.go
index 8f466b36df..5771ef16c0 100644
--- a/internal/lsp/signature_help.go
+++ b/internal/lsp/signature_help.go
@@ -17,7 +17,7 @@ import (
 func (s *Server) signatureHelp(ctx context.Context, params *protocol.SignatureHelpParams) (*protocol.SignatureHelp, error) {
 	uri := span.NewURI(params.TextDocument.URI)
 	view := s.session.ViewOf(uri)
-	f, err := getGoFile(ctx, view, uri)
+	f, err := view.GetFile(ctx, uri)
 	if err != nil {
 		return nil, err
 	}
diff --git a/internal/lsp/source/completion.go b/internal/lsp/source/completion.go
index 12d036e974..6a4b1c81e3 100644
--- a/internal/lsp/source/completion.go
+++ b/internal/lsp/source/completion.go
@@ -126,7 +126,8 @@ func (ipm insensitivePrefixMatcher) Score(candidateLabel string) float32 {
 
 // completer contains the necessary information for a single completion request.
 type completer struct {
-	pkg Package
+	snapshot Snapshot
+	pkg      Package
 
 	qf   types.Qualifier
 	opts CompletionOptions
@@ -376,13 +377,13 @@ func (e ErrIsDefinition) Error() string {
 // The selection is computed based on the preceding identifier and can be used by
 // the client to score the quality of the completion. For instance, some clients
 // may tolerate imperfect matches as valid completion results, since users may make typos.
-func Completion(ctx context.Context, view View, f GoFile, pos protocol.Position, opts CompletionOptions) ([]CompletionItem, *Selection, error) {
+func Completion(ctx context.Context, view View, f File, pos protocol.Position, opts CompletionOptions) ([]CompletionItem, *Selection, error) {
 	ctx, done := trace.StartSpan(ctx, "source.Completion")
 	defer done()
 
 	startTime := time.Now()
 
-	cphs, err := f.CheckPackageHandles(ctx)
+	snapshot, cphs, err := view.CheckPackageHandles(ctx, f)
 	if err != nil {
 		return nil, nil, err
 	}
@@ -427,6 +428,7 @@ func Completion(ctx context.Context, view View, f GoFile, pos protocol.Position,
 	clInfo := enclosingCompositeLiteral(path, rng.Start, pkg.GetTypesInfo())
 	c := &completer{
 		pkg:                       pkg,
+		snapshot:                  snapshot,
 		qf:                        qualifier(file, pkg.GetTypes(), pkg.GetTypesInfo()),
 		view:                      view,
 		ctx:                       ctx,
diff --git a/internal/lsp/source/completion_format.go b/internal/lsp/source/completion_format.go
index 9ccb573322..199dde8e40 100644
--- a/internal/lsp/source/completion_format.go
+++ b/internal/lsp/source/completion_format.go
@@ -133,7 +133,7 @@ func (c *completer) item(cand candidate) (CompletionItem, error) {
 	if !(file.Pos() <= obj.Pos() && obj.Pos() <= file.End()) {
 		return CompletionItem{}, errors.Errorf("no file for %s", obj.Name())
 	}
-	ident, err := findIdentifier(c.ctx, c.view, pkg, file, obj.Pos())
+	ident, err := findIdentifier(c.ctx, c.view, c.snapshot, pkg, file, obj.Pos())
 	if err != nil {
 		return CompletionItem{}, err
 	}
diff --git a/internal/lsp/source/diagnostics.go b/internal/lsp/source/diagnostics.go
index 5176ca5e28..04c4737a6b 100644
--- a/internal/lsp/source/diagnostics.go
+++ b/internal/lsp/source/diagnostics.go
@@ -17,7 +17,6 @@ import (
 	"golang.org/x/tools/internal/span"
 	"golang.org/x/tools/internal/telemetry/log"
 	"golang.org/x/tools/internal/telemetry/trace"
-	errors "golang.org/x/xerrors"
 )
 
 type Diagnostic struct {
@@ -38,11 +37,11 @@ const (
 	SeverityError
 )
 
-func Diagnostics(ctx context.Context, view View, f GoFile, disabledAnalyses map[string]struct{}) (map[span.URI][]Diagnostic, string, error) {
+func Diagnostics(ctx context.Context, view View, f File, disabledAnalyses map[string]struct{}) (map[span.URI][]Diagnostic, string, error) {
 	ctx, done := trace.StartSpan(ctx, "source.Diagnostics", telemetry.File.Of(f.URI()))
 	defer done()
 
-	cphs, err := f.CheckPackageHandles(ctx)
+	_, cphs, err := view.CheckPackageHandles(ctx, f)
 	if err != nil {
 		return nil, "", err
 	}
@@ -85,7 +84,7 @@ func Diagnostics(ctx context.Context, view View, f GoFile, disabledAnalyses map[
 		}
 	}
 	// Updates to the diagnostics for this package may need to be propagated.
-	revDeps := view.GetActiveReverseDeps(ctx, f.URI())
+	revDeps := view.GetActiveReverseDeps(ctx, f)
 	for _, cph := range revDeps {
 		pkg, err := cph.Check(ctx)
 		if err != nil {
@@ -215,13 +214,9 @@ func toDiagnostic(ctx context.Context, view View, diag analysis.Diagnostic, cate
 	if err != nil {
 		return Diagnostic{}, err
 	}
-	gof, ok := f.(GoFile)
-	if !ok {
-		return Diagnostic{}, errors.Errorf("%s is not a Go file", f.URI())
-	}
 	// If the package has changed since these diagnostics were computed,
 	// this may be incorrect. Should the package be associated with the diagnostic?
-	cphs, err := gof.CheckPackageHandles(ctx)
+	_, cphs, err := view.CheckPackageHandles(ctx, f)
 	if err != nil {
 		return Diagnostic{}, err
 	}
diff --git a/internal/lsp/source/folding_range.go b/internal/lsp/source/folding_range.go
index f66d958416..e944e9b6d1 100644
--- a/internal/lsp/source/folding_range.go
+++ b/internal/lsp/source/folding_range.go
@@ -16,10 +16,12 @@ type FoldingRangeInfo struct {
 }
 
 // FoldingRange gets all of the folding range for f.
-func FoldingRange(ctx context.Context, view View, f GoFile, lineFoldingOnly bool) (ranges []*FoldingRangeInfo, err error) {
+func FoldingRange(ctx context.Context, view View, f File, lineFoldingOnly bool) (ranges []*FoldingRangeInfo, err error) {
 	// TODO(suzmue): consider limiting the number of folding ranges returned, and
 	// implement a way to prioritize folding ranges in that case.
-	ph := view.Session().Cache().ParseGoHandle(f.Handle(ctx), ParseFull)
+	s := view.Snapshot()
+	fh := s.Handle(ctx, f)
+	ph := view.Session().Cache().ParseGoHandle(fh, ParseFull)
 	file, m, _, err := ph.Parse(ctx)
 	if err != nil {
 		return nil, err
diff --git a/internal/lsp/source/format.go b/internal/lsp/source/format.go
index 746de0ef5f..50563d39fc 100644
--- a/internal/lsp/source/format.go
+++ b/internal/lsp/source/format.go
@@ -24,11 +24,7 @@ func Format(ctx context.Context, view View, f File) ([]protocol.TextEdit, error)
 	ctx, done := trace.StartSpan(ctx, "source.Format")
 	defer done()
 
-	gof, ok := f.(GoFile)
-	if !ok {
-		return nil, errors.Errorf("formatting is not supported for non-Go files")
-	}
-	cphs, err := gof.CheckPackageHandles(ctx)
+	snapshot, cphs, err := view.CheckPackageHandles(ctx, f)
 	if err != nil {
 		return nil, err
 	}
@@ -55,7 +51,7 @@ func Format(ctx context.Context, view View, f File) ([]protocol.TextEdit, error)
 		// have any parse errors and can still be formatted. Using format.Node
 		// on an ast with errors may result in code being added or removed.
 		// Attempt to format the source of this file instead.
-		formatted, err := formatSource(ctx, f)
+		formatted, err := formatSource(ctx, snapshot, f)
 		if err != nil {
 			return nil, err
 		}
@@ -75,10 +71,11 @@ func Format(ctx context.Context, view View, f File) ([]protocol.TextEdit, error)
 	return computeTextEdits(ctx, ph.File(), m, buf.String())
 }
 
-func formatSource(ctx context.Context, file File) ([]byte, error) {
+func formatSource(ctx context.Context, s Snapshot, f File) ([]byte, error) {
 	ctx, done := trace.StartSpan(ctx, "source.formatSource")
 	defer done()
-	data, _, err := file.Handle(ctx).Read(ctx)
+
+	data, _, err := s.Handle(ctx, f).Read(ctx)
 	if err != nil {
 		return nil, err
 	}
@@ -86,11 +83,11 @@ func formatSource(ctx context.Context, file File) ([]byte, error) {
 }
 
 // Imports formats a file using the goimports tool.
-func Imports(ctx context.Context, view View, f GoFile, rng span.Range) ([]protocol.TextEdit, error) {
+func Imports(ctx context.Context, view View, f File, rng span.Range) ([]protocol.TextEdit, error) {
 	ctx, done := trace.StartSpan(ctx, "source.Imports")
 	defer done()
 
-	cphs, err := f.CheckPackageHandles(ctx)
+	_, cphs, err := view.CheckPackageHandles(ctx, f)
 	if err != nil {
 		return nil, err
 	}
@@ -149,11 +146,11 @@ type ImportFix struct {
 // In addition to returning the result of applying all edits,
 // it returns a list of fixes that could be applied to the file, with the
 // corresponding TextEdits that would be needed to apply that fix.
-func AllImportsFixes(ctx context.Context, view View, f GoFile) (edits []protocol.TextEdit, editsPerFix []*ImportFix, err error) {
+func AllImportsFixes(ctx context.Context, view View, f File) (edits []protocol.TextEdit, editsPerFix []*ImportFix, err error) {
 	ctx, done := trace.StartSpan(ctx, "source.AllImportsFixes")
 	defer done()
 
-	cphs, err := f.CheckPackageHandles(ctx)
+	_, cphs, err := view.CheckPackageHandles(ctx, f)
 	if err != nil {
 		return nil, nil, err
 	}
diff --git a/internal/lsp/source/highlight.go b/internal/lsp/source/highlight.go
index 992ada5e0b..64fa906e74 100644
--- a/internal/lsp/source/highlight.go
+++ b/internal/lsp/source/highlight.go
@@ -23,7 +23,8 @@ func Highlight(ctx context.Context, view View, uri span.URI, pos protocol.Positi
 	if err != nil {
 		return nil, err
 	}
-	ph := view.Session().Cache().ParseGoHandle(f.Handle(ctx), ParseFull)
+	fh := view.Snapshot().Handle(ctx, f)
+	ph := view.Session().Cache().ParseGoHandle(fh, ParseFull)
 	file, m, _, err := ph.Parse(ctx)
 	if err != nil {
 		return nil, err
diff --git a/internal/lsp/source/identifier.go b/internal/lsp/source/identifier.go
index ea8bed1302..2aa0613c42 100644
--- a/internal/lsp/source/identifier.go
+++ b/internal/lsp/source/identifier.go
@@ -20,9 +20,10 @@ import (
 
 // IdentifierInfo holds information about an identifier in Go source.
 type IdentifierInfo struct {
-	Name string
-	View View
-	File ParseGoHandle
+	Name     string
+	View     View
+	snapshot Snapshot
+	File     ParseGoHandle
 	mappedRange
 
 	Type struct {
@@ -47,8 +48,8 @@ type Declaration struct {
 
 // Identifier returns identifier information for a position
 // in a file, accounting for a potentially incomplete selector.
-func Identifier(ctx context.Context, view View, f GoFile, pos protocol.Position) (*IdentifierInfo, error) {
-	cphs, err := f.CheckPackageHandles(ctx)
+func Identifier(ctx context.Context, view View, f File, pos protocol.Position) (*IdentifierInfo, error) {
+	snapshot, cphs, err := view.CheckPackageHandles(ctx, f)
 	if err != nil {
 		return nil, err
 	}
@@ -73,17 +74,17 @@ func Identifier(ctx context.Context, view View, f GoFile, pos protocol.Position)
 	if err != nil {
 		return nil, err
 	}
-	return findIdentifier(ctx, view, pkg, file, rng.Start)
+	return findIdentifier(ctx, view, snapshot, pkg, file, rng.Start)
 }
 
-func findIdentifier(ctx context.Context, view View, pkg Package, file *ast.File, pos token.Pos) (*IdentifierInfo, error) {
-	if result, err := identifier(ctx, view, pkg, file, pos); err != nil || result != nil {
+func findIdentifier(ctx context.Context, view View, snapshot Snapshot, pkg Package, file *ast.File, pos token.Pos) (*IdentifierInfo, error) {
+	if result, err := identifier(ctx, view, snapshot, pkg, file, pos); err != nil || result != nil {
 		return result, err
 	}
 	// If the position is not an identifier but immediately follows
 	// an identifier or selector period (as is common when
 	// requesting a completion), use the path to the preceding node.
-	ident, err := identifier(ctx, view, pkg, file, pos-1)
+	ident, err := identifier(ctx, view, snapshot, pkg, file, pos-1)
 	if ident == nil && err == nil {
 		err = errors.New("no identifier found")
 	}
@@ -91,14 +92,14 @@ func findIdentifier(ctx context.Context, view View, pkg Package, file *ast.File,
 }
 
 // identifier checks a single position for a potential identifier.
-func identifier(ctx context.Context, view View, pkg Package, file *ast.File, pos token.Pos) (*IdentifierInfo, error) {
+func identifier(ctx context.Context, view View, snapshot Snapshot, pkg Package, file *ast.File, pos token.Pos) (*IdentifierInfo, error) {
 	ctx, done := trace.StartSpan(ctx, "source.identifier")
 	defer done()
 
 	var err error
 
 	// Handle import specs separately, as there is no formal position for a package declaration.
-	if result, err := importSpec(ctx, view, file, pkg, pos); result != nil || err != nil {
+	if result, err := importSpec(ctx, view, snapshot, file, pkg, pos); result != nil || err != nil {
 		return result, err
 	}
 	path, _ := astutil.PathEnclosingInterval(file, pos, pos)
@@ -113,11 +114,12 @@ func identifier(ctx context.Context, view View, pkg Package, file *ast.File, pos
 		}
 	}
 	result := &IdentifierInfo{
-		View:  view,
-		File:  ph,
-		qf:    qualifier(file, pkg.GetTypes(), pkg.GetTypesInfo()),
-		pkg:   pkg,
-		ident: searchForIdent(path[0]),
+		View:     view,
+		snapshot: snapshot,
+		File:     ph,
+		qf:       qualifier(file, pkg.GetTypes(), pkg.GetTypesInfo()),
+		pkg:      pkg,
+		ident:    searchForIdent(path[0]),
 	}
 	// No identifier at the given position.
 	if result.ident == nil {
@@ -273,7 +275,7 @@ func objToNode(ctx context.Context, view View, pkg Package, obj types.Object) (a
 }
 
 // importSpec handles positions inside of an *ast.ImportSpec.
-func importSpec(ctx context.Context, view View, file *ast.File, pkg Package, pos token.Pos) (*IdentifierInfo, error) {
+func importSpec(ctx context.Context, view View, snapshot Snapshot, file *ast.File, pkg Package, pos token.Pos) (*IdentifierInfo, error) {
 	var imp *ast.ImportSpec
 	for _, spec := range file.Imports {
 		if spec.Path.Pos() <= pos && pos < spec.Path.End() {
@@ -295,10 +297,11 @@ func importSpec(ctx context.Context, view View, file *ast.File, pkg Package, pos
 		}
 	}
 	result := &IdentifierInfo{
-		View: view,
-		File: ph,
-		Name: importPath,
-		pkg:  pkg,
+		View:     view,
+		snapshot: snapshot,
+		File:     ph,
+		Name:     importPath,
+		pkg:      pkg,
 	}
 	if result.mappedRange, err = posToMappedRange(ctx, view, pkg, imp.Path.Pos(), imp.Path.End()); err != nil {
 		return nil, err
diff --git a/internal/lsp/source/rename.go b/internal/lsp/source/rename.go
index bb4cebccc4..100b55c488 100644
--- a/internal/lsp/source/rename.go
+++ b/internal/lsp/source/rename.go
@@ -41,7 +41,7 @@ type PrepareItem struct {
 	Text  string
 }
 
-func PrepareRename(ctx context.Context, view View, f GoFile, pos protocol.Position) (*PrepareItem, error) {
+func PrepareRename(ctx context.Context, view View, f File, pos protocol.Position) (*PrepareItem, error) {
 	ctx, done := trace.StartSpan(ctx, "source.PrepareRename")
 	defer done()
 
@@ -151,7 +151,7 @@ func (i *IdentifierInfo) Rename(ctx context.Context, view View, newName string)
 		if err != nil {
 			return nil, err
 		}
-		fh := f.Handle(ctx)
+		fh := i.snapshot.Handle(ctx, f)
 		data, _, err := fh.Read(ctx)
 		if err != nil {
 			return nil, err
@@ -227,6 +227,7 @@ func getPkgNameIdentifier(ctx context.Context, ident *IdentifierInfo, pkgName *t
 	return &IdentifierInfo{
 		Name:             pkgName.Name(),
 		View:             ident.View,
+		snapshot:         ident.snapshot,
 		mappedRange:      decl.mappedRange,
 		File:             ident.File,
 		Declaration:      decl,
diff --git a/internal/lsp/source/signature_help.go b/internal/lsp/source/signature_help.go
index b582fb6bc2..de6b1b35c3 100644
--- a/internal/lsp/source/signature_help.go
+++ b/internal/lsp/source/signature_help.go
@@ -27,11 +27,11 @@ type ParameterInformation struct {
 	Label string
 }
 
-func SignatureHelp(ctx context.Context, view View, f GoFile, pos protocol.Position) (*SignatureInformation, error) {
+func SignatureHelp(ctx context.Context, view View, f File, pos protocol.Position) (*SignatureInformation, error) {
 	ctx, done := trace.StartSpan(ctx, "source.SignatureHelp")
 	defer done()
 
-	cphs, err := f.CheckPackageHandles(ctx)
+	_, cphs, err := view.CheckPackageHandles(ctx, f)
 	if err != nil {
 		return nil, err
 	}
@@ -94,7 +94,7 @@ FindCall:
 
 	// Handle builtin functions separately.
 	if obj, ok := obj.(*types.Builtin); ok {
-		return builtinSignature(ctx, f.View(), callExpr, obj.Name(), rng.Start)
+		return builtinSignature(ctx, view, callExpr, obj.Name(), rng.Start)
 	}
 
 	// Get the type information for the function being called.
@@ -118,7 +118,7 @@ FindCall:
 		comment *ast.CommentGroup
 	)
 	if obj != nil {
-		node, err := objToNode(ctx, f.View(), pkg, obj)
+		node, err := objToNode(ctx, view, pkg, obj)
 		if err != nil {
 			return nil, err
 		}
diff --git a/internal/lsp/source/source_test.go b/internal/lsp/source/source_test.go
index 640ebae268..161085d187 100644
--- a/internal/lsp/source/source_test.go
+++ b/internal/lsp/source/source_test.go
@@ -68,7 +68,7 @@ func (r *runner) Diagnostics(t *testing.T, uri span.URI, want []source.Diagnosti
 	if err != nil {
 		t.Fatal(err)
 	}
-	results, _, err := source.Diagnostics(r.ctx, r.view, f.(source.GoFile), nil)
+	results, _, err := source.Diagnostics(r.ctx, r.view, f, nil)
 	if err != nil {
 		t.Fatal(err)
 	}
@@ -243,7 +243,7 @@ func (r *runner) callCompletion(t *testing.T, src span.Span, options source.Comp
 	if err != nil {
 		t.Fatal(err)
 	}
-	list, surrounding, err := source.Completion(r.ctx, r.view, f.(source.GoFile), protocol.Position{
+	list, surrounding, err := source.Completion(r.ctx, r.view, f, protocol.Position{
 		Line:      float64(src.Start().Line() - 1),
 		Character: float64(src.Start().Column() - 1),
 	}, options)
@@ -284,14 +284,15 @@ func (r *runner) FoldingRange(t *testing.T, spn span.Span) {
 	if err != nil {
 		t.Fatalf("failed for %v: %v", spn, err)
 	}
-	data, _, err := f.Handle(r.ctx).Read(r.ctx)
+	fh := r.view.Snapshot().Handle(r.ctx, f)
+	data, _, err := fh.Read(r.ctx)
 	if err != nil {
 		t.Error(err)
 		return
 	}
 
 	// Test all folding ranges.
-	ranges, err := source.FoldingRange(r.ctx, r.view, f.(source.GoFile), false)
+	ranges, err := source.FoldingRange(r.ctx, r.view, f, false)
 	if err != nil {
 		t.Error(err)
 		return
@@ -299,7 +300,7 @@ func (r *runner) FoldingRange(t *testing.T, spn span.Span) {
 	r.foldingRanges(t, "foldingRange", uri, string(data), ranges)
 
 	// Test folding ranges with lineFoldingOnly
-	ranges, err = source.FoldingRange(r.ctx, r.view, f.(source.GoFile), true)
+	ranges, err = source.FoldingRange(r.ctx, r.view, f, true)
 	if err != nil {
 		t.Error(err)
 		return
@@ -434,7 +435,8 @@ func (r *runner) Format(t *testing.T, spn span.Span) {
 		}
 		return
 	}
-	data, _, err := f.Handle(ctx).Read(ctx)
+	fh := r.view.Snapshot().Handle(r.ctx, f)
+	data, _, err := fh.Read(ctx)
 	if err != nil {
 		t.Fatal(err)
 	}
@@ -465,7 +467,7 @@ func (r *runner) Import(t *testing.T, spn span.Span) {
 	if err != nil {
 		t.Fatalf("failed for %v: %v", spn, err)
 	}
-	fh := f.Handle(ctx)
+	fh := r.view.Snapshot().Handle(r.ctx, f)
 	tok, err := r.view.Session().Cache().TokenHandle(fh).Token(ctx)
 	if err != nil {
 		t.Fatal(err)
@@ -474,7 +476,7 @@ func (r *runner) Import(t *testing.T, spn span.Span) {
 	if err != nil {
 		t.Fatalf("failed for %v: %v", spn, err)
 	}
-	edits, err := source.Imports(ctx, r.view, f.(source.GoFile), rng)
+	edits, err := source.Imports(ctx, r.view, f, rng)
 	if err != nil {
 		if goimported != "" {
 			t.Error(err)
@@ -512,7 +514,7 @@ func (r *runner) Definition(t *testing.T, spn span.Span, d tests.Definition) {
 	if err != nil {
 		t.Fatal(err)
 	}
-	ident, err := source.Identifier(ctx, r.view, f.(source.GoFile), srcRng.Start)
+	ident, err := source.Identifier(ctx, r.view, f, srcRng.Start)
 	if err != nil {
 		t.Fatalf("failed for %v: %v", d.Src, err)
 	}
@@ -590,7 +592,7 @@ func (r *runner) Reference(t *testing.T, src span.Span, itemList []span.Span) {
 	if err != nil {
 		t.Fatal(err)
 	}
-	ident, err := source.Identifier(ctx, r.view, f.(source.GoFile), srcRng.Start)
+	ident, err := source.Identifier(ctx, r.view, f, srcRng.Start)
 	if err != nil {
 		t.Fatalf("failed for %v: %v", src, err)
 	}
@@ -637,7 +639,7 @@ func (r *runner) Rename(t *testing.T, spn span.Span, newText string) {
 	if err != nil {
 		t.Fatal(err)
 	}
-	ident, err := source.Identifier(r.ctx, r.view, f.(source.GoFile), srcRng.Start)
+	ident, err := source.Identifier(r.ctx, r.view, f, srcRng.Start)
 	if err != nil {
 		t.Error(err)
 		return
@@ -659,7 +661,7 @@ func (r *runner) Rename(t *testing.T, spn span.Span, newText string) {
 		if err != nil {
 			t.Fatalf("failed for %v: %v", spn, err)
 		}
-		fh := f.Handle(ctx)
+		fh := r.view.Snapshot().Handle(r.ctx, f)
 		data, _, err := fh.Read(ctx)
 		if err != nil {
 			t.Fatal(err)
@@ -726,7 +728,7 @@ func (r *runner) PrepareRename(t *testing.T, src span.Span, want *source.Prepare
 		t.Fatal(err)
 	}
 	// Find the identifier at the position.
-	item, err := source.PrepareRename(ctx, r.view, f.(source.GoFile), srcRng.Start)
+	item, err := source.PrepareRename(ctx, r.view, f, srcRng.Start)
 	if err != nil {
 		if want.Text != "" { // expected an ident.
 			t.Errorf("prepare rename failed for %v: got error: %v", src, err)
@@ -754,7 +756,7 @@ func (r *runner) Symbol(t *testing.T, uri span.URI, expectedSymbols []protocol.D
 	if err != nil {
 		t.Fatalf("failed for %v: %v", uri, err)
 	}
-	symbols, err := source.DocumentSymbols(ctx, r.view, f.(source.GoFile))
+	symbols, err := source.DocumentSymbols(ctx, r.view, f)
 	if err != nil {
 		t.Errorf("symbols failed for %s: %v", uri, err)
 	}
@@ -820,7 +822,7 @@ func (r *runner) SignatureHelp(t *testing.T, spn span.Span, expectedSignature *s
 	if err != nil {
 		t.Fatal(err)
 	}
-	gotSignature, err := source.SignatureHelp(ctx, r.view, f.(source.GoFile), rng.Start)
+	gotSignature, err := source.SignatureHelp(ctx, r.view, f, rng.Start)
 	if err != nil {
 		// Only fail if we got an error we did not expect.
 		if expectedSignature != nil {
diff --git a/internal/lsp/source/symbols.go b/internal/lsp/source/symbols.go
index 5d58b372e2..5f249b4fb3 100644
--- a/internal/lsp/source/symbols.go
+++ b/internal/lsp/source/symbols.go
@@ -14,11 +14,11 @@ import (
 	"golang.org/x/tools/internal/telemetry/trace"
 )
 
-func DocumentSymbols(ctx context.Context, view View, f GoFile) ([]protocol.DocumentSymbol, error) {
+func DocumentSymbols(ctx context.Context, view View, f File) ([]protocol.DocumentSymbol, error) {
 	ctx, done := trace.StartSpan(ctx, "source.DocumentSymbols")
 	defer done()
 
-	cphs, err := f.CheckPackageHandles(ctx)
+	_, cphs, err := view.CheckPackageHandles(ctx, f)
 	if err != nil {
 		return nil, err
 	}
diff --git a/internal/lsp/source/util.go b/internal/lsp/source/util.go
index 238821f748..c65b8705c3 100644
--- a/internal/lsp/source/util.go
+++ b/internal/lsp/source/util.go
@@ -91,7 +91,7 @@ func IsGenerated(ctx context.Context, view View, uri span.URI) bool {
 	if err != nil {
 		return false
 	}
-	ph := view.Session().Cache().ParseGoHandle(f.Handle(ctx), ParseHeader)
+	ph := view.Session().Cache().ParseGoHandle(view.Snapshot().Handle(ctx, f), ParseHeader)
 	parsed, _, _, err := ph.Parse(ctx)
 	if err != nil {
 		return false
diff --git a/internal/lsp/source/view.go b/internal/lsp/source/view.go
index 77556afc53..90bd1f069b 100644
--- a/internal/lsp/source/view.go
+++ b/internal/lsp/source/view.go
@@ -117,6 +117,10 @@ type CheckPackageHandle interface {
 	// Config is the *packages.Config that the package metadata was loaded with.
 	Config() *packages.Config
 
+	// Mode returns the ParseMode for all of the files in the CheckPackageHandle.
+	// The files should always have the same parse mode.
+	Mode() ParseMode
+
 	// Check returns the type-checked Package for the CheckPackageHandle.
 	Check(ctx context.Context) (Package, error)
 
@@ -240,6 +244,7 @@ type View interface {
 	// Ignore returns true if this file should be ignored by this view.
 	Ignore(span.URI) bool
 
+	// Config returns the configuration for the view.
 	Config(ctx context.Context) *packages.Config
 
 	// RunProcessEnvFunc runs fn with the process env for this view inserted into opts.
@@ -257,33 +262,28 @@ type View interface {
 	// Analyzers returns the set of Analyzers active for this view.
 	Analyzers() []*analysis.Analyzer
 
+	// CheckPackageHandles returns the CheckPackageHandles for the packages
+	// that this file belongs to.
+	CheckPackageHandles(ctx context.Context, f File) (Snapshot, []CheckPackageHandle, error)
+
 	// GetActiveReverseDeps returns the active files belonging to the reverse
 	// dependencies of this file's package.
-	GetActiveReverseDeps(ctx context.Context, uri span.URI) []CheckPackageHandle
+	GetActiveReverseDeps(ctx context.Context, f File) []CheckPackageHandle
+
+	// Snapshot returns the current snapshot for the view.
+	Snapshot() Snapshot
+}
+
+// Snapshot represents the current state for the given view.
+type Snapshot interface {
+	// Handle returns the FileHandle for the given file.
+	Handle(ctx context.Context, f File) FileHandle
 }
 
 // File represents a source file of any type.
 type File interface {
 	URI() span.URI
-	View() View
-	Handle(ctx context.Context) FileHandle
-}
-
-// GoFile represents a Go source file that has been type-checked.
-type GoFile interface {
-	File
-
-	// GetCheckPackageHandles returns the CheckPackageHandles for the packages
-	// that this file belongs to.
-	CheckPackageHandles(ctx context.Context) ([]CheckPackageHandle, error)
-}
-
-type ModFile interface {
-	File
-}
-
-type SumFile interface {
-	File
+	Kind() FileKind
 }
 
 // Package represents a Go package that has been type-checked. It maintains
diff --git a/internal/lsp/symbols.go b/internal/lsp/symbols.go
index addbe443e0..66f1654e68 100644
--- a/internal/lsp/symbols.go
+++ b/internal/lsp/symbols.go
@@ -19,7 +19,7 @@ func (s *Server) documentSymbol(ctx context.Context, params *protocol.DocumentSy
 
 	uri := span.NewURI(params.TextDocument.URI)
 	view := s.session.ViewOf(uri)
-	f, err := getGoFile(ctx, view, uri)
+	f, err := view.GetFile(ctx, uri)
 	if err != nil {
 		return nil, err
 	}
diff --git a/internal/lsp/text_synchronization.go b/internal/lsp/text_synchronization.go
index 201b1423b3..303f66f41f 100644
--- a/internal/lsp/text_synchronization.go
+++ b/internal/lsp/text_synchronization.go
@@ -136,7 +136,7 @@ func (s *Server) didSave(ctx context.Context, params *protocol.DidSaveTextDocume
 
 func (s *Server) didClose(ctx context.Context, params *protocol.DidCloseTextDocumentParams) error {
 	uri := span.NewURI(params.TextDocument.URI)
-	ctx = telemetry.File.With(ctx, uri)
+	ctx = telemetry.URI.With(ctx, uri)
 	s.session.DidClose(uri)
 	view := s.session.ViewOf(uri)
 	if _, err := view.SetContent(ctx, uri, nil); err != nil {
@@ -154,18 +154,11 @@ func (s *Server) didClose(ctx context.Context, params *protocol.DidCloseTextDocu
 	// clear out all diagnostics for the package.
 	f, err := view.GetFile(ctx, uri)
 	if err != nil {
-		log.Error(ctx, "no file for %s: %v", err, telemetry.File)
-		return nil
+		log.Error(ctx, "no file", err, telemetry.URI)
 	}
-	// For non-Go files, don't return any diagnostics.
-	gof, ok := f.(source.GoFile)
-	if !ok {
-		log.Error(ctx, "closing a non-Go file, no diagnostics to clear", nil, telemetry.File)
-		return nil
-	}
-	cphs, err := gof.CheckPackageHandles(ctx)
+	_, cphs, err := view.CheckPackageHandles(ctx, f)
 	if err != nil {
-		log.Error(ctx, "no CheckPackageHandles", err, telemetry.URI.Of(gof.URI()))
+		log.Error(ctx, "no CheckPackageHandles", err, telemetry.URI.Of(uri))
 		return nil
 	}
 	for _, cph := range cphs {
diff --git a/internal/lsp/util.go b/internal/lsp/util.go
deleted file mode 100644
index 60323b1ebd..0000000000
--- a/internal/lsp/util.go
+++ /dev/null
@@ -1,25 +0,0 @@
-// Copyright 2019 The Go Authors. All rights reserved.
-// Use of this source code is governed by a BSD-style
-// license that can be found in the LICENSE file.
-
-package lsp
-
-import (
-	"context"
-
-	"golang.org/x/tools/internal/lsp/source"
-	"golang.org/x/tools/internal/span"
-	errors "golang.org/x/xerrors"
-)
-
-func getGoFile(ctx context.Context, view source.View, uri span.URI) (source.GoFile, error) {
-	f, err := view.GetFile(ctx, uri)
-	if err != nil {
-		return nil, err
-	}
-	gof, ok := f.(source.GoFile)
-	if !ok {
-		return nil, errors.Errorf("%s is not a Go file", uri)
-	}
-	return gof, nil
-}
diff --git a/internal/lsp/watched_files.go b/internal/lsp/watched_files.go
index 281b7ab796..a923afeeda 100644
--- a/internal/lsp/watched_files.go
+++ b/internal/lsp/watched_files.go
@@ -27,10 +27,10 @@ func (s *Server) didChangeWatchedFiles(ctx context.Context, params *protocol.Did
 		ctx := telemetry.File.With(ctx, uri)
 
 		for _, view := range s.session.Views() {
-			gof, _ := view.FindFile(ctx, uri).(source.GoFile)
+			f := view.FindFile(ctx, uri)
 
 			// If we have never seen this file before, there is nothing to do.
-			if gof == nil {
+			if f == nil {
 				continue
 			}
 
@@ -53,14 +53,14 @@ func (s *Server) didChangeWatchedFiles(ctx context.Context, params *protocol.Did
 			case protocol.Deleted:
 				log.Print(ctx, "watched file deleted", telemetry.File)
 
-				cphs, err := gof.CheckPackageHandles(ctx)
+				_, cphs, err := view.CheckPackageHandles(ctx, f)
 				if err != nil {
 					log.Error(ctx, "didChangeWatchedFiles: GetPackage", err, telemetry.File)
 					continue
 				}
 				// Find a different file in the same package we can use to trigger diagnostics.
 				// TODO(rstambler): Allow diagnostics to be called per-package to avoid this.
-				var otherFile source.GoFile
+				var otherFile source.File
 				sort.Slice(cphs, func(i, j int) bool {
 					return len(cphs[i].Files()) > len(cphs[j].Files())
 				})
@@ -69,10 +69,10 @@ func (s *Server) didChangeWatchedFiles(ctx context.Context, params *protocol.Did
 						continue
 					}
 					ident := ph.File().Identity()
-					if ident.URI == gof.URI() {
+					if ident.URI == f.URI() {
 						continue
 					}
-					otherFile, _ = view.FindFile(ctx, ident.URI).(source.GoFile)
+					otherFile := view.FindFile(ctx, ident.URI)
 					if otherFile != nil {
 						break
 					}