TUN-7373: Streaming logs override for same actor

To help accommodate web browser interactions with websockets, when a
streaming logs session is requested for the same actor while already
serving a session for that user in a separate request, the original
request will be closed and the new request start streaming logs
instead. This should help with rogue sessions holding on for too long
with no client on the other side (before idle timeout or connection
close).

vendor/golang.org/x/tools/go/packages/packages.go

@@ -15,10 +15,12 @@ import (
 	"go/scanner"
 	"go/token"
 	"go/types"
+	"io"
 	"io/ioutil"
 	"log"
 	"os"
 	"path/filepath"
+	"runtime"
 	"strings"
 	"sync"
 	"time"
@@ -233,6 +235,11 @@ type driverResponse struct {
 	// Imports will be connected and then type and syntax information added in a
 	// later pass (see refine).
 	Packages []*Package
+
+	// GoVersion is the minor version number used by the driver
+	// (e.g. the go command on the PATH) when selecting .go files.
+	// Zero means unknown.
+	GoVersion int
 }
 
 // Load loads and returns the Go packages named by the given patterns.
@@ -256,7 +263,7 @@ func Load(cfg *Config, patterns ...string) ([]*Package, error) {
 		return nil, err
 	}
 	l.sizes = response.Sizes
-	return l.refine(response.Roots, response.Packages...)
+	return l.refine(response)
 }
 
 // defaultDriver is a driver that implements go/packages' fallback behavior.
@@ -297,6 +304,9 @@ type Package struct {
 	// of the package, or while parsing or type-checking its files.
 	Errors []Error
 
+	// TypeErrors contains the subset of errors produced during type checking.
+	TypeErrors []types.Error
+
 	// GoFiles lists the absolute file paths of the package's Go source files.
 	GoFiles []string
 
@@ -532,6 +542,7 @@ type loaderPackage struct {
 	needsrc      bool  // load from source (Mode >= LoadTypes)
 	needtypes    bool  // type information is either requested or depended on
 	initial      bool  // package was matched by a pattern
+	goVersion    int   // minor version number of go command on PATH
 }
 
 // loader holds the working state of a single call to load.
@@ -618,7 +629,8 @@ func newLoader(cfg *Config) *loader {
 
 // refine connects the supplied packages into a graph and then adds type and
 // and syntax information as requested by the LoadMode.
-func (ld *loader) refine(roots []string, list ...*Package) ([]*Package, error) {
+func (ld *loader) refine(response *driverResponse) ([]*Package, error) {
+	roots := response.Roots
 	rootMap := make(map[string]int, len(roots))
 	for i, root := range roots {
 		rootMap[root] = i
@@ -626,7 +638,7 @@ func (ld *loader) refine(roots []string, list ...*Package) ([]*Package, error) {
 	ld.pkgs = make(map[string]*loaderPackage)
 	// first pass, fixup and build the map and roots
 	var initial = make([]*loaderPackage, len(roots))
-	for _, pkg := range list {
+	for _, pkg := range response.Packages {
 		rootIndex := -1
 		if i, found := rootMap[pkg.ID]; found {
 			rootIndex = i
@@ -648,6 +660,7 @@ func (ld *loader) refine(roots []string, list ...*Package) ([]*Package, error) {
 			Package:   pkg,
 			needtypes: needtypes,
 			needsrc:   needsrc,
+			goVersion: response.GoVersion,
 		}
 		ld.pkgs[lpkg.ID] = lpkg
 		if rootIndex >= 0 {
@@ -865,12 +878,19 @@ func (ld *loader) loadPackage(lpkg *loaderPackage) {
 	// never has to create a types.Package for an indirect dependency,
 	// which would then require that such created packages be explicitly
 	// inserted back into the Import graph as a final step after export data loading.
+	// (Hence this return is after the Types assignment.)
 	// The Diamond test exercises this case.
 	if !lpkg.needtypes && !lpkg.needsrc {
 		return
 	}
 	if !lpkg.needsrc {
-		ld.loadFromExportData(lpkg)
+		if err := ld.loadFromExportData(lpkg); err != nil {
+			lpkg.Errors = append(lpkg.Errors, Error{
+				Pos:  "-",
+				Msg:  err.Error(),
+				Kind: UnknownError, // e.g. can't find/open/parse export data
+			})
+		}
 		return // not a source package, don't get syntax trees
 	}
 
@@ -902,6 +922,7 @@ func (ld *loader) loadPackage(lpkg *loaderPackage) {
 
 		case types.Error:
 			// from type checker
+			lpkg.TypeErrors = append(lpkg.TypeErrors, err)
 			errs = append(errs, Error{
 				Pos:  err.Fset.Position(err.Pos).String(),
 				Msg:  err.Msg,
@@ -923,11 +944,41 @@ func (ld *loader) loadPackage(lpkg *loaderPackage) {
 		lpkg.Errors = append(lpkg.Errors, errs...)
 	}
 
+	// If the go command on the PATH is newer than the runtime,
+	// then the go/{scanner,ast,parser,types} packages from the
+	// standard library may be unable to process the files
+	// selected by go list.
+	//
+	// There is currently no way to downgrade the effective
+	// version of the go command (see issue 52078), so we proceed
+	// with the newer go command but, in case of parse or type
+	// errors, we emit an additional diagnostic.
+	//
+	// See:
+	// - golang.org/issue/52078 (flag to set release tags)
+	// - golang.org/issue/50825 (gopls legacy version support)
+	// - golang.org/issue/55883 (go/packages confusing error)
+	//
+	// Should we assert a hard minimum of (currently) go1.16 here?
+	var runtimeVersion int
+	if _, err := fmt.Sscanf(runtime.Version(), "go1.%d", &runtimeVersion); err == nil && runtimeVersion < lpkg.goVersion {
+		defer func() {
+			if len(lpkg.Errors) > 0 {
+				appendError(Error{
+					Pos:  "-",
+					Msg:  fmt.Sprintf("This application uses version go1.%d of the source-processing packages but runs version go1.%d of 'go list'. It may fail to process source files that rely on newer language features. If so, rebuild the application using a newer version of Go.", runtimeVersion, lpkg.goVersion),
+					Kind: UnknownError,
+				})
+			}
+		}()
+	}
+
 	if ld.Config.Mode&NeedTypes != 0 && len(lpkg.CompiledGoFiles) == 0 && lpkg.ExportFile != "" {
 		// The config requested loading sources and types, but sources are missing.
 		// Add an error to the package and fall back to loading from export data.
 		appendError(Error{"-", fmt.Sprintf("sources missing for package %s", lpkg.ID), ParseError})
-		ld.loadFromExportData(lpkg)
+		_ = ld.loadFromExportData(lpkg) // ignore any secondary errors
+
 		return // can't get syntax trees for this package
 	}
 
@@ -981,7 +1032,7 @@ func (ld *loader) loadPackage(lpkg *loaderPackage) {
 	tc := &types.Config{
 		Importer: importer,
 
-		// Type-check bodies of functions only in non-initial packages.
+		// Type-check bodies of functions only in initial packages.
 		// Example: for import graph A->B->C and initial packages {A,C},
 		// we can ignore function bodies in B.
 		IgnoreFuncBodies: ld.Mode&NeedDeps == 0 && !lpkg.initial,
@@ -1151,9 +1202,10 @@ func sameFile(x, y string) bool {
 	return false
 }
 
-// loadFromExportData returns type information for the specified
+// loadFromExportData ensures that type information is present for the specified
 // package, loading it from an export data file on the first request.
-func (ld *loader) loadFromExportData(lpkg *loaderPackage) (*types.Package, error) {
+// On success it sets lpkg.Types to a new Package.
+func (ld *loader) loadFromExportData(lpkg *loaderPackage) error {
 	if lpkg.PkgPath == "" {
 		log.Fatalf("internal error: Package %s has no PkgPath", lpkg)
 	}
@@ -1164,8 +1216,8 @@ func (ld *loader) loadFromExportData(lpkg *loaderPackage) (*types.Package, error
 	// must be sequential. (Finer-grained locking would require
 	// changes to the gcexportdata API.)
 	//
-	// The exportMu lock guards the Package.Pkg field and the
-	// types.Package it points to, for each Package in the graph.
+	// The exportMu lock guards the lpkg.Types field and the
+	// types.Package it points to, for each loaderPackage in the graph.
 	//
 	// Not all accesses to Package.Pkg need to be protected by exportMu:
 	// graph ordering ensures that direct dependencies of source
@@ -1174,18 +1226,18 @@ func (ld *loader) loadFromExportData(lpkg *loaderPackage) (*types.Package, error
 	defer ld.exportMu.Unlock()
 
 	if tpkg := lpkg.Types; tpkg != nil && tpkg.Complete() {
-		return tpkg, nil // cache hit
+		return nil // cache hit
 	}
 
 	lpkg.IllTyped = true // fail safe
 
 	if lpkg.ExportFile == "" {
 		// Errors while building export data will have been printed to stderr.
-		return nil, fmt.Errorf("no export data file")
+		return fmt.Errorf("no export data file")
 	}
 	f, err := os.Open(lpkg.ExportFile)
 	if err != nil {
-		return nil, err
+		return err
 	}
 	defer f.Close()
 
@@ -1197,7 +1249,7 @@ func (ld *loader) loadFromExportData(lpkg *loaderPackage) (*types.Package, error
 	// queries.)
 	r, err := gcexportdata.NewReader(f)
 	if err != nil {
-		return nil, fmt.Errorf("reading %s: %v", lpkg.ExportFile, err)
+		return fmt.Errorf("reading %s: %v", lpkg.ExportFile, err)
 	}
 
 	// Build the view.
@@ -1241,7 +1293,7 @@ func (ld *loader) loadFromExportData(lpkg *loaderPackage) (*types.Package, error
 	// (May modify incomplete packages in view but not create new ones.)
 	tpkg, err := gcexportdata.Read(r, ld.Fset, view, lpkg.PkgPath)
 	if err != nil {
-		return nil, fmt.Errorf("reading %s: %v", lpkg.ExportFile, err)
+		return fmt.Errorf("reading %s: %v", lpkg.ExportFile, err)
 	}
 	if _, ok := view["go.shape"]; ok {
 		// Account for the pseudopackage "go.shape" that gets
@@ -1254,8 +1306,7 @@ func (ld *loader) loadFromExportData(lpkg *loaderPackage) (*types.Package, error
 
 	lpkg.Types = tpkg
 	lpkg.IllTyped = false
-
-	return tpkg, nil
+	return nil
 }
 
 // impliedLoadMode returns loadMode with its dependencies.
@@ -1271,3 +1322,5 @@ func impliedLoadMode(loadMode LoadMode) LoadMode {
 func usesExportData(cfg *Config) bool {
 	return cfg.Mode&NeedExportFile != 0 || cfg.Mode&NeedTypes != 0 && cfg.Mode&NeedDeps == 0
 }
+
+var _ interface{} = io.Discard // assert build toolchain is go1.16 or later