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cmd/go: make module index loading O(1)

Browse Source 
For a large module, opening the index was populating tables with
entries for every package in the module. If we are only using a small
number of those packages, this is wasted work that can dwarf the
benefit from the index.

This CL changes the index reader to avoid loading all packages
at module index open time. It also refactors the code somewhat
for clarity.

It also removes some duplication by defining that a per-package
index is a per-module index containing a single package, rather
than having two different formats and two different decoders.

It also changes the string table to use uvarint-prefixed data
instead of having to scan for a NUL byte. This makes random access
to long strings more efficient - O(1) instead of O(n) - and can significantly
speed up the strings.Compare operation in the binary search looking
for a given package.

Also add a direct test of the indexing code.

For #53577.

Change-Id: I7428d28133e4e7fe2d2993fa014896cd15af48af
Reviewed-on: https://go-review.googlesource.com/c/go/+/416178
Reviewed-by: Bryan Mills <bcmills@google.com>
This commit is contained in:
Russ Cox 2022-07-06 09:49:32 -04:00
parent b8bf820d5d
commit 7510e597de
4 changed files with 356 additions and 304 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

87
src/cmd/go/internal/modindex/index_test.go Normal file
View File

@ -0,0 +1,87 @@
// Copyright 2022 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 modindex
import (
"encoding/hex"
"encoding/json"
"go/build"
"internal/diff"
"path/filepath"
"reflect"
"runtime"
"testing"
)
func init() {
isTest = true
enabled = true // to allow GODEBUG=goindex=0 go test, when things are very broken
}
func TestIndex(t *testing.T) {
src := filepath.Join(runtime.GOROOT(), "src")
checkPkg := func(t *testing.T, m *Module, pkg string, data []byte) {
p := m.Package(pkg)
bp, err := p.Import(build.Default, build.ImportComment)
if err != nil {
t.Fatal(err)
}
bp1, err := build.Default.Import(pkg, filepath.Join(src, pkg), build.ImportComment)
if err != nil {
t.Fatal(err)
}
if !reflect.DeepEqual(bp, bp1) {
t.Errorf("mismatch")
t.Logf("index:\n%s", hex.Dump(data))
js, err := json.MarshalIndent(bp, "", "\t")
if err != nil {
t.Fatal(err)
}
js1, err := json.MarshalIndent(bp1, "", "\t")
if err != nil {
t.Fatal(err)
}
t.Logf("diff:\n%s", diff.Diff("index", js, "correct", js1))
t.FailNow()
}
}
// Check packages in increasing complexity, one at a time.
pkgs := []string{
"crypto",
"encoding",
"unsafe",
"encoding/json",
"runtime",
"net",
}
var raws []*rawPackage
for _, pkg := range pkgs {
raw := importRaw(src, pkg)
raws = append(raws, raw)
t.Run(pkg, func(t *testing.T) {
data := encodeModuleBytes([]*rawPackage{raw})
m, err := fromBytes(src, data)
if err != nil {
t.Fatal(err)
}
checkPkg(t, m, pkg, data)
})
}
// Check that a multi-package index works too.
t.Run("all", func(t *testing.T) {
data := encodeModuleBytes(raws)
m, err := fromBytes(src, data)
if err != nil {
t.Fatal(err)
}
for _, pkg := range pkgs {
checkPkg(t, m, pkg, data)
}
})
}

510
src/cmd/go/internal/modindex/read.go
View File

@ -15,7 +15,6 @@ import (
"internal/godebug"
"internal/goroot"
"internal/unsafeheader"
"math"
"path"
"path/filepath"
"runtime"
@ -46,9 +45,8 @@ var enabled bool = godebug.Get("goindex") != "0"
// questions based on the index file's data.
type Module struct {
modroot string
od offsetDecoder
packages map[string]int // offsets of each package
packagePaths []string // paths to package directories relative to modroot; these are the keys of packages
d *decoder
n int // number of packages
}
// moduleHash returns an ActionID corresponding to the state of the module
@ -236,110 +234,131 @@ func openIndexPackage(modroot, pkgdir string) (*IndexPackage, error) {
return r.pkg, r.err
}
var errCorrupt = errors.New("corrupt index")
// protect marks the start of a large section of code that accesses the index.
// It should be used as:
//
// defer unprotect(protect, &err)
//
// It should not be used for trivial accesses which would be
// dwarfed by the overhead of the defer.
func protect() bool {
return debug.SetPanicOnFault(true)
}
var isTest = false
// unprotect marks the end of a large section of code that accesses the index.
// It should be used as:
//
// defer unprotect(protect, &err)
//
// end looks for panics due to errCorrupt or bad mmap accesses.
// When it finds them, it adds explanatory text, consumes the panic, and sets *errp instead.
// If errp is nil, end adds the explanatory text but then calls base.Fatalf.
func unprotect(old bool, errp *error) {
// SetPanicOnFault's errors _may_ satisfy this interface. Even though it's not guaranteed
// that all its errors satisfy this interface, we'll only check for these errors so that
// we don't suppress panics that could have been produced from other sources.
type addrer interface {
Addr() uintptr
}
debug.SetPanicOnFault(old)
if e := recover(); e != nil {
if _, ok := e.(addrer); ok || e == errCorrupt {
// This panic was almost certainly caused by SetPanicOnFault or our panic(errCorrupt).
err := fmt.Errorf("error reading module index: %v", e)
if errp != nil {
*errp = err
return
}
if isTest {
panic(err)
}
base.Fatalf("%v", err)
}
// The panic was likely not caused by SetPanicOnFault.
panic(e)
}
}
// fromBytes returns a *Module given the encoded representation.
func fromBytes(moddir string, data []byte) (mi *Module, err error) {
func fromBytes(moddir string, data []byte) (m *Module, err error) {
if !enabled {
panic("use of index")
}
// SetPanicOnFault's errors _may_ satisfy this interface. Even though it's not guaranteed
// that all its errors satisfy this interface, we'll only check for these errors so that
// we don't suppress panics that could have been produced from other sources.
type addrer interface {
Addr() uintptr
defer unprotect(protect(), &err)
if !bytes.HasPrefix(data, []byte(indexVersion+"\n")) {
return nil, errCorrupt
}
// set PanicOnFault to true so that we can catch errors on the initial reads of the slice,
// in case it's mmapped (the common case).
old := debug.SetPanicOnFault(true)
defer func() {
debug.SetPanicOnFault(old)
if e := recover(); e != nil {
if _, ok := e.(addrer); ok {
// This panic was almost certainly caused by SetPanicOnFault.
err = fmt.Errorf("error reading module index: %v", e)
return
const hdr = len(indexVersion + "\n")
d := &decoder{data: data}
str := d.intAt(hdr)
if str < hdr+8 || len(d.data) < str {
return nil, errCorrupt
}
// The panic was likely not caused by SetPanicOnFault.
panic(e)
}
}()
gotVersion, unread, _ := bytes.Cut(data, []byte{'\n'})
if string(gotVersion) != indexVersion {
return nil, fmt.Errorf("bad index version string: %q", gotVersion)
}
stringTableOffset, unread := binary.LittleEndian.Uint32(unread[:4]), unread[4:]
st := newStringTable(data[stringTableOffset:])
d := decoder{unread, st}
numPackages := d.int()
packagePaths := make([]string, numPackages)
for i := range packagePaths {
packagePaths[i] = d.string()
}
packageOffsets := make([]int, numPackages)
for i := range packageOffsets {
packageOffsets[i] = d.int()
}
packages := make(map[string]int, numPackages)
for i := range packagePaths {
packages[packagePaths[i]] = packageOffsets[i]
d.data, d.str = data[:str], d.data[str:]
// Check that string table looks valid.
// First string is empty string (length 0),
// and we leave a marker byte 0xFF at the end
// just to make sure that the file is not truncated.
if len(d.str) == 0 || d.str[0] != 0 || d.str[len(d.str)-1] != 0xFF {
return nil, errCorrupt
}
return &Module{
n := d.intAt(hdr + 4)
if n < 0 || n > (len(d.data)-8)/8 {
return nil, errCorrupt
}
m = &Module{
moddir,
offsetDecoder{data, st},
packages,
packagePaths,
}, nil
d,
n,
}
return m, nil
}
// packageFromBytes returns a *IndexPackage given the encoded representation.
func packageFromBytes(modroot string, data []byte) (p *IndexPackage, err error) {
if !enabled {
panic("use of package index when not enabled")
m, err := fromBytes(modroot, data)
if err != nil {
return nil, err
}
if m.n != 1 {
return nil, fmt.Errorf("corrupt single-package index")
}
return m.pkg(0), nil
}
// SetPanicOnFault's errors _may_ satisfy this interface. Even though it's not guaranteed
// that all its errors satisfy this interface, we'll only check for these errors so that
// we don't suppress panics that could have been produced from other sources.
type addrer interface {
Addr() uintptr
// pkgDir returns the dir string of the i'th package in the index.
func (m *Module) pkgDir(i int) string {
if i < 0 || i >= m.n {
panic(errCorrupt)
}
return m.d.stringAt(12 + 8 + 8*i)
}
// set PanicOnFault to true so that we can catch errors on the initial reads of the slice,
// in case it's mmapped (the common case).
old := debug.SetPanicOnFault(true)
defer func() {
debug.SetPanicOnFault(old)
if e := recover(); e != nil {
if _, ok := e.(addrer); ok {
// This panic was almost certainly caused by SetPanicOnFault.
err = fmt.Errorf("error reading module index: %v", e)
return
// pkgOff returns the offset of the data for the i'th package in the index.
func (m *Module) pkgOff(i int) int {
if i < 0 || i >= m.n {
panic(errCorrupt)
}
// The panic was likely not caused by SetPanicOnFault.
panic(e)
}
}()
gotVersion, unread, _ := bytes.Cut(data, []byte{'\n'})
if string(gotVersion) != indexVersion {
return nil, fmt.Errorf("bad index version string: %q", gotVersion)
}
stringTableOffset, unread := binary.LittleEndian.Uint32(unread[:4]), unread[4:]
st := newStringTable(data[stringTableOffset:])
d := &decoder{unread, st}
p = decodePackage(d, offsetDecoder{data, st})
p.modroot = modroot
return p, nil
return m.d.intAt(12 + 8 + 8*i + 4)
}
// Returns a list of directory paths, relative to the modroot, for
// packages contained in the module index.
func (mi *Module) Packages() []string {
return mi.packagePaths
// Walk calls f for each package in the index, passing the path to that package relative to the module root.
func (m *Module) Walk(f func(path string)) {
defer unprotect(protect(), nil)
for i := 0; i < m.n; i++ {
f(m.pkgDir(i))
}
}
// relPath returns the path relative to the module's root.
@ -349,11 +368,7 @@ func relPath(path, modroot string) string {
// Import is the equivalent of build.Import given the information in Module.
func (rp *IndexPackage) Import(bctxt build.Context, mode build.ImportMode) (p *build.Package, err error) {
defer func() {
if e := recover(); e != nil {
err = fmt.Errorf("error reading module index: %v", e)
}
}()
defer unprotect(protect(), &err)
ctxt := (*Context)(&bctxt)
@ -794,46 +809,44 @@ type IndexPackage struct {
var errCannotFindPackage = errors.New("cannot find package")
// Package returns an IndexPackage constructed using the information in the Module.
func (mi *Module) Package(path string) *IndexPackage {
defer func() {
if e := recover(); e != nil {
base.Fatalf("error reading module index: %v", e)
}
}()
offset, ok := mi.packages[path]
// Package and returns finds the package with the given path (relative to the module root).
// If the package does not exist, Package returns an IndexPackage that will return an
// appropriate error from its methods.
func (m *Module) Package(path string) *IndexPackage {
defer unprotect(protect(), nil)
i, ok := sort.Find(m.n, func(i int) int {
return strings.Compare(path, m.pkgDir(i))
})
if !ok {
return &IndexPackage{error: fmt.Errorf("%w %q in:\n\t%s", errCannotFindPackage, path, filepath.Join(mi.modroot, path))}
return &IndexPackage{error: fmt.Errorf("%w %q in:\n\t%s", errCannotFindPackage, path, filepath.Join(m.modroot, path))}
}
return m.pkg(i)
}
// TODO(matloob): do we want to lock on the module index?
d := mi.od.decoderAt(offset)
p := decodePackage(d, mi.od)
p.modroot = mi.modroot
// pkgAt returns the i'th IndexPackage in m.
func (m *Module) pkg(i int) *IndexPackage {
r := m.d.readAt(m.pkgOff(i))
p := new(IndexPackage)
if errstr := r.string(); errstr != "" {
p.error = errors.New(errstr)
}
p.dir = r.string()
p.sourceFiles = make([]*sourceFile, r.int())
for i := range p.sourceFiles {
p.sourceFiles[i] = &sourceFile{
d: m.d,
pos: r.int(),
}
}
p.modroot = m.modroot
return p
}
func decodePackage(d *decoder, od offsetDecoder) *IndexPackage {
rp := new(IndexPackage)
if errstr := d.string(); errstr != "" {
rp.error = errors.New(errstr)
}
rp.dir = d.string()
numSourceFiles := d.uint32()
rp.sourceFiles = make([]*sourceFile, numSourceFiles)
for i := uint32(0); i < numSourceFiles; i++ {
offset := d.uint32()
rp.sourceFiles[i] = &sourceFile{
od: od.offsetDecoderAt(offset),
}
}
return rp
}
// sourceFile represents the information of a given source file in the module index.
type sourceFile struct {
od offsetDecoder // od interprets all offsets relative to the start of the source file's data
d *decoder // encoding of this source file
pos int // start of sourceFile encoding in d
onceReadImports sync.Once
savedImports []rawImport // saved imports so that they're only read once
}
@ -853,73 +866,67 @@ const (
)
func (sf *sourceFile) error() string {
return sf.od.stringAt(sourceFileError)
return sf.d.stringAt(sf.pos + sourceFileError)
}
func (sf *sourceFile) parseError() string {
return sf.od.stringAt(sourceFileParseError)
return sf.d.stringAt(sf.pos + sourceFileParseError)
}
func (sf *sourceFile) synopsis() string {
return sf.od.stringAt(sourceFileSynopsis)
return sf.d.stringAt(sf.pos + sourceFileSynopsis)
}
func (sf *sourceFile) name() string {
return sf.od.stringAt(sourceFileName)
return sf.d.stringAt(sf.pos + sourceFileName)
}
func (sf *sourceFile) pkgName() string {
return sf.od.stringAt(sourceFilePkgName)
return sf.d.stringAt(sf.pos + sourceFilePkgName)
}
func (sf *sourceFile) ignoreFile() bool {
return sf.od.boolAt(sourceFileIgnoreFile)
return sf.d.boolAt(sf.pos + sourceFileIgnoreFile)
}
func (sf *sourceFile) binaryOnly() bool {
return sf.od.boolAt(sourceFileBinaryOnly)
return sf.d.boolAt(sf.pos + sourceFileBinaryOnly)
}
func (sf *sourceFile) cgoDirectives() string {
return sf.od.stringAt(sourceFileCgoDirectives)
return sf.d.stringAt(sf.pos + sourceFileCgoDirectives)
}
func (sf *sourceFile) goBuildConstraint() string {
return sf.od.stringAt(sourceFileGoBuildConstraint)
return sf.d.stringAt(sf.pos + sourceFileGoBuildConstraint)
}
func (sf *sourceFile) plusBuildConstraints() []string {
d := sf.od.decoderAt(sourceFileNumPlusBuildConstraints)
n := d.int()
pos := sf.pos + sourceFileNumPlusBuildConstraints
n := sf.d.intAt(pos)
pos += 4
ret := make([]string, n)
for i := 0; i < n; i++ {
ret[i] = d.string()
ret[i] = sf.d.stringAt(pos)
pos += 4
}
return ret
}
func importsOffset(numPlusBuildConstraints int) int {
// 4 bytes per uin32, add one to advance past numPlusBuildConstraints itself
return sourceFileNumPlusBuildConstraints + 4*(numPlusBuildConstraints+1)
}
func (sf *sourceFile) importsOffset() int {
numPlusBuildConstraints := sf.od.intAt(sourceFileNumPlusBuildConstraints)
return importsOffset(numPlusBuildConstraints)
}
func embedsOffset(importsOffset, numImports int) int {
// 4 bytes per uint32; 1 to advance past numImports itself, and 5 uint32s per import
return importsOffset + 4*(1+(5*numImports))
pos := sf.pos + sourceFileNumPlusBuildConstraints
n := sf.d.intAt(pos)
// each build constraint is 1 uint32
return pos + 4 + n*4
}
func (sf *sourceFile) embedsOffset() int {
importsOffset := sf.importsOffset()
numImports := sf.od.intAt(importsOffset)
return embedsOffset(importsOffset, numImports)
pos := sf.importsOffset()
n := sf.d.intAt(pos)
// each import is 5 uint32s (string + tokpos)
return pos + 4 + n*(4*5)
}
func (sf *sourceFile) imports() []rawImport {
sf.onceReadImports.Do(func() {
importsOffset := sf.importsOffset()
d := sf.od.decoderAt(importsOffset)
numImports := d.int()
r := sf.d.readAt(importsOffset)
numImports := r.int()
ret := make([]rawImport, numImports)
for i := 0; i < numImports; i++ {
ret[i].path = d.string()
ret[i].position = d.tokpos()
ret[i] = rawImport{r.string(), r.tokpos()}
}
sf.savedImports = ret
})
@ -928,125 +935,15 @@ func (sf *sourceFile) imports() []rawImport {
func (sf *sourceFile) embeds() []embed {
embedsOffset := sf.embedsOffset()
d := sf.od.decoderAt(embedsOffset)
numEmbeds := d.int()
r := sf.d.readAt(embedsOffset)
numEmbeds := r.int()
ret := make([]embed, numEmbeds)
for i := range ret {
pattern := d.string()
pos := d.tokpos()
ret[i] = embed{pattern, pos}
ret[i] = embed{r.string(), r.tokpos()}
}
return ret
}
// A decoder reads from the current position of the file and advances its position as it
// reads.
type decoder struct {
b []byte
st *stringTable
}
func (d *decoder) uint32() uint32 {
n := binary.LittleEndian.Uint32(d.b[:4])
d.b = d.b[4:]
return n
}
func (d *decoder) int() int {
n := d.uint32()
if int64(n) > math.MaxInt {
base.Fatalf("go: attempting to read a uint32 from the index that overflows int")
}
return int(n)
}
func (d *decoder) tokpos() token.Position {
file := d.string()
offset := d.int()
line := d.int()
column := d.int()
return token.Position{
Filename: file,
Offset: offset,
Line: line,
Column: column,
}
}
func (d *decoder) string() string {
return d.st.string(d.int())
}
// And offset decoder reads information offset from its position in the file.
// It's either offset from the beginning of the index, or the beginning of a sourceFile's data.
type offsetDecoder struct {
b []byte
st *stringTable
}
func (od *offsetDecoder) uint32At(offset int) uint32 {
if offset > len(od.b) {
base.Fatalf("go: trying to read from index file at offset higher than file length. This indicates a corrupt offset file in the cache.")
}
return binary.LittleEndian.Uint32(od.b[offset:])
}
func (od *offsetDecoder) intAt(offset int) int {
n := od.uint32At(offset)
if int64(n) > math.MaxInt {
base.Fatalf("go: attempting to read a uint32 from the index that overflows int")
}
return int(n)
}
func (od *offsetDecoder) boolAt(offset int) bool {
switch v := od.uint32At(offset); v {
case 0:
return false
case 1:
return true
default:
base.Fatalf("go: invalid bool value in index file encoding: %v", v)
}
panic("unreachable")
}
func (od *offsetDecoder) stringAt(offset int) string {
return od.st.string(od.intAt(offset))
}
func (od *offsetDecoder) decoderAt(offset int) *decoder {
return &decoder{od.b[offset:], od.st}
}
func (od *offsetDecoder) offsetDecoderAt(offset uint32) offsetDecoder {
return offsetDecoder{od.b[offset:], od.st}
}
type stringTable struct {
b []byte
}
func newStringTable(b []byte) *stringTable {
return &stringTable{b: b}
}
func (st *stringTable) string(pos int) string {
if pos == 0 {
return ""
}
bb := st.b[pos:]
i := bytes.IndexByte(bb, 0)
if i == -1 {
panic("reached end of string table trying to read string")
}
s := asString(bb[:i])
return s
}
func asString(b []byte) string {
p := (*unsafeheader.Slice)(unsafe.Pointer(&b)).Data
@ -1057,3 +954,82 @@ func asString(b []byte) string {
return s
}
// A decoder helps decode the index format.
type decoder struct {
data []byte // data after header
str []byte // string table
}
// intAt returns the int at the given offset in d.data.
func (d *decoder) intAt(off int) int {
if off < 0 || len(d.data)-off < 4 {
panic(errCorrupt)
}
i := binary.LittleEndian.Uint32(d.data[off : off+4])
if int32(i)>>31 != 0 {
panic(errCorrupt)
}
return int(i)
}
// boolAt returns the bool at the given offset in d.data.
func (d *decoder) boolAt(off int) bool {
return d.intAt(off) != 0
}
// stringTableAt returns the string pointed at by the int at the given offset in d.data.
func (d *decoder) stringAt(off int) string {
return d.stringTableAt(d.intAt(off))
}
// stringTableAt returns the string at the given offset in the string table d.str.
func (d *decoder) stringTableAt(off int) string {
if off < 0 || off >= len(d.str) {
panic(errCorrupt)
}
s := d.str[off:]
v, n := binary.Uvarint(s)
if n <= 0 || v > uint64(len(s[n:])) {
panic(errCorrupt)
}
return asString(s[n : n+int(v)])
}
// A reader reads sequential fields from a section of the index format.
type reader struct {
d *decoder
pos int
}
// readAt returns a reader starting at the given position in d.
func (d *decoder) readAt(pos int) *reader {
return &reader{d, pos}
}
// int reads the next int.
func (r *reader) int() int {
i := r.d.intAt(r.pos)
r.pos += 4
return i
}
// string reads the next string.
func (r *reader) string() string {
return r.d.stringTableAt(r.int())
}
// bool reads the next bool.
func (r *reader) bool() bool {
return r.int() != 0
}
// tokpos reads the next token.Position.
func (r *reader) tokpos() token.Position {
return token.Position{
Filename: r.string(),
Offset: r.int(),
Line: r.int(),
Column: r.int(),
}
}

46
src/cmd/go/internal/modindex/write.go
View File

@ -1,54 +1,46 @@
// Copyright 2022 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 modindex
import (
"cmd/go/internal/base"
"encoding/binary"
"go/token"
"math"
"sort"
"strings"
)
const indexVersion = "go index v0"
const indexVersion = "go index v1" // 11 bytes (plus \n), to align uint32s in index
// encodeModuleBytes produces the encoded representation of the module index.
// encodeModuleBytes may modify the packages slice.
func encodeModuleBytes(packages []*rawPackage) []byte {
e := newEncoder()
e.Bytes([]byte(indexVersion))
e.Bytes([]byte{'\n'})
e.Bytes([]byte(indexVersion + "\n"))
stringTableOffsetPos := e.Pos() // fill this at the end
e.Uint32(0) // string table offset
e.Int(len(packages))
sort.Slice(packages, func(i, j int) bool {
return packages[i].dir < packages[j].dir
})
e.Int(len(packages))
packagesPos := e.Pos()
for _, p := range packages {
e.String(p.dir)
}
packagesOffsetPos := e.Pos()
for range packages {
e.Int(0)
}
for i, p := range packages {
e.IntAt(e.Pos(), packagesOffsetPos+4*i)
e.IntAt(e.Pos(), packagesPos+8*i+4)
encodePackage(e, p)
}
e.IntAt(e.Pos(), stringTableOffsetPos)
e.Bytes(e.stringTable)
e.Bytes([]byte{0xFF}) // end of string table marker
return e.b
}
func encodePackageBytes(p *rawPackage) []byte {
e := newEncoder()
e.Bytes([]byte(indexVersion))
e.Bytes([]byte{'\n'})
stringTableOffsetPos := e.Pos() // fill this at the end
e.Uint32(0) // string table offset
encodePackage(e, p)
e.IntAt(e.Pos(), stringTableOffsetPos)
e.Bytes(e.stringTable)
return e.b
return encodeModuleBytes([]*rawPackage{p})
}
func encodePackage(e *encoder, p *rawPackage) {
@ -126,9 +118,6 @@ func (e *encoder) Bytes(b []byte) {
}
func (e *encoder) String(s string) {
if strings.IndexByte(s, 0) >= 0 {
base.Fatalf("go: attempting to encode a string containing a null byte")
}
if n, ok := e.strings[s]; ok {
e.Int(n)
return
@ -136,8 +125,8 @@ func (e *encoder) String(s string) {
pos := len(e.stringTable)
e.strings[s] = pos
e.Int(pos)
e.stringTable = binary.AppendUvarint(e.stringTable, uint64(len(s)))
e.stringTable = append(e.stringTable, []byte(s)...)
e.stringTable = append(e.stringTable, 0)
}
func (e *encoder) Bool(b bool) {
@ -152,17 +141,18 @@ func (e *encoder) Uint32(n uint32) {
e.b = binary.LittleEndian.AppendUint32(e.b, n)
}
// Int encodes n. Note that all ints are written to the index as uint32s.
// Int encodes n. Note that all ints are written to the index as uint32s,
// and to avoid problems on 32-bit systems we require fitting into a 32-bit int.
func (e *encoder) Int(n int) {
if n < 0 || int64(n) > math.MaxUint32 {
base.Fatalf("go: attempting to write an int to the index that overflows uint32")
if n < 0 || int(int32(n)) != n {
base.Fatalf("go: attempting to write an int to the index that overflows int32")
}
e.Uint32(uint32(n))
}
func (e *encoder) IntAt(n int, at int) {
if n < 0 || int64(n) > math.MaxUint32 {
base.Fatalf("go: attempting to write an int to the index that overflows uint32")
if n < 0 || int(int32(n)) != n {
base.Fatalf("go: attempting to write an int to the index that overflows int32")
}
binary.LittleEndian.PutUint32(e.b[at:], uint32(n))
}

13
src/cmd/go/internal/modload/search.go
View File

@ -216,21 +216,20 @@ func matchPackages(ctx context.Context, m *search.Match, tags map[string]bool, f
// is the module's root directory on disk, index is the modindex.Module for the
// module, and importPathRoot is the module's path prefix.
func walkFromIndex(index *modindex.Module, importPathRoot string, isMatch, treeCanMatch func(string) bool, tags, have map[string]bool, addPkg func(string)) {
loopPackages:
for _, reldir := range index.Packages() {
index.Walk(func(reldir string) {
// Avoid .foo, _foo, and testdata subdirectory trees.
p := reldir
for {
elem, rest, found := strings.Cut(p, string(filepath.Separator))
if strings.HasPrefix(elem, ".") || strings.HasPrefix(elem, "_") || elem == "testdata" {
continue loopPackages
return
}
if found && elem == "vendor" {
// Ignore this path if it contains the element "vendor" anywhere
// except for the last element (packages named vendor are allowed
// for historical reasons). Note that found is true when this
// isn't the last path element.
continue loopPackages
return
}
if !found {
// Didn't find the separator, so we're considering the last element.
@ -241,12 +240,12 @@ loopPackages:
// Don't use GOROOT/src.
if reldir == "" && importPathRoot == "" {
continue
return
}
name := path.Join(importPathRoot, filepath.ToSlash(reldir))
if !treeCanMatch(name) {
continue
return
}
if !have[name] {
@ -257,7 +256,7 @@ loopPackages:
}
}
}
}
})
}
// MatchInModule identifies the packages matching the given pattern within the