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txn_writer.go
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/
txn_writer.go
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// Copyright 2016 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 dep
import (
"bytes"
"encoding/hex"
"fmt"
"io/ioutil"
"os"
"path/filepath"
"sort"
"strings"
"github.com/pelletier/go-toml"
"github.com/pkg/errors"
"github.com/golang/dep/gps"
)
// SafeWriter transactionalizes writes of manifest, lock, and vendor dir, both
// individually and in any combination, into a pseudo-atomic action with
// transactional rollback.
//
// It is not impervious to errors (writing to disk is hard), but it should
// guard against non-arcane failure conditions.
type SafeWriter struct {
Payload *SafeWriterPayload
}
// SafeWriterPayload represents the actions SafeWriter will execute when SafeWriter.Write is called.
type SafeWriterPayload struct {
Manifest *Manifest
Lock *Lock
LockDiff *LockDiff
WriteVendor bool
}
func (payload *SafeWriterPayload) HasLock() bool {
return payload.Lock != nil
}
func (payload *SafeWriterPayload) HasManifest() bool {
return payload.Manifest != nil
}
func (payload *SafeWriterPayload) HasVendor() bool {
return payload.WriteVendor
}
// LockDiff is the set of differences between an existing lock file and an updated lock file.
// Fields are only populated when there is a difference, otherwise they are empty.
// TODO(carolynvs) this should be moved to gps
type LockDiff struct {
HashDiff *StringDiff
Add []LockedProjectDiff
Remove []LockedProjectDiff
Modify []LockedProjectDiff
}
type rawLockedProjectDiffs struct {
Projects []LockedProjectDiff `toml:"projects"`
}
func (diff *LockDiff) Format() (string, error) {
if diff == nil {
return "", nil
}
var buf bytes.Buffer
if diff.HashDiff != nil {
buf.WriteString(fmt.Sprintf("Memo: %s\n\n", diff.HashDiff))
}
writeDiffs := func(diffs []LockedProjectDiff) error {
raw := rawLockedProjectDiffs{diffs}
chunk, err := toml.Marshal(raw)
if err != nil {
return err
}
buf.Write(chunk)
buf.WriteString("\n")
return nil
}
if len(diff.Add) > 0 {
buf.WriteString("Add:")
err := writeDiffs(diff.Add)
if err != nil {
return "", errors.Wrap(err, "Unable to format LockDiff.Add")
}
}
if len(diff.Remove) > 0 {
buf.WriteString("Remove:")
err := writeDiffs(diff.Remove)
if err != nil {
return "", errors.Wrap(err, "Unable to format LockDiff.Remove")
}
}
if len(diff.Modify) > 0 {
buf.WriteString("Modify:")
err := writeDiffs(diff.Modify)
if err != nil {
return "", errors.Wrap(err, "Unable to format LockDiff.Modify")
}
}
return buf.String(), nil
}
// LockedProjectDiff contains the before and after snapshot of a project reference.
// Fields are only populated when there is a difference, otherwise they are empty.
// TODO(carolynvs) this should be moved to gps
type LockedProjectDiff struct {
Name gps.ProjectRoot `toml:"name"`
Source *StringDiff `toml:"source,omitempty"`
Version *StringDiff `toml:"version,omitempty"`
Branch *StringDiff `toml:"branch,omitempty"`
Revision *StringDiff `toml:"revision,omitempty"`
Packages []StringDiff `toml:"packages,omitempty"`
}
type StringDiff struct {
Previous string
Current string
}
func (diff StringDiff) String() string {
if diff.Previous == "" && diff.Current != "" {
return fmt.Sprintf("+ %s", diff.Current)
}
if diff.Previous != "" && diff.Current == "" {
return fmt.Sprintf("- %s", diff.Previous)
}
if diff.Previous != diff.Current {
return fmt.Sprintf("%s -> %s", diff.Previous, diff.Current)
}
return diff.Current
}
func (diff StringDiff) MarshalTOML() ([]byte, error) {
return []byte(diff.String()), nil
}
// VendorBehavior defines when the vendor directory should be written.
type VendorBehavior int
const (
// VendorOnChanged indicates that the vendor directory should be written when the lock is new or changed.
VendorOnChanged VendorBehavior = iota
// VendorAlways forces the vendor directory to always be written.
VendorAlways
// VendorNever indicates the vendor directory should never be written.
VendorNever
)
// Prepare to write a set of config yaml, lock and vendor tree.
//
// - If manifest is provided, it will be written to the standard manifest file
// name beneath root.
// - If newLock is provided, it will be written to the standard lock file
// name beneath root.
// - If vendor is VendorAlways, or is VendorOnChanged and the locks are different,
// the vendor directory will be written beneath root based on newLock.
// - If oldLock is provided without newLock, error.
// - If vendor is VendorAlways without a newLock, error.
func (sw *SafeWriter) Prepare(manifest *Manifest, oldLock, newLock *Lock, vendor VendorBehavior) error {
sw.Payload = &SafeWriterPayload{
Manifest: manifest,
Lock: newLock,
}
if oldLock != nil {
if newLock == nil {
return errors.New("must provide newLock when oldLock is specified")
}
sw.Payload.LockDiff = diffLocks(oldLock, newLock)
}
switch vendor {
case VendorAlways:
sw.Payload.WriteVendor = true
case VendorOnChanged:
if sw.Payload.LockDiff != nil || (newLock != nil && oldLock == nil) {
sw.Payload.WriteVendor = true
}
}
if sw.Payload.WriteVendor && newLock == nil {
return errors.New("must provide newLock in order to write out vendor")
}
return nil
}
func (payload SafeWriterPayload) validate(root string, sm gps.SourceManager) error {
if root == "" {
return errors.New("root path must be non-empty")
}
if is, err := IsDir(root); !is {
if err != nil {
return err
}
return errors.Errorf("root path %q does not exist", root)
}
if payload.HasVendor() && sm == nil {
return errors.New("must provide a SourceManager if writing out a vendor dir")
}
return nil
}
// Write saves some combination of config yaml, lock, and a vendor tree.
// root is the absolute path of root dir in which to write.
// sm is only required if vendor is being written.
//
// It first writes to a temp dir, then moves them in place if and only if all the write
// operations succeeded. It also does its best to roll back if any moves fail.
// This mostly guarantees that dep cannot exit with a partial write that would
// leave an undefined state on disk.
func (sw *SafeWriter) Write(root string, sm gps.SourceManager) error {
if sw.Payload == nil {
return errors.New("Cannot call SafeWriter.Write before SafeWriter.Prepare")
}
err := sw.Payload.validate(root, sm)
if err != nil {
return err
}
if !sw.Payload.HasManifest() && !sw.Payload.HasLock() && !sw.Payload.HasVendor() {
// nothing to do
return nil
}
mpath := filepath.Join(root, ManifestName)
lpath := filepath.Join(root, LockName)
vpath := filepath.Join(root, "vendor")
td, err := ioutil.TempDir(os.TempDir(), "dep")
if err != nil {
return errors.Wrap(err, "error while creating temp dir for writing manifest/lock/vendor")
}
defer os.RemoveAll(td)
if sw.Payload.HasManifest() {
if err := writeFile(filepath.Join(td, ManifestName), sw.Payload.Manifest); err != nil {
return errors.Wrap(err, "failed to write manifest file to temp dir")
}
}
if sw.Payload.HasLock() {
if err := writeFile(filepath.Join(td, LockName), sw.Payload.Lock); err != nil {
return errors.Wrap(err, "failed to write lock file to temp dir")
}
}
if sw.Payload.HasVendor() {
err = gps.WriteDepTree(filepath.Join(td, "vendor"), sw.Payload.Lock, sm, true)
if err != nil {
return errors.Wrap(err, "error while writing out vendor tree")
}
}
// Move the existing files and dirs to the temp dir while we put the new
// ones in, to provide insurance against errors for as long as possible.
type pathpair struct {
from, to string
}
var restore []pathpair
var failerr error
var vendorbak string
if sw.Payload.HasManifest() {
if _, err := os.Stat(mpath); err == nil {
// Move out the old one.
tmploc := filepath.Join(td, ManifestName+".orig")
failerr = renameWithFallback(mpath, tmploc)
if failerr != nil {
goto fail
}
restore = append(restore, pathpair{from: tmploc, to: mpath})
}
// Move in the new one.
failerr = renameWithFallback(filepath.Join(td, ManifestName), mpath)
if failerr != nil {
goto fail
}
}
if sw.Payload.HasLock() {
if _, err := os.Stat(lpath); err == nil {
// Move out the old one.
tmploc := filepath.Join(td, LockName+".orig")
failerr = renameWithFallback(lpath, tmploc)
if failerr != nil {
goto fail
}
restore = append(restore, pathpair{from: tmploc, to: lpath})
}
// Move in the new one.
failerr = renameWithFallback(filepath.Join(td, LockName), lpath)
if failerr != nil {
goto fail
}
}
if sw.Payload.HasVendor() {
if _, err := os.Stat(vpath); err == nil {
// Move out the old vendor dir. just do it into an adjacent dir, to
// try to mitigate the possibility of a pointless cross-filesystem
// move with a temp directory.
vendorbak = vpath + ".orig"
if _, err := os.Stat(vendorbak); err == nil {
// If the adjacent dir already exists, bite the bullet and move
// to a proper tempdir.
vendorbak = filepath.Join(td, "vendor.orig")
}
failerr = renameWithFallback(vpath, vendorbak)
if failerr != nil {
goto fail
}
restore = append(restore, pathpair{from: vendorbak, to: vpath})
}
// Move in the new one.
failerr = renameWithFallback(filepath.Join(td, "vendor"), vpath)
if failerr != nil {
goto fail
}
}
// Renames all went smoothly. The deferred os.RemoveAll will get the temp
// dir, but if we wrote vendor, we have to clean that up directly
if sw.Payload.HasVendor() {
// Nothing we can really do about an error at this point, so ignore it
os.RemoveAll(vendorbak)
}
return nil
fail:
// If we failed at any point, move all the things back into place, then bail.
for _, pair := range restore {
// Nothing we can do on err here, as we're already in recovery mode.
renameWithFallback(pair.from, pair.to)
}
return failerr
}
func (sw *SafeWriter) PrintPreparedActions() error {
if sw.Payload.HasManifest() {
fmt.Printf("Would have written the following %s:\n", ManifestName)
m, err := sw.Payload.Manifest.MarshalTOML()
if err != nil {
return errors.Wrap(err, "ensure DryRun cannot serialize manifest")
}
fmt.Println(string(m))
}
if sw.Payload.HasLock() {
if sw.Payload.LockDiff == nil {
fmt.Printf("Would have written the following %s:\n", LockName)
l, err := sw.Payload.Lock.MarshalTOML()
if err != nil {
return errors.Wrap(err, "ensure DryRun cannot serialize lock")
}
fmt.Println(string(l))
} else {
fmt.Printf("Would have written the following changes to %s:\n", LockName)
diff, err := sw.Payload.LockDiff.Format()
if err != nil {
return errors.Wrap(err, "ensure DryRun cannot serialize the lock diff")
}
fmt.Println(diff)
}
}
if sw.Payload.HasVendor() {
fmt.Println("Would have written the following projects to the vendor directory:")
for _, project := range sw.Payload.Lock.Projects() {
prj := project.Ident()
rev, _, _ := getVersionInfo(project.Version())
if prj.Source == "" {
fmt.Printf("%s@%s\n", prj.ProjectRoot, rev)
} else {
fmt.Printf("%s -> %s@%s\n", prj.ProjectRoot, prj.Source, rev)
}
}
}
return nil
}
// diffLocks compares two locks and identifies the differences between them.
// Returns nil if there are no differences.
// TODO(carolynvs) this should be moved to gps
func diffLocks(l1 gps.Lock, l2 gps.Lock) *LockDiff {
// Default nil locks to empty locks, so that we can still generate a diff
if l1 == nil {
l1 = &gps.SimpleLock{}
}
if l2 == nil {
l2 = &gps.SimpleLock{}
}
p1, p2 := l1.Projects(), l2.Projects()
// Check if the slices are sorted already. If they are, we can compare
// without copying. Otherwise, we have to copy to avoid altering the
// original input.
sp1, sp2 := SortedLockedProjects(p1), SortedLockedProjects(p2)
if len(p1) > 1 && !sort.IsSorted(sp1) {
p1 = make([]gps.LockedProject, len(p1))
copy(p1, l1.Projects())
sort.Sort(SortedLockedProjects(p1))
}
if len(p2) > 1 && !sort.IsSorted(sp2) {
p2 = make([]gps.LockedProject, len(p2))
copy(p2, l2.Projects())
sort.Sort(SortedLockedProjects(p2))
}
diff := LockDiff{}
h1 := hex.EncodeToString(l1.InputHash())
h2 := hex.EncodeToString(l2.InputHash())
if h1 != h2 {
diff.HashDiff = &StringDiff{Previous: h1, Current: h2}
}
var i2next int
for i1 := 0; i1 < len(p1); i1++ {
lp1 := p1[i1]
pr1 := lp1.Ident().ProjectRoot
var matched bool
for i2 := i2next; i2 < len(p2); i2++ {
lp2 := p2[i2]
pr2 := lp2.Ident().ProjectRoot
switch strings.Compare(string(pr1), string(pr2)) {
case 0: // Found a matching project
matched = true
pdiff := diffProjects(lp1, lp2)
if pdiff != nil {
diff.Modify = append(diff.Modify, *pdiff)
}
i2next = i2 + 1 // Don't evaluate to this again
case -1: // Found a new project
add := buildLockedProjectDiff(lp2)
diff.Add = append(diff.Add, add)
i2next = i2 + 1 // Don't evaluate to this again
continue // Keep looking for a matching project
case +1:
// Project has been removed, handled below
}
break // Done evaluating this project, move onto the next
}
if !matched {
remove := buildLockedProjectDiff(lp1)
diff.Remove = append(diff.Remove, remove)
}
}
// Anything that still hasn't been evaluated are adds
for i2 := i2next; i2 < len(p2); i2++ {
lp2 := p2[i2]
add := buildLockedProjectDiff(lp2)
diff.Add = append(diff.Add, add)
}
if diff.HashDiff == nil && len(diff.Add) == 0 && len(diff.Remove) == 0 && len(diff.Modify) == 0 {
return nil // The locks are the equivalent
}
return &diff
}
func buildLockedProjectDiff(lp gps.LockedProject) LockedProjectDiff {
r2, b2, v2 := getVersionInfo(lp.Version())
var rev, version, branch *StringDiff
if r2 != "" {
rev = &StringDiff{Previous: r2, Current: r2}
}
if b2 != "" {
branch = &StringDiff{Previous: b2, Current: b2}
}
if v2 != "" {
version = &StringDiff{Previous: v2, Current: v2}
}
add := LockedProjectDiff{
Name: lp.Ident().ProjectRoot,
Revision: rev,
Version: version,
Branch: branch,
Packages: make([]StringDiff, len(lp.Packages())),
}
for i, pkg := range lp.Packages() {
add.Packages[i] = StringDiff{Previous: pkg, Current: pkg}
}
return add
}
// diffProjects compares two projects and identifies the differences between them.
// Returns nil if there are no differences
// TODO(carolynvs) this should be moved to gps and updated once the gps unexported fields are available to use.
func diffProjects(lp1 gps.LockedProject, lp2 gps.LockedProject) *LockedProjectDiff {
diff := LockedProjectDiff{Name: lp1.Ident().ProjectRoot}
s1 := lp1.Ident().Source
s2 := lp2.Ident().Source
if s1 != s2 {
diff.Source = &StringDiff{Previous: s1, Current: s2}
}
r1, b1, v1 := getVersionInfo(lp1.Version())
r2, b2, v2 := getVersionInfo(lp2.Version())
if r1 != r2 {
diff.Revision = &StringDiff{Previous: r1, Current: r2}
}
if b1 != b2 {
diff.Branch = &StringDiff{Previous: b1, Current: b2}
}
if v1 != v2 {
diff.Version = &StringDiff{Previous: v1, Current: v2}
}
p1 := lp1.Packages()
p2 := lp2.Packages()
if !sort.StringsAreSorted(p1) {
p1 = make([]string, len(p1))
copy(p1, lp1.Packages())
sort.Strings(p1)
}
if !sort.StringsAreSorted(p2) {
p2 = make([]string, len(p2))
copy(p2, lp2.Packages())
sort.Strings(p2)
}
var i2next int
for i1 := 0; i1 < len(p1); i1++ {
pkg1 := p1[i1]
var matched bool
for i2 := i2next; i2 < len(p2); i2++ {
pkg2 := p2[i2]
switch strings.Compare(pkg1, pkg2) {
case 0: // Found matching package
matched = true
i2next = i2 + 1 // Don't evaluate to this again
case +1: // Found a new package
add := StringDiff{Current: pkg2}
diff.Packages = append(diff.Packages, add)
i2next = i2 + 1 // Don't evaluate to this again
continue // Keep looking for a match
case -1: // Package has been removed (handled below)
}
break // Done evaluating this package, move onto the next
}
if !matched {
diff.Packages = append(diff.Packages, StringDiff{Previous: pkg1})
}
}
// Anything that still hasn't been evaluated are adds
for i2 := i2next; i2 < len(p2); i2++ {
pkg2 := p2[i2]
add := StringDiff{Current: pkg2}
diff.Packages = append(diff.Packages, add)
}
if diff.Source == nil && diff.Version == nil && diff.Revision == nil && len(diff.Packages) == 0 {
return nil // The projects are equivalent
}
return &diff
}
func PruneProject(p *Project, sm gps.SourceManager) error {
td, err := ioutil.TempDir(os.TempDir(), "dep")
if err != nil {
return errors.Wrap(err, "error while creating temp dir for writing manifest/lock/vendor")
}
defer os.RemoveAll(td)
if err := gps.WriteDepTree(td, p.Lock, sm, true); err != nil {
return err
}
var toKeep []string
for _, project := range p.Lock.Projects() {
projectRoot := string(project.Ident().ProjectRoot)
for _, pkg := range project.Packages() {
toKeep = append(toKeep, filepath.Join(projectRoot, pkg))
}
}
toDelete, err := calculatePrune(td, toKeep)
if err != nil {
return err
}
if err := deleteDirs(toDelete); err != nil {
return err
}
vpath := filepath.Join(p.AbsRoot, "vendor")
vendorbak := vpath + ".orig"
var failerr error
if _, err := os.Stat(vpath); err == nil {
// Move out the old vendor dir. just do it into an adjacent dir, to
// try to mitigate the possibility of a pointless cross-filesystem
// move with a temp directory.
if _, err := os.Stat(vendorbak); err == nil {
// If the adjacent dir already exists, bite the bullet and move
// to a proper tempdir.
vendorbak = filepath.Join(td, "vendor.orig")
}
failerr = renameWithFallback(vpath, vendorbak)
if failerr != nil {
goto fail
}
}
// Move in the new one.
failerr = renameWithFallback(td, vpath)
if failerr != nil {
goto fail
}
os.RemoveAll(vendorbak)
return nil
fail:
renameWithFallback(vendorbak, vpath)
return failerr
}
func calculatePrune(vendorDir string, keep []string) ([]string, error) {
sort.Strings(keep)
toDelete := []string{}
err := filepath.Walk(vendorDir, func(path string, info os.FileInfo, err error) error {
if _, err := os.Lstat(path); err != nil {
return nil
}
if !info.IsDir() {
return nil
}
if path == vendorDir {
return nil
}
name := strings.TrimPrefix(path, vendorDir+"/")
i := sort.Search(len(keep), func(i int) bool {
return name <= keep[i]
})
if i >= len(keep) || !strings.HasPrefix(keep[i], name) {
toDelete = append(toDelete, path)
}
return nil
})
return toDelete, err
}
func deleteDirs(toDelete []string) error {
// sort by length so we delete sub dirs first
sort.Sort(byLen(toDelete))
for _, path := range toDelete {
if err := os.RemoveAll(path); err != nil {
return err
}
}
return nil
}
type byLen []string
func (a byLen) Len() int { return len(a) }
func (a byLen) Swap(i, j int) { a[i], a[j] = a[j], a[i] }
func (a byLen) Less(i, j int) bool { return len(a[i]) > len(a[j]) }