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|
package publish
import (
"context"
"fmt"
"path"
"sort"
"strings"
"sync"
"time"
"github.com/npfaro/dumbforge/internal/gitutil"
"github.com/npfaro/dumbforge/internal/s3store"
)
const (
mutableCache = "no-cache, max-age=0, must-revalidate"
immutableCache = "public, max-age=31536000, immutable"
smallPushMaxBytes = 8 << 20
smallPushMaxObjects = 64
)
type Update struct {
Src string
Dst string
Force bool
}
type AppliedUpdate struct {
Dst string
OldOID string
NewOID string
}
type Result struct {
Updates []AppliedUpdate
PackName string
PackObjects uint32
Head string
Branches []string
SiteVersion string
}
type Publisher struct {
Store *s3store.Store
Git gitutil.Git
Progress func(format string, args ...any)
AfterPublish func(context.Context, Result)
prepared *preparedPush
}
type preparedPush struct {
lock *s3store.Lock
metadata Metadata
}
func (p *Publisher) List(ctx context.Context) (Metadata, error) {
return LoadMetadata(ctx, p.Store)
}
// Prepare serializes a push before refs are advertised. Holding the lock from
// advertisement through publication removes a redundant metadata read without
// weakening the concurrent-update check.
func (p *Publisher) Prepare(ctx context.Context) (Metadata, error) {
if p.prepared != nil {
return p.prepared.metadata, nil
}
lock, err := p.Store.AcquireLock(ctx)
if err != nil {
return Metadata{}, err
}
metadata, err := LoadMetadata(ctx, p.Store)
if err != nil {
_ = lock.Release(context.WithoutCancel(ctx))
return Metadata{}, err
}
p.prepared = &preparedPush{lock: lock, metadata: metadata}
return metadata, nil
}
// Abort releases a prepared push if the remote-helper session ends before it
// sends a push command.
func (p *Publisher) Abort(ctx context.Context) error {
if p.prepared == nil {
return nil
}
lock := p.prepared.lock
p.prepared = nil
return lock.Release(ctx)
}
// Push applies a batch as one publication. expected contains the refs advertised
// to Git before it sent the push commands and prevents a concurrent update from
// being silently overwritten.
func (p *Publisher) Push(ctx context.Context, updates []Update, expected map[string]string) (result Result, err error) {
if len(updates) == 0 {
return Result{}, nil
}
shallow, err := p.Git.IsShallow(ctx)
if err != nil {
return Result{}, err
}
if shallow {
return Result{}, fmt.Errorf("cannot publish from a shallow repository; fetch the complete history first")
}
var lock *s3store.Lock
var metadata Metadata
if p.prepared != nil {
lock = p.prepared.lock
metadata = p.prepared.metadata
p.prepared = nil
} else {
lock, err = p.Store.AcquireLock(ctx)
if err != nil {
return Result{}, err
}
metadata, err = LoadMetadata(ctx, p.Store)
if err != nil {
_ = lock.Release(context.WithoutCancel(ctx))
return Result{}, err
}
}
defer func() {
if releaseErr := lock.Release(context.WithoutCancel(ctx)); err == nil && releaseErr != nil {
err = releaseErr
}
}()
if err := checkExpected(metadata, updates, expected); err != nil {
return Result{}, err
}
resolved, err := p.resolveAndValidate(ctx, metadata, updates)
if err != nil {
return Result{}, err
}
wants := make([]string, 0, len(resolved))
for _, update := range resolved {
if update.NewOID != "" {
wants = append(wants, update.NewOID)
}
}
haves := make([]string, 0, len(metadata.Refs))
for _, ref := range metadata.Refs {
haves = append(haves, ref.OID)
}
pack, err := p.Git.PackObjects(ctx, wants, haves)
if err != nil {
return Result{}, err
}
defer pack.Close()
packAdded := false
refsPublishedEarly := false
if pack != nil && pack.Objects > 0 {
looseObjects, useLoose, looseErr := p.Git.SmallLooseObjects(ctx, pack, smallPushMaxObjects, smallPushMaxBytes)
if looseErr != nil {
return Result{}, looseErr
}
if useLoose {
p.progress("uploading %d loose objects", len(looseObjects))
publications := make([]func() error, 0, len(looseObjects)+len(resolved))
for _, object := range looseObjects {
object := object
publications = append(publications, func() error {
return p.Store.PutFile(ctx, path.Join("objects", object.OID[:2], object.OID[2:]), object.Path, "application/x-git-loose-object", immutableCache)
})
}
// Individual ref files are not used for discovery by dumb HTTP; publish
// them in the same wave and update the authoritative info/refs only
// after every object and ref write has succeeded.
for _, update := range resolved {
update := update
if update.OldOID == update.NewOID {
continue
}
if update.NewOID == "" {
publications = append(publications, func() error { return p.Store.Delete(ctx, update.Dst) })
} else {
publications = append(publications, func() error {
return p.Store.Put(ctx, update.Dst, []byte(update.NewOID+"\n"), "text/plain; charset=utf-8", mutableCache)
})
}
}
if err := runParallel(publications...); err != nil {
return Result{}, err
}
refsPublishedEarly = true
result.PackObjects = pack.Objects
} else {
packName := "pack-" + pack.Hash + ".pack"
indexName := "pack-" + pack.Hash + ".idx"
p.progress("uploading %s (%d objects)", packName, pack.Objects)
if err := runParallel(
func() error {
return p.Store.PutFile(ctx, path.Join("objects/pack", packName), pack.PackPath, "application/x-git-packed-objects", immutableCache)
},
func() error {
return p.Store.PutFile(ctx, path.Join("objects/pack", indexName), pack.IndexPath, "application/x-git-packed-objects-toc", immutableCache)
},
); err != nil {
return Result{}, err
}
metadata.Packs[packName] = struct{}{}
result.PackName = packName
result.PackObjects = pack.Objects
packAdded = true
}
}
previousHead := metadata.Head
for _, update := range resolved {
result.Updates = append(result.Updates, update)
if update.NewOID == "" {
delete(metadata.Refs, update.Dst)
continue
}
ref := Ref{OID: update.NewOID}
if strings.HasPrefix(update.Dst, "refs/tags/") {
peeled, peelErr := p.Git.Peel(ctx, update.NewOID)
if peelErr == nil && peeled != update.NewOID {
ref.Peeled = peeled
}
}
metadata.Refs[update.Dst] = ref
}
if metadata.Head == "" {
metadata.Head = p.chooseInitialHead(ctx, resolved)
}
result.Head = metadata.Head
result.Branches = metadata.BranchNames()
result.SiteVersion = metadata.SiteVersion
if err := lock.RefreshIfOlderThan(ctx, 30*time.Minute); err != nil {
return Result{}, err
}
// Packs are already durable. Publish the remaining internal pointers in
// parallel, then info/refs last so dumb-HTTP clients cannot discover a ref
// before all of the objects needed to read it are available.
var publications []func() error
if packAdded {
publications = append(publications, func() error {
return p.Store.Put(ctx, "objects/info/packs", renderPackList(metadata.Packs), "text/plain; charset=utf-8", mutableCache)
})
}
if !refsPublishedEarly {
for _, update := range resolved {
update := update
if update.OldOID == update.NewOID {
continue
}
if update.NewOID == "" {
publications = append(publications, func() error { return p.Store.Delete(ctx, update.Dst) })
continue
}
publications = append(publications, func() error {
return p.Store.Put(ctx, update.Dst, []byte(update.NewOID+"\n"), "text/plain; charset=utf-8", mutableCache)
})
}
}
if metadata.Head != "" && metadata.Head != previousHead {
publications = append(publications, func() error {
return p.Store.Put(ctx, "HEAD", []byte("ref: "+metadata.Head+"\n"), "text/plain; charset=utf-8", mutableCache)
})
}
if err := runParallel(publications...); err != nil {
return Result{}, err
}
if err := p.Store.Put(ctx, "info/refs", renderInfoRefs(metadata.Refs), "text/plain; charset=utf-8", mutableCache); err != nil {
return Result{}, err
}
p.progress("published %d ref update(s)", len(resolved))
if p.AfterPublish != nil {
p.AfterPublish(ctx, result)
}
return result, nil
}
func (p *Publisher) resolveAndValidate(ctx context.Context, metadata Metadata, updates []Update) ([]AppliedUpdate, error) {
seen := map[string]struct{}{}
resolved := make([]AppliedUpdate, 0, len(updates))
for _, update := range updates {
if err := p.Git.CheckRef(ctx, update.Dst); err != nil {
return nil, err
}
if _, ok := seen[update.Dst]; ok {
return nil, fmt.Errorf("destination ref %s appears more than once", update.Dst)
}
seen[update.Dst] = struct{}{}
oldOID := metadata.Refs[update.Dst].OID
if update.Src == "" {
if update.Dst == metadata.Head {
return nil, fmt.Errorf("refusing to delete the remote HEAD branch %s", update.Dst)
}
resolved = append(resolved, AppliedUpdate{Dst: update.Dst, OldOID: oldOID})
continue
}
newOID, err := p.Git.RevParse(ctx, update.Src)
if err != nil {
return nil, fmt.Errorf("resolve %s: %w", update.Src, err)
}
if oldOID != "" && oldOID != newOID && !update.Force {
if !strings.HasPrefix(update.Dst, "refs/heads/") {
return nil, fmt.Errorf("ref %s already exists; use force to replace it", update.Dst)
}
if !p.Git.ObjectExists(ctx, oldOID) {
return nil, fmt.Errorf("remote tip %s is missing locally; fetch before pushing", oldOID)
}
ancestor, err := p.Git.IsAncestor(ctx, oldOID, newOID)
if err != nil {
return nil, err
}
if !ancestor {
return nil, fmt.Errorf("non-fast-forward update to %s", update.Dst)
}
}
resolved = append(resolved, AppliedUpdate{Dst: update.Dst, OldOID: oldOID, NewOID: newOID})
}
return resolved, nil
}
func checkExpected(metadata Metadata, updates []Update, expected map[string]string) error {
if expected == nil {
return nil
}
for _, update := range updates {
current := metadata.Refs[update.Dst].OID
if advertised, ok := expected[update.Dst]; ok && advertised != current {
return fmt.Errorf("remote ref %s changed during push; retry", update.Dst)
}
if _, ok := expected[update.Dst]; !ok && current != "" {
return fmt.Errorf("remote ref %s was created during push; retry", update.Dst)
}
}
return nil
}
func chooseHead(updates []AppliedUpdate) string {
for _, preferred := range []string{"refs/heads/main", "refs/heads/master"} {
for _, update := range updates {
if update.Dst == preferred && update.NewOID != "" {
return preferred
}
}
}
names := make([]string, 0, len(updates))
for _, update := range updates {
if strings.HasPrefix(update.Dst, "refs/heads/") && update.NewOID != "" {
names = append(names, update.Dst)
}
}
sort.Strings(names)
if len(names) > 0 {
return names[0]
}
return ""
}
func (p *Publisher) chooseInitialHead(ctx context.Context, updates []AppliedUpdate) string {
if localHead, err := p.Git.SymbolicRef(ctx, "HEAD"); err == nil {
for _, update := range updates {
if update.Dst == localHead && update.NewOID != "" {
return localHead
}
}
}
return chooseHead(updates)
}
func (p *Publisher) progress(format string, args ...any) {
if p.Progress != nil {
p.Progress(format, args...)
}
}
func runParallel(tasks ...func() error) error {
if len(tasks) == 0 {
return nil
}
var workers sync.WaitGroup
errCh := make(chan error, len(tasks))
for _, task := range tasks {
task := task
workers.Add(1)
go func() {
defer workers.Done()
if err := task(); err != nil {
errCh <- err
}
}()
}
workers.Wait()
close(errCh)
for err := range errCh {
return err
}
return nil
}
|
