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|
package hook
import (
"bytes"
"context"
"crypto/sha256"
"encoding/hex"
"errors"
"fmt"
"hash"
"io"
"io/ioutil"
"os"
"strings"
"github.com/grpc-ecosystem/go-grpc-middleware/logging/logrus/ctxlogrus"
"github.com/prometheus/client_golang/prometheus"
"github.com/prometheus/client_golang/prometheus/promauto"
"github.com/sirupsen/logrus"
"gitlab.com/gitlab-org/gitaly/v14/internal/git"
"gitlab.com/gitlab-org/gitaly/v14/internal/git/pktline"
"gitlab.com/gitlab-org/gitaly/v14/internal/helper"
"gitlab.com/gitlab-org/gitaly/v14/proto/go/gitalypb"
"gitlab.com/gitlab-org/gitaly/v14/streamio"
"google.golang.org/protobuf/encoding/protojson"
)
var (
packObjectsServedBytes = promauto.NewCounter(prometheus.CounterOpts{
Name: "gitaly_pack_objects_served_bytes_total",
Help: "Number of bytes of git-pack-objects data served to clients",
})
packObjectsCacheLookups = promauto.NewCounterVec(prometheus.CounterOpts{
Name: "gitaly_pack_objects_cache_lookups_total",
Help: "Number of lookups in the PackObjectsHook cache, divided by hit/miss",
}, []string{"result"})
packObjectsGeneratedBytes = promauto.NewCounter(prometheus.CounterOpts{
Name: "gitaly_pack_objects_generated_bytes_total",
Help: "Number of bytes generated in PackObjectsHook by running git-pack-objects",
})
)
func (s *server) PackObjectsHook(stream gitalypb.HookService_PackObjectsHookServer) error {
if s.packObjectsCache == nil {
return helper.ErrInternalf("packObjectsCache is not available")
}
firstRequest, err := stream.Recv()
if err != nil {
return helper.ErrInternal(err)
}
if firstRequest.GetRepository() == nil {
return helper.ErrInvalidArgument(errors.New("repository is empty"))
}
args, err := parsePackObjectsArgs(firstRequest.Args)
if err != nil {
return helper.ErrInvalidArgumentf("invalid pack-objects command: %v: %w", firstRequest.Args, err)
}
if err := s.packObjectsHook(stream, firstRequest, args); err != nil {
return helper.ErrInternal(err)
}
return nil
}
const (
bandStdout = 1
bandStderr = 2
)
func (s *server) packObjectsHook(stream gitalypb.HookService_PackObjectsHookServer, firstRequest *gitalypb.PackObjectsHookRequest, args *packObjectsArgs) error {
ctx := stream.Context()
data, err := protojson.Marshal(firstRequest)
if err != nil {
return err
}
h := sha256.New()
if _, err := h.Write(data); err != nil {
return err
}
stdin, err := bufferStdin(stream, h)
if err != nil {
return err
}
// We do not know yet who has to close stdin. In case of a cache hit, it
// is us. In case of a cache miss, a separate goroutine will run
// git-pack-objects, and that goroutine may outlive the current request.
// In that case, that separate goroutine will be responsible for closing
// stdin.
closeStdin := true
defer func() {
if closeStdin {
stdin.Close()
}
}()
key := hex.EncodeToString(h.Sum(nil))
r, created, err := s.packObjectsCache.FindOrCreate(key, func(w io.Writer) error {
return s.runPackObjects(ctx, w, firstRequest.Repository, args, stdin, key)
})
if err != nil {
return err
}
defer r.Close()
if created {
closeStdin = false
packObjectsCacheLookups.WithLabelValues("miss").Inc()
} else {
packObjectsCacheLookups.WithLabelValues("hit").Inc()
}
var servedBytes int64
defer func() {
ctxlogrus.Extract(ctx).WithFields(logrus.Fields{
"cache_key": key,
"bytes": servedBytes,
}).Info("served bytes")
packObjectsServedBytes.Add(float64(servedBytes))
}()
if err := pktline.EachSidebandPacket(r, func(band byte, data []byte) error {
resp := &gitalypb.PackObjectsHookResponse{}
switch band {
case bandStdout:
resp.Stdout = data
case bandStderr:
resp.Stderr = data
default:
return fmt.Errorf("invalid side band: %d", band)
}
servedBytes += int64(len(data))
return stream.Send(resp)
}); err != nil {
return err
}
return r.Wait(ctx)
}
type contextWithoutCancel struct {
context.Context
valueCtx context.Context
}
func (cwc *contextWithoutCancel) Value(key interface{}) interface{} { return cwc.valueCtx.Value(key) }
func cloneContextValues(ctx context.Context) context.Context {
return &contextWithoutCancel{
Context: context.Background(),
valueCtx: ctx,
}
}
func (s *server) runPackObjects(ctx context.Context, w io.Writer, repo *gitalypb.Repository, args *packObjectsArgs, stdin io.ReadCloser, key string) error {
// We want to keep the context for logging, but we want to block all its
// cancelation signals (deadline, cancel etc.). This is because of
// the following scenario. Imagine client1 calls PackObjectsHook and
// causes runPackObjects to run in a goroutine. Now suppose that client2
// calls PackObjectsHook with the same arguments and stdin, so it joins
// client1 in waiting for this goroutine. Now client1 hangs up before the
// runPackObjects goroutine is done.
//
// If the cancelation of client1 propagated into the runPackObjects
// goroutine this would affect client2. We don't want that. So to prevent
// that, we suppress the cancelation of the originating context.
ctx = cloneContextValues(ctx)
ctx, cancel := context.WithCancel(ctx)
defer cancel()
defer stdin.Close()
sw := pktline.NewSidebandWriter(w)
stdout := &countingWriter{W: sw.Writer(bandStdout)}
stderrBuf := &bytes.Buffer{}
stderr := &countingWriter{W: io.MultiWriter(sw.Writer(bandStderr), stderrBuf)}
defer func() {
generatedBytes := stdout.N + stderr.N
packObjectsGeneratedBytes.Add(float64(generatedBytes))
logger := ctxlogrus.Extract(ctx)
logger.WithFields(logrus.Fields{
"cache_key": key,
"bytes": generatedBytes,
}).Info("generated bytes")
if total := totalMessage(stderrBuf.Bytes()); total != "" {
logger.WithField("pack.stat", total).Info("pack file compression statistic")
}
}()
cmd, err := s.gitCmdFactory.New(ctx, repo, args.subcmd(),
git.WithStdin(stdin),
git.WithStdout(stdout),
git.WithStderr(stderr),
git.WithGlobalOption(args.globals()...),
)
if err != nil {
return err
}
if err := cmd.Wait(); err != nil {
return fmt.Errorf("git-pack-objects: stderr: %q err: %w", stderrBuf.String(), err)
}
return nil
}
func totalMessage(stderr []byte) string {
start := bytes.Index(stderr, []byte("Total "))
if start < 0 {
return ""
}
end := bytes.Index(stderr[start:], []byte("\n"))
if end < 0 {
return ""
}
return string(stderr[start : start+end])
}
var (
errNoPackObjects = errors.New("missing pack-objects")
errNonFlagArg = errors.New("non-flag argument")
errNoStdout = errors.New("missing --stdout")
)
func parsePackObjectsArgs(args []string) (*packObjectsArgs, error) {
result := &packObjectsArgs{}
// Check for special argument used with shallow clone:
// https://gitlab.com/gitlab-org/git/-/blob/v2.30.0/upload-pack.c#L287-290
if len(args) >= 2 && args[0] == "--shallow-file" && args[1] == "" {
result.shallowFile = true
args = args[2:]
}
if len(args) < 1 || args[0] != "pack-objects" {
return nil, errNoPackObjects
}
args = args[1:]
// There should always be "--stdout" somewhere. Git-pack-objects can
// write to a file too but we don't want that in this RPC.
// https://gitlab.com/gitlab-org/git/-/blob/v2.30.0/upload-pack.c#L296
seenStdout := false
for _, a := range args {
if !strings.HasPrefix(a, "-") {
return nil, errNonFlagArg
}
if a == "--stdout" {
seenStdout = true
} else {
result.flags = append(result.flags, a)
}
}
if !seenStdout {
return nil, errNoStdout
}
return result, nil
}
type packObjectsArgs struct {
shallowFile bool
flags []string
}
func (p *packObjectsArgs) globals() []git.GlobalOption {
var globals []git.GlobalOption
if p.shallowFile {
globals = append(globals, git.ValueFlag{Name: "--shallow-file", Value: ""})
}
return globals
}
func (p *packObjectsArgs) subcmd() git.SubCmd {
sc := git.SubCmd{
Name: "pack-objects",
Flags: []git.Option{git.Flag{Name: "--stdout"}},
}
for _, f := range p.flags {
sc.Flags = append(sc.Flags, git.Flag{Name: f})
}
return sc
}
func bufferStdin(stream gitalypb.HookService_PackObjectsHookServer, h hash.Hash) (_ io.ReadCloser, err error) {
f, err := ioutil.TempFile("", "PackObjectsHook-stdin")
if err != nil {
return nil, err
}
defer func() {
if err != nil {
f.Close()
}
}()
if err := os.Remove(f.Name()); err != nil {
return nil, err
}
stdin := io.TeeReader(
streamio.NewReader(func() ([]byte, error) {
resp, err := stream.Recv()
return resp.GetStdin(), err
}),
h,
)
_, err = io.Copy(f, stdin)
if err != nil {
return nil, err
}
if _, err := f.Seek(0, io.SeekStart); err != nil {
return nil, err
}
return f, nil
}
type countingWriter struct {
W io.Writer
N int64
}
func (cw *countingWriter) Write(p []byte) (int, error) {
n, err := cw.W.Write(p)
cw.N += int64(n)
return n, err
}
|