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package graphdriver // import "github.com/docker/docker/daemon/graphdriver"
import (
"io"
"time"
"github.com/docker/docker/pkg/archive"
"github.com/docker/docker/pkg/chrootarchive"
"github.com/docker/docker/pkg/idtools"
"github.com/docker/docker/pkg/ioutils"
"github.com/sirupsen/logrus"
)
var (
// ApplyUncompressedLayer defines the unpack method used by the graph
// driver.
ApplyUncompressedLayer = chrootarchive.ApplyUncompressedLayer
)
// NaiveDiffDriver takes a ProtoDriver and adds the
// capability of the Diffing methods on the local file system,
// which it may or may not support on its own. See the comment
// on the exported NewNaiveDiffDriver function below.
// Notably, the AUFS driver doesn't need to be wrapped like this.
type NaiveDiffDriver struct {
ProtoDriver
uidMaps []idtools.IDMap
gidMaps []idtools.IDMap
}
// NewNaiveDiffDriver returns a fully functional driver that wraps the
// given ProtoDriver and adds the capability of the following methods which
// it may or may not support on its own:
//
// Diff(id, parent string) (archive.Archive, error)
// Changes(id, parent string) ([]archive.Change, error)
// ApplyDiff(id, parent string, diff archive.Reader) (size int64, err error)
// DiffSize(id, parent string) (size int64, err error)
func NewNaiveDiffDriver(driver ProtoDriver, uidMaps, gidMaps []idtools.IDMap) Driver {
return &NaiveDiffDriver{ProtoDriver: driver,
uidMaps: uidMaps,
gidMaps: gidMaps}
}
// Diff produces an archive of the changes between the specified
// layer and its parent layer which may be "".
func (gdw *NaiveDiffDriver) Diff(id, parent string) (arch io.ReadCloser, err error) {
startTime := time.Now()
driver := gdw.ProtoDriver
layerRootFs, err := driver.Get(id, "")
if err != nil {
return nil, err
}
layerFs := layerRootFs.Path()
defer func() {
if err != nil {
driver.Put(id)
}
}()
if parent == "" {
archive, err := archive.Tar(layerFs, archive.Uncompressed)
if err != nil {
return nil, err
}
return ioutils.NewReadCloserWrapper(archive, func() error {
err := archive.Close()
driver.Put(id)
return err
}), nil
}
parentRootFs, err := driver.Get(parent, "")
if err != nil {
return nil, err
}
defer driver.Put(parent)
parentFs := parentRootFs.Path()
changes, err := archive.ChangesDirs(layerFs, parentFs)
if err != nil {
return nil, err
}
archive, err := archive.ExportChanges(layerFs, changes, gdw.uidMaps, gdw.gidMaps)
if err != nil {
return nil, err
}
return ioutils.NewReadCloserWrapper(archive, func() error {
err := archive.Close()
driver.Put(id)
// NaiveDiffDriver compares file metadata with parent layers. Parent layers
// are extracted from tar's with full second precision on modified time.
// We need this hack here to make sure calls within same second receive
// correct result.
time.Sleep(time.Until(startTime.Truncate(time.Second).Add(time.Second)))
return err
}), nil
}
// Changes produces a list of changes between the specified layer
// and its parent layer. If parent is "", then all changes will be ADD changes.
func (gdw *NaiveDiffDriver) Changes(id, parent string) ([]archive.Change, error) {
driver := gdw.ProtoDriver
layerRootFs, err := driver.Get(id, "")
if err != nil {
return nil, err
}
defer driver.Put(id)
layerFs := layerRootFs.Path()
parentFs := ""
if parent != "" {
parentRootFs, err := driver.Get(parent, "")
if err != nil {
return nil, err
}
defer driver.Put(parent)
parentFs = parentRootFs.Path()
}
return archive.ChangesDirs(layerFs, parentFs)
}
// ApplyDiff extracts the changeset from the given diff into the
// layer with the specified id and parent, returning the size of the
// new layer in bytes.
func (gdw *NaiveDiffDriver) ApplyDiff(id, parent string, diff io.Reader) (size int64, err error) {
driver := gdw.ProtoDriver
// Mount the root filesystem so we can apply the diff/layer.
layerRootFs, err := driver.Get(id, "")
if err != nil {
return
}
defer driver.Put(id)
layerFs := layerRootFs.Path()
options := &archive.TarOptions{UIDMaps: gdw.uidMaps,
GIDMaps: gdw.gidMaps}
start := time.Now().UTC()
logrus.WithField("id", id).Debug("Start untar layer")
if size, err = ApplyUncompressedLayer(layerFs, diff, options); err != nil {
return
}
logrus.WithField("id", id).Debugf("Untar time: %vs", time.Now().UTC().Sub(start).Seconds())
return
}
// DiffSize calculates the changes between the specified layer
// and its parent and returns the size in bytes of the changes
// relative to its base filesystem directory.
func (gdw *NaiveDiffDriver) DiffSize(id, parent string) (size int64, err error) {
driver := gdw.ProtoDriver
changes, err := gdw.Changes(id, parent)
if err != nil {
return
}
layerFs, err := driver.Get(id, "")
if err != nil {
return
}
defer driver.Put(id)
return archive.ChangesSize(layerFs.Path(), changes), nil
}
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