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@@ -0,0 +1,162 @@
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+package graphdriver
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+
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+import (
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+ "fmt"
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+ "time"
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+
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+ "github.com/docker/docker/archive"
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+ "github.com/docker/docker/pkg/ioutils"
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+ "github.com/docker/docker/pkg/log"
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+ "github.com/docker/docker/utils"
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+)
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+
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+// GenericDriverWrapper takes a generic Driver and adds the
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+// capability of the following methods which it doesn't
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+// support on its own:
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+// Diff(id, parent string) (archive.Archive, error)
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+// Changes(id, parent string) ([]archive.Change, error)
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+// ApplyDiff(id, parent string, diff archive.ArchiveReader) (bytes int64, err error)
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+// DiffSize(id, parent string) (bytes int64, err error)
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+// Notably, the AUFS driver doesn't need to be wrapped like this.
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+type GenericDriverWrapper struct {
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+ GenericDriver
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+}
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+
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+// NewGenericDriverWrapper returns a fully functional driver that wraps the given GenericDriver.
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+func NewGenericDriverWrapper(driver GenericDriver) Driver {
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+ return &GenericDriverWrapper{GenericDriver: driver}
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+}
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+
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+// Diff produces an archive of the changes between the specified
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+// layer and its parent layer which may be "".
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+func (gdw *GenericDriverWrapper) Diff(id, parent string) (arch archive.Archive, err error) {
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+ driver := gdw.GenericDriver
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+
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+ layerFs, err := driver.Get(id, "")
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+ if err != nil {
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+ return nil, err
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+ }
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+
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+ defer func() {
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+ if err != nil {
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+ driver.Put(id)
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+ }
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+ }()
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+
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+ if parent == "" {
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+ archive, err := archive.Tar(layerFs, archive.Uncompressed)
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+ if err != nil {
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+ return nil, err
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+ }
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+ return ioutils.NewReadCloserWrapper(archive, func() error {
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+ err := archive.Close()
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+ driver.Put(id)
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+ return err
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+ }), nil
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+ }
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+
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+ parentFs, err := driver.Get(parent, "")
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+ if err != nil {
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+ return nil, err
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+ }
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+ defer driver.Put(parent)
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+
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+ changes, err := archive.ChangesDirs(layerFs, parentFs)
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+ if err != nil {
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+ return nil, err
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+ }
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+
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+ archive, err := archive.ExportChanges(layerFs, changes)
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+ if err != nil {
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+ return nil, err
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+ }
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+
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+ return ioutils.NewReadCloserWrapper(archive, func() error {
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+ err := archive.Close()
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+ driver.Put(id)
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+ return err
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+ }), nil
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+}
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+
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+// Changes produces a list of changes between the specified layer
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+// and its parent layer. If parent is "", then all changes will be ADD changes.
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+func (gdw *GenericDriverWrapper) Changes(id, parent string) ([]archive.Change, error) {
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+ driver := gdw.GenericDriver
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+
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+ layerFs, err := driver.Get(id, "")
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+ if err != nil {
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+ return nil, err
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+ }
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+ defer driver.Put(id)
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+
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+ parentFs := ""
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+
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+ if parent != "" {
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+ parentFs, err = driver.Get(parent, "")
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+ if err != nil {
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+ return nil, err
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+ }
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+ defer driver.Put(parent)
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+ }
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+
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+ return archive.ChangesDirs(layerFs, parentFs)
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+}
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+
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+// ApplyDiff extracts the changeset from the given diff into the
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+// layer with the specified id and parent, returning the size of the
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+// new layer in bytes.
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+func (gdw *GenericDriverWrapper) ApplyDiff(id, parent string, diff archive.ArchiveReader) (bytes int64, err error) {
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+ driver := gdw.GenericDriver
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+
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+ // Mount the root filesystem so we can apply the diff/layer.
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+ layerFs, err := driver.Get(id, "")
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+ if err != nil {
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+ return
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+ }
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+ defer driver.Put(id)
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+
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+ start := time.Now().UTC()
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+ log.Debugf("Start untar layer")
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+ if err = archive.ApplyLayer(layerFs, diff); err != nil {
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+ return
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+ }
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+ log.Debugf("Untar time: %vs", time.Now().UTC().Sub(start).Seconds())
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+
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+ if parent == "" {
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+ return utils.TreeSize(layerFs)
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+ }
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+
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+ parentFs, err := driver.Get(parent, "")
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+ if err != nil {
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+ err = fmt.Errorf("Driver %s failed to get image parent %s: %s", driver, parent, err)
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+ return
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+ }
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+ defer driver.Put(parent)
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+
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+ changes, err := archive.ChangesDirs(layerFs, parentFs)
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+ if err != nil {
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+ return
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+ }
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+
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+ return archive.ChangesSize(layerFs, changes), nil
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+}
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+
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+// DiffSize calculates the changes between the specified layer
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+// and its parent and returns the size in bytes of the changes
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+// relative to its base filesystem directory.
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+func (gdw *GenericDriverWrapper) DiffSize(id, parent string) (bytes int64, err error) {
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+ driver := gdw.GenericDriver
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+
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+ changes, err := gdw.Changes(id, parent)
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+ if err != nil {
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+ return
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+ }
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+
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+ layerFs, err := driver.Get(id, "")
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+ if err != nil {
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+ return
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+ }
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+ defer driver.Put(id)
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+
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+ return archive.ChangesSize(layerFs, changes), nil
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+}
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