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c8d/changes: Fix concurrents diffs

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Use a unique parent view snapshot key for each diff request.

I considered using singleflight at first, but I realized it wouldn't
really be correct.
The diff can take some time, so there's a window of time between the
diff start and finish, where the file system can change.
These changes not always will be reflected in the running diff.
With singleflight, the second diff request which happened before the
previous diff was finished, would not include changes made to the
container filesystem after the first diff request has started.

Signed-off-by: Paweł Gronowski <pawel.gronowski@docker.com>
This commit is contained in:
Paweł Gronowski 2023-10-13 13:13:25 +02:00
parent 8047b69ba3
commit bb7408e851
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GPG key ID: B85EFCFE26DEF92A
1 changed files with 5 additions and 2 deletions
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7
daemon/containerd/image_changes.go
View file

@ -7,6 +7,7 @@ import (
"github.com/containerd/log"
"github.com/docker/docker/container"
"github.com/docker/docker/pkg/archive"
"github.com/docker/docker/pkg/stringid"
)
func (i *ImageService) Changes(ctx context.Context, container *container.Container) ([]archive.Change, error) {
@ -16,10 +17,12 @@ func (i *ImageService) Changes(ctx context.Context, container *container.Contain
return nil, err
}
imageMounts, _ := snapshotter.View(ctx, container.ID+"-parent-view", info.Parent)
id := stringid.GenerateRandomID()
parentViewKey := container.ID + "-parent-view-" + id
imageMounts, _ := snapshotter.View(ctx, parentViewKey, info.Parent)
defer func() {
if err := snapshotter.Remove(ctx, container.ID+"-parent-view"); err != nil {
if err := snapshotter.Remove(ctx, parentViewKey); err != nil {
log.G(ctx).WithError(err).Warn("error removing the parent view snapshot")
}
}()