snapshot

type Diff struct {
	Lower string
	Upper string
}

type MergeSnapshotter interface {
	Snapshotter
	// Merge creates a snapshot whose contents are the provided diffs applied onto one
	// another in the provided order, starting from scratch. The diffs are calculated
	// the same way that diffs are calculated during exports, which ensures that the
	// result of merging these diffs looks the same as exporting the diffs as layer
	// blobs and unpacking them as an image.
	//
	// Each key in the provided diffs is expected to be a committed snapshot. The
	// snapshot created by Merge is also committed.
	//
	// The size of a merged snapshot (as returned by the Usage method) depends on the merge
	// implementation. Implementations using hardlinks to create merged views will take up
	// less space than those that use copies, for example.
	Merge(ctx context.Context, key string, diffs []Diff, opts ...snapshots.Opt) error
}

type Mountable interface {
	// ID() string
	Mount() ([]mount.Mount, func() error, error)
	IdentityMapping() *idtools.IdentityMapping
}

type Mounter interface {
	Mount() (string, error)
	Unmount() error
}

type Snapshotter interface {
	Name() string
	Mounts(ctx context.Context, key string) (Mountable, error)
	Prepare(ctx context.Context, key, parent string, opts ...snapshots.Opt) error
	View(ctx context.Context, key, parent string, opts ...snapshots.Opt) (Mountable, error)

	Stat(ctx context.Context, key string) (snapshots.Info, error)
	Update(ctx context.Context, info snapshots.Info, fieldpaths ...string) (snapshots.Info, error)
	Usage(ctx context.Context, key string) (snapshots.Usage, error)
	Commit(ctx context.Context, name, key string, opts ...snapshots.Opt) error
	Remove(ctx context.Context, key string) error
	Walk(ctx context.Context, fn snapshots.WalkFunc, filters ...string) error
	Close() error
	IdentityMapping() *idtools.IdentityMapping
}