TODO: figure out why the Init calls are wrapped in once.Do - implies it can be called multiple times, but once Finalize is called things will not be functional.

GetExporter retrieves an exporter registered with the provided store.

GetExporters returns the set of known importers.

GetImporter retrieves an importer registered with the provided store.

GetImporters returns the set of known importers.

Init performs basic initialization, including population of storage.Config.

given an ID, compute the volume's label.

NewMountDataSink creates a new data sink associated with a specific mount, with the mount point being the path argument.

NewMountDataSource creates a new data source associated with a specific mount, with the mount point being the path argument.

NewVolume creates a Volume.

RegisterExporter registers the specified exporter against the provided store for later retrieval.

RegisterImporter registers the specified importer against the provided store for later retrieval.

Configuration is a slice of the VCH config that is relevant to the exec part of the port layer.

Image is the handle to identify an image layer on the backing store.

MountDataSink implements the DataSink interface for mounted devices This is a single use mechanism and will be tidied up on exit from MountDataSink.Import.

MountDataSource implements the DataSource interface for mounted devices.

NameLookupCache the global view of all of the image stores.

ProxyReadCloser is a read closer that provides for wrapping the Close with a custom Close call.

Volume is the handle to identify a volume on the backing store.

VolumeExistsError : custom error type for when a create operation targets and already occupied ID.

VolumeLookupCache caches Volume references to volumes in the system.

VolumeStoreNotFoundError : custom error type for when we fail to find a target volume store.

DataSink defines the methods for importing data to a specific storage element from a tar stream.

DataSource defines the methods for exporting data from a specific storage element as a tar stream.

Exporter defines the methods needed to read data from a storage element, optionally diff with an ancestor.

ImageStorer is an interface to store images in the Image Store.

Importer defines the methods needed to write data into a storage element.

Resolver defines methods for mapping ids to URLS, and urls to owners of that device.

VolumeStorer is an interface to create, remove, enumerate, and get Volumes.