db

type DB interface {
	// Set given key in the database equal to the processed metadata.
	Set(namespace, key, metadata []byte) error
	// Get the stored metadata from the database using the given key.
	Get(namespace, key []byte) (metadata []byte, err error)
	// Delete the metadata which is stored as the given key.
	Delete(namespace, key []byte) error
	// Update metadata stored as the given key,
	// as an in-memory-transaction, providing protection against data races.
	// When wishing to update metadata always use this method,
	// rather than a combination of Set+Get.
	Update(namespace, key []byte, cb UpdateCallback) error

	// ListKeys all keys in the given namespace.
	// The keys are sorted in lexicographically order.
	ListKeys(namespace []byte, cb ListCallback) error

	// Close any open (database) resources.
	Close() error
}

type InternalError struct {
	Type string
	Err  error
}

type ListCallback func(key []byte) error

type UpdateCallback func(orgMetadata []byte) (newMetadata []byte, err error)