store

Documentation

Index

• Variables
• type MetadataStore
  • func NewMetadataStore() MetadataStore
• type UpdateFunc

Variables

var (
	// ErrNotExist is the error returned when specified id does
	// not exist.
	ErrNotExist = errors.New("does not exist")
	// ErrAlreadyExist is the error returned when specified id already
	// exists.
	ErrAlreadyExist = errors.New("already exists")
)

Types

type MetadataStore

type MetadataStore interface {
	// Create the metadata containing the passed in data with the
	// specified id.
	// Note:
	// * Create MUST return error if the id already exists.
	// * The id and data MUST be added in one transaction to the store.
	Create(string, []byte) error
	// Get the data by id.
	// Note that Get MUST return ErrNotExist if the id doesn't exist.
	Get(string) ([]byte, error)
	// Update the data by id.
	// Note:
	// * Update MUST return ErrNotExist is the id doesn't exist.
	// * The update MUST be applied in one transaction.
	Update(string, UpdateFunc) error
	// List returns entire array of data from the store.
	List() ([][]byte, error)
	// Delete the data by id.
	// Note:
	// * Delete should be idempotent, it MUST not return error if the id
	// doesn't exist or has been removed.
	// * The id and data MUST be deleted in one transaction.
	Delete(string) error
}

MetadataStore is the interface for storing metadata. All methods should be thread-safe. TODO(random-liu): Initialize the metadata store with a type, and replace []byte with interface{}, so as to avoid extra marshal/unmarshal on the user side.

func NewMetadataStore

func NewMetadataStore() MetadataStore

NewMetadataStore creates a MetadataStore.

type UpdateFunc

type UpdateFunc func([]byte) ([]byte, error)

UpdateFunc is function used to update a specific metadata. The value passed in is the old value, it MUST NOT be changed in the function. The function should make a copy of the old value and apply update on the copy. The updated value should be returned. If there is an error, the update will be rolled back.