store

Documentation

Index

• Variables
• type Store

Variables

var (
	// ErrKeyExists means the given key already exists in the store.
	ErrKeyExists = verror.NewID("KeyExists")
	// ErrUnknownKey means the given key does not exist in the store.
	ErrUnknownKey = verror.NewID("UnknownKey")
)

Types

type Store

type Store interface {
	// Get returns the value for the given key (decoding into v).
	// Fails if the given key is unknown (ErrUnknownKey).
	Get(k string, v interface{}) (version string, err error)

	// Insert writes the given value for the given key.
	// Fails if an entry already exists for the given key (ErrKeyExists).
	Insert(k string, v interface{}) error

	// Update writes the given value for the given key.
	// Fails if the given key is unknown (ErrUnknownKey).
	// Fails if version doesn't match (ErrBadVersion).
	Update(k string, v interface{}, version string) error

	// Delete deletes the entry for the given key.
	// Fails if the given key is unknown (ErrUnknownKey).
	// Fails if version doesn't match (ErrBadVersion).
	Delete(k string, version string) error

	// Close closes the store. All subsequent method calls will fail.
	Close() error
}

Store is a key-value store that uses versions for optimistic concurrency control. The versions passed to Update and Delete must come from Get. If in the meantime some client has called Update or Delete on the same key, the version will be stale and the method call will fail.

Note, this API disallows empty versions to simplify implementation. The group server is the only client of this API and always specifies versions.