storage_interface.go

type Storage interface {
	// Put...
	// if prevVersion < 0, we will set the object with current largest resource version,
	// put the object on the key, and returns the stored object.
	// If prevVersion >= 0, we will use it to do Compare-And-Swap against existing object's resource version.
	// Note that prevVersion = 0 means no previous object on given key.
	// - If compare failed, it will return current object (nil if non-exist) and StorageError of VersionConflicts.
	// - If compare succeed, it will behave like "prevVersion < 0".
	Put(key string, obj runtime.Object, prevVersion int64) (cur runtime.Object, err error)

	// Delete...
	// If prevVersion < 0, we will try to delete the object and return the deleted object. If no object existed
	// on given key, we returns nil object and nil error.
	// If prevVersion > 0, we will use it to do Compare-And-Delete against existing object's resource version.
	// - If compare failed, it will return current object (nil if non-exist) and StorageError of VersionConflicts.
	// - If compare succeed, it will behave like "prevVersion < 0".
	Delete(key string, prevRev int64) (cur runtime.Object, err error)

	// Get gets the most recent version of a key.
	// What is "most recent version" of a key? -- A key that was modified by this interface
	// should be reflected on read after write succeeded.
	// If no object exists on the key, it will return nil object and nil error.
	Get(key string) (cur runtime.Object, err error)

	// if version >=0, list should wait until we have seen object with version >= given version.
	List(key string, version int64, ss ...selector.Selector) (objects []runtime.Object, globalRev int64, err error)

	// WatchPrefix watches a prefix after given rev. If rev is 0, we will watch from current state.
	// It returns notifications of any keys that has given prefix.
	// Given selectors, it returns events that contained object of interest, either of current and previous.
	// If there is any problem establishing the watch channel, it will return error. After channel is established,
	// any error that happened will be returned from WatchChan immediately before it's closed.
	WatchPrefix(ctx context.Context, prefix string, version int64, ss ...selector.Selector) (WatchChan, error)

	//
	AddIndex(idxName, field string, g selector.FieldValueGetFunc) error
	DeleteIndex(idxName string)

	//
	AddWatcherIndex(idxName, field string, g selector.FieldValueGetFunc) error
	DeleteWatcherIndex(idxName string)
}

type FieldValueGetFunc func(field string, obj runtime.Object) (string, bool)

type Selector struct {
	Op     labels.Operator // TODO: define storage layer its own selector
	Field  string
	Values []string
	//
	FVGetFunc FieldValueGetFunc
}