putAsync
Creates a new entry for key using creationFunction and returns a Deferred. Any existing value or in-progress creation of key would be replaced by the new function. You can imply that the creation has failed by returning null.
Creates a new entry for key using creationFunction and returns a Deferred. Any existing value or in-progress creation of key would be replaced by the new function. You can imply that the creation has failed by returning null.