Returns an com.twitter.util.Activity for a named T-typed variable.
Returns an com.twitter.util.Activity for a named T-typed variable.
Produces an ActivitySource which queries this ActivitySource, falling back to a secondary ActivitySource only when the primary result is ActivitySource.Failed.
Produces an ActivitySource which queries this ActivitySource, falling back to a secondary ActivitySource only when the primary result is ActivitySource.Failed.
the secondary ActivitySource
An ActivitySource for observing the contents of a file with periodic polling.