This is Haskell library implementing the logic for refreshing of expiring data according to user-provided actions.
-
Create a new configuration using
newAsyncRefreshConf
, providing the action to be used for data refreshing. -
Adjust the configuration using the
asyncRefreshConfSet*
functions, in particular usingasyncRefreshConfSetCallback
. -
Use
newAsyncRefresh
to initiate a new thread managing the asynchronous refreshing.
The following IO action produces a TVar
which is updated every ten
seconds to contain the current time (wrapped in an Either SomeException
, because refreshing may fail).
periodicTimeUpdater :: IO (TVar (Either SomeException UTCTime))
periodicTimeUpdater = runStderrLoggingT $ do
timeStore <- liftIO $ newTVarIO (Left (toException NotFound))
let conf = newAsyncRefreshConf (RefreshResult <$> liftIO getCurrentTime <*> pure Nothing)
& asyncRefreshConfSetLabel "CurrentTime updated every 10 seconds"
& asyncRefreshConfSetDefaultInterval (10 * 10^3)
& asyncRefreshConfSetCallback (liftIO . atomically . writeTVar timeStore . fmap refreshResult)
_ <- newAsyncRefresh conf
return timeStore