async-refresh

Package implementing core logic for refreshing of expiring data. https://github.com/mtesseract/async-refresh

LTS Haskell 9.18:0.2.0.2
Stackage Nightly 2017-12-15:0.2.0.2
Latest on Hackage:0.2.0.2
BSD3 licensed by Moritz Schulte
Maintained by mtesseract@silverratio.net

Module documentation for 0.2.0.2

async-refresh Hackage version Stackage version Build Status

About

This is Haskell library implementing the logic for refreshing of expiring data according to user-provided actions.

Usage

  • Create a new configuration using newAsyncRefreshConf, providing the action to be used for data refreshing.

  • Adjust the configuration using the asyncRefreshConfSet* functions, in particular using asyncRefreshConfSetCallback.

  • Use newAsyncRefresh to initiate a new thread managing the asynchronous refreshing.

Example

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
comments powered byDisqus