async-refresh

Package implementing core logic for refreshing of expiring data.

http://github.com/mtesseract/async-refresh

LTS Haskell 23.22:	0.3.0.0
Stackage Nightly 2025-05-16:	0.3.0.0
Latest on Hackage:	0.3.0.0

See all snapshots async-refresh appears in

BSD-3-Clause licensed by Moritz Clasmeier

Maintained by mtesseract@silverratio.net

This version can be pinned in stack with:async-refresh-0.3.0.0@sha256:319441b58a67e256222aa6751f51fba525caba3182a27152a6d71e986aff91eb,2503

Module documentation for 0.3.0.0

Control
- Control.Concurrent
  - Control.Concurrent.Async
    - Control.Concurrent.Async.Refresh

Depends on 11 packages(full list with versions):

base, formatting, lifted-async, microlens, microlens-th, monad-logger, safe-exceptions, stm, text, unliftio, unliftio-core

Used by 1 package in lts-21.25(full list with versions):

async-refresh-tokens

async-refresh

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