arbiter-orville (orville-postgresql)

orville-postgresql. Orville owns its connections and transactions. OrvilleDb runs over the application's own MonadOrville monad, so Arbiter queries use its connection and join its open transaction:

O.withTransaction $ do
  O.insertEntity ordersTable order
  ArbO.runOrvilleDb @AppRegistry (ArbO.OrvilleEnv {ArbO.schema = "arbiter", ArbO.listener = Nothing}) $
    Arb.insertJob (Arb.defaultJob (ProcessOrder orderId))

Single-job handlers run in the application monad, as JobRead payload -> AppM result. A handler that inserts jobs wraps those calls in runOrvilleDb to share its transaction.

Batched and manual handlers, and observability hooks, run in the worker's monad. Arbiter.Orville.Worker adapts ones written in AppM. orvilleBatchedHandler runs the callbacks in the worker's own OrvilleEnv, on the handler's connection and inside its transaction:

import Arbiter.Orville.Worker (orvilleBatchedHandler, orvilleHooks)

processEmail :: Arb.JobRead EmailPayload -> Worker.BatchCallbacks AppM EmailPayload () -> AppM ()

config <- Worker.manualWorkerConfig 5 (orvilleBatchedHandler processEmail)
let emailPool = config {Worker.observabilityHooks = orvilleHooks appHooks}

For LISTEN/NOTIFY, build a Listener with newLibPQListener from arbiter-libpq and the pool's connection string, and put it in the OrvilleEnv. Nothing polls.

Size the Orville pool with poolConfigForWorkers:

import Arbiter.LibPQ (newLibPQListener)
import Arbiter.Orville qualified as ArbO

main :: IO ()
main = do
  poolCfg <- Worker.poolConfigForWorkers workers
  orvillePool <- O.createConnectionPool (ArbO.toOrvilleConnectionOptions connStr poolCfg)
  listen <- newLibPQListener connStr
  let orvilleState = O.newOrvilleState O.defaultErrorDetailLevel orvillePool
      arbiterEnv = ArbO.OrvilleEnv {ArbO.schema = "arbiter", ArbO.listener = Just listen}
  runAppM orvilleState . ArbO.runOrvilleDb arbiterEnv $
    Worker.runWorkerPools workers

AppM needs MonadOrville and MonadUnliftIO. An application that wants AppM itself to be the MonadArbiter instance can write one from the primitives in Arbiter.Orville.MonadArbiter. Writing a Backend lists the members.

Connection options: arbiter-orville Haddocks.