Arbiter.Simple.MonadArbiter

postgresql-simple primitives for writing a custom MonadArbiter instance.

Handlers receive a Database.PostgreSQL.Simple.Connection for running queries inside the worker transaction:

import Arbiter.Core qualified as Arb
import Arbiter.Simple qualified as ArbS
import Database.PostgreSQL.Simple (Connection)

instance Arb.MonadArbiter MyApp where
  type RegistryOf MyApp = MyRegistry
  type Handler MyApp job result = Connection -> job -> MyApp result
  getSchema                = asks appSchema
  executeQuery             = ArbS.simpleExecuteQuery
  executeStatement         = ArbS.simpleExecuteStatement
  withDbTransaction        = ArbS.simpleWithDbTransaction
  runHandlerWithConnection = ArbS.simpleRunHandlerWithConnection
  getListener              = asks appListener

The primitives also need a HasPoolState Connection MyApp instance. See HasPoolState.

Write a handler's own signature as JobHandler MyApp MyPayload MyResult, which is Handler at that queue's job and declared result types.