Data.PowerQueue

Worker descriptions

data QueueWorker j

Instances

Divisible QueueWorker

Methods

divide :: (a -> (b, c)) -> QueueWorker b -> QueueWorker c -> QueueWorker a

conquer :: QueueWorker a

Contravariant QueueWorker

Methods

contramap :: (a -> b) -> QueueWorker b -> QueueWorker a

(>$) :: b -> QueueWorker b -> QueueWorker a

newQueueWorker :: (j -> IO JobResult) -> QueueWorker j

data JobResult

Result of the job

Constructors

JOk

job is complete

JRetry

job execution should be retried

Instances

Eq JobResult

Methods

(==) :: JobResult -> JobResult -> Bool

(/=) :: JobResult -> JobResult -> Bool

Show JobResult

Methods

showsPrec :: Int -> JobResult -> ShowS

show :: JobResult -> String

showList :: [JobResult] -> ShowS

Queue control

data Queue j

newQueue :: QueueBackend j -> QueueWorker j -> Queue j

Create a new queue description

mapQueue :: (a -> b) -> (b -> a) -> Queue a -> Queue b

enqueueJob :: j -> Queue j -> IO Bool

Add a Job to the Queue

(persistent) queue backends

data QueueBackend j

Constructors

Monad m => QueueBackend

Fields

• qb_lift :: forall a. m a -> IO a

  lift an action from the backend monad into IO

• qb_enqueue :: j -> m Bool

  enqueue a job

• qb_dequeue :: m (tx, j)

  dequeue a single job, block if no job available

• qb_confirm :: tx -> m ()

  mark a single job as confirmed

• qb_rollback :: tx -> m ()

  mark a single job as failed

mapBackend :: (a -> b) -> (b -> a) -> QueueBackend a -> QueueBackend b

basicChanBackend :: forall j. IO (QueueBackend j)

A very basic in memory backend using only data structures from the base library. It should only be used for testing and serves as an implementation example

execution strategies

workStep :: Queue j -> IO ()

Execute a single work step: attempt a dequeue and run the job. Use to implement a queue worker, such as localQueueWorker

A local worker

data LocalWorkerConfig

Constructors

LocalWorkerConfig

Fields

• lwc_concurrentJobs :: !Int

localQueueWorker :: LocalWorkerConfig -> Queue j -> IO ()

(Concurrently) run pending jobs on local machine in current process