unliftio-0.2.23.0: The MonadUnliftIO typeclass for unlifting monads to IO (batteries included)
Safe Haskell None
Language Haskell2010

UnliftIO.Async

Description

Unlifted Control.Concurrent.Async .

Since: 0.1.0.0

Synopsis

Asynchronous actions

data Async a Source #

An asynchronous action spawned by async or withAsync . Asynchronous actions are executed in a separate thread, and operations are provided for waiting for asynchronous actions to complete and obtaining their results (see e.g. wait ).

Spawning

async :: MonadUnliftIO m => m a -> m ( Async a) Source #

Unlifted async .

Since: 0.1.0.0

asyncBound :: MonadUnliftIO m => m a -> m ( Async a) Source #

Unlifted asyncBound .

Since: 0.1.0.0

asyncOn :: MonadUnliftIO m => Int -> m a -> m ( Async a) Source #

Unlifted asyncOn .

Since: 0.1.0.0

asyncWithUnmask :: MonadUnliftIO m => (( forall b. m b -> m b) -> m a) -> m ( Async a) Source #

Unlifted asyncWithUnmask .

Since: 0.1.0.0

asyncOnWithUnmask :: MonadUnliftIO m => Int -> (( forall b. m b -> m b) -> m a) -> m ( Async a) Source #

Unlifted asyncOnWithUnmask .

Since: 0.1.0.0

Spawning with automatic cancel ation

withAsync :: MonadUnliftIO m => m a -> ( Async a -> m b) -> m b Source #

Unlifted withAsync .

Since: 0.1.0.0

withAsyncBound :: MonadUnliftIO m => m a -> ( Async a -> m b) -> m b Source #

Unlifted withAsyncBound .

Since: 0.1.0.0

withAsyncOn :: MonadUnliftIO m => Int -> m a -> ( Async a -> m b) -> m b Source #

Unlifted withAsyncOn .

Since: 0.1.0.0

withAsyncWithUnmask :: MonadUnliftIO m => (( forall c. m c -> m c) -> m a) -> ( Async a -> m b) -> m b Source #

Unlifted withAsyncWithUnmask .

Since: 0.1.0.0

withAsyncOnWithUnmask :: MonadUnliftIO m => Int -> (( forall c. m c -> m c) -> m a) -> ( Async a -> m b) -> m b Source #

Unlifted withAsyncOnWithMask .

Since: 0.1.0.0

Querying Async s

wait :: MonadIO m => Async a -> m a Source #

Lifted wait .

Since: 0.1.0.0

cancel :: MonadIO m => Async a -> m () Source #

Lifted cancel .

Since: 0.1.0.0

cancelWith :: ( Exception e, MonadIO m) => Async a -> e -> m () Source #

Lifted cancelWith . Additionally uses toAsyncException to ensure async exception safety.

Since: 0.1.0.0

asyncThreadId :: Async a -> ThreadId Source #

Returns the ThreadId of the thread running the given Async .

STM operations

waitSTM :: Async a -> STM a Source #

A version of wait that can be used inside an STM transaction.

pollSTM :: Async a -> STM ( Maybe ( Either SomeException a)) Source #

A version of poll that can be used inside an STM transaction.

waitCatchSTM :: Async a -> STM ( Either SomeException a) Source #

A version of waitCatch that can be used inside an STM transaction.

Waiting for multiple Async s

waitAny :: MonadIO m => [ Async a] -> m ( Async a, a) Source #

Lifted waitAny .

Since: 0.1.0.0

waitAnyCancel :: MonadIO m => [ Async a] -> m ( Async a, a) Source #

Lifted waitAnyCancel .

Since: 0.1.0.0

waitEither :: MonadIO m => Async a -> Async b -> m ( Either a b) Source #

Lifted waitEither .

Since: 0.1.0.0

waitEither_ :: MonadIO m => Async a -> Async b -> m () Source #

Lifted waitEither_ .

Since: 0.1.0.0

waitBoth :: MonadIO m => Async a -> Async b -> m (a, b) Source #

Lifted waitBoth .

Since: 0.1.0.0

Waiting for multiple Async s in STM

waitAnySTM :: [ Async a] -> STM ( Async a, a) Source #

A version of waitAny that can be used inside an STM transaction.

Since: async-2.1.0

waitAnyCatchSTM :: [ Async a] -> STM ( Async a, Either SomeException a) Source #

A version of waitAnyCatch that can be used inside an STM transaction.

Since: async-2.1.0

waitEitherSTM :: Async a -> Async b -> STM ( Either a b) Source #

A version of waitEither that can be used inside an STM transaction.

Since: async-2.1.0

waitEitherCatchSTM :: Async a -> Async b -> STM ( Either ( Either SomeException a) ( Either SomeException b)) Source #

A version of waitEitherCatch that can be used inside an STM transaction.

Since: async-2.1.0

waitEitherSTM_ :: Async a -> Async b -> STM () Source #

A version of waitEither_ that can be used inside an STM transaction.

Since: async-2.1.0

waitBothSTM :: Async a -> Async b -> STM (a, b) Source #

A version of waitBoth that can be used inside an STM transaction.

Since: async-2.1.0

Linking

link :: MonadIO m => Async a -> m () Source #

Lifted link .

Since: 0.1.0.0

link2 :: MonadIO m => Async a -> Async b -> m () Source #

Lifted link2 .

Since: 0.1.0.0

Pooled concurrency

pooledMapConcurrentlyN Source #

Arguments

:: ( MonadUnliftIO m, Traversable t)
=> Int

Max. number of threads. Should not be less than 1.

-> (a -> m b)
-> t a
-> m (t b)

Like mapConcurrently from async, but instead of one thread per element, it does pooling from a set of threads. This is useful in scenarios where resource consumption is bounded and for use cases where too many concurrent tasks aren't allowed.

Example usage

Expand
import Say

action :: Int -> IO Int
action n = do
  tid <- myThreadId
  sayString $ show tid
  threadDelay (2 * 10^6) -- 2 seconds
  return n

main :: IO ()
main = do
  yx <- pooledMapConcurrentlyN 5 (\x -> action x) [1..5]
  print yx

On executing you can see that five threads have been spawned:

$ ./pool
ThreadId 36
ThreadId 38
ThreadId 40
ThreadId 42
ThreadId 44
[1,2,3,4,5]

Let's modify the above program such that there are less threads than the number of items in the list:

import Say

action :: Int -> IO Int
action n = do
  tid <- myThreadId
  sayString $ show tid
  threadDelay (2 * 10^6) -- 2 seconds
  return n

main :: IO ()
main = do
  yx <- pooledMapConcurrentlyN 3 (\x -> action x) [1..5]
  print yx

On executing you can see that only three threads are active totally:

$ ./pool
ThreadId 35
ThreadId 37
ThreadId 39
ThreadId 35
ThreadId 39
[1,2,3,4,5]

Since: 0.2.10

pooledMapConcurrently :: ( MonadUnliftIO m, Traversable t) => (a -> m b) -> t a -> m (t b) Source #

Similar to pooledMapConcurrentlyN but with number of threads set from getNumCapabilities . Usually this is useful for CPU bound tasks.

Since: 0.2.10

pooledMapConcurrentlyN_ Source #

Arguments

:: ( MonadUnliftIO m, Foldable f)
=> Int

Max. number of threads. Should not be less than 1.

-> (a -> m b)
-> f a
-> m ()

Like pooledMapConcurrentlyN but with the return value discarded.

Since: 0.2.10

pooledMapConcurrently_ :: ( MonadUnliftIO m, Foldable f) => (a -> m b) -> f a -> m () Source #

Like pooledMapConcurrently but with the return value discarded.

Since: 0.2.10

pooledForConcurrentlyN Source #

Arguments

:: ( MonadUnliftIO m, Traversable t)
=> Int

Max. number of threads. Should not be less than 1.

-> t a
-> (a -> m b)
-> m (t b)

Similar to pooledMapConcurrentlyN but with flipped arguments.

Since: 0.2.10

pooledForConcurrently :: ( MonadUnliftIO m, Traversable t) => t a -> (a -> m b) -> m (t b) Source #

Similar to pooledForConcurrentlyN but with number of threads set from getNumCapabilities . Usually this is useful for CPU bound tasks.

Since: 0.2.10

pooledForConcurrentlyN_ Source #

Arguments

:: ( MonadUnliftIO m, Foldable t)
=> Int

Max. number of threads. Should not be less than 1.

-> t a
-> (a -> m b)
-> m ()

Like pooledMapConcurrentlyN_ but with flipped arguments.

Since: 0.2.10

pooledForConcurrently_ :: ( MonadUnliftIO m, Foldable f) => f a -> (a -> m b) -> m () Source #

Like pooledMapConcurrently_ but with flipped arguments.

Since: 0.2.10

pooledReplicateConcurrentlyN Source #

Arguments

:: MonadUnliftIO m
=> Int

Max. number of threads. Should not be less than 1.

-> Int

Number of times to perform the action.

-> m a
-> m [a]

Pooled version of replicateConcurrently . Performs the action in the pooled threads.

Since: 0.2.10

pooledReplicateConcurrently Source #

Arguments

:: MonadUnliftIO m
=> Int

Number of times to perform the action.

-> m a
-> m [a]

Similar to pooledReplicateConcurrentlyN but with number of threads set from getNumCapabilities . Usually this is useful for CPU bound tasks.

Since: 0.2.10

pooledReplicateConcurrentlyN_ Source #

Arguments

:: MonadUnliftIO m
=> Int

Max. number of threads. Should not be less than 1.

-> Int

Number of times to perform the action.

-> m a
-> m ()

Pooled version of replicateConcurrently_ . Performs the action in the pooled threads.

Since: 0.2.10

pooledReplicateConcurrently_ Source #

Arguments

:: MonadUnliftIO m
=> Int

Number of times to perform the action.

-> m a
-> m ()

Similar to pooledReplicateConcurrently_ but with number of threads set from getNumCapabilities . Usually this is useful for CPU bound tasks.

Since: 0.2.10

Convenient utilities

race :: MonadUnliftIO m => m a -> m b -> m ( Either a b) Source #

Unlifted race .

Since: 0.1.0.0

race_ :: MonadUnliftIO m => m a -> m b -> m () Source #

Unlifted race_ .

Since: 0.1.0.0

concurrently :: MonadUnliftIO m => m a -> m b -> m (a, b) Source #

Unlifted concurrently .

Since: 0.1.0.0

concurrently_ :: MonadUnliftIO m => m a -> m b -> m () Source #

Unlifted concurrently_ .

Since: 0.1.0.0

mapConcurrently :: MonadUnliftIO m => Traversable t => (a -> m b) -> t a -> m (t b) Source #

Executes a Traversable container of items concurrently, it uses the Flat type internally.

Since: 0.1.0.0

forConcurrently :: MonadUnliftIO m => Traversable t => t a -> (a -> m b) -> m (t b) Source #

Similar to mapConcurrently but with arguments flipped

Since: 0.1.0.0

mapConcurrently_ :: MonadUnliftIO m => Foldable f => (a -> m b) -> f a -> m () Source #

Executes a Traversable container of items concurrently, it uses the Flat type internally. This function ignores the results.

Since: 0.1.0.0

forConcurrently_ :: MonadUnliftIO m => Foldable f => f a -> (a -> m b) -> m () Source #

Similar to mapConcurrently_ but with arguments flipped

Since: 0.1.0.0

newtype Concurrently m a Source #

Unlifted Concurrently .

Since: 0.1.0.0

Constructors

Concurrently

Fields

Instances

Instances details
Monad m => Functor ( Concurrently m) Source #

Since: 0.1.0.0

Instance details

Defined in UnliftIO.Internals.Async

MonadUnliftIO m => Applicative ( Concurrently m) Source #

Since: 0.1.0.0

Instance details

Defined in UnliftIO.Internals.Async

MonadUnliftIO m => Alternative ( Concurrently m) Source #

Composing two unlifted Concurrently values using Alternative is the equivalent to using a race combinator, the asynchrounous sub-routine that returns a value first is the one that gets it's value returned, the slowest sub-routine gets cancelled and it's thread is killed.

Since: 0.1.0.0

Instance details

Defined in UnliftIO.Internals.Async

( MonadUnliftIO m, Semigroup a) => Semigroup ( Concurrently m a) Source #

Only defined by async for base >= 4.9 .

Since: 0.1.0.0

Instance details

Defined in UnliftIO.Internals.Async

( Semigroup a, Monoid a, MonadUnliftIO m) => Monoid ( Concurrently m a) Source #

Since: 0.1.0.0

Instance details

Defined in UnliftIO.Internals.Async

data Conc m a Source #

A more efficient alternative to Concurrently , which reduces the number of threads that need to be forked. For more information, see this blog post . This is provided as a separate type to Concurrently as it has a slightly different API.

Use the conc function to construct values of type Conc , and runConc to execute the composed actions. You can use the Applicative instance to run different actions and wait for all of them to complete, or the Alternative instance to wait for the first thread to complete.

In the event of a runtime exception thrown by any of the children threads, or an asynchronous exception received in the parent thread, all threads will be killed with an AsyncCancelled exception and the original exception rethrown. If multiple exceptions are generated by different threads, there are no guarantees on which exception will end up getting rethrown.

For many common use cases, you may prefer using helper functions in this module like mapConcurrently .

There are some intentional differences in behavior to Concurrently :

  • Children threads are always launched in an unmasked state, not the inherited state of the parent thread.

Note that it is a programmer error to use the Alternative instance in such a way that there are no alternatives to an empty, e.g. runConc (empty | empty) . In such a case, a ConcException will be thrown. If there was an Alternative in the standard libraries without empty , this library would use it instead.

Since: 0.2.9.0

conc :: m a -> Conc m a Source #

Construct a value of type Conc from an action. Compose these values using the typeclass instances (most commonly Applicative and Alternative ) and then run with runConc .

Since: 0.2.9.0

runConc :: MonadUnliftIO m => Conc m a -> m a Source #

Run a Conc value on multiple threads.

Since: 0.2.9.0

data ConcException Source #

Things that can go wrong in the structure of a Conc . These are programmer errors .

Since: 0.2.9.0

Instances

Instances details
Eq ConcException Source #
Instance details

Defined in UnliftIO.Internals.Async

Ord ConcException Source #
Instance details

Defined in UnliftIO.Internals.Async

Show ConcException Source #
Instance details

Defined in UnliftIO.Internals.Async

Generic ConcException Source #
Instance details

Defined in UnliftIO.Internals.Async

Exception ConcException Source #
Instance details

Defined in UnliftIO.Internals.Async

type Rep ConcException Source #
Instance details

Defined in UnliftIO.Internals.Async

type Rep ConcException = D1 (' MetaData "ConcException" "UnliftIO.Internals.Async" "unliftio-0.2.23.0-BJNCtN4eNMn3DzDTkYkSnJ" ' False ) ( C1 (' MetaCons "EmptyWithNoAlternative" ' PrefixI ' False ) ( U1 :: Type -> Type ))

Re-exports