Stability | experimental |
---|---|

Maintainer | Bas van Dijk <v.dijk.bas@gmail.com> |

Safe Haskell | Trustworthy |

This is a wrapped version of Control.Concurrent with types generalized
from `IO`

to all monads in either `MonadBase`

or `MonadBaseControl`

.

- data ThreadId
- myThreadId :: MonadBase IO m => m ThreadId
- fork :: MonadBaseControl IO m => m () -> m ThreadId
- forkWithUnmask :: MonadBaseControl IO m => ((forall a. m a -> m a) -> m ()) -> m ThreadId
- forkFinally :: MonadBaseControl IO m => m a -> (Either SomeException a -> m ()) -> m ThreadId
- killThread :: MonadBase IO m => ThreadId -> m ()
- throwTo :: (MonadBase IO m, Exception e) => ThreadId -> e -> m ()
- forkOn :: MonadBaseControl IO m => Int -> m () -> m ThreadId
- forkOnWithUnmask :: MonadBaseControl IO m => Int -> ((forall a. m a -> m a) -> m ()) -> m ThreadId
- getNumCapabilities :: MonadBase IO m => m Int
- setNumCapabilities :: MonadBase IO m => Int -> m ()
- threadCapability :: MonadBase IO m => ThreadId -> m (Int, Bool)
- yield :: MonadBase IO m => m ()
- threadDelay :: MonadBase IO m => Int -> m ()
- threadWaitRead :: MonadBase IO m => Fd -> m ()
- threadWaitWrite :: MonadBase IO m => Fd -> m ()
- module Control.Concurrent.MVar.Lifted
- module Control.Concurrent.Chan.Lifted
- rtsSupportsBoundThreads :: Bool
- forkOS :: MonadBaseControl IO m => m () -> m ThreadId
- isCurrentThreadBound :: MonadBase IO m => m Bool
- runInBoundThread :: MonadBaseControl IO m => m a -> m a
- runInUnboundThread :: MonadBaseControl IO m => m a -> m a
- mkWeakThreadId :: MonadBase IO m => ThreadId -> m (Weak ThreadId)

# Concurrent Haskell

data ThreadId

A `ThreadId`

is an abstract type representing a handle to a thread.
`ThreadId`

is an instance of `Eq`

, `Ord`

and `Show`

, where
the `Ord`

instance implements an arbitrary total ordering over
`ThreadId`

s. The `Show`

instance lets you convert an arbitrary-valued
`ThreadId`

to string form; showing a `ThreadId`

value is occasionally
useful when debugging or diagnosing the behaviour of a concurrent
program.

*Note*: in GHC, if you have a `ThreadId`

, you essentially have
a pointer to the thread itself. This means the thread itself can't be
garbage collected until you drop the `ThreadId`

.
This misfeature will hopefully be corrected at a later date.

*Note*: Hugs does not provide any operations on other threads;
it defines `ThreadId`

as a synonym for ().

# Basic concurrency operations

myThreadId :: MonadBase IO m => m ThreadIdSource

Generalized version of `myThreadId`

.

fork :: MonadBaseControl IO m => m () -> m ThreadIdSource

forkWithUnmask :: MonadBaseControl IO m => ((forall a. m a -> m a) -> m ()) -> m ThreadIdSource

Generalized version of `forkIOWithUnmask`

.

Note that, while the forked computation `m ()`

has access to the captured
state, all its side-effects in `m`

are discarded. It is run only for its
side-effects in `IO`

.

forkFinally :: MonadBaseControl IO m => m a -> (Either SomeException a -> m ()) -> m ThreadIdSource

Generalized version of `forkFinally`

.

Note that in `forkFinally action and_then`

, while the forked
`action`

and the `and_then`

function have access to the captured
state, all their side-effects in `m`

are discarded. They're run
only for their side-effects in `IO`

.

killThread :: MonadBase IO m => ThreadId -> m ()Source

Generalized version of `killThread`

.

throwTo :: (MonadBase IO m, Exception e) => ThreadId -> e -> m ()Source

Generalized version of `throwTo`

.

## Threads with affinity

forkOnWithUnmask :: MonadBaseControl IO m => Int -> ((forall a. m a -> m a) -> m ()) -> m ThreadIdSource

Generalized version of `forkOnWithUnmask`

.

Note that, while the forked computation `m ()`

has access to the captured
state, all its side-effects in `m`

are discarded. It is run only for its
side-effects in `IO`

.

getNumCapabilities :: MonadBase IO m => m IntSource

Generalized version of `getNumCapabilities`

.

setNumCapabilities :: MonadBase IO m => Int -> m ()Source

Generalized version of `setNumCapabilities`

.

threadCapability :: MonadBase IO m => ThreadId -> m (Int, Bool)Source

Generalized version of `threadCapability`

.

# Scheduling

## Blocking

## Waiting

threadDelay :: MonadBase IO m => Int -> m ()Source

Generalized version of `threadDelay`

.

threadWaitRead :: MonadBase IO m => Fd -> m ()Source

Generalized version of `threadWaitRead`

.

threadWaitWrite :: MonadBase IO m => Fd -> m ()Source

Generalized version of `threadWaitWrite`

.

# Communication abstractions

# Bound Threads

rtsSupportsBoundThreads :: Bool

`True`

if bound threads are supported.
If `rtsSupportsBoundThreads`

is `False`

, `isCurrentThreadBound`

will always return `False`

and both `forkOS`

and `runInBoundThread`

will
fail.

forkOS :: MonadBaseControl IO m => m () -> m ThreadIdSource

isCurrentThreadBound :: MonadBase IO m => m BoolSource

Generalized version of `isCurrentThreadBound`

.

runInBoundThread :: MonadBaseControl IO m => m a -> m aSource

Generalized version of `runInBoundThread`

.

runInUnboundThread :: MonadBaseControl IO m => m a -> m aSource

Generalized version of `runInUnboundThread`

.

# Weak references to ThreadIds

mkWeakThreadId :: MonadBase IO m => ThreadId -> m (Weak ThreadId)Source

Generalized versio of `mkWeakThreadId`

.