Copyright	(c) 2010-2012 Bas van Dijk & Roel van Dijk
License	BSD3 (see the file LICENSE)
Maintainer	Bas van Dijk <v.dijk.bas@gmail.com> , Roel van Dijk <vandijk.roel@gmail.com>
Safe Haskell	Trustworthy
Language	Haskell98

Control.Concurrent.Thread.Group

Contents

Forking threads

Description

This module extends Control.Concurrent.Thread with the ability to wait for a group of threads to terminate.

This module exports equivalently named functions from Control.Concurrent, (GHC.Conc), and Control.Concurrent.Thread. Avoid ambiguities by importing this module qualified. May we suggest:

import Control.Concurrent.Thread.Group ( ThreadGroup )
import qualified Control.Concurrent.Thread.Group as ThreadGroup ( ... )

Synopsis

data ThreadGroup
new :: IO ThreadGroup
nrOfRunning :: ThreadGroup -> STM Int
wait :: ThreadGroup -> IO ()
waitN :: Int -> ThreadGroup -> IO ()
forkIO :: ThreadGroup -> IO a -> IO (ThreadId, IO (Result a))
forkOS :: ThreadGroup -> IO a -> IO (ThreadId, IO (Result a))
forkOn :: Int -> ThreadGroup -> IO a -> IO (ThreadId, IO (Result a))
forkIOWithUnmask :: ThreadGroup -> ((forall b. IO b -> IO b) -> IO a) -> IO (ThreadId, IO (Result a))
forkOnWithUnmask :: Int -> ThreadGroup -> ((forall b. IO b -> IO b) -> IO a) -> IO (ThreadId, IO (Result a))

Documentation

data ThreadGroup Source #

A ThreadGroup can be understood as a counter which counts the number of threads that were added to the group minus the ones that have terminated.

More formally a ThreadGroup has the following semantics:

new initializes the counter to 0.
Forking a thread increments the counter.
When a forked thread terminates, whether normally or by raising an exception, the counter is decremented.
nrOfRunning yields a transaction that returns the counter.
wait blocks as long as the counter is greater than 0.
waitN blocks as long as the counter is greater or equal to the specified number.

Instances

Instances details

Eq ThreadGroup Source #
Instance details Defined in Control.Concurrent.Thread.Group Methods (==) :: ThreadGroup -> ThreadGroup -> Bool (/=) :: ThreadGroup -> ThreadGroup -> Bool

new :: IO ThreadGroup Source #

Create an empty group of threads.

nrOfRunning :: ThreadGroup -> STM Int Source #

Yield a transaction that returns the number of running threads in the group.

Note that because this function yields a STM computation, the returned number is guaranteed to be consistent inside the transaction.

wait :: ThreadGroup -> IO () Source #

Block until all threads in the group have terminated.

Note that: wait = waitN 1.

waitN :: Int -> ThreadGroup -> IO () Source #

Block until there are fewer than N running threads in the group.

Forking threads

forkIO :: ThreadGroup -> IO a -> IO (ThreadId, IO (Result a)) Source #

Same as Control.Concurrent.Thread.forkIO but additionaly adds the thread to the group.

forkOS :: ThreadGroup -> IO a -> IO (ThreadId, IO (Result a)) Source #

Same as Control.Concurrent.Thread.forkOS but additionaly adds the thread to the group.

forkOn :: Int -> ThreadGroup -> IO a -> IO (ThreadId, IO (Result a)) Source #

Same as Control.Concurrent.Thread.forkOn but additionaly adds the thread to the group.

forkIOWithUnmask :: ThreadGroup -> ((forall b. IO b -> IO b) -> IO a) -> IO (ThreadId, IO (Result a)) Source #

Same as Control.Concurrent.Thread.forkIOWithUnmask but additionaly adds the thread to the group.

forkOnWithUnmask :: Int -> ThreadGroup -> ((forall b. IO b -> IO b) -> IO a) -> IO (ThreadId, IO (Result a)) Source #

Like Control.Concurrent.Thread.forkOnWithUnmask but additionaly adds the thread to the group.