base-4.17.0.0: Basic libraries
Copyright(c) The University of Glasgow 1994-2002
Licensesee libraries/base/LICENSE
Maintainercvs-ghc@haskell.org
Stabilityinternal
Portabilitynon-portable (GHC extensions)
Safe HaskellTrustworthy
LanguageHaskell2010

GHC.Conc.IO

Contents

Description

Basic concurrency stuff.

Synopsis

Documentation

interruptIOManager :: IO () Source #

Interrupts the current wait of the I/O manager if it is currently blocked. This instructs it to re-read how much it should wait and to process any pending events.

Since: base-4.15

Waiting

threadDelay :: Int -> IO () Source #

Suspends the current thread for a given number of microseconds (GHC only).

There is no guarantee that the thread will be rescheduled promptly when the delay has expired, but the thread will never continue to run earlier than specified.

Be careful not to exceed maxBound :: Int, which on 32-bit machines is only 2147483647 μs, less than 36 minutes. Consider using Control.Concurrent.Thread.Delay.delay from unbounded-delays package.

registerDelay :: Int -> IO (TVar Bool) Source #

Switch the value of returned TVar from initial value False to True after a given number of microseconds. The caveats associated with threadDelay also apply.

Be careful not to exceed maxBound :: Int, which on 32-bit machines is only 2147483647 μs, less than 36 minutes.

threadWaitRead :: Fd -> IO () Source #

Block the current thread until data is available to read on the given file descriptor (GHC only).

This will throw an IOError if the file descriptor was closed while this thread was blocked. To safely close a file descriptor that has been used with threadWaitRead, use closeFdWith.

threadWaitWrite :: Fd -> IO () Source #

Block the current thread until data can be written to the given file descriptor (GHC only).

This will throw an IOError if the file descriptor was closed while this thread was blocked. To safely close a file descriptor that has been used with threadWaitWrite, use closeFdWith.

threadWaitReadSTM :: Fd -> IO (STM (), IO ()) Source #

Returns an STM action that can be used to wait for data to read from a file descriptor. The second returned value is an IO action that can be used to deregister interest in the file descriptor.

threadWaitWriteSTM :: Fd -> IO (STM (), IO ()) Source #

Returns an STM action that can be used to wait until data can be written to a file descriptor. The second returned value is an IO action that can be used to deregister interest in the file descriptor.

closeFdWith Source #

Arguments

:: (Fd -> IO ())

Low-level action that performs the real close.

-> Fd

File descriptor to close.

-> IO () 

Close a file descriptor in a concurrency-safe way (GHC only). If you are using threadWaitRead or threadWaitWrite to perform blocking I/O, you must use this function to close file descriptors, or blocked threads may not be woken.

Any threads that are blocked on the file descriptor via threadWaitRead or threadWaitWrite will be unblocked by having IO exceptions thrown.