GHC.Conc.IO

base-4.3.1.0: Basic libraries

Portability | non-portable (GHC extensions)
Stability | internal
Maintainer | cvs-ghc@haskell.org

GHC.Conc.IO

Contents

- Waiting

Description

Basic concurrency stuff.

Synopsis

- ensureIOManagerIsRunning :: IO ()
- threadDelay :: Int -> IO ()
- registerDelay :: Int -> IO (TVar Bool)
- threadWaitRead :: Fd -> IO ()
- threadWaitWrite :: Fd -> IO ()
- closeFdWith :: (Fd -> IO ()) -> Fd -> IO ()

# Documentation

ensureIOManagerIsRunning :: IO ()

# Waiting

threadDelay :: Int -> IO ()

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.

registerDelay :: Int -> IO (TVar Bool)

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

threadWaitRead :: Fd -> IO ()

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 ()

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`.

closeFdWith

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.