/Haskell 8


Copyright (c) Daniel Franke 2007
License BSD-style (see the file libraries/base/LICENSE)
Maintainer [email protected]
Stability experimental
Portability non-portable (requires POSIX)
Safe Haskell Safe
Language Haskell2010


POSIX named semaphore support.

data OpenSemFlags Source




  • semCreate :: Bool

    If true, create the semaphore if it does not yet exist.

  • semExclusive :: Bool

    If true, throw an exception if the semaphore already exists.

data Semaphore Source

semOpen :: String -> OpenSemFlags -> FileMode -> Int -> IO Semaphore Source

Open a named semaphore with the given name, flags, mode, and initial value.

semUnlink :: String -> IO () Source

Delete the semaphore with the given name.

semWait :: Semaphore -> IO () Source

Lock the semaphore, blocking until it becomes available. Since this is done through a system call, this will block the *entire runtime*, not just the current thread. If this is not the behaviour you want, use semThreadWait instead.

semTryWait :: Semaphore -> IO Bool Source

Attempt to lock the semaphore without blocking. Immediately return False if it is not available.

semThreadWait :: Semaphore -> IO () Source

Poll the semaphore until it is available, then lock it. Unlike semWait, this will block only the current thread rather than the entire process.

semPost :: Semaphore -> IO () Source

Unlock the semaphore.

semGetValue :: Semaphore -> IO Int Source

Return the semaphore's current value.

© The University of Glasgow and others
Licensed under a BSD-style license (see top of the page).