System.Posix.MQueue

Create a circular buffer over shared memory that can be accessed from - separate processes. - - This module assumes that exactly one WriteBuffer and one ReadBuffer will be - used to access the same shared memory object. The ReadBuffer and - WriteBuffer may exist in separate processes. - - to use this library, in one process - - > bracket (createBuffer aBuffer aSemaphore 256 0o600) (removeBuffer) - > (buffer -> doSomethingWith buffer) - - and in the other - - > bracket (openBuffer aBuffer aSemaphore 256 0o600) (closeBuffer) - > (buffer -> doSomethingWith buffer) - - The buffer may be opened from either the reader or writer end, but you - should ensure that the buffer is created before it is opened. - - As the underlying objects (shm and named posix semaphores) exist in the file - system, failing to call removeBuffer will leave stale objects in the - filesystem. - - Opening multiple ReadBuffers or WriteBuffers with the same names (whether in - one process or several) results in undefined behavior.

Documentation

data WriteBuffer a

Instances

Storable a => Shared (WriteBuffer a)

data ReadBuffer a

Instances

Storable a => Shared (ReadBuffer a)

class Shared b where

Functions for creatingopeningclosing/removing shared buffers.

Methods

createBuffer :: String -> String -> Int -> FileMode -> IO b

openBuffer :: String -> String -> Int -> FileMode -> IO b

closeBuffer :: b -> IO ()

removeBuffer :: b -> IO ()

unlinkBuffer :: b -> IO ()

Instances

Storable a => Shared (ReadBuffer a)

Storable a => Shared (WriteBuffer a)

Storable a => Shared (ReadBuffer a)

Storable a => Shared (WriteBuffer a)

normal interface

putBuffer :: Storable a => WriteBuffer a -> a -> IO ()

Write a value to the writer end.

This function is thread-safe.

getBuffer :: forall a. Storable a => ReadBuffer a -> IO a

read the next value from the reader end.

This function is *NOT* thread-safe.

putBufferList :: Storable a => WriteBuffer a -> [a] -> IO ()

Write a list of values to the writer end.

This function is thread-safe.

getAvailable :: Storable a => ReadBuffer a -> IO [a]

read all currently available values from the reader end.

This function is *NOT* thread-safe.