Safe Haskell	Safe
Language	Haskell2010

Clckwrks.IOThread

Description

this module provides a simple mechanism for adding IO operations to a queue and running them in a single thread. This is useful if the IO operations have side-effects which could collide if run from multiple threads. For example, creating an image thumbnail and storing it on disk, running LaTeX, etc.

Synopsis

data IOThread a b = IOThread {
- ioThreadId :: ThreadId
- ioThreadChan :: Chan (a, MVar (Either SomeException b))
}
startIOThread :: (a -> IO b) -> IO (IOThread a b)
killIOThread :: IOThread a b -> IO ()
ioRequest :: IOThread a b -> a -> IO b

Documentation

data IOThread a b Source #

Constructors

IOThread
Fields ioThreadId :: ThreadId ioThreadChan :: Chan (a, MVar (Either SomeException b))

startIOThread Source #

Arguments

:: (a -> IO b)	the IO function that does all the work
-> IO (IOThread a b)	a handle to the IOThread

start the IO thread.

killIOThread :: IOThread a b -> IO () Source #

kill the IOThread

WARNING: no attempt is made to wait for the queue to empty... we should probably have safer version that waits for the operations to complete?

ioRequest Source #

Arguments

:: IOThread a b	handle to the IOThread
-> a	argument to the function in the IOThread
-> IO b	value returned by the function in the IOThread

issue a request to the IO thread and get back the result if the thread function throws an exception ioRequest will rethrow the exception.