base- Basic libraries

Safe HaskellTrustworthy




This module provides scalable event notification for file descriptors and timeouts.

This module should be considered GHC internal.

  • ---------------------------------------------------------------------------



data EventManager #

The event manager state.

data TimerManager #

The event manager state.


getSystemEventManager :: IO (Maybe EventManager) #

Retrieve the system event manager for the capability on which the calling thread is running.

This function always returns Just the current thread's event manager when using the threaded RTS and Nothing otherwise.

new :: IO EventManager #

Create a new event manager.

Registering interest in I/O events

data Event #

An I/O event.


evtRead :: Event #

Data is available to be read.

evtWrite :: Event #

The file descriptor is ready to accept a write.

type IOCallback = FdKey -> Event -> IO () #

Callback invoked on I/O events.

data FdKey #

A file descriptor registration cookie.


Eq FdKey # 


(==) :: FdKey -> FdKey -> Bool Source #

(/=) :: FdKey -> FdKey -> Bool Source #

Show FdKey # 


showsPrec :: Int -> FdKey -> ShowS #

show :: FdKey -> String #

showList :: [FdKey] -> ShowS #

data Lifetime #

The lifetime of an event registration.




the registration will be active for only one event


the registration will trigger multiple times

registerFd :: EventManager -> IOCallback -> Fd -> Event -> Lifetime -> IO FdKey #

registerFd mgr cb fd evs lt registers interest in the events evs on the file descriptor fd for lifetime lt. cb is called for each event that occurs. Returns a cookie that can be handed to unregisterFd.

unregisterFd :: EventManager -> FdKey -> IO () #

Drop a previous file descriptor registration.

unregisterFd_ :: EventManager -> FdKey -> IO Bool #

Drop a previous file descriptor registration, without waking the event manager thread. The return value indicates whether the event manager ought to be woken.

closeFd :: EventManager -> (Fd -> IO ()) -> Fd -> IO () #

Close a file descriptor in a race-safe way.

Registering interest in timeout events

type TimeoutCallback = IO () #

Callback invoked on timeout events.

data TimeoutKey #

A timeout registration cookie.

registerTimeout :: TimerManager -> Int -> TimeoutCallback -> IO TimeoutKey #

Register a timeout in the given number of microseconds. The returned TimeoutKey can be used to later unregister or update the timeout. The timeout is automatically unregistered after the given time has passed.

updateTimeout :: TimerManager -> TimeoutKey -> Int -> IO () #

Update an active timeout to fire in the given number of microseconds.

unregisterTimeout :: TimerManager -> TimeoutKey -> IO () #

Unregister an active timeout.