System.Event

Contents

Description

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

This module should be considered GHC internal.

Synopsis

Types

data EventManager Source

The event manager state.

Creation

new :: IO EventManager Source

Create a new event manager.

Running

loop :: EventManager -> IO ()Source

Start handling events. This function loops until told to stop, using shutdown.

Note: This loop can only be run once per EventManager, as it closes all of its control resources when it finishes.

Stepwise running

step :: EventManager -> TimeoutQueue -> IO (Bool, TimeoutQueue)Source

shutdown :: EventManager -> IO ()Source

Asynchronously shuts down the event manager, if running.

Registering interest in I/O events

data Event Source

An I/O event.

Instances

Eq Event
Show Event
Show IOCallback
Monoid Event

evtRead :: Event Source

Data is available to be read.

evtWrite :: Event Source

The file descriptor is ready to accept a write.

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

Callback invoked on I/O events.

data FdKey Source

A file descriptor registration cookie.

Instances

Eq FdKey
Show IOCallback
Show FdKey

registerFd :: EventManager -> IOCallback -> Fd -> Event -> IO FdKey Source

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

registerFd_ :: EventManager -> IOCallback -> Fd -> Event -> IO (FdKey, Bool)Source

Register interest in the given events, without waking the event manager thread. The Bool return value indicates whether the event manager ought to be woken.

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

Drop a previous file descriptor registration.

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

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 ()Source

Close a file descriptor in a race-safe way.

Registering interest in timeout events

type TimeoutCallback = IO ()Source

Callback invoked on timeout events.

data TimeoutKey Source

A timeout registration cookie.

Instances

Eq TimeoutKey

registerTimeout :: EventManager -> Int -> TimeoutCallback -> IO TimeoutKey Source

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 :: EventManager -> TimeoutKey -> Int -> IO ()Source

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

unregisterTimeout :: EventManager -> TimeoutKey -> IO ()Source

Unregister an active timeout.