GHC.Event

base-4.8.2.0: Basic libraries

Safe Haskell | Trustworthy
Language | Haskell2010

GHC.Event

Contents

- Types
- Creation
- Registering interest in I/O events
- Registering interest in timeout events

Description

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

This module should be considered GHC internal.

- ---------------------------------------------------------------------------

Synopsis

- data EventManager
- data TimerManager
- getSystemEventManager :: IO (Maybe EventManager)
- new :: IO EventManager
- getSystemTimerManager :: IO TimerManager
- data Event
- evtRead :: Event
- evtWrite :: Event
- type IOCallback = FdKey -> Event -> IO ()
- data FdKey
- data Lifetime
  - = OneShot
  - | MultiShot
- registerFd :: EventManager -> IOCallback -> Fd -> Event -> Lifetime -> IO FdKey
- unregisterFd :: EventManager -> FdKey -> IO ()
- unregisterFd_ :: EventManager -> FdKey -> IO Bool
- closeFd :: EventManager -> (Fd -> IO ()) -> Fd -> IO ()
- type TimeoutCallback = IO ()
- data TimeoutKey
- registerTimeout :: TimerManager -> Int -> TimeoutCallback -> IO TimeoutKey
- updateTimeout :: TimerManager -> TimeoutKey -> Int -> IO ()
- unregisterTimeout :: TimerManager -> TimeoutKey -> IO ()

# Types

data EventManager

The event manager state.

data TimerManager

The event manager state.

# Creation

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.

getSystemTimerManager :: IO TimerManager

# Registering interest in I/O events

data Event

An I/O event.

Instances

Eq Event |
Show Event |
Monoid 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.

Instances

Eq FdKey |
Show FdKey |

data Lifetime

The lifetime of an event registration.

Since: 4.8.1.0

Constructors

OneShot | the registration will be active for only one event
MultiShot | the registration will trigger multiple times

Instances

Eq Lifetime |
Show Lifetime |
Monoid Lifetime | `mappend` == `elSupremum`

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.

Instances

Eq TimeoutKey |

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.