GHC.Event

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

This module should be considered GHC internal.

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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

Monoid Event

Since: base-4.4.0.0

Defined in GHC.Event.Internal.Types

Methods

mempty :: Event

mappend :: Event -> Event -> Event

mconcat :: [Event] -> Event

Semigroup Event

Since: base-4.10.0.0

Defined in GHC.Event.Internal.Types

Methods

(<>) :: Event -> Event -> Event

sconcat :: NonEmpty Event -> Event

stimes :: Integral b => b -> Event -> Event

Show Event

Since: base-4.4.0.0

Defined in GHC.Event.Internal.Types

Methods

showsPrec :: Int -> Event -> ShowS

show :: Event -> String

showList :: [Event] -> ShowS

Eq Event

Since: base-4.4.0.0

Defined in GHC.Event.Internal.Types

Methods

(==) :: Event -> Event -> Bool

(/=) :: Event -> Event -> Bool

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

Show FdKey

Since: base-4.4.0.0

Defined in GHC.Event.Manager

Methods

showsPrec :: Int -> FdKey -> ShowS

show :: FdKey -> String

showList :: [FdKey] -> ShowS

Eq FdKey

Since: base-4.4.0.0

Defined in GHC.Event.Manager

Methods

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

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

data Lifetime

The lifetime of an event registration.

Since: base-4.8.1.0

Constructors

OneShot

the registration will be active for only one event

MultiShot

the registration will trigger multiple times

Instances

Monoid Lifetime

mappend takes the longer of two lifetimes.

Since: base-4.8.0.0

Defined in GHC.Event.Internal.Types

Methods

mempty :: Lifetime

mappend :: Lifetime -> Lifetime -> Lifetime

mconcat :: [Lifetime] -> Lifetime

Semigroup Lifetime

Since: base-4.10.0.0

Defined in GHC.Event.Internal.Types

Methods

(<>) :: Lifetime -> Lifetime -> Lifetime

sconcat :: NonEmpty Lifetime -> Lifetime

stimes :: Integral b => b -> Lifetime -> Lifetime

Show Lifetime

Since: base-4.8.1.0

Defined in GHC.Event.Internal.Types

Methods

showsPrec :: Int -> Lifetime -> ShowS

show :: Lifetime -> String

showList :: [Lifetime] -> ShowS

Eq Lifetime

Since: base-4.8.1.0

Defined in GHC.Event.Internal.Types

Methods

(==) :: Lifetime -> Lifetime -> Bool

(/=) :: Lifetime -> Lifetime -> Bool

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. It might block, although for a very short time; and thus it is interruptible by asynchronous exceptions.

Registering interest in timeout events

type TimeoutCallback = IO ()

Warning: since the TimeoutCallback is called from the I/O manager, it must not throw an exception or block for a long period of time. In particular, be wary of throwTo and killThread: if the target thread is making a foreign call, these functions will block until the call completes.

data TimeoutKey

A timeout registration cookie.

Instances

Eq TimeoutKey

Defined in GHC.Event.TimeOut

Methods

(==) :: TimeoutKey -> TimeoutKey -> Bool

(/=) :: TimeoutKey -> TimeoutKey -> Bool

Ord TimeoutKey

Defined in GHC.Event.TimeOut

Methods

compare :: TimeoutKey -> TimeoutKey -> Ordering

(<) :: TimeoutKey -> TimeoutKey -> Bool

(<=) :: TimeoutKey -> TimeoutKey -> Bool

(>) :: TimeoutKey -> TimeoutKey -> Bool

(>=) :: TimeoutKey -> TimeoutKey -> Bool

max :: TimeoutKey -> TimeoutKey -> TimeoutKey

min :: TimeoutKey -> TimeoutKey -> 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.