Copyright	Will Thompson and Iñaki García Etxebarria
License	LGPL-2.1
Maintainer	Iñaki García Etxebarria
Safe Haskell	Safe-Inferred
Language	Haskell2010

GI.GLib.Structs.ThreadPool

Contents

Description

The GThreadPool struct represents a thread pool.

A thread pool is useful when you wish to asynchronously fork out the execution of work and continue working in your own thread. If that will happen often, the overhead of starting and destroying a thread each time might be too high. In such cases reusing already started threads seems like a good idea. And it indeed is, but implementing this can be tedious and error-prone.

Therefore GLib provides thread pools for your convenience. An added advantage is, that the threads can be shared between the different subsystems of your program, when they are using GLib.

To create a new thread pool, you use [funcgLib.ThreadPool.new]. It is destroyed by threadPoolFree.

If you want to execute a certain task within a thread pool, use threadPoolPush.

To get the current number of running threads you call threadPoolGetNumThreads. To get the number of still unprocessed tasks you call threadPoolUnprocessed. To control the maximum number of threads for a thread pool, you use threadPoolGetMaxThreads. and threadPoolSetMaxThreads.

Finally you can control the number of unused threads, that are kept alive by GLib for future use. The current number can be fetched with [funcgLib.ThreadPool.get_num_unused_threads]. The maximum number can be controlled by [funcgLib.ThreadPool.get_max_unused_threads] and [funcgLib.ThreadPool.set_max_unused_threads]. All currently unused threads can be stopped by calling [funcgLib.ThreadPool.stop_unused_threads].

Synopsis

newtype ThreadPool = ThreadPool (ManagedPtr ThreadPool)
newZeroThreadPool :: MonadIO m => m ThreadPool
threadPoolFree :: (HasCallStack, MonadIO m) => ThreadPool -> Bool -> Bool -> m ()
threadPoolGetMaxIdleTime :: (HasCallStack, MonadIO m) => m Word32
threadPoolGetMaxThreads :: (HasCallStack, MonadIO m) => ThreadPool -> m Int32
threadPoolGetMaxUnusedThreads :: (HasCallStack, MonadIO m) => m Int32
threadPoolGetNumThreads :: (HasCallStack, MonadIO m) => ThreadPool -> m Word32
threadPoolGetNumUnusedThreads :: (HasCallStack, MonadIO m) => m Word32
threadPoolMoveToFront :: (HasCallStack, MonadIO m) => ThreadPool -> Ptr () -> m Bool
threadPoolPush :: (HasCallStack, MonadIO m) => ThreadPool -> Ptr () -> m ()
threadPoolSetMaxIdleTime :: (HasCallStack, MonadIO m) => Word32 -> m ()
threadPoolSetMaxThreads :: (HasCallStack, MonadIO m) => ThreadPool -> Int32 -> m ()
threadPoolSetMaxUnusedThreads :: (HasCallStack, MonadIO m) => Int32 -> m ()
threadPoolStopUnusedThreads :: (HasCallStack, MonadIO m) => m ()
threadPoolUnprocessed :: (HasCallStack, MonadIO m) => ThreadPool -> m Word32
getThreadPoolExclusive :: MonadIO m => ThreadPool -> m Bool
setThreadPoolExclusive :: MonadIO m => ThreadPool -> Bool -> m ()
clearThreadPoolFunc :: MonadIO m => ThreadPool -> m ()
getThreadPoolFunc :: MonadIO m => ThreadPool -> m (Maybe Func_WithClosures)
setThreadPoolFunc :: MonadIO m => ThreadPool -> FunPtr C_Func -> m ()
clearThreadPoolUserData :: MonadIO m => ThreadPool -> m ()
getThreadPoolUserData :: MonadIO m => ThreadPool -> m (Ptr ())
setThreadPoolUserData :: MonadIO m => ThreadPool -> Ptr () -> m ()

Exported types

newtype ThreadPool Source #

Memory-managed wrapper type.

Constructors

ThreadPool (ManagedPtr ThreadPool)

Instances

Instances details

Eq ThreadPool Source #
Instance details Defined in GI.GLib.Structs.ThreadPool Methods (==) :: ThreadPool -> ThreadPool -> Bool # (/=) :: ThreadPool -> ThreadPool -> Bool #
BoxedPtr ThreadPool Source #
Instance details Defined in GI.GLib.Structs.ThreadPool Methods boxedPtrCopy :: ThreadPool -> IO ThreadPool boxedPtrFree :: ThreadPool -> IO ()
CallocPtr ThreadPool Source #
Instance details Defined in GI.GLib.Structs.ThreadPool Methods boxedPtrCalloc :: IO (Ptr ThreadPool)
ManagedPtrNewtype ThreadPool Source #
Instance details Defined in GI.GLib.Structs.ThreadPool Methods toManagedPtr :: ThreadPool -> ManagedPtr ThreadPool
tag ~ 'AttrSet => Constructible ThreadPool tag Source #
Instance details Defined in GI.GLib.Structs.ThreadPool Methods new :: MonadIO m => (ManagedPtr ThreadPool -> ThreadPool) -> [AttrOp ThreadPool tag] -> m ThreadPool

newZeroThreadPool :: MonadIO m => m ThreadPool Source #

Construct a ThreadPool struct initialized to zero.

Methods

Click to display all available methods, including inherited ones

Expand

free

threadPoolFree Source #

Arguments

:: (HasCallStack, MonadIO m)
=> ThreadPool	`pool`: a `ThreadPool`
-> Bool	`immediate`: should `pool` shut down immediately?
-> Bool	`wait_`: should the function wait for all tasks to be finished?
-> m ()

Frees all resources allocated for pool.

If immediate is True, no new task is processed for pool. Otherwise pool is not freed before the last task is processed. Note however, that no thread of this pool is interrupted while processing a task. Instead at least all still running threads can finish their tasks before the pool is freed.

If wait_ is True, this function does not return before all tasks to be processed (dependent on immediate, whether all or only the currently running) are ready. Otherwise this function returns immediately.

After calling this function pool must not be used anymore.

getMaxIdleTime

threadPoolGetMaxIdleTime Source #

Arguments

:: (HasCallStack, MonadIO m)
=> m Word32	Returns: the maximum `interval` (milliseconds) to wait for new tasks in the thread pool before stopping the thread

This function will return the maximum interval that a thread will wait in the thread pool for new tasks before being stopped.

If this function returns 0, threads waiting in the thread pool for new work are not stopped.

Since: 2.10

getMaxThreads

threadPoolGetMaxThreads Source #

Arguments

:: (HasCallStack, MonadIO m)
=> ThreadPool	`pool`: a `ThreadPool`
-> m Int32	Returns: the maximal number of threads

Returns the maximal number of threads for pool.

getMaxUnusedThreads

threadPoolGetMaxUnusedThreads Source #

Arguments

:: (HasCallStack, MonadIO m)
=> m Int32	Returns: the maximal number of unused threads

Returns the maximal allowed number of unused threads.

getNumThreads

threadPoolGetNumThreads Source #

Arguments

:: (HasCallStack, MonadIO m)
=> ThreadPool	`pool`: a `ThreadPool`
-> m Word32	Returns: the number of threads currently running

Returns the number of threads currently running in pool.

getNumUnusedThreads

threadPoolGetNumUnusedThreads Source #

Arguments

:: (HasCallStack, MonadIO m)
=> m Word32	Returns: the number of currently unused threads

Returns the number of currently unused threads.

moveToFront

threadPoolMoveToFront Source #

Arguments

:: (HasCallStack, MonadIO m)
=> ThreadPool	`pool`: a `ThreadPool`
-> Ptr ()	`data`: an unprocessed item in the pool
-> m Bool	Returns: `True` if the item was found and moved

Moves the item to the front of the queue of unprocessed items, so that it will be processed next.

Since: 2.46

push

threadPoolPush Source #

Arguments

:: (HasCallStack, MonadIO m)
=> ThreadPool	`pool`: a `ThreadPool`
-> Ptr ()	`data`: a new task for `pool`
-> m ()	(Can throw `GError`)

Inserts data into the list of tasks to be executed by pool.

When the number of currently running threads is lower than the maximal allowed number of threads, a new thread is started (or reused) with the properties given to g_thread_pool_new(). Otherwise, data stays in the queue until a thread in this pool finishes its previous task and processes data.

error can be Nothing to ignore errors, or non-Nothing to report errors. An error can only occur when a new thread couldn't be created. In that case data is simply appended to the queue of work to do.

Before version 2.32, this function did not return a success status.

setMaxIdleTime

threadPoolSetMaxIdleTime Source #

Arguments

:: (HasCallStack, MonadIO m)
=> Word32	`interval`: the maximum `interval` (in milliseconds) a thread can be idle
-> m ()

This function will set the maximum interval that a thread waiting in the pool for new tasks can be idle for before being stopped. This function is similar to calling threadPoolStopUnusedThreads on a regular timeout, except this is done on a per thread basis.

By setting interval to 0, idle threads will not be stopped.

The default value is 15000 (15 seconds).

Since: 2.10

setMaxThreads

threadPoolSetMaxThreads Source #

Arguments

:: (HasCallStack, MonadIO m)
=> ThreadPool	`pool`: a `ThreadPool`
-> Int32	`maxThreads`: a new maximal number of threads for `pool`, or -1 for unlimited
-> m ()	(Can throw `GError`)

Sets the maximal allowed number of threads for pool. A value of -1 means that the maximal number of threads is unlimited. If pool is an exclusive thread pool, setting the maximal number of threads to -1 is not allowed.

Setting maxThreads to 0 means stopping all work for pool. It is effectively frozen until maxThreads is set to a non-zero value again.

A thread is never terminated while calling func, as supplied by g_thread_pool_new(). Instead the maximal number of threads only has effect for the allocation of new threads in threadPoolPush. A new thread is allocated, whenever the number of currently running threads in pool is smaller than the maximal number.

error can be Nothing to ignore errors, or non-Nothing to report errors. An error can only occur when a new thread couldn't be created.

Before version 2.32, this function did not return a success status.

setMaxUnusedThreads

threadPoolSetMaxUnusedThreads Source #

Arguments

:: (HasCallStack, MonadIO m)
=> Int32	`maxThreads`: maximal number of unused threads
-> m ()

Sets the maximal number of unused threads to maxThreads. If maxThreads is -1, no limit is imposed on the number of unused threads.

The default value is 2.

stopUnusedThreads

threadPoolStopUnusedThreads :: (HasCallStack, MonadIO m) => m () Source #

Stops all currently unused threads. This does not change the maximal number of unused threads. This function can be used to regularly stop all unused threads e.g. from g_timeout_add().