GI.GLib.Structs.Thread

The Thread struct represents a running thread. This struct is returned by threadNew or threadTryNew. You can obtain the Thread struct representing the current thread by calling threadSelf.

GThread is refcounted, see threadRef and threadUnref. The thread represented by it holds a reference while it is running, and threadJoin consumes the reference that it is given, so it is normally not necessary to manage GThread references explicitly.

The structure is opaque -- none of its fields may be directly accessed.

Exported types

newtype Thread

Memory-managed wrapper type.

Constructors

Thread (ManagedPtr Thread)

Instances

Eq Thread

Defined in GI.GLib.Structs.Thread

Methods

(==) :: Thread -> Thread -> Bool

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

GBoxed Thread

Defined in GI.GLib.Structs.Thread

ManagedPtrNewtype Thread

Defined in GI.GLib.Structs.Thread

Methods

toManagedPtr :: Thread -> ManagedPtr Thread

TypedObject Thread

Defined in GI.GLib.Structs.Thread

Methods

glibType :: IO GType

HasParentTypes Thread

Defined in GI.GLib.Structs.Thread

tag ~ 'AttrSet => Constructible Thread tag

Defined in GI.GLib.Structs.Thread

Methods

new :: MonadIO m => (ManagedPtr Thread -> Thread) -> [AttrOp Thread tag] -> m Thread

IsGValue (Maybe Thread)

Convert Thread to and from GValue. See toGValue and fromGValue.

Defined in GI.GLib.Structs.Thread

Methods

gvalueGType_ :: IO GType

gvalueSet_ :: Ptr GValue -> Maybe Thread -> IO ()

gvalueGet_ :: Ptr GValue -> IO (Maybe Thread)

type ParentTypes Thread

Defined in GI.GLib.Structs.Thread

type ParentTypes Thread = '[] :: [Type]

newZeroThread :: MonadIO m => m Thread

Construct a Thread struct initialized to zero.

Methods

Click to display all available methods, including inherited ones

Methods

join, ref, unref.

Getters

None.

Setters

None.

errorQuark

threadErrorQuark :: (HasCallStack, MonadIO m) => m Word32

No description available in the introspection data.

exit

threadExit

Arguments

:: (HasCallStack, MonadIO m)

=> Ptr ()

retval: the return value of this thread

-> m ()

Terminates the current thread.

If another thread is waiting for us using threadJoin then the waiting thread will be woken up and get retval as the return value of threadJoin.

Calling threadExit with a parameter retval is equivalent to returning retval from the function func, as given to threadNew.

You must only call threadExit from a thread that you created yourself with threadNew or related APIs. You must not call this function from a thread created with another threading library or or from within a ThreadPool.

join

threadJoin

Arguments

:: (HasCallStack, MonadIO m)

=> Thread

thread: a Thread

-> m (Ptr ())

Returns: the return value of the thread

Waits until thread finishes, i.e. the function func, as given to threadNew, returns or threadExit is called. If thread has already terminated, then threadJoin returns immediately.

Any thread can wait for any other thread by calling threadJoin, not just its 'creator'. Calling threadJoin from multiple threads for the same thread leads to undefined behaviour.

The value returned by func or given to threadExit is returned by this function.

threadJoin consumes the reference to the passed-in thread. This will usually cause the Thread struct and associated resources to be freed. Use threadRef to obtain an extra reference if you want to keep the GThread alive beyond the threadJoin call.

new

threadNew

Arguments

:: (HasCallStack, MonadIO m)

=> Maybe Text

name: an (optional) name for the new thread

-> ThreadFunc

func: a function to execute in the new thread

-> m Thread

Returns: the new Thread

This function creates a new thread. The new thread starts by invoking func with the argument data. The thread will run until func returns or until threadExit is called from the new thread. The return value of func becomes the return value of the thread, which can be obtained with threadJoin.

The name can be useful for discriminating threads in a debugger. It is not used for other purposes and does not have to be unique. Some systems restrict the length of name to 16 bytes.

If the thread can not be created the program aborts. See threadTryNew if you want to attempt to deal with failures.

If you are using threads to offload (potentially many) short-lived tasks, ThreadPool may be more appropriate than manually spawning and tracking multiple GThreads.

To free the struct returned by this function, use threadUnref. Note that threadJoin implicitly unrefs the Thread as well.

New threads by default inherit their scheduler policy (POSIX) or thread priority (Windows) of the thread creating the new thread.

This behaviour changed in GLib 2.64: before threads on Windows were not inheriting the thread priority but were spawned with the default priority. Starting with GLib 2.64 the behaviour is now consistent between Windows and POSIX and all threads inherit their parent thread's priority.

Since: 2.32

ref

threadRef

Arguments

:: (HasCallStack, MonadIO m)

=> Thread

thread: a Thread

-> m Thread

Returns: a new reference to thread

Increase the reference count on thread.

Since: 2.32

self

threadSelf

Arguments

:: (HasCallStack, MonadIO m)

=> m Thread

Returns: the Thread representing the current thread

This function returns the Thread corresponding to the current thread. Note that this function does not increase the reference count of the returned struct.

This function will return a Thread even for threads that were not created by GLib (i.e. those created by other threading APIs). This may be useful for thread identification purposes (i.e. comparisons) but you must not use GLib functions (such as threadJoin) on these threads.

tryNew

threadTryNew

Arguments

:: (HasCallStack, MonadIO m)

=> Maybe Text

name: an (optional) name for the new thread

-> ThreadFunc

func: a function to execute in the new thread

-> m Thread

Returns: the new Thread, or Nothing if an error occurred (Can throw GError)

This function is the same as threadNew except that it allows for the possibility of failure.

If a thread can not be created (due to resource limits), error is set and Nothing is returned.

Since: 2.32

unref

threadUnref

Arguments

:: (HasCallStack, MonadIO m)

=> Thread

thread: a Thread

-> m ()

Decrease the reference count on thread, possibly freeing all resources associated with it.

Note that each thread holds a reference to its Thread while it is running, so it is safe to drop your own reference to it if you don't need it anymore.

Since: 2.32

yield

threadYield :: (HasCallStack, MonadIO m) => m ()

Causes the calling thread to voluntarily relinquish the CPU, so that other threads can run.

This function is often used as a method to make busy wait less evil.