Concurrency::task_handle< _Function > Class Template Reference

The task_handle class represents an individual parallel work item. It encapsulates the instructions and the data required to execute a piece of work. More...

#include <ppl.h>

Inheritance diagram for Concurrency::task_handle< _Function >:

Public Member Functions
	task_handle (const _Function &_Func)
	Constructs a new task_handle object. The work of the task is performed by invoking the function specified as a parameter to the constructor. More...
	~task_handle ()
	Destroys the task_handle object. More...
void	operator() () const
	The function call operator that the runtime invokes to perform the work of the task handle. More...
Public Member Functions inherited from Concurrency::details::_UnrealizedChore
	_UnrealizedChore ()
virtual	~_UnrealizedChore ()
void	_Invoke ()
void	_SetDetached (bool _FDetached)
::Concurrency::details::_TaskCollectionBase *	_OwningCollection () const
void	_SetRuntimeOwnsLifetime (bool _FValue)
bool	_GetRuntimeOwnsLifetime () const
void	_PrepareSteal (ContextBase *_PContext)
Public Member Functions inherited from Concurrency::details::_AllocBase
void *	operator new (size_t _Size)
void	operator delete (void *_Ptr) throw ()
void *	operator new (size_t _Size, const std::nothrow_t &) throw ()
void	operator delete (void *_Ptr, const std::nothrow_t &) throw ()
void *	operator new[] (size_t _Size)
void	operator delete[] (void *_Ptr) throw ()
void *	operator new[] (size_t _Size, const std::nothrow_t &_No_throw) throw ()
void	operator delete[] (void *_Ptr, const std::nothrow_t &_No_throw) throw ()
void *	operator new (size_t, void *_Location) throw ()
void	operator delete (void *, void *) throw ()
void *__cdecl	operator new[] (size_t, void *_Location) throw ()
void __cdecl	operator delete[] (void *, void *) throw ()

Private Member Functions
task_handle const &	operator= (task_handle const &)

Private Attributes
_Function	_M_function

Friends
class	task_group
class	structured_task_group

Additional Inherited Members
Static Public Member Functions inherited from Concurrency::details::_UnrealizedChore
template<typename _ChoreType , typename _Function >
static _ChoreType *	_InternalAlloc (const _Function &_Func)
Public Attributes inherited from Concurrency::details::_Chore
TaskProc	m_pFunction
Protected Member Functions inherited from Concurrency::details::_UnrealizedChore
_CONCRTIMP void	_CheckTaskCollection ()
Protected Member Functions inherited from Concurrency::details::_Chore
	_Chore (TaskProc _PFunction)
	_Chore ()
virtual	~_Chore ()
Static Protected Member Functions inherited from Concurrency::details::_UnrealizedChore
template<typename _ChoreType >
static void __cdecl	_InvokeBridge (void *_PContext)

Detailed Description

template<typename _Function>
class Concurrency::task_handle< _Function >

The task_handle class represents an individual parallel work item. It encapsulates the instructions and the data required to execute a piece of work.

Template Parameters

_Function

The type of the function object that will be invoked to execute the work represented by the task_handle object.

task_handle objects can be used in conjunction with a structured_task_group or a more general task_group object, to decompose work into parallel tasks. For more information, see Task Parallelism.

Note that the creator of a task_handle object is responsible for maintaining the lifetime of the created task_handle object until it is no longer required by the Concurrency Runtime. Typically, this means that the task_handle object must not destruct until either the wait or run_and_wait method of the task_group or structured_task_group to which it is queued has been called.

task_handle objects are typically used in conjunction with C++ lambdas. Because you do not know the true type of the lambda, the make_task function is typically used to create a task_handle object.

The runtime creates a copy of the work function that you pass to a task_handle object. Therefore, any state changes that occur in a function object that you pass to a task_handle object will not appear in your copy of that function object.

See also

task_group Class, structured_task_group Class, make_task Function, task_group::run Method, task_group::wait Method, task_group::run_and_wait Method, structured_task_group::run Method, structured_task_group::wait Method, structured_task_group::run_and_wait Method

Constructor & Destructor Documentation

template<typename _Function>

Concurrency::task_handle< _Function >::task_handle ( const _Function &  _Func )

inline

Constructs a new task_handle object. The work of the task is performed by invoking the function specified as a parameter to the constructor.

Parameters

_Func

The function that will be invoked to execute the work represented by the task_handle object. This may be a lambda functor, a pointer to a function, or any object that supports a version of the function call operator with the signature void operator()().

The runtime creates a copy of the work function that you pass to the constructor. Therefore, any state changes that occur in a function object that you pass to a task_handle object will not appear in your copy of that function object.

                                        : _M_function(_Func)
    {
        m_pFunction = reinterpret_cast <TaskProc> (&::Concurrency::details::_UnrealizedChore::_InvokeBridge<task_handle>);
    }

template<typename _Function>

Concurrency::task_handle< _Function >::~task_handle ( )

inline

Destroys the task_handle object.

    {
        //
        // We only need to perform a liveness check if the client owns the lifetime of the handle. Doing this for runtime owned handles
        // is not only unnecessary -- it is also dangerous.
        //
        if (_OwningCollection() != NULL && !_GetRuntimeOwnsLifetime())
        {
            _CheckTaskCollection();
        }
    }

Member Function Documentation

template<typename _Function>

void Concurrency::task_handle< _Function >::operator() ( ) const

inline

The function call operator that the runtime invokes to perform the work of the task handle.

    {
        _M_function();
    }

template<typename _Function>

task_handle const& Concurrency::task_handle< _Function >::operator= ( task_handle< _Function > const &  )

private

Friends And Related Function Documentation

template<typename _Function>

friend class structured_task_group

friend

template<typename _Function>

friend class task_group

friend

Member Data Documentation

template<typename _Function>

_Function Concurrency::task_handle< _Function >::_M_function

private

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The documentation for this class was generated from the following file:

• VS2017/inc/ppl.h