FAsyncTaskBase Class Reference

#include <AsyncWork.h>

Inheritance diagram for FAsyncTaskBase:

Public Member Functions
virtual	~FAsyncTaskBase ()
int64	GetRequiredMemory () const final
const TCHAR *	GetDebugName () const final
void	StartSynchronousTask (EQueuedWorkPriority InQueuedWorkPriority=EQueuedWorkPriority::Normal, EQueuedWorkFlags InQueuedWorkFlags=EQueuedWorkFlags::None, int64 InRequiredMemory=-1, const TCHAR *InDebugName=nullptr)
void	StartBackgroundTask (FQueuedThreadPool *InQueuedPool=GThreadPool, EQueuedWorkPriority InQueuedWorkPriority=EQueuedWorkPriority::Normal, EQueuedWorkFlags InQueuedWorkFlags=EQueuedWorkFlags::None, int64 InRequiredMemory=-1, const TCHAR *InDebugName=nullptr)
void	EnsureCompletion (bool bDoWorkOnThisThreadIfNotStarted=true, bool bIsLatencySensitive=false)
bool	Reschedule (FQueuedThreadPool *InQueuedPool=GThreadPool, EQueuedWorkPriority InQueuedWorkPriority=EQueuedWorkPriority::Normal)
bool	Cancel ()
bool	WaitCompletionWithTimeout (float TimeLimitSeconds)
bool	IsDone ()
bool	IsWorkDone () const
bool	IsIdle () const
bool	SetPriority (EQueuedWorkPriority QueuedWorkPriority)
EQueuedWorkPriority	GetPriority () const

Protected Member Functions
void	Init (TStatId InStatId)
void	CheckIdle () const
virtual void	DoTaskWork ()=0
virtual bool	TryAbandonTask ()=0
virtual void	MarkAsCanceled ()

Detailed Description

FAsyncTask - template task for jobs queued to thread pools

Sample code:

class ExampleAsyncTask : public FNonAbandonableTask
{
    friend class FAsyncTask<ExampleAsyncTask>;

    int32 ExampleData;

    ExampleAsyncTask(int32 InExampleData)
     : ExampleData(InExampleData)
    {
    }

    void DoWork()
    {
        ... do the work here
    }

    FORCEINLINE TStatId GetStatId() const
    {
        RETURN_QUICK_DECLARE_CYCLE_STAT(ExampleAsyncTask, STATGROUP_ThreadPoolAsyncTasks);
    }
};

void Example()
{

start an example job

    FAsyncTask<ExampleAsyncTask>* MyTask = new FAsyncTask<ExampleAsyncTask>( 5 );
    MyTask->StartBackgroundTask();

–or –

    MyTask->StartSynchronousTask();

to just do it now on this thread Check if the task is done :

    if (MyTask->IsDone())
    {
    }

Spinning on IsDone is not acceptable( see EnsureCompletion ), but it is ok to check once a frame. Ensure the task is done, doing the task on the current thread if it has not been started, waiting until completion in all cases.

    MyTask->EnsureCompletion();
    delete Task;
}

Constructor & Destructor Documentation

~FAsyncTaskBase()

virtual FAsyncTaskBase::~FAsyncTaskBase ( )

inlinevirtual

Destructor, not legal when a task is in process

Member Function Documentation

Cancel()

bool FAsyncTaskBase::Cancel ( )

inline

Cancel the task, if possible. Note that this is different than abandoning (which is called by the thread pool at shutdown).

Returns

true if the task was canceled and is safe to delete. If it wasn't canceled, it may be done, but that isn't checked here.

CheckIdle()

void FAsyncTaskBase::CheckIdle ( ) const

inlineprotected

Internal call to assert that we are idle

DoTaskWork()

virtual void FAsyncTaskBase::DoTaskWork ( )

protectedpure virtual

Perform task's work

Implemented in FAsyncTask< TTask >, FAsyncTask< Audio::FAsyncDecodeWorker >, FAsyncTask< Chaos::FPersistentPhysicsTask >, FAsyncTask< FAsyncRealtimeAudioTaskWorker< T > >, FAsyncTask< FAudioAnalyzeTask >, FAsyncTask< FD3D12PipelineStateWorker >, FAsyncTask< FDoWorkTask >, FAsyncTask< FGenericReadRequestWorker >, FAsyncTask< FMicrosoftReadRequestWorker >, FAsyncTask< FRenderAssetStreamingMipCalcTask >, FAsyncTask< FResolveInfoAsyncWorker >, FAsyncTask< FVulkanAsyncPoolSetDeletionWorker >, and FPSOPrecacheAsyncTask.

EnsureCompletion()

void FAsyncTaskBase::EnsureCompletion ( bool  bDoWorkOnThisThreadIfNotStarted = true, bool  bIsLatencySensitive = false  )

inline

Wait until the job is complete

Parameters

bDoWorkOnThisThreadIfNotStarted	if true and the work has not been started, retract the async task and do it now on this thread
specifies	if waiting for the task should return as soon as possible even if this delays other tasks

GetDebugName()

const TCHAR * FAsyncTaskBase::GetDebugName ( ) const

inlinefinalvirtual

Returns text to identify the Work, for debug/log purposes only

Reimplemented from IQueuedWork.

GetPriority()

EQueuedWorkPriority FAsyncTaskBase::GetPriority ( ) const

inline

GetRequiredMemory()

int64 FAsyncTaskBase::GetRequiredMemory ( ) const

inlinefinalvirtual

Returns an approximation of the peak memory (in bytes) this task could require during it's execution.

Reimplemented from IQueuedWork.

Init()

void FAsyncTaskBase::Init ( TStatId  InStatId )

inlineprotected

IsDone()

bool FAsyncTaskBase::IsDone ( )

inline

Returns true if the work and TASK has completed, false while it's still in progress. prior to returning true, it synchronizes so the task can be destroyed or reused

IsIdle()

bool FAsyncTaskBase::IsIdle ( ) const

inline

Returns true if the work has not been started or has been completed. NOT to be used for synchronization, but great for check()'s

IsWorkDone()

bool FAsyncTaskBase::IsWorkDone ( ) const

inline

Returns true if the work has completed, false while it's still in progress. This does not block and if true, you can use the results. But you can't destroy or reuse the task without IsDone() being true or EnsureCompletion()

MarkAsCanceled()

virtual void FAsyncTaskBase::MarkAsCanceled ( )

inlineprotectedvirtual

Mark the task as canceled (i.e. no longer needed).

Reschedule()

bool FAsyncTaskBase::Reschedule ( FQueuedThreadPool *  InQueuedPool = GThreadPool, EQueuedWorkPriority  InQueuedWorkPriority = EQueuedWorkPriority::Normal  )

inline

If not already being processed, will be rescheduled on given thread pool and priority.

Returns

true if the reschedule was successful, false if was already being processed.

SetPriority()

bool FAsyncTaskBase::SetPriority ( EQueuedWorkPriority  QueuedWorkPriority )

inline

StartBackgroundTask()

void FAsyncTaskBase::StartBackgroundTask ( FQueuedThreadPool *  InQueuedPool = GThreadPool, EQueuedWorkPriority  InQueuedWorkPriority = EQueuedWorkPriority::Normal, EQueuedWorkFlags  InQueuedWorkFlags = EQueuedWorkFlags::None, int64  InRequiredMemory = -1, const TCHAR *  InDebugName = nullptr  )

inline

Queue this task for processing by the background thread pool

StartSynchronousTask()

void FAsyncTaskBase::StartSynchronousTask ( EQueuedWorkPriority  InQueuedWorkPriority = EQueuedWorkPriority::Normal, EQueuedWorkFlags  InQueuedWorkFlags = EQueuedWorkFlags::None, int64  InRequiredMemory = -1, const TCHAR *  InDebugName = nullptr  )

inline

Run this task on this thread

Parameters

bDoNow

if true then do the job now instead of at EnsureCompletion

TryAbandonTask()

virtual bool FAsyncTaskBase::TryAbandonTask ( )

protectedpure virtual

Abandon task if possible, returns true on success, false otherwise.

Implemented in FAsyncTask< TTask >, FAsyncTask< Audio::FAsyncDecodeWorker >, FAsyncTask< Chaos::FPersistentPhysicsTask >, FAsyncTask< FAsyncRealtimeAudioTaskWorker< T > >, FAsyncTask< FAudioAnalyzeTask >, FAsyncTask< FD3D12PipelineStateWorker >, FAsyncTask< FDoWorkTask >, FAsyncTask< FGenericReadRequestWorker >, FAsyncTask< FMicrosoftReadRequestWorker >, FAsyncTask< FRenderAssetStreamingMipCalcTask >, FAsyncTask< FResolveInfoAsyncWorker >, FAsyncTask< FVulkanAsyncPoolSetDeletionWorker >, and FPSOPrecacheAsyncTask.

WaitCompletionWithTimeout()

bool FAsyncTaskBase::WaitCompletionWithTimeout ( float  TimeLimitSeconds )

inline

Wait until the job is complete, up to a time limit

Parameters

TimeLimitSeconds

Must be positive, otherwise polls – same as calling IsDone()

Returns

true if the task is completed

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

• Engine/Source/Runtime/Core/Public/Async/AsyncWork.h