1 // The MIT License (MIT)
2 //
3 // 	Copyright (c) 2015 Sergey Makeev, Vadim Slyusarev
4 //
5 // 	Permission is hereby granted, free of charge, to any person obtaining a copy
6 // 	of this software and associated documentation files (the "Software"), to deal
7 // 	in the Software without restriction, including without limitation the rights
8 // 	to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
9 // 	copies of the Software, and to permit persons to whom the Software is
10 // 	furnished to do so, subject to the following conditions:
11 //
12 //  The above copyright notice and this permission notice shall be included in
13 // 	all copies or substantial portions of the Software.
14 //
15 // 	THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
16 // 	IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
17 // 	FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
18 // 	AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
19 // 	LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
20 // 	OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
21 // 	THE SOFTWARE.
22 
23 #include <MTScheduler.h>
24 #include <MTStaticVector.h>
25 #include <string.h> // for memset
26 
27 namespace MT
28 {
29 
30 #ifdef MT_INSTRUMENTED_BUILD
31 	TaskScheduler::TaskScheduler(uint32 workerThreadsCount, WorkerThreadParams* workerParameters, IProfilerEventListener* listener, TaskStealingMode::Type stealMode)
32 #else
33 	TaskScheduler::TaskScheduler(uint32 workerThreadsCount, WorkerThreadParams* workerParameters, TaskStealingMode::Type stealMode)
34 #endif
35 		: roundRobinThreadIndex(0)
36 		, startedThreadsCount(0)
37 		, taskStealingDisabled(stealMode == TaskStealingMode::DISABLED)
38 	{
39 
40 #ifdef MT_INSTRUMENTED_BUILD
41 		profilerEventListener = listener;
42 #endif
43 
44 		if (workerThreadsCount != 0)
45 		{
46 			threadsCount.StoreRelaxed( MT::Clamp(workerThreadsCount, (uint32)1, (uint32)MT_MAX_THREAD_COUNT) );
47 		} else
48 		{
49 			//query number of processor
50 			threadsCount.StoreRelaxed( (uint32)MT::Clamp(Thread::GetNumberOfHardwareThreads() - 1, 1, (int)MT_MAX_THREAD_COUNT) );
51 		}
52 
53 		// create fiber pool (fibers with standard stack size)
54 		for (uint32 i = 0; i < MT_MAX_STANDART_FIBERS_COUNT; i++)
55 		{
56 			FiberContext& context = standartFiberContexts[i];
57 			context.fiber.Create(MT_STANDART_FIBER_STACK_SIZE, FiberMain, &context);
58 			bool res = standartFibersAvailable.TryPush( &context );
59 			MT_USED_IN_ASSERT(res);
60 			MT_ASSERT(res == true, "Can't add fiber to storage");
61 		}
62 
63 		// create fiber pool (fibers with extended stack size)
64 		for (uint32 i = 0; i < MT_MAX_EXTENDED_FIBERS_COUNT; i++)
65 		{
66 			FiberContext& context = extendedFiberContexts[i];
67 			context.fiber.Create(MT_EXTENDED_FIBER_STACK_SIZE, FiberMain, &context);
68 			bool res = extendedFibersAvailable.TryPush( &context );
69 			MT_USED_IN_ASSERT(res);
70 			MT_ASSERT(res == true, "Can't add fiber to storage");
71 		}
72 
73 
74 		for (int16 i = 0; i < TaskGroup::MT_MAX_GROUPS_COUNT; i++)
75 		{
76 			if (i != TaskGroup::DEFAULT)
77 			{
78 				bool res = availableGroups.TryPush( TaskGroup(i) );
79 				MT_USED_IN_ASSERT(res);
80 				MT_ASSERT(res == true, "Can't add group to storage");
81 			}
82 		}
83 
84 #if MT_GROUP_DEBUG
85 		groupStats[TaskGroup::DEFAULT].SetDebugIsFree(false);
86 #endif
87 
88 		// create worker thread pool
89 		int32 totalThreadsCount = GetWorkersCount();
90 		for (int32 i = 0; i < totalThreadsCount; i++)
91 		{
92 			threadContext[i].SetThreadIndex(i);
93 			threadContext[i].taskScheduler = this;
94 
95 			uint32 threadCore = i;
96 			ThreadPriority::Type priority = ThreadPriority::DEFAULT;
97 			if (workerParameters != nullptr)
98 			{
99 				const WorkerThreadParams& params = workerParameters[i];
100 
101 				threadCore = params.core;
102 				priority = params.priority;
103 			}
104 
105 			threadContext[i].thread.Start( MT_SCHEDULER_STACK_SIZE, WorkerThreadMain, &threadContext[i], threadCore, priority);
106 		}
107 	}
108 
109 
110 	TaskScheduler::~TaskScheduler()
111 	{
112 		int32 totalThreadsCount = GetWorkersCount();
113 		for (int32 i = 0; i < totalThreadsCount; i++)
114 		{
115 			threadContext[i].state.Store(internal::ThreadState::EXIT);
116 			threadContext[i].hasNewTasksEvent.Signal();
117 		}
118 
119 		for (int32 i = 0; i < totalThreadsCount; i++)
120 		{
121 			threadContext[i].thread.Join();
122 		}
123 	}
124 
125 	FiberContext* TaskScheduler::RequestFiberContext(internal::GroupedTask& task)
126 	{
127 		FiberContext *fiberContext = task.awaitingFiber;
128 		if (fiberContext)
129 		{
130 			task.awaitingFiber = nullptr;
131 			return fiberContext;
132 		}
133 
134 		MT::StackRequirements::Type stackRequirements = task.desc.stackRequirements;
135 
136 		fiberContext = nullptr;
137 		bool res = false;
138 		MT_USED_IN_ASSERT(res);
139 		switch(stackRequirements)
140 		{
141 		case MT::StackRequirements::STANDARD:
142 			res = standartFibersAvailable.TryPop(fiberContext);
143 			MT_ASSERT(res, "Can't get more standard fibers!");
144 			break;
145 		case MT::StackRequirements::EXTENDED:
146 			res = extendedFibersAvailable.TryPop(fiberContext);
147 			MT_ASSERT(res, "Can't get more extended fibers!");
148 			break;
149 		default:
150 			MT_REPORT_ASSERT("Unknown stack requrements");
151 		}
152 
153 		MT_ASSERT(fiberContext != nullptr, "Can't get more fibers. Too many tasks in flight simultaneously?");
154 
155 		fiberContext->currentTask = task.desc;
156 		fiberContext->currentGroup = task.group;
157 		fiberContext->parentFiber = task.parentFiber;
158 		fiberContext->stackRequirements = stackRequirements;
159 		return fiberContext;
160 	}
161 
162 	void TaskScheduler::ReleaseFiberContext(FiberContext*&& fiberContext)
163 	{
164 		MT_ASSERT(fiberContext, "Can't release nullptr Fiber. fiberContext is nullptr");
165 
166 		MT::StackRequirements::Type stackRequirements = fiberContext->stackRequirements;
167 		fiberContext->Reset();
168 
169 		MT_ASSERT(fiberContext != nullptr, "Fiber context can't be nullptr");
170 
171 		bool res = false;
172 		MT_USED_IN_ASSERT(res);
173 		switch(stackRequirements)
174 		{
175 		case MT::StackRequirements::STANDARD:
176 			res = standartFibersAvailable.TryPush(std::move(fiberContext));
177 			break;
178 		case MT::StackRequirements::EXTENDED:
179 			res = extendedFibersAvailable.TryPush(std::move(fiberContext));
180 			break;
181 		default:
182 			MT_REPORT_ASSERT("Unknown stack requrements");
183 		}
184 
185 		MT_USED_IN_ASSERT(res);
186 		MT_ASSERT(res != false, "Can't return fiber to storage");
187 	}
188 
189 	FiberContext* TaskScheduler::ExecuteTask(internal::ThreadContext& threadContext, FiberContext* fiberContext)
190 	{
191 		MT_ASSERT(threadContext.thread.IsCurrentThread(), "Thread context sanity check failed");
192 
193 		MT_ASSERT(fiberContext, "Invalid fiber context");
194 		MT_ASSERT(fiberContext->currentTask.IsValid(), "Invalid task");
195 
196 		// Set actual thread context to fiber
197 		fiberContext->SetThreadContext(&threadContext);
198 
199 		// Update task status
200 		fiberContext->SetStatus(FiberTaskStatus::RUNNED);
201 
202 		MT_ASSERT(fiberContext->GetThreadContext()->thread.IsCurrentThread(), "Thread context sanity check failed");
203 
204 		const void* poolUserData = fiberContext->currentTask.userData;
205 		TPoolTaskDestroy poolDestroyFunc = fiberContext->currentTask.poolDestroyFunc;
206 
207 #ifdef MT_INSTRUMENTED_BUILD
208 		//threadContext.NotifyTaskExecuteStateChanged( MT_SYSTEM_TASK_COLOR, MT_SYSTEM_TASK_NAME, TaskExecuteState::SUSPEND);
209 		threadContext.NotifyTaskExecuteStateChanged( MT_SYSTEM_TASK_COLOR, MT_SYSTEM_TASK_NAME, TaskExecuteState::STOP);
210 #endif
211 
212 		// Run current task code
213 		Fiber::SwitchTo(threadContext.schedulerFiber, fiberContext->fiber);
214 
215 #ifdef MT_INSTRUMENTED_BUILD
216 		//threadContext.NotifyTaskExecuteStateChanged( MT_SYSTEM_TASK_COLOR, MT_SYSTEM_TASK_NAME, TaskExecuteState::RESUME);
217 		threadContext.NotifyTaskExecuteStateChanged( MT_SYSTEM_TASK_COLOR, MT_SYSTEM_TASK_NAME, TaskExecuteState::START);
218 #endif
219 
220 		// If task was done
221 		FiberTaskStatus::Type taskStatus = fiberContext->GetStatus();
222 		if (taskStatus == FiberTaskStatus::FINISHED)
223 		{
224 			//destroy task (call dtor) for "fire and forget" type of task from TaskPool
225 			if (poolDestroyFunc != nullptr)
226 			{
227 				poolDestroyFunc(poolUserData);
228 			}
229 
230 			TaskGroup taskGroup = fiberContext->currentGroup;
231 
232 			TaskScheduler::TaskGroupDescription  & groupDesc = threadContext.taskScheduler->GetGroupDesc(taskGroup);
233 
234 			// Update group status
235 			int groupTaskCount = groupDesc.Dec();
236 			MT_ASSERT(groupTaskCount >= 0, "Sanity check failed!");
237 			if (groupTaskCount == 0)
238 			{
239 				// Signal pending threads that group work is finished. Group can be destroyed after this call.
240 				groupDesc.Signal();
241 
242 				fiberContext->currentGroup = TaskGroup::INVALID;
243 			}
244 
245 			// Update total task count
246 			int allGroupTaskCount = threadContext.taskScheduler->allGroups.Dec();
247 			MT_ASSERT(allGroupTaskCount >= 0, "Sanity check failed!");
248 			if (allGroupTaskCount == 0)
249 			{
250 				// Notify all tasks in all group finished
251 				threadContext.taskScheduler->allGroups.Signal();
252 			}
253 
254 			FiberContext* parentFiberContext = fiberContext->parentFiber;
255 			if (parentFiberContext != nullptr)
256 			{
257 				int childrenFibersCount = parentFiberContext->childrenFibersCount.DecFetch();
258 				MT_ASSERT(childrenFibersCount >= 0, "Sanity check failed!");
259 
260 				if (childrenFibersCount == 0)
261 				{
262 					// This is a last subtask. Restore parent task
263 					MT_ASSERT(threadContext.thread.IsCurrentThread(), "Thread context sanity check failed");
264 					MT_ASSERT(parentFiberContext->GetThreadContext() == nullptr, "Inactive parent should not have a valid thread context");
265 
266 					// WARNING!! Thread context can changed here! Set actual current thread context.
267 					parentFiberContext->SetThreadContext(&threadContext);
268 
269 					MT_ASSERT(parentFiberContext->GetThreadContext()->thread.IsCurrentThread(), "Thread context sanity check failed");
270 
271 					// All subtasks is done.
272 					// Exiting and return parent fiber to scheduler
273 					return parentFiberContext;
274 				} else
275 				{
276 					// Other subtasks still exist
277 					// Exiting
278 					return nullptr;
279 				}
280 			} else
281 			{
282 				// Task is finished and no parent task
283 				// Exiting
284 				return nullptr;
285 			}
286 		}
287 
288 		MT_ASSERT(taskStatus != FiberTaskStatus::RUNNED, "Incorrect task status")
289 		return nullptr;
290 	}
291 
292 
293 	void TaskScheduler::FiberMain(void* userData)
294 	{
295 		FiberContext& fiberContext = *(FiberContext*)(userData);
296 		for(;;)
297 		{
298 			MT_ASSERT(fiberContext.currentTask.IsValid(), "Invalid task in fiber context");
299 			MT_ASSERT(fiberContext.GetThreadContext(), "Invalid thread context");
300 			MT_ASSERT(fiberContext.GetThreadContext()->thread.IsCurrentThread(), "Thread context sanity check failed");
301 
302 #ifdef MT_INSTRUMENTED_BUILD
303 			fiberContext.fiber.SetName( MT_SYSTEM_TASK_FIBER_NAME );
304 			fiberContext.GetThreadContext()->NotifyTaskExecuteStateChanged( fiberContext.currentTask.debugColor, fiberContext.currentTask.debugID, TaskExecuteState::START );
305 #endif
306 
307 			fiberContext.currentTask.taskFunc( fiberContext, fiberContext.currentTask.userData );
308 			fiberContext.SetStatus(FiberTaskStatus::FINISHED);
309 
310 #ifdef MT_INSTRUMENTED_BUILD
311 			fiberContext.fiber.SetName( MT_SYSTEM_TASK_FIBER_NAME );
312 			fiberContext.GetThreadContext()->NotifyTaskExecuteStateChanged( fiberContext.currentTask.debugColor, fiberContext.currentTask.debugID, TaskExecuteState::STOP );
313 #endif
314 
315 			Fiber::SwitchTo(fiberContext.fiber, fiberContext.GetThreadContext()->schedulerFiber);
316 		}
317 
318 	}
319 
320 
321 	bool TaskScheduler::TryStealTask(internal::ThreadContext& threadContext, internal::GroupedTask & task, uint32 workersCount, bool taskStealingDisabled)
322 	{
323 		if (workersCount <= 1 || taskStealingDisabled )
324 		{
325 			return false;
326 		}
327 
328 		uint32 victimIndex = threadContext.random.Get();
329 
330 		for (uint32 attempt = 0; attempt < workersCount; attempt++)
331 		{
332 			uint32 index = victimIndex % workersCount;
333 			if (index == threadContext.workerIndex)
334 			{
335 				victimIndex++;
336 				index = victimIndex % workersCount;
337 			}
338 
339 			internal::ThreadContext& victimContext = threadContext.taskScheduler->threadContext[index];
340 			if (victimContext.queue.TryPopNewest(task))
341 			{
342 				return true;
343 			}
344 
345 			victimIndex++;
346 		}
347 		return false;
348 	}
349 
350 
351 	void TaskScheduler::WorkerThreadMain( void* userData )
352 	{
353 		internal::ThreadContext& context = *(internal::ThreadContext*)(userData);
354 		MT_ASSERT(context.taskScheduler, "Task scheduler must be not null!");
355 
356 #ifdef MT_INSTRUMENTED_BUILD
357 		const char* threadNames[] = {"worker0","worker1","worker2","worker3","worker4","worker5","worker6","worker7","worker8","worker9","worker10","worker11","worker12"};
358 		if (context.workerIndex < MT_ARRAY_SIZE(threadNames))
359 		{
360 			Thread::SetThreadName(threadNames[context.workerIndex]);
361 		} else
362 		{
363 			Thread::SetThreadName("worker_thread");
364 		}
365 #endif
366 
367 		context.schedulerFiber.CreateFromCurrentThreadAndRun(SchedulerFiberMain, userData);
368 	}
369 
370 
371 	void TaskScheduler::SchedulerFiberMain( void* userData )
372 	{
373 		internal::ThreadContext& context = *(internal::ThreadContext*)(userData);
374 		MT_ASSERT(context.taskScheduler, "Task scheduler must be not null!");
375 
376 #ifdef MT_INSTRUMENTED_BUILD
377 		context.NotifyThreadCreate(context.workerIndex);
378 #endif
379 
380 		bool taskStealingDisabled = context.taskScheduler->IsTaskStealingDisabled();
381 		uint32 workersCount = context.taskScheduler->GetWorkersCount();
382 		int32 totalThreadsCount = context.taskScheduler->threadsCount.LoadRelaxed();
383 
384 		context.taskScheduler->startedThreadsCount.IncFetch();
385 
386 		//Simple spinlock until all threads is started and initialized
387 		for(;;)
388 		{
389 			int32 initializedThreadsCount = context.taskScheduler->startedThreadsCount.Load();
390 			if (initializedThreadsCount == totalThreadsCount)
391 			{
392 				break;
393 			}
394 
395 			// sleep some time until all other thread initialized
396 			Thread::Sleep(1);
397 		}
398 
399 		HardwareFullMemoryBarrier();
400 
401 #ifdef MT_INSTRUMENTED_BUILD
402 		context.NotifyThreadStart(context.workerIndex);
403 		context.NotifyTaskExecuteStateChanged( MT_SYSTEM_TASK_COLOR, MT_SYSTEM_TASK_NAME, TaskExecuteState::START);
404 #endif
405 
406 		while(context.state.Load() != internal::ThreadState::EXIT)
407 		{
408 			internal::GroupedTask task;
409 			if (context.queue.TryPopOldest(task) || TryStealTask(context, task, workersCount, taskStealingDisabled) )
410 			{
411 #ifdef MT_INSTRUMENTED_BUILD
412 				bool isNewTask = (task.awaitingFiber == nullptr);
413 #endif
414 
415 				// There is a new task
416 				FiberContext* fiberContext = context.taskScheduler->RequestFiberContext(task);
417 				MT_ASSERT(fiberContext, "Can't get execution context from pool");
418 				MT_ASSERT(fiberContext->currentTask.IsValid(), "Sanity check failed");
419 				MT_ASSERT(fiberContext->stackRequirements == task.desc.stackRequirements, "Sanity check failed");
420 
421 				while(fiberContext)
422 				{
423 #ifdef MT_INSTRUMENTED_BUILD
424 					if (isNewTask)
425 					{
426 						//TODO:
427 						isNewTask = false;
428 					}
429 #endif
430 					// prevent invalid fiber resume from child tasks, before ExecuteTask is done
431 					fiberContext->childrenFibersCount.IncFetch();
432 
433 					FiberContext* parentFiber = ExecuteTask(context, fiberContext);
434 
435 					FiberTaskStatus::Type taskStatus = fiberContext->GetStatus();
436 
437 					//release guard
438 					int childrenFibersCount = fiberContext->childrenFibersCount.DecFetch();
439 
440 					// Can drop fiber context - task is finished
441 					if (taskStatus == FiberTaskStatus::FINISHED)
442 					{
443 						MT_ASSERT( childrenFibersCount == 0, "Sanity check failed");
444 						context.taskScheduler->ReleaseFiberContext(std::move(fiberContext));
445 
446 						// If parent fiber is exist transfer flow control to parent fiber, if parent fiber is null, exit
447 						fiberContext = parentFiber;
448 					} else
449 					{
450 						MT_ASSERT( childrenFibersCount >= 0, "Sanity check failed");
451 
452 						// No subtasks here and status is not finished, this mean all subtasks already finished before parent return from ExecuteTask
453 						if (childrenFibersCount == 0)
454 						{
455 							MT_ASSERT(parentFiber == nullptr, "Sanity check failed");
456 						} else
457 						{
458 							// If subtasks still exist, drop current task execution. task will be resumed when last subtask finished
459 							break;
460 						}
461 
462 						// If task is yielded execution, get another task from queue.
463 						if (taskStatus == FiberTaskStatus::YIELDED)
464 						{
465 							// Task is yielded, add to tasks queue
466 							ArrayView<internal::GroupedTask> buffer(context.descBuffer, 1);
467 							ArrayView<internal::TaskBucket> buckets( MT_ALLOCATE_ON_STACK(sizeof(internal::TaskBucket)), 1 );
468 
469 							FiberContext* yieldedTask = fiberContext;
470 							StaticVector<FiberContext*, 1> yieldedTasksQueue(1, yieldedTask);
471 							internal::DistibuteDescriptions( TaskGroup(TaskGroup::ASSIGN_FROM_CONTEXT), yieldedTasksQueue.Begin(), buffer, buckets );
472 
473 							// add yielded task to scheduler
474 							context.taskScheduler->RunTasksImpl(buckets, nullptr, true);
475 
476 							// ATENTION! yielded task can be already completed at this point
477 
478 							break;
479 						}
480 					}
481 				} //while(fiberContext)
482 
483 			} else
484 			{
485 #ifdef MT_INSTRUMENTED_BUILD
486 				context.NotifyThreadIdleBegin(context.workerIndex);
487 #endif
488 
489 				// Queue if empty and stealing attempt failed
490 				// Wait for new events
491 				context.hasNewTasksEvent.Wait(2000);
492 
493 #ifdef MT_INSTRUMENTED_BUILD
494 				context.NotifyThreadIdleEnd(context.workerIndex);
495 #endif
496 
497 			}
498 
499 		} // main thread loop
500 
501 #ifdef MT_INSTRUMENTED_BUILD
502 		context.NotifyTaskExecuteStateChanged( MT_SYSTEM_TASK_COLOR, MT_SYSTEM_TASK_NAME, TaskExecuteState::STOP);
503 		context.NotifyThreadStop(context.workerIndex);
504 #endif
505 
506 	}
507 
508 	void TaskScheduler::RunTasksImpl(ArrayView<internal::TaskBucket>& buckets, FiberContext * parentFiber, bool restoredFromAwaitState)
509 	{
510 		// This storage is necessary to calculate how many tasks we add to different groups
511 		int newTaskCountInGroup[TaskGroup::MT_MAX_GROUPS_COUNT];
512 
513 		// Default value is 0
514 		memset(&newTaskCountInGroup[0], 0, sizeof(newTaskCountInGroup));
515 
516 		// Set parent fiber pointer
517 		// Calculate the number of tasks per group
518 		// Calculate total number of tasks
519 		size_t count = 0;
520 		for (size_t i = 0; i < buckets.Size(); ++i)
521 		{
522 			internal::TaskBucket& bucket = buckets[i];
523 			for (size_t taskIndex = 0; taskIndex < bucket.count; taskIndex++)
524 			{
525 				internal::GroupedTask & task = bucket.tasks[taskIndex];
526 
527 				task.parentFiber = parentFiber;
528 
529 				int idx = task.group.GetValidIndex();
530 				MT_ASSERT(idx >= 0 && idx < TaskGroup::MT_MAX_GROUPS_COUNT, "Invalid index");
531 				newTaskCountInGroup[idx]++;
532 			}
533 
534 			count += bucket.count;
535 		}
536 
537 		// Increments child fibers count on parent fiber
538 		if (parentFiber)
539 		{
540 			parentFiber->childrenFibersCount.AddFetch((int)count);
541 		}
542 
543 		if (restoredFromAwaitState == false)
544 		{
545 			// Increase the number of active tasks in the group using data from temporary storage
546 			for (size_t i = 0; i < TaskGroup::MT_MAX_GROUPS_COUNT; i++)
547 			{
548 				int groupNewTaskCount = newTaskCountInGroup[i];
549 				if (groupNewTaskCount > 0)
550 				{
551 					groupStats[i].Reset();
552 					groupStats[i].Add((uint32)groupNewTaskCount);
553 				}
554 			}
555 
556 			// Increments all task in progress counter
557 			allGroups.Reset();
558 			allGroups.Add((uint32)count);
559 		} else
560 		{
561 			// If task's restored from await state, counters already in correct state
562 		}
563 
564 		// Add to thread queue
565 		for (size_t i = 0; i < buckets.Size(); ++i)
566 		{
567 			int bucketIndex = roundRobinThreadIndex.IncFetch() % threadsCount.LoadRelaxed();
568 			internal::ThreadContext & context = threadContext[bucketIndex];
569 
570 			internal::TaskBucket& bucket = buckets[i];
571 
572 			for(;;)
573 			{
574 				bool res = context.queue.Add(bucket.tasks, bucket.count);
575 				if (res == true)
576 				{
577 					break;
578 				}
579 
580 				//Can't add new tasks onto the queue. Look like the job system is overloaded. Wait some time and try again.
581 				//TODO: implement waiting until workers done using events.
582 				Thread::Sleep(10);
583 			}
584 
585 			context.hasNewTasksEvent.Signal();
586 		}
587 	}
588 
589 	void TaskScheduler::RunAsync(TaskGroup group, const TaskHandle* taskHandleArray, uint32 taskHandleCount)
590 	{
591 		MT_ASSERT(!IsWorkerThread(), "Can't use RunAsync inside Task. Use FiberContext.RunAsync() instead.");
592 
593 		ArrayView<internal::GroupedTask> buffer(MT_ALLOCATE_ON_STACK(sizeof(internal::GroupedTask) * taskHandleCount), taskHandleCount);
594 
595 		uint32 bucketCount = MT::Min((uint32)GetWorkersCount(), taskHandleCount);
596 		ArrayView<internal::TaskBucket> buckets(MT_ALLOCATE_ON_STACK(sizeof(internal::TaskBucket) * bucketCount), bucketCount);
597 
598 		internal::DistibuteDescriptions(group, taskHandleArray, buffer, buckets);
599 		RunTasksImpl(buckets, nullptr, false);
600 	}
601 
602 	bool TaskScheduler::WaitGroup(TaskGroup group, uint32 milliseconds)
603 	{
604 		MT_VERIFY(IsWorkerThread() == false, "Can't use WaitGroup inside Task. Use FiberContext.WaitGroupAndYield() instead.", return false);
605 
606 		TaskScheduler::TaskGroupDescription & groupDesc = GetGroupDesc(group);
607 
608 		return groupDesc.Wait(milliseconds);
609 	}
610 
611 	bool TaskScheduler::WaitAll(uint32 milliseconds)
612 	{
613 		MT_VERIFY(IsWorkerThread() == false, "Can't use WaitAll inside Task.", return false);
614 
615 		return allGroups.Wait(milliseconds);
616 	}
617 
618 	bool TaskScheduler::IsTaskStealingDisabled() const
619 	{
620 		return taskStealingDisabled;
621 	}
622 
623 	int32 TaskScheduler::GetWorkersCount() const
624 	{
625 		return threadsCount.LoadRelaxed();
626 	}
627 
628 	bool TaskScheduler::IsWorkerThread() const
629 	{
630 		for (uint32 i = 0; i < MT_MAX_THREAD_COUNT; i++)
631 		{
632 			if (threadContext[i].thread.IsCurrentThread())
633 			{
634 				return true;
635 			}
636 		}
637 		return false;
638 	}
639 
640 	TaskGroup TaskScheduler::CreateGroup()
641 	{
642 		MT_ASSERT(IsWorkerThread() == false, "Can't use CreateGroup inside Task.");
643 
644 		TaskGroup group;
645 		if (!availableGroups.TryPop(group))
646 		{
647 			MT_REPORT_ASSERT("Group pool is empty");
648 		}
649 
650 		int idx = group.GetValidIndex();
651 		MT_USED_IN_ASSERT(idx);
652 		MT_ASSERT(groupStats[idx].GetDebugIsFree() == true, "Bad logic!");
653 #if MT_GROUP_DEBUG
654 		groupStats[idx].SetDebugIsFree(false);
655 #endif
656 
657 		return group;
658 	}
659 
660 	void TaskScheduler::ReleaseGroup(TaskGroup group)
661 	{
662 		MT_ASSERT(IsWorkerThread() == false, "Can't use ReleaseGroup inside Task.");
663 		MT_ASSERT(group.IsValid(), "Invalid group ID");
664 
665 		int idx = group.GetValidIndex();
666 		MT_USED_IN_ASSERT(idx);
667 		MT_ASSERT(groupStats[idx].GetDebugIsFree() == false, "Group already released");
668 #if MT_GROUP_DEBUG
669 		groupStats[idx].SetDebugIsFree(true);
670 #endif
671 
672 		bool res = availableGroups.TryPush(std::move(group));
673 		MT_USED_IN_ASSERT(res);
674 		MT_ASSERT(res, "Can't return group to pool");
675 	}
676 
677 	TaskScheduler::TaskGroupDescription & TaskScheduler::GetGroupDesc(TaskGroup group)
678 	{
679 		MT_ASSERT(group.IsValid(), "Invalid group ID");
680 
681 		int idx = group.GetValidIndex();
682 		TaskScheduler::TaskGroupDescription & groupDesc = groupStats[idx];
683 
684 		MT_ASSERT(groupDesc.GetDebugIsFree() == false, "Invalid group");
685 		return groupDesc;
686 	}
687 }
688 
689 
690