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 	mt_thread_local uint32 isWorkerThreadTLS = 0;
30 
31 
32 #ifdef MT_INSTRUMENTED_BUILD
33 	TaskScheduler::TaskScheduler(uint32 workerThreadsCount, WorkerThreadParams* workerParameters, IProfilerEventListener* listener, TaskStealingMode::Type stealMode)
34 #else
35 	TaskScheduler::TaskScheduler(uint32 workerThreadsCount, WorkerThreadParams* workerParameters, TaskStealingMode::Type stealMode)
36 #endif
37 		: roundRobinThreadIndex(0)
38 		, startedThreadsCount(0)
39 		, taskStealingDisabled(stealMode == TaskStealingMode::DISABLED)
40 	{
41 
42 #ifdef MT_INSTRUMENTED_BUILD
43 		profilerEventListener = listener;
44 #endif
45 
46 		if (workerThreadsCount != 0)
47 		{
48 			threadsCount.StoreRelaxed( MT::Clamp(workerThreadsCount, (uint32)1, (uint32)MT_MAX_THREAD_COUNT) );
49 		} else
50 		{
51 			//query number of processor
52 			threadsCount.StoreRelaxed( (uint32)MT::Clamp(Thread::GetNumberOfHardwareThreads() - 1, 1, (int)MT_MAX_THREAD_COUNT) );
53 		}
54 
55 		// create fiber pool (fibers with standard stack size)
56 		for (uint32 i = 0; i < MT_MAX_STANDART_FIBERS_COUNT; i++)
57 		{
58 			FiberContext& context = standartFiberContexts[i];
59 			context.fiber.Create(MT_STANDART_FIBER_STACK_SIZE, FiberMain, &context);
60 			bool res = standartFibersAvailable.TryPush( &context );
61 			MT_USED_IN_ASSERT(res);
62 			MT_ASSERT(res == true, "Can't add fiber to storage");
63 		}
64 
65 		// create fiber pool (fibers with extended stack size)
66 		for (uint32 i = 0; i < MT_MAX_EXTENDED_FIBERS_COUNT; i++)
67 		{
68 			FiberContext& context = extendedFiberContexts[i];
69 			context.fiber.Create(MT_EXTENDED_FIBER_STACK_SIZE, FiberMain, &context);
70 			bool res = extendedFibersAvailable.TryPush( &context );
71 			MT_USED_IN_ASSERT(res);
72 			MT_ASSERT(res == true, "Can't add fiber to storage");
73 		}
74 
75 
76 		for (int16 i = 0; i < TaskGroup::MT_MAX_GROUPS_COUNT; i++)
77 		{
78 			if (i != TaskGroup::DEFAULT)
79 			{
80 				bool res = availableGroups.TryPush( TaskGroup(i) );
81 				MT_USED_IN_ASSERT(res);
82 				MT_ASSERT(res == true, "Can't add group to storage");
83 			}
84 		}
85 
86 #if MT_GROUP_DEBUG
87 		groupStats[TaskGroup::DEFAULT].SetDebugIsFree(false);
88 #endif
89 
90 		// create worker thread pool
91 		int32 totalThreadsCount = GetWorkersCount();
92 		for (int32 i = 0; i < totalThreadsCount; i++)
93 		{
94 			threadContext[i].SetThreadIndex(i);
95 			threadContext[i].taskScheduler = this;
96 
97 			uint32 threadCore = i;
98 			ThreadPriority::Type priority = ThreadPriority::DEFAULT;
99 			if (workerParameters != nullptr)
100 			{
101 				const WorkerThreadParams& params = workerParameters[i];
102 
103 				threadCore = params.core;
104 				priority = params.priority;
105 			}
106 
107 			threadContext[i].thread.Start( MT_SCHEDULER_STACK_SIZE, WorkerThreadMain, &threadContext[i], threadCore, priority);
108 		}
109 	}
110 
111 
112 	TaskScheduler::~TaskScheduler()
113 	{
114 		int32 totalThreadsCount = GetWorkersCount();
115 		for (int32 i = 0; i < totalThreadsCount; i++)
116 		{
117 			threadContext[i].state.Store(internal::ThreadState::EXIT);
118 			threadContext[i].hasNewTasksEvent.Signal();
119 		}
120 
121 		for (int32 i = 0; i < totalThreadsCount; i++)
122 		{
123 			threadContext[i].thread.Join();
124 		}
125 	}
126 
127 	FiberContext* TaskScheduler::RequestFiberContext(internal::GroupedTask& task)
128 	{
129 		FiberContext *fiberContext = task.awaitingFiber;
130 		if (fiberContext)
131 		{
132 			task.awaitingFiber = nullptr;
133 			return fiberContext;
134 		}
135 
136 		MT::StackRequirements::Type stackRequirements = task.desc.stackRequirements;
137 
138 		fiberContext = nullptr;
139 		bool res = false;
140 		MT_USED_IN_ASSERT(res);
141 		switch(stackRequirements)
142 		{
143 		case MT::StackRequirements::STANDARD:
144 			res = standartFibersAvailable.TryPop(fiberContext);
145 			MT_ASSERT(res, "Can't get more standard fibers!");
146 			break;
147 		case MT::StackRequirements::EXTENDED:
148 			res = extendedFibersAvailable.TryPop(fiberContext);
149 			MT_ASSERT(res, "Can't get more extended fibers!");
150 			break;
151 		default:
152 			MT_REPORT_ASSERT("Unknown stack requrements");
153 		}
154 
155 		MT_ASSERT(fiberContext != nullptr, "Can't get more fibers. Too many tasks in flight simultaneously?");
156 
157 		fiberContext->currentTask = task.desc;
158 		fiberContext->currentGroup = task.group;
159 		fiberContext->parentFiber = task.parentFiber;
160 		fiberContext->stackRequirements = stackRequirements;
161 		return fiberContext;
162 	}
163 
164 	void TaskScheduler::ReleaseFiberContext(FiberContext*&& fiberContext)
165 	{
166 		MT_ASSERT(fiberContext, "Can't release nullptr Fiber. fiberContext is nullptr");
167 
168 		MT::StackRequirements::Type stackRequirements = fiberContext->stackRequirements;
169 		fiberContext->Reset();
170 
171 		MT_ASSERT(fiberContext != nullptr, "Fiber context can't be nullptr");
172 
173 		bool res = false;
174 		MT_USED_IN_ASSERT(res);
175 		switch(stackRequirements)
176 		{
177 		case MT::StackRequirements::STANDARD:
178 			res = standartFibersAvailable.TryPush(std::move(fiberContext));
179 			break;
180 		case MT::StackRequirements::EXTENDED:
181 			res = extendedFibersAvailable.TryPush(std::move(fiberContext));
182 			break;
183 		default:
184 			MT_REPORT_ASSERT("Unknown stack requrements");
185 		}
186 
187 		MT_USED_IN_ASSERT(res);
188 		MT_ASSERT(res != false, "Can't return fiber to storage");
189 	}
190 
191 	FiberContext* TaskScheduler::ExecuteTask(internal::ThreadContext& threadContext, FiberContext* fiberContext)
192 	{
193 		MT_ASSERT(threadContext.threadId.IsCurrentThread(), "Thread context sanity check failed");
194 
195 		MT_ASSERT(fiberContext, "Invalid fiber context");
196 		MT_ASSERT(fiberContext->currentTask.IsValid(), "Invalid task");
197 
198 		// Set actual thread context to fiber
199 		fiberContext->SetThreadContext(&threadContext);
200 
201 		// Update task status
202 		fiberContext->SetStatus(FiberTaskStatus::RUNNED);
203 
204 		MT_ASSERT(fiberContext->GetThreadContext()->threadId.IsCurrentThread(), "Thread context sanity check failed");
205 
206 		const void* poolUserData = fiberContext->currentTask.userData;
207 		TPoolTaskDestroy poolDestroyFunc = fiberContext->currentTask.poolDestroyFunc;
208 
209 #ifdef MT_INSTRUMENTED_BUILD
210 		//threadContext.NotifyTaskExecuteStateChanged( MT_SYSTEM_TASK_COLOR, MT_SYSTEM_TASK_NAME, TaskExecuteState::SUSPEND);
211 		threadContext.NotifyTaskExecuteStateChanged( MT_SYSTEM_TASK_COLOR, MT_SYSTEM_TASK_NAME, TaskExecuteState::STOP);
212 #endif
213 
214 		// Run current task code
215 		Fiber::SwitchTo(threadContext.schedulerFiber, fiberContext->fiber);
216 
217 #ifdef MT_INSTRUMENTED_BUILD
218 		//threadContext.NotifyTaskExecuteStateChanged( MT_SYSTEM_TASK_COLOR, MT_SYSTEM_TASK_NAME, TaskExecuteState::RESUME);
219 		threadContext.NotifyTaskExecuteStateChanged( MT_SYSTEM_TASK_COLOR, MT_SYSTEM_TASK_NAME, TaskExecuteState::START);
220 #endif
221 
222 		// If task was done
223 		FiberTaskStatus::Type taskStatus = fiberContext->GetStatus();
224 		if (taskStatus == FiberTaskStatus::FINISHED)
225 		{
226 			//destroy task (call dtor) for "fire and forget" type of task from TaskPool
227 			if (poolDestroyFunc != nullptr)
228 			{
229 				poolDestroyFunc(poolUserData);
230 			}
231 
232 			TaskGroup taskGroup = fiberContext->currentGroup;
233 
234 			TaskScheduler::TaskGroupDescription  & groupDesc = threadContext.taskScheduler->GetGroupDesc(taskGroup);
235 
236 			// Update group status
237 			int groupTaskCount = groupDesc.Dec();
238 			MT_ASSERT(groupTaskCount >= 0, "Sanity check failed!");
239 			if (groupTaskCount == 0)
240 			{
241 				fiberContext->currentGroup = TaskGroup::INVALID;
242 			}
243 
244 			// Update total task count
245 			int allGroupTaskCount = threadContext.taskScheduler->allGroups.Dec();
246 			MT_ASSERT(allGroupTaskCount >= 0, "Sanity check failed!");
247 
248 			FiberContext* parentFiberContext = fiberContext->parentFiber;
249 			if (parentFiberContext != nullptr)
250 			{
251 				int childrenFibersCount = parentFiberContext->childrenFibersCount.DecFetch();
252 				MT_ASSERT(childrenFibersCount >= 0, "Sanity check failed!");
253 
254 				if (childrenFibersCount == 0)
255 				{
256 					// This is a last subtask. Restore parent task
257 					MT_ASSERT(threadContext.threadId.IsCurrentThread(), "Thread context sanity check failed");
258 					MT_ASSERT(parentFiberContext->GetThreadContext() == nullptr, "Inactive parent should not have a valid thread context");
259 
260 					// WARNING!! Thread context can changed here! Set actual current thread context.
261 					parentFiberContext->SetThreadContext(&threadContext);
262 
263 					MT_ASSERT(parentFiberContext->GetThreadContext()->threadId.IsCurrentThread(), "Thread context sanity check failed");
264 
265 					// All subtasks is done.
266 					// Exiting and return parent fiber to scheduler
267 					return parentFiberContext;
268 				} else
269 				{
270 					// Other subtasks still exist
271 					// Exiting
272 					return nullptr;
273 				}
274 			} else
275 			{
276 				// Task is finished and no parent task
277 				// Exiting
278 				return nullptr;
279 			}
280 		}
281 
282 		MT_ASSERT(taskStatus != FiberTaskStatus::RUNNED, "Incorrect task status")
283 		return nullptr;
284 	}
285 
286 
287 	void TaskScheduler::FiberMain(void* userData)
288 	{
289 		FiberContext& fiberContext = *(FiberContext*)(userData);
290 		for(;;)
291 		{
292 			MT_ASSERT(fiberContext.currentTask.IsValid(), "Invalid task in fiber context");
293 			MT_ASSERT(fiberContext.GetThreadContext(), "Invalid thread context");
294 			MT_ASSERT(fiberContext.GetThreadContext()->threadId.IsCurrentThread(), "Thread context sanity check failed");
295 
296 #ifdef MT_INSTRUMENTED_BUILD
297 			fiberContext.fiber.SetName( MT_SYSTEM_TASK_FIBER_NAME );
298 			fiberContext.GetThreadContext()->NotifyTaskExecuteStateChanged( fiberContext.currentTask.debugColor, fiberContext.currentTask.debugID, TaskExecuteState::START );
299 #endif
300 
301 			fiberContext.currentTask.taskFunc( fiberContext, fiberContext.currentTask.userData );
302 			fiberContext.SetStatus(FiberTaskStatus::FINISHED);
303 
304 #ifdef MT_INSTRUMENTED_BUILD
305 			fiberContext.fiber.SetName( MT_SYSTEM_TASK_FIBER_NAME );
306 			fiberContext.GetThreadContext()->NotifyTaskExecuteStateChanged( fiberContext.currentTask.debugColor, fiberContext.currentTask.debugID, TaskExecuteState::STOP );
307 #endif
308 
309 			Fiber::SwitchTo(fiberContext.fiber, fiberContext.GetThreadContext()->schedulerFiber);
310 		}
311 
312 	}
313 
314 
315 	bool TaskScheduler::TryStealTask(internal::ThreadContext& threadContext, internal::GroupedTask & task)
316 	{
317 		bool taskStealingDisabled = threadContext.taskScheduler->IsTaskStealingDisabled();
318 		uint32 workersCount = threadContext.taskScheduler->GetWorkersCount();
319 
320 		if (workersCount <= 1 || taskStealingDisabled )
321 		{
322 			return false;
323 		}
324 
325 		uint32 victimIndex = threadContext.random.Get();
326 
327 		for (uint32 attempt = 0; attempt < workersCount; attempt++)
328 		{
329 			uint32 index = victimIndex % workersCount;
330 			if (index == threadContext.workerIndex)
331 			{
332 				victimIndex++;
333 				index = victimIndex % workersCount;
334 			}
335 
336 			internal::ThreadContext& victimContext = threadContext.taskScheduler->threadContext[index];
337 			if (victimContext.queue.TryPopNewest(task))
338 			{
339 				return true;
340 			}
341 
342 			victimIndex++;
343 		}
344 		return false;
345 	}
346 
347 	void TaskScheduler::WorkerThreadMain( void* userData )
348 	{
349 		internal::ThreadContext& context = *(internal::ThreadContext*)(userData);
350 		MT_ASSERT(context.taskScheduler, "Task scheduler must be not null!");
351 
352 		isWorkerThreadTLS = 1;
353 		context.threadId.SetAsCurrentThread();
354 
355 #ifdef MT_INSTRUMENTED_BUILD
356 		const char* threadNames[] = {"worker0","worker1","worker2","worker3","worker4","worker5","worker6","worker7","worker8","worker9","worker10","worker11","worker12"};
357 		if (context.workerIndex < MT_ARRAY_SIZE(threadNames))
358 		{
359 			Thread::SetThreadName(threadNames[context.workerIndex]);
360 		} else
361 		{
362 			Thread::SetThreadName("worker_thread");
363 		}
364 #endif
365 
366 		context.schedulerFiber.CreateFromCurrentThreadAndRun(SchedulerFiberMain, userData);
367 	}
368 
369 
370 	void TaskScheduler::SchedulerFiberWait( void* userData )
371 	{
372 		WaitContext& waitContext = *(WaitContext*)(userData);
373 		internal::ThreadContext& context = *waitContext.threadContext;
374 		MT_ASSERT(context.taskScheduler, "Task scheduler must be not null!");
375 		MT_ASSERT(waitContext.waitCounter, "Wait counter must be not null!");
376 
377 #ifdef MT_INSTRUMENTED_BUILD
378 		context.NotifyWaitStarted();
379 		context.NotifyTaskExecuteStateChanged( MT_SYSTEM_TASK_COLOR, MT_SYSTEM_TASK_NAME, TaskExecuteState::START);
380 #endif
381 
382 		int64 timeOut = GetTimeMicroSeconds() + (waitContext.waitTimeMs * 1000);
383 
384 		int32 idleIteration = 0;
385 
386 		for(;;)
387 		{
388 			if ( SchedulerFiberStep(context) == false )
389 			{
390 				//---- Wait for new tasks using hybrid spin ------------------------
391 				// http://www.1024cores.net/home/lock-free-algorithms/tricks/spinning
392 				//
393 				if (idleIteration < 10)
394 				{
395 					MT::YieldCpu();
396 				} else
397 				{
398 					if (idleIteration < 20)
399 					{
400 						for (int32 i = 0; i < 50; i++)
401 						{
402 							MT::YieldCpu();
403 						}
404 					} else
405 					{
406 						if (idleIteration < 24)
407 						{
408 							MT::Thread::Sleep(0);
409 						} else
410 						{
411 							if (idleIteration < 60)
412 							{
413 								MT::Thread::Sleep(1);
414 							} else
415 							{
416 								MT_REPORT_ASSERT("Sanity check failed. Wait too long (at least 60 ms) and still no tasks to processing");
417 								MT::Thread::Sleep(15);
418 							}
419 						}
420 					}
421 				}
422 				//---- spin wait for new tasks ------------------------
423 
424 				idleIteration++;
425 			} else
426 			{
427 				idleIteration = 0;
428 			}
429 
430 			int32 groupTaskCount = waitContext.waitCounter->Load();
431 			if (groupTaskCount == 0)
432 			{
433 				waitContext.exitCode = 0;
434 				break;
435 			}
436 
437 			int64 timeNow = GetTimeMicroSeconds();
438 			if (timeNow >= timeOut)
439 			{
440 				waitContext.exitCode = 1;
441 				break;
442 			}
443 		}
444 
445 #ifdef MT_INSTRUMENTED_BUILD
446 		context.NotifyTaskExecuteStateChanged( MT_SYSTEM_TASK_COLOR, MT_SYSTEM_TASK_NAME, TaskExecuteState::STOP);
447 		context.NotifyWaitFinished();
448 #endif
449 
450 	}
451 
452 	void TaskScheduler::SchedulerFiberMain( void* userData )
453 	{
454 		internal::ThreadContext& context = *(internal::ThreadContext*)(userData);
455 		MT_ASSERT(context.taskScheduler, "Task scheduler must be not null!");
456 
457 #ifdef MT_INSTRUMENTED_BUILD
458 		context.NotifyThreadCreated(context.workerIndex);
459 #endif
460 
461 		int32 totalThreadsCount = context.taskScheduler->threadsCount.LoadRelaxed();
462 		context.taskScheduler->startedThreadsCount.IncFetch();
463 
464 		//Simple spinlock until all threads is started and initialized
465 		for(;;)
466 		{
467 			int32 initializedThreadsCount = context.taskScheduler->startedThreadsCount.Load();
468 			if (initializedThreadsCount == totalThreadsCount)
469 			{
470 				break;
471 			}
472 
473 			// sleep some time until all other thread initialized
474 			Thread::Sleep(1);
475 		}
476 
477 		HardwareFullMemoryBarrier();
478 
479 #ifdef MT_INSTRUMENTED_BUILD
480 		context.NotifyThreadStarted(context.workerIndex);
481 		context.NotifyTaskExecuteStateChanged( MT_SYSTEM_TASK_COLOR, MT_SYSTEM_TASK_NAME, TaskExecuteState::START);
482 #endif
483 
484 		while(context.state.Load() != internal::ThreadState::EXIT)
485 		{
486 			if ( SchedulerFiberStep(context) == false )
487 			{
488 #ifdef MT_INSTRUMENTED_BUILD
489 				context.NotifyThreadIdleStarted(context.workerIndex);
490 #endif
491 				// Queue is empty and stealing attempt has failed
492 				// Wait for new events
493 				context.hasNewTasksEvent.Wait(2000);
494 
495 #ifdef MT_INSTRUMENTED_BUILD
496 				context.NotifyThreadIdleFinished(context.workerIndex);
497 #endif
498 			}
499 
500 		} // main thread loop
501 
502 #ifdef MT_INSTRUMENTED_BUILD
503 		context.NotifyTaskExecuteStateChanged( MT_SYSTEM_TASK_COLOR, MT_SYSTEM_TASK_NAME, TaskExecuteState::STOP);
504 		context.NotifyThreadStoped(context.workerIndex);
505 #endif
506 
507 	}
508 
509 	bool TaskScheduler::SchedulerFiberStep( internal::ThreadContext& context )
510 	{
511 		internal::GroupedTask task;
512 		if (context.queue.TryPopOldest(task) || TryStealTask(context, task) )
513 		{
514 #ifdef MT_INSTRUMENTED_BUILD
515 			bool isNewTask = (task.awaitingFiber == nullptr);
516 #endif
517 
518 			// There is a new task
519 			FiberContext* fiberContext = context.taskScheduler->RequestFiberContext(task);
520 			MT_ASSERT(fiberContext, "Can't get execution context from pool");
521 			MT_ASSERT(fiberContext->currentTask.IsValid(), "Sanity check failed");
522 			MT_ASSERT(fiberContext->stackRequirements == task.desc.stackRequirements, "Sanity check failed");
523 
524 			while(fiberContext)
525 			{
526 #ifdef MT_INSTRUMENTED_BUILD
527 				if (isNewTask)
528 				{
529 					//TODO:
530 					isNewTask = false;
531 				}
532 #endif
533 				// prevent invalid fiber resume from child tasks, before ExecuteTask is done
534 				fiberContext->childrenFibersCount.IncFetch();
535 
536 				FiberContext* parentFiber = ExecuteTask(context, fiberContext);
537 
538 				FiberTaskStatus::Type taskStatus = fiberContext->GetStatus();
539 
540 				//release guard
541 				int childrenFibersCount = fiberContext->childrenFibersCount.DecFetch();
542 
543 				// Can drop fiber context - task is finished
544 				if (taskStatus == FiberTaskStatus::FINISHED)
545 				{
546 					MT_ASSERT( childrenFibersCount == 0, "Sanity check failed");
547 					context.taskScheduler->ReleaseFiberContext(std::move(fiberContext));
548 
549 					// If parent fiber is exist transfer flow control to parent fiber, if parent fiber is null, exit
550 					fiberContext = parentFiber;
551 				} else
552 				{
553 					MT_ASSERT( childrenFibersCount >= 0, "Sanity check failed");
554 
555 					// No subtasks here and status is not finished, this mean all subtasks already finished before parent return from ExecuteTask
556 					if (childrenFibersCount == 0)
557 					{
558 						MT_ASSERT(parentFiber == nullptr, "Sanity check failed");
559 					} else
560 					{
561 						// If subtasks still exist, drop current task execution. task will be resumed when last subtask finished
562 						break;
563 					}
564 
565 					// If task is yielded execution, get another task from queue.
566 					if (taskStatus == FiberTaskStatus::YIELDED)
567 					{
568 						// Task is yielded, add to tasks queue
569 						ArrayView<internal::GroupedTask> buffer(context.descBuffer, 1);
570 						ArrayView<internal::TaskBucket> buckets( MT_ALLOCATE_ON_STACK(sizeof(internal::TaskBucket)), 1 );
571 
572 						FiberContext* yieldedTask = fiberContext;
573 						StaticVector<FiberContext*, 1> yieldedTasksQueue(1, yieldedTask);
574 						internal::DistibuteDescriptions( TaskGroup(TaskGroup::ASSIGN_FROM_CONTEXT), yieldedTasksQueue.Begin(), buffer, buckets );
575 
576 						// add yielded task to scheduler
577 						context.taskScheduler->RunTasksImpl(buckets, nullptr, true);
578 
579 						// ATENTION! yielded task can be already completed at this point
580 
581 						break;
582 					}
583 				}
584 			} //while(fiberContext)
585 
586 			return true;
587 		}
588 
589 		return false;
590 	}
591 
592 	void TaskScheduler::RunTasksImpl(ArrayView<internal::TaskBucket>& buckets, FiberContext * parentFiber, bool restoredFromAwaitState)
593 	{
594 		// This storage is necessary to calculate how many tasks we add to different groups
595 		int newTaskCountInGroup[TaskGroup::MT_MAX_GROUPS_COUNT];
596 
597 		// Default value is 0
598 		memset(&newTaskCountInGroup[0], 0, sizeof(newTaskCountInGroup));
599 
600 		// Set parent fiber pointer
601 		// Calculate the number of tasks per group
602 		// Calculate total number of tasks
603 		size_t count = 0;
604 		for (size_t i = 0; i < buckets.Size(); ++i)
605 		{
606 			internal::TaskBucket& bucket = buckets[i];
607 			for (size_t taskIndex = 0; taskIndex < bucket.count; taskIndex++)
608 			{
609 				internal::GroupedTask & task = bucket.tasks[taskIndex];
610 
611 				task.parentFiber = parentFiber;
612 
613 				int idx = task.group.GetValidIndex();
614 				MT_ASSERT(idx >= 0 && idx < TaskGroup::MT_MAX_GROUPS_COUNT, "Invalid index");
615 				newTaskCountInGroup[idx]++;
616 			}
617 
618 			count += bucket.count;
619 		}
620 
621 		// Increments child fibers count on parent fiber
622 		if (parentFiber)
623 		{
624 			parentFiber->childrenFibersCount.AddFetch((int)count);
625 		}
626 
627 		if (restoredFromAwaitState == false)
628 		{
629 			// Increase the number of active tasks in the group using data from temporary storage
630 			for (size_t i = 0; i < TaskGroup::MT_MAX_GROUPS_COUNT; i++)
631 			{
632 				int groupNewTaskCount = newTaskCountInGroup[i];
633 				if (groupNewTaskCount > 0)
634 				{
635 					groupStats[i].Add((uint32)groupNewTaskCount);
636 				}
637 			}
638 
639 			// Increments all task in progress counter
640 			allGroups.Add((uint32)count);
641 		} else
642 		{
643 			// If task's restored from await state, counters already in correct state
644 		}
645 
646 		// Add to thread queue
647 		for (size_t i = 0; i < buckets.Size(); ++i)
648 		{
649 			int bucketIndex = roundRobinThreadIndex.IncFetch() % threadsCount.LoadRelaxed();
650 			internal::ThreadContext & context = threadContext[bucketIndex];
651 
652 			internal::TaskBucket& bucket = buckets[i];
653 
654 			for(;;)
655 			{
656 				bool res = context.queue.Add(bucket.tasks, bucket.count);
657 				if (res == true)
658 				{
659 					break;
660 				}
661 
662 				//Can't add new tasks onto the queue. Look like the job system is overloaded. Wait some time and try again.
663 				//TODO: implement waiting until workers done using events.
664 				Thread::Sleep(10);
665 			}
666 
667 			context.hasNewTasksEvent.Signal();
668 		}
669 	}
670 
671 	void TaskScheduler::RunAsync(TaskGroup group, const TaskHandle* taskHandleArray, uint32 taskHandleCount)
672 	{
673 		MT_ASSERT(!IsWorkerThread(), "Can't use RunAsync inside Task. Use FiberContext.RunAsync() instead.");
674 
675 		ArrayView<internal::GroupedTask> buffer(MT_ALLOCATE_ON_STACK(sizeof(internal::GroupedTask) * taskHandleCount), taskHandleCount);
676 
677 		uint32 bucketCount = MT::Min((uint32)GetWorkersCount(), taskHandleCount);
678 		ArrayView<internal::TaskBucket> buckets(MT_ALLOCATE_ON_STACK(sizeof(internal::TaskBucket) * bucketCount), bucketCount);
679 
680 		internal::DistibuteDescriptions(group, taskHandleArray, buffer, buckets);
681 		RunTasksImpl(buckets, nullptr, false);
682 	}
683 
684 	bool TaskScheduler::WaitGroup(TaskGroup group, uint32 milliseconds)
685 	{
686 		MT_VERIFY(IsWorkerThread() == false, "Can't use WaitGroup inside Task. Use FiberContext.WaitGroupAndYield() instead.", return false);
687 
688 		TaskScheduler::TaskGroupDescription& groupDesc = GetGroupDesc(group);
689 
690 		size_t bytesCountForDescBuffer = internal::ThreadContext::GetMemoryRequrementInBytesForDescBuffer();
691 		void* descBuffer = MT_ALLOCATE_ON_STACK(bytesCountForDescBuffer);
692 
693 		internal::ThreadContext context(descBuffer);
694 		context.taskScheduler = this;
695 		context.SetThreadIndex(0xFFFFFFFF);
696 		context.threadId.SetAsCurrentThread();
697 
698 		WaitContext waitContext;
699 		waitContext.threadContext = &context;
700 		waitContext.waitCounter = groupDesc.GetWaitCounter();
701 		waitContext.waitTimeMs = milliseconds;
702 		waitContext.exitCode = 0;
703 
704 		isWorkerThreadTLS = 1;
705 
706 		context.schedulerFiber.CreateFromCurrentThreadAndRun(SchedulerFiberWait, &waitContext);
707 
708 		isWorkerThreadTLS = 0;
709 		return (waitContext.exitCode == 0);
710 	}
711 
712 	bool TaskScheduler::WaitAll(uint32 milliseconds)
713 	{
714 		MT_VERIFY(IsWorkerThread() == false, "Can't use WaitAll inside Task.", return false);
715 
716 		size_t bytesCountForDescBuffer = internal::ThreadContext::GetMemoryRequrementInBytesForDescBuffer();
717 		void* descBuffer = MT_ALLOCATE_ON_STACK(bytesCountForDescBuffer);
718 
719 		internal::ThreadContext context(descBuffer);
720 		context.taskScheduler = this;
721 		context.SetThreadIndex(0xFFFFFFFF);
722 		context.threadId.SetAsCurrentThread();
723 
724 		WaitContext waitContext;
725 		waitContext.threadContext = &context;
726 		waitContext.waitCounter = allGroups.GetWaitCounter();
727 		waitContext.waitTimeMs = milliseconds;
728 		waitContext.exitCode = 0;
729 
730 		isWorkerThreadTLS = 1;
731 
732 		context.schedulerFiber.CreateFromCurrentThreadAndRun(SchedulerFiberWait, &waitContext);
733 
734 		isWorkerThreadTLS = 0;
735 		return (waitContext.exitCode == 0);
736 	}
737 
738 	bool TaskScheduler::IsTaskStealingDisabled() const
739 	{
740 		return taskStealingDisabled;
741 	}
742 
743 	int32 TaskScheduler::GetWorkersCount() const
744 	{
745 		return threadsCount.LoadRelaxed();
746 	}
747 
748 
749 	bool TaskScheduler::IsWorkerThread() const
750 	{
751 		return (isWorkerThreadTLS != 0);
752 	}
753 
754 	TaskGroup TaskScheduler::CreateGroup()
755 	{
756 		MT_ASSERT(IsWorkerThread() == false, "Can't use CreateGroup inside Task.");
757 
758 		TaskGroup group;
759 		if (!availableGroups.TryPop(group))
760 		{
761 			MT_REPORT_ASSERT("Group pool is empty");
762 		}
763 
764 		int idx = group.GetValidIndex();
765 		MT_USED_IN_ASSERT(idx);
766 		MT_ASSERT(groupStats[idx].GetDebugIsFree() == true, "Bad logic!");
767 #if MT_GROUP_DEBUG
768 		groupStats[idx].SetDebugIsFree(false);
769 #endif
770 
771 		return group;
772 	}
773 
774 	void TaskScheduler::ReleaseGroup(TaskGroup group)
775 	{
776 		MT_ASSERT(IsWorkerThread() == false, "Can't use ReleaseGroup inside Task.");
777 		MT_ASSERT(group.IsValid(), "Invalid group ID");
778 
779 		int idx = group.GetValidIndex();
780 		MT_USED_IN_ASSERT(idx);
781 		MT_ASSERT(groupStats[idx].GetDebugIsFree() == false, "Group already released");
782 #if MT_GROUP_DEBUG
783 		groupStats[idx].SetDebugIsFree(true);
784 #endif
785 
786 		bool res = availableGroups.TryPush(std::move(group));
787 		MT_USED_IN_ASSERT(res);
788 		MT_ASSERT(res, "Can't return group to pool");
789 	}
790 
791 	TaskScheduler::TaskGroupDescription & TaskScheduler::GetGroupDesc(TaskGroup group)
792 	{
793 		MT_ASSERT(group.IsValid(), "Invalid group ID");
794 
795 		int idx = group.GetValidIndex();
796 		TaskScheduler::TaskGroupDescription & groupDesc = groupStats[idx];
797 
798 		MT_ASSERT(groupDesc.GetDebugIsFree() == false, "Invalid group");
799 		return groupDesc;
800 	}
801 }
802 
803 
804