FIBER_START_FUNCTION_CLASS_IMPL(TaskScheduler, FiberStart) {
GlobalArgs *globalArgs = reinterpret_cast<GlobalArgs *>(arg);
TaskScheduler *taskScheduler = &globalArgs->g_taskScheduler;
while (!taskScheduler->m_quit.load()) {
// Check if any of the waiting tasks are ready
WaitingTask waitingTask;
bool waitingTaskReady = false;
taskScheduler->m_waitingTaskLock.lock();
auto iter = taskScheduler->m_waitingTasks.begin();
for (; iter != taskScheduler->m_waitingTasks.end(); ++iter) {
if (iter->Counter->load() == iter->Value) {
waitingTaskReady = true;
break;
}
}
if (waitingTaskReady) {
waitingTask = *iter;
// Optimization for removing an item from a vector as suggested by ryeguy on reddit
// Explained here: http://stackoverflow.com/questions/4442477/remove-ith-item-from-c-stdvector/4442529#4442529
// Essentially, rather than forcing a memcpy to shift all the remaining elements down after the erase,
// we move the last element into the place where the erased element was. Then we pop off the last element
// Check that we're not already the last item
// Move assignment to self is not defined
if (iter != (--taskScheduler->m_waitingTasks.end())) {
*iter = std::move(taskScheduler->m_waitingTasks.back());
}
taskScheduler->m_waitingTasks.pop_back();
}
taskScheduler->m_waitingTaskLock.unlock();
if (waitingTaskReady) {
taskScheduler->SwitchFibers(waitingTask.Fiber);
}
TaskBundle nextTask;
if (!taskScheduler->GetNextTask(&nextTask)) {
std::this_thread::yield();
} else {
nextTask.TaskToExecute.Function(&globalArgs->g_taskScheduler, &globalArgs->g_heap, &globalArgs->g_allocator, nextTask.TaskToExecute.ArgData);
nextTask.Counter->fetch_sub(1);
}
}
FTLConvertFiberToThread(FTLGetCurrentFiber());
globalArgs->g_taskScheduler.m_numActiveWorkerThreads.fetch_sub(1);
FTLEndCurrentThread();
}
void TaskScheduler::FiberStart(void *arg) {
GlobalArgs *globalArgs = (GlobalArgs *)arg;
TaskScheduler *taskScheduler = &globalArgs->TaskScheduler;
while (!taskScheduler->m_quit.load()) {
// Check if any of the waiting tasks are ready
WaitingTask waitingTask;
bool waitingTaskReady = false;
EnterCriticalSection(&taskScheduler->m_waitingTaskLock);
auto iter = taskScheduler->m_waitingTasks.begin();
for ( ; iter != taskScheduler->m_waitingTasks.end(); ++iter) {
if (iter->Counter->load() == iter->Value) {
waitingTaskReady = true;
break;
}
}
if (waitingTaskReady) {
waitingTask = *iter;
taskScheduler->m_waitingTasks.erase(iter);
}
LeaveCriticalSection(&taskScheduler->m_waitingTaskLock);
if (waitingTaskReady) {
taskScheduler->SwitchFibers(waitingTask.Fiber);
}
TaskBundle nextTask;
if (!taskScheduler->GetNextTask(&nextTask)) {
SwitchToThread();
} else {
nextTask.Task.Function(&globalArgs->TaskScheduler, &globalArgs->Heap, &globalArgs->Allocator, nextTask.Task.ArgData);
nextTask.Counter->fetch_sub(1);
}
}
}
void TaskScheduler::FiberStart(intptr_t arg) {
TaskScheduler *taskScheduler = reinterpret_cast<TaskScheduler *>(arg);
while (!taskScheduler->m_quit.load(std::memory_order_acquire)) {
// Clean up from the last fiber to run on this thread
taskScheduler->CleanUpOldFiber();
// Check if any of the waiting tasks are ready
std::size_t waitingFiberIndex = FTL_INVALID_INDEX;
for (std::size_t i = 0; i < taskScheduler->m_fiberPoolSize; ++i) {
// Double lock
if (!taskScheduler->m_waitingFibers[i].load(std::memory_order_relaxed)) {
continue;
}
if (!taskScheduler->m_waitingFibers[i].load(std::memory_order_acquire)) {
continue;
}
// Found a waiting fiber
// Test if it's ready
WaitingBundle *bundle = &taskScheduler->m_waitingBundles[i];
if (bundle->Counter->load(std::memory_order_relaxed) != bundle->TargetValue) {
continue;
}
bool expected = true;
if (std::atomic_compare_exchange_weak_explicit(&taskScheduler->m_waitingFibers[i], &expected, false, std::memory_order_release, std::memory_order_relaxed)) {
waitingFiberIndex = i;
break;
}
}
if (waitingFiberIndex != FTL_INVALID_INDEX) {
// Found a waiting task that is ready to continue
ThreadLocalStorage &tls = taskScheduler->m_tls[taskScheduler->GetCurrentThreadIndex()];
tls.OldFiberIndex = tls.CurrentFiberIndex;
tls.CurrentFiberIndex = waitingFiberIndex;
tls.OldFiberDestination = FiberDestination::ToPool;
// Switch
taskScheduler->m_fibers[tls.OldFiberIndex].SwitchToFiber(&taskScheduler->m_fibers[tls.CurrentFiberIndex]);
// And we're back
} else {
// Get a new task from the queue, and execute it
TaskBundle nextTask;
if (!taskScheduler->GetNextTask(&nextTask)) {
// Spin
} else {
nextTask.TaskToExecute.Function(taskScheduler, nextTask.TaskToExecute.ArgData);
nextTask.Counter->fetch_sub(1);
}
}
}
// Start the quit sequence
// Switch to the thread fibers
ThreadLocalStorage &tls = taskScheduler->m_tls[taskScheduler->GetCurrentThreadIndex()];
taskScheduler->m_fibers[tls.CurrentFiberIndex].SwitchToFiber(&tls.ThreadFiber);
// We should never get here
printf("Error: FiberStart should never return");
}
