godot/thirdparty/embree/common/tasking/taskschedulerinternal.cpp
jfons 767e374dce Upgrade Embree to the latest official release.
Since Embree v3.13.0 supports AARCH64, switch back to the
official repo instead of using Embree-aarch64.

`thirdparty/embree/patches/godot-changes.patch` should now contain
an accurate diff of the changes done to the library.
2021-05-21 17:00:24 +02:00

421 lines
12 KiB
C++

// Copyright 2009-2021 Intel Corporation
// SPDX-License-Identifier: Apache-2.0
#include "taskschedulerinternal.h"
#include "../math/math.h"
#include "../sys/sysinfo.h"
#include <algorithm>
namespace embree
{
RTC_NAMESPACE_BEGIN
static MutexSys g_mutex;
size_t TaskScheduler::g_numThreads = 0;
__thread TaskScheduler* TaskScheduler::g_instance = nullptr;
std::vector<Ref<TaskScheduler>> g_instance_vector;
__thread TaskScheduler::Thread* TaskScheduler::thread_local_thread = nullptr;
TaskScheduler::ThreadPool* TaskScheduler::threadPool = nullptr;
template<typename Predicate, typename Body>
__forceinline void TaskScheduler::steal_loop(Thread& thread, const Predicate& pred, const Body& body)
{
while (true)
{
/*! some rounds that yield */
for (size_t i=0; i<32; i++)
{
/*! some spinning rounds */
const size_t threadCount = thread.threadCount();
for (size_t j=0; j<1024; j+=threadCount)
{
if (!pred()) return;
if (thread.scheduler->steal_from_other_threads(thread)) {
i=j=0;
body();
}
}
yield();
}
}
}
/*! run this task */
void TaskScheduler::Task::run_internal (Thread& thread) // FIXME: avoid as many dll_exports as possible
{
/* try to run if not already stolen */
if (try_switch_state(INITIALIZED,DONE))
{
Task* prevTask = thread.task;
thread.task = this;
// -- GODOT start --
// try {
// if (thread.scheduler->cancellingException == nullptr)
closure->execute();
// } catch (...) {
// if (thread.scheduler->cancellingException == nullptr)
// thread.scheduler->cancellingException = std::current_exception();
// }
// -- GODOT end --
thread.task = prevTask;
add_dependencies(-1);
}
/* steal until all dependencies have completed */
steal_loop(thread,
[&] () { return dependencies>0; },
[&] () { while (thread.tasks.execute_local_internal(thread,this)); });
/* now signal our parent task that we are finished */
if (parent)
parent->add_dependencies(-1);
}
/*! run this task */
dll_export void TaskScheduler::Task::run (Thread& thread) {
run_internal(thread);
}
bool TaskScheduler::TaskQueue::execute_local_internal(Thread& thread, Task* parent)
{
/* stop if we run out of local tasks or reach the waiting task */
if (right == 0 || &tasks[right-1] == parent)
return false;
/* execute task */
size_t oldRight = right;
tasks[right-1].run_internal(thread);
if (right != oldRight) {
THROW_RUNTIME_ERROR("you have to wait for spawned subtasks");
}
/* pop task and closure from stack */
right--;
if (tasks[right].stackPtr != size_t(-1))
stackPtr = tasks[right].stackPtr;
/* also move left pointer */
if (left >= right) left.store(right.load());
return right != 0;
}
dll_export bool TaskScheduler::TaskQueue::execute_local(Thread& thread, Task* parent) {
return execute_local_internal(thread,parent);
}
bool TaskScheduler::TaskQueue::steal(Thread& thread)
{
size_t l = left;
size_t r = right;
if (l < r)
{
l = left++;
if (l >= r)
return false;
}
else
return false;
if (!tasks[l].try_steal(thread.tasks.tasks[thread.tasks.right]))
return false;
thread.tasks.right++;
return true;
}
/* we steal from the left */
size_t TaskScheduler::TaskQueue::getTaskSizeAtLeft()
{
if (left >= right) return 0;
return tasks[left].N;
}
void threadPoolFunction(std::pair<TaskScheduler::ThreadPool*,size_t>* pair)
{
TaskScheduler::ThreadPool* pool = pair->first;
size_t threadIndex = pair->second;
delete pair;
pool->thread_loop(threadIndex);
}
TaskScheduler::ThreadPool::ThreadPool(bool set_affinity)
: numThreads(0), numThreadsRunning(0), set_affinity(set_affinity), running(false) {}
dll_export void TaskScheduler::ThreadPool::startThreads()
{
if (running) return;
setNumThreads(numThreads,true);
}
void TaskScheduler::ThreadPool::setNumThreads(size_t newNumThreads, bool startThreads)
{
Lock<MutexSys> lock(g_mutex);
assert(newNumThreads);
newNumThreads = min(newNumThreads, (size_t) getNumberOfLogicalThreads());
numThreads = newNumThreads;
if (!startThreads && !running) return;
running = true;
size_t numThreadsActive = numThreadsRunning;
mutex.lock();
numThreadsRunning = newNumThreads;
mutex.unlock();
condition.notify_all();
/* start new threads */
for (size_t t=numThreadsActive; t<numThreads; t++)
{
if (t == 0) continue;
auto pair = new std::pair<TaskScheduler::ThreadPool*,size_t>(this,t);
threads.push_back(createThread((thread_func)threadPoolFunction,pair,4*1024*1024,set_affinity ? t : -1));
}
/* stop some threads if we reduce the number of threads */
for (ssize_t t=numThreadsActive-1; t>=ssize_t(numThreadsRunning); t--) {
if (t == 0) continue;
embree::join(threads.back());
threads.pop_back();
}
}
TaskScheduler::ThreadPool::~ThreadPool()
{
/* leave all taskschedulers */
mutex.lock();
numThreadsRunning = 0;
mutex.unlock();
condition.notify_all();
/* wait for threads to terminate */
for (size_t i=0; i<threads.size(); i++)
embree::join(threads[i]);
}
dll_export void TaskScheduler::ThreadPool::add(const Ref<TaskScheduler>& scheduler)
{
mutex.lock();
schedulers.push_back(scheduler);
mutex.unlock();
condition.notify_all();
}
dll_export void TaskScheduler::ThreadPool::remove(const Ref<TaskScheduler>& scheduler)
{
Lock<MutexSys> lock(mutex);
for (std::list<Ref<TaskScheduler> >::iterator it = schedulers.begin(); it != schedulers.end(); it++) {
if (scheduler == *it) {
schedulers.erase(it);
return;
}
}
}
void TaskScheduler::ThreadPool::thread_loop(size_t globalThreadIndex)
{
while (globalThreadIndex < numThreadsRunning)
{
Ref<TaskScheduler> scheduler = NULL;
ssize_t threadIndex = -1;
{
Lock<MutexSys> lock(mutex);
condition.wait(mutex, [&] () { return globalThreadIndex >= numThreadsRunning || !schedulers.empty(); });
if (globalThreadIndex >= numThreadsRunning) break;
scheduler = schedulers.front();
threadIndex = scheduler->allocThreadIndex();
}
scheduler->thread_loop(threadIndex);
}
}
TaskScheduler::TaskScheduler()
: threadCounter(0), anyTasksRunning(0), hasRootTask(false)
{
threadLocal.resize(2*getNumberOfLogicalThreads()); // FIXME: this has to be 2x as in the compatibility join mode with rtcCommitScene the worker threads also join. When disallowing rtcCommitScene to join a build we can remove the 2x.
for (size_t i=0; i<threadLocal.size(); i++)
threadLocal[i].store(nullptr);
}
TaskScheduler::~TaskScheduler()
{
assert(threadCounter == 0);
}
dll_export size_t TaskScheduler::threadID()
{
Thread* thread = TaskScheduler::thread();
if (thread) return thread->threadIndex;
else return 0;
}
dll_export size_t TaskScheduler::threadIndex()
{
Thread* thread = TaskScheduler::thread();
if (thread) return thread->threadIndex;
else return 0;
}
dll_export size_t TaskScheduler::threadCount() {
return threadPool->size();
}
dll_export TaskScheduler* TaskScheduler::instance()
{
if (g_instance == NULL) {
Lock<MutexSys> lock(g_mutex);
g_instance = new TaskScheduler;
g_instance_vector.push_back(g_instance);
}
return g_instance;
}
void TaskScheduler::create(size_t numThreads, bool set_affinity, bool start_threads)
{
if (!threadPool) threadPool = new TaskScheduler::ThreadPool(set_affinity);
threadPool->setNumThreads(numThreads,start_threads);
}
void TaskScheduler::destroy() {
delete threadPool; threadPool = nullptr;
}
dll_export ssize_t TaskScheduler::allocThreadIndex()
{
size_t threadIndex = threadCounter++;
assert(threadIndex < threadLocal.size());
return threadIndex;
}
void TaskScheduler::join()
{
mutex.lock();
size_t threadIndex = allocThreadIndex();
condition.wait(mutex, [&] () { return hasRootTask.load(); });
mutex.unlock();
// -- GODOT start --
// std::exception_ptr except = thread_loop(threadIndex);
// if (except != nullptr) std::rethrow_exception(except);
thread_loop(threadIndex);
// -- GODOT end --
}
void TaskScheduler::reset() {
hasRootTask = false;
}
void TaskScheduler::wait_for_threads(size_t threadCount)
{
while (threadCounter < threadCount-1)
pause_cpu();
}
dll_export TaskScheduler::Thread* TaskScheduler::thread() {
return thread_local_thread;
}
dll_export TaskScheduler::Thread* TaskScheduler::swapThread(Thread* thread)
{
Thread* old = thread_local_thread;
thread_local_thread = thread;
return old;
}
dll_export bool TaskScheduler::wait()
{
Thread* thread = TaskScheduler::thread();
if (thread == nullptr) return true;
while (thread->tasks.execute_local_internal(*thread,thread->task)) {};
return thread->scheduler->cancellingException == nullptr;
}
// -- GODOT start --
// std::exception_ptr TaskScheduler::thread_loop(size_t threadIndex)
void TaskScheduler::thread_loop(size_t threadIndex)
// -- GODOT end --
{
/* allocate thread structure */
std::unique_ptr<Thread> mthread(new Thread(threadIndex,this)); // too large for stack allocation
Thread& thread = *mthread;
threadLocal[threadIndex].store(&thread);
Thread* oldThread = swapThread(&thread);
/* main thread loop */
while (anyTasksRunning)
{
steal_loop(thread,
[&] () { return anyTasksRunning > 0; },
[&] () {
anyTasksRunning++;
while (thread.tasks.execute_local_internal(thread,nullptr));
anyTasksRunning--;
});
}
threadLocal[threadIndex].store(nullptr);
swapThread(oldThread);
/* remember exception to throw */
// -- GODOT start --
// std::exception_ptr except = nullptr;
// if (cancellingException != nullptr) except = cancellingException;
// -- GODOT end --
/* wait for all threads to terminate */
threadCounter--;
#if defined(__WIN32__)
size_t loopIndex = 1;
#endif
#define LOOP_YIELD_THRESHOLD (4096)
while (threadCounter > 0) {
#if defined(__WIN32__)
if ((loopIndex % LOOP_YIELD_THRESHOLD) == 0)
yield();
else
_mm_pause();
loopIndex++;
#else
yield();
#endif
}
// -- GODOT start --
// return except;
return;
// -- GODOT end --
}
bool TaskScheduler::steal_from_other_threads(Thread& thread)
{
const size_t threadIndex = thread.threadIndex;
const size_t threadCount = this->threadCounter;
for (size_t i=1; i<threadCount; i++)
{
pause_cpu(32);
size_t otherThreadIndex = threadIndex+i;
if (otherThreadIndex >= threadCount) otherThreadIndex -= threadCount;
Thread* othread = threadLocal[otherThreadIndex].load();
if (!othread)
continue;
if (othread->tasks.steal(thread))
return true;
}
return false;
}
dll_export void TaskScheduler::startThreads() {
threadPool->startThreads();
}
dll_export void TaskScheduler::addScheduler(const Ref<TaskScheduler>& scheduler) {
threadPool->add(scheduler);
}
dll_export void TaskScheduler::removeScheduler(const Ref<TaskScheduler>& scheduler) {
threadPool->remove(scheduler);
}
RTC_NAMESPACE_END
}