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// This file is part of Eigen, a lightweight C++ template library
// for linear algebra.
//
// Copyright (C) 2014 Benoit Steiner <benoit.steiner.goog@gmail.com>
//
// This Source Code Form is subject to the terms of the Mozilla
// Public License v. 2.0. If a copy of the MPL was not distributed
// with this file, You can obtain one at http://mozilla.org/MPL/2.0/.
#if defined(EIGEN_USE_THREADS) && !defined(EIGEN_CXX11_TENSOR_TENSOR_DEVICE_THREAD_POOL_H)
#define EIGEN_CXX11_TENSOR_TENSOR_DEVICE_THREAD_POOL_H
namespace Eigen {
// Use the SimpleThreadPool by default. We'll switch to the new non blocking
// thread pool later.
#ifdef EIGEN_USE_NONBLOCKING_THREAD_POOL
template <typename Env> using ThreadPoolTempl = NonBlockingThreadPoolTempl<Env>;
typedef NonBlockingThreadPool ThreadPool;
#else
template <typename Env> using ThreadPoolTempl = SimpleThreadPoolTempl<Env>;
typedef SimpleThreadPool ThreadPool;
#endif
// Barrier is an object that allows one or more threads to wait until
// Notify has been called a specified number of times.
class Barrier {
public:
Barrier(unsigned int count) : state_(count << 1), notified_(false) {
eigen_assert(((count << 1) >> 1) == count);
}
~Barrier() {
eigen_assert((state_>>1) == 0);
}
void Notify() {
unsigned int v = state_.fetch_sub(2, std::memory_order_acq_rel) - 2;
if (v != 1) {
eigen_assert(((v + 2) & ~1) != 0);
return; // either count has not dropped to 0, or waiter is not waiting
}
std::unique_lock<std::mutex> l(mu_);
eigen_assert(!notified_);
notified_ = true;
cv_.notify_all();
}
void Wait() {
unsigned int v = state_.fetch_or(1, std::memory_order_acq_rel);
if ((v >> 1) == 0) return;
std::unique_lock<std::mutex> l(mu_);
while (!notified_) {
cv_.wait(l);
}
}
private:
std::mutex mu_;
std::condition_variable cv_;
std::atomic<unsigned int> state_; // low bit is waiter flag
bool notified_;
};
// Notification is an object that allows a user to to wait for another
// thread to signal a notification that an event has occurred.
//
// Multiple threads can wait on the same Notification object,
// but only one caller must call Notify() on the object.
struct Notification : Barrier {
Notification() : Barrier(1) {};
};
// Runs an arbitrary function and then calls Notify() on the passed in
// Notification.
template <typename Function, typename... Args> struct FunctionWrapperWithNotification
{
static void run(Notification* n, Function f, Args... args) {
f(args...);
if (n) {
n->Notify();
}
}
};
template <typename Function, typename... Args> struct FunctionWrapperWithBarrier
{
static void run(Barrier* b, Function f, Args... args) {
f(args...);
if (b) {
b->Notify();
}
}
};
template <typename SyncType>
static EIGEN_STRONG_INLINE void wait_until_ready(SyncType* n) {
if (n) {
n->Wait();
}
}
// Build a thread pool device on top the an existing pool of threads.
struct ThreadPoolDevice {
// The ownership of the thread pool remains with the caller.
ThreadPoolDevice(ThreadPoolInterface* pool, size_t num_cores) : pool_(pool), num_threads_(num_cores) { }
EIGEN_STRONG_INLINE void* allocate(size_t num_bytes) const {
return internal::aligned_malloc(num_bytes);
}
EIGEN_STRONG_INLINE void deallocate(void* buffer) const {
internal::aligned_free(buffer);
}
EIGEN_STRONG_INLINE void memcpy(void* dst, const void* src, size_t n) const {
::memcpy(dst, src, n);
}
EIGEN_STRONG_INLINE void memcpyHostToDevice(void* dst, const void* src, size_t n) const {
memcpy(dst, src, n);
}
EIGEN_STRONG_INLINE void memcpyDeviceToHost(void* dst, const void* src, size_t n) const {
memcpy(dst, src, n);
}
EIGEN_STRONG_INLINE void memset(void* buffer, int c, size_t n) const {
::memset(buffer, c, n);
}
EIGEN_STRONG_INLINE size_t numThreads() const {
return num_threads_;
}
EIGEN_STRONG_INLINE size_t firstLevelCacheSize() const {
return l1CacheSize();
}
EIGEN_STRONG_INLINE size_t lastLevelCacheSize() const {
// The l3 cache size is shared between all the cores.
return l3CacheSize() / num_threads_;
}
EIGEN_DEVICE_FUNC EIGEN_STRONG_INLINE int majorDeviceVersion() const {
// Should return an enum that encodes the ISA supported by the CPU
return 1;
}
template <class Function, class... Args>
EIGEN_STRONG_INLINE Notification* enqueue(Function&& f, Args&&... args) const {
Notification* n = new Notification();
std::function<void()> func =
std::bind(&FunctionWrapperWithNotification<Function, Args...>::run, n, f, args...);
pool_->Schedule(func);
return n;
}
template <class Function, class... Args>
EIGEN_STRONG_INLINE void enqueue_with_barrier(Barrier* b,
Function&& f,
Args&&... args) const {
std::function<void()> func = std::bind(
&FunctionWrapperWithBarrier<Function, Args...>::run, b, f, args...);
pool_->Schedule(func);
}
template <class Function, class... Args>
EIGEN_STRONG_INLINE void enqueueNoNotification(Function&& f, Args&&... args) const {
std::function<void()> func = std::bind(f, args...);
pool_->Schedule(func);
}
private:
ThreadPoolInterface* pool_;
size_t num_threads_;
};
} // end namespace Eigen
#endif // EIGEN_CXX11_TENSOR_TENSOR_DEVICE_THREAD_POOL_H
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