From 66665e7e76d2ad5aa37775b3777e9a53c6d1c18c Mon Sep 17 00:00:00 2001
From: Eugene Zhulenev <ezhulenev@google.com>
Date: Fri, 30 Aug 2019 14:49:40 -0700
Subject: Asynchronous expression evaluation with TensorAsyncDevice

---
 unsupported/Eigen/CXX11/src/Tensor/TensorDevice.h | 41 +++++++++++++++++++++++
 1 file changed, 41 insertions(+)

(limited to 'unsupported/Eigen/CXX11/src/Tensor/TensorDevice.h')

diff --git a/unsupported/Eigen/CXX11/src/Tensor/TensorDevice.h b/unsupported/Eigen/CXX11/src/Tensor/TensorDevice.h
index 29e50a3b2..5122b3623 100644
--- a/unsupported/Eigen/CXX11/src/Tensor/TensorDevice.h
+++ b/unsupported/Eigen/CXX11/src/Tensor/TensorDevice.h
@@ -63,6 +63,47 @@ template <typename ExpressionType, typename DeviceType> class TensorDevice {
     ExpressionType& m_expression;
 };
 
+#ifdef EIGEN_USE_THREADS
+
+/** \class TensorAsyncDevice
+  * \ingroup CXX11_Tensor_Module
+  *
+  * \brief Pseudo expression providing an operator = that will evaluate its
+  * argument asynchronously on the specified device (currently supports only
+  * ThreadPoolDevice).
+  *
+  * Example:
+  *    std::function<void()> done = []() {};
+  *    C.device(EIGEN_THREAD_POOL, std::move(done)) = A + B;
+ */
+
+template <typename ExpressionType, typename DeviceType>
+class TensorAsyncDevice {
+ public:
+  TensorAsyncDevice(const DeviceType& device, ExpressionType& expression,
+                    std::function<void()> done)
+      : m_device(device), m_expression(expression), m_done(std::move(done)) {}
+
+  template <typename OtherDerived>
+  EIGEN_STRONG_INLINE TensorAsyncDevice& operator=(const OtherDerived& other) {
+    typedef TensorAssignOp<ExpressionType, const OtherDerived> Assign;
+    typedef internal::TensorAsyncExecutor<const Assign, DeviceType> Executor;
+
+    // WARNING: After assignment 'm_done' callback will be in undefined state.
+    Assign assign(m_expression, other);
+    Executor::runAsync(assign, m_device, std::move(m_done));
+
+    return *this;
+  }
+
+ protected:
+  const DeviceType& m_device;
+  ExpressionType& m_expression;
+  std::function<void()> m_done;
+};
+
+#endif  // EIGEN_USE_THREADS
+
 } // end namespace Eigen
 
 #endif // EIGEN_CXX11_TENSOR_TENSOR_DEVICE_H
-- 
cgit v1.2.3