Merge pull request #3088 from NervanaSystems/bob/async

First cut at async interface for backend tensor allocation and execution

src/ngraph/runtime/executable.cpp

@@ -123,3 +123,25 @@ void runtime::Executable::save(std::ostream& output_stream)
 {
     throw runtime_error("save opertion unimplemented.");
 }
+
+shared_ptr<runtime::Tensor> runtime::Executable::create_input_tensor(size_t input_index)
+{
+    throw runtime_error("create_input_tensor unimplemented");
+}
+
+shared_ptr<runtime::Tensor> runtime::Executable::create_output_tensor(size_t output_index)
+{
+    throw runtime_error("create_output_tensor unimplemented");
+}
+
+vector<shared_ptr<runtime::Tensor>> runtime::Executable::create_input_tensor(size_t input_index,
+                                                                             size_t pipeline_depth)
+{
+    throw runtime_error("create_input_tensor unimplemented");
+}
+
+vector<shared_ptr<runtime::Tensor>> runtime::Executable::create_output_tensor(size_t output_index,
+                                                                              size_t pipeline_depth)
+{
+    throw runtime_error("create_output_tensor unimplemented");
+}

src/ngraph/runtime/executable.hpp

@@ -73,6 +73,36 @@ public:
     ///    Saved stream may be read with Backend::load
     virtual void save(std::ostream& output_stream);
 
+    /// \brief Create an input Tensor
+    /// \param input_index The index position in the input Parameter vector. This would be the same
+    /// order of Parameters passed into the inputs in the call() method.
+    /// \returns A Tensor
+    virtual std::shared_ptr<runtime::Tensor> create_input_tensor(size_t input_index);
+
+    /// \brief Create an output Tensor
+    /// \param output_index The index position in the output Result vector. This would be the same
+    /// order of Results passed into the outputs in the call() method.
+    /// \returns A Tensor
+    virtual std::shared_ptr<runtime::Tensor> create_output_tensor(size_t output_index);
+
+    /// \brief Create a vector of input Tensors
+    /// \param input_index The index position in the input Parameter vector. This would be the same
+    /// order of Parameters passed into the inputs in the call() method.
+    /// \param pipeline_depth The number of stages in the input pipeline. For double-buffered input
+    /// you would specify pipeline_depth=2
+    /// \returns A vector of Tensors, one for each stage of the pipeline
+    virtual std::vector<std::shared_ptr<runtime::Tensor>>
+        create_input_tensor(size_t input_index, size_t pipeline_depth);
+
+    /// \brief Create a vector of output Tensors
+    /// \param output_index The index position in the output Result vector. This would be the same
+    /// order of Results passed into the outputs in the call() method.
+    /// \param pipeline_depth The number of stages in the output pipeline. For double-buffered output
+    /// you would specify pipeline_depth=2
+    /// \returns A vector of Tensors, one for each stage of the pipeline
+    virtual std::vector<std::shared_ptr<runtime::Tensor>>
+        create_output_tensor(size_t output_index, size_t pipeline_depth);
+
 protected:
     /// \brief Called at the end of compile to the values to be returned by get_parameters
     ///     and get_results