[GitHub] anirudh2290 commented on a change in pull request #12157: Subgraph API for integrating accelerators with MXNet

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anirudh2290 commented on a change in pull request #12157: Subgraph API for integrating accelerators with MXNet
URL: https://github.com/apache/incubator-mxnet/pull/12157#discussion_r211504269
 
 

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 File path: src/operator/subgraph/subgraph_property.h
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+/*
+ * Licensed to the Apache Software Foundation (ASF) under one
+ * or more contributor license agreements.  See the NOTICE file
+ * distributed with this work for additional information
+ * regarding copyright ownership.  The ASF licenses this file
+ * to you under the Apache License, Version 2.0 (the
+ * "License"); you may not use this file except in compliance
+ * with the License.  You may obtain a copy of the License at
+ *
+ *   http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing,
+ * software distributed under the License is distributed on an
+ * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+ * KIND, either express or implied.  See the License for the
+ * specific language governing permissions and limitations
+ * under the License.
+ */
+
+#ifndef MXNET_OPERATOR_SUBGRAPH_SUBGRAPH_PROPERTY_H_
+#define MXNET_OPERATOR_SUBGRAPH_SUBGRAPH_PROPERTY_H_
+
+#include <nnvm/node.h>
+#include <dmlc/base.h>
+#include <dmlc/thread_local.h>
+#include <unordered_map>
+#include <vector>
+#include <string>
+
+namespace mxnet {
+namespace op {
+
+/*
+ * This provides criteria for selecting nodes in a subgraph.
+ * When a node is passed to this object, the selection criteria may be changed.
+ * We can also specify what links we should use when traversing the neighbor
+ * nodes.
+ */
+class SubgraphSelector {
+ public:
+  virtual ~SubgraphSelector() {}
+  // Determine if the node should be selected for a subgraph.
+  virtual bool Select(const nnvm::Node &n) = 0;
+  // Determine if the input node should be selected for a subgraph.
+  virtual bool SelectInput(const nnvm::Node &n, const nnvm::Node &new_node) = 0;
+  // Determine if the output node should be selected for a subgraph.
+  virtual bool SelectOutput(const nnvm::Node &n, const nnvm::Node &new_node) = 0;
+  // Post processes pre-selected subgraph nodes. Return a list of nodes that
+  // users want to keep in subgraph(s).
+  virtual std::vector<nnvm::Node*> Filter(const std::vector<nnvm::Node*>& candidates) {
+    return candidates;
+  }
+};
+
+using SubgraphSelectorPtr = std::shared_ptr<SubgraphSelector>;
+
+/*!
+ * \brief This provides a set of properties for partitioning a graph into subgraphs,
+ * reconstructing a new graph from the subgraphs and creating a subgraph
+ * operator to execute the subgraph.
+ */
+class SubgraphProperty {
+ public:
+  // the criteria of selecting the subgraph nodes.
+  virtual SubgraphSelectorPtr CreateSubgraphSelector() const = 0;
+  // create an nnvm node for a given subgraph. Here users can customize how to
+  // execute the operators in the subgraph.
+  virtual nnvm::NodePtr CreateSubgraphNode(const nnvm::Symbol &s,
+                                           const int subgraph_id = 0) const = 0;
+  // set an attr with name in the attr map
+  template<typename T>
+  SubgraphProperty& SetAttr(const std::string& name, const T& value) {
+    attrs_[name] = std::make_shared<dmlc::any>(value);
+    return *this;
+  }
+  // get the attr with the name
+  template<typename T>
+  const T& GetAttr(const std::string& name) const {
+    auto it = attrs_.find(name);
+    CHECK(it != attrs_.end()) << "Cannot find attribute " << name << " in SubgraphProperty";
+    return nnvm::get<T>(*it->second);
+  }
+ protected:
+  std::unordered_map<std::string, std::shared_ptr<nnvm::any>> attrs_;
+};
+
+using SubgraphPropertyPtr = std::shared_ptr<SubgraphProperty>;
+
+class SubgraphPropertyRegistry {
+ public:
+  typedef SubgraphPropertyPtr (*SubgraphPropertyCreateFn)(void);
+  static SubgraphPropertyRegistry* Get() {
+    static SubgraphPropertyRegistry inst;
+    return &inst;
+  }
+
+  SubgraphPropertyPtr CreateSubgraphProperty(const std::string& name) {
+    auto it = prop_fn_map_.find(name);
+    CHECK(it != prop_fn_map_.end()) << "SubgraphProperty " << name
+                                    << " is not found in SubgraphPropertyRegistry";
+    return it->second();
+  }
+
+  SubgraphPropertyCreateFn __REGISTER__(const std::string& name, SubgraphPropertyCreateFn fn) {
+    CHECK_EQ(prop_fn_map_.count(name), 0U) << "Subgraph property " << name
+                                           << " has been registered";
+    prop_fn_map_[name] = fn;
+    return prop_fn_map_[name];
+  }
+
+ private:
+  SubgraphPropertyRegistry() = default;
+  SubgraphPropertyRegistry(const SubgraphPropertyRegistry&) = delete;
+  SubgraphPropertyRegistry(SubgraphPropertyRegistry&&) = delete;
+  SubgraphPropertyRegistry& operator=(const SubgraphPropertyRegistry&) = delete;
+  std::unordered_map<std::string, SubgraphPropertyCreateFn> prop_fn_map_;
+};
+
+// This op name set is for setting the names of operators that should be grouped into
+// subgraphs. In practice, every backend accelerator should have a predefined name set.
+// This set is only used for the testing purpose.
+// key: property name, value: op name set
+typedef dmlc::ThreadLocalStore<std::unordered_map<std::string, std::unordered_set<std::string>>>
+  SubgraphPropertyOpNameSet;
+
+#define MXNET_REGISTER_SUBGRAPH_PROPERTY(Name, SubgraphPropertyType) \
+  static DMLC_ATTRIBUTE_UNUSED auto __make_ ## SubgraphPropertyType ## _ ## Name ## __ = \
+    SubgraphPropertyRegistry::Get()->__REGISTER__(#Name, &SubgraphPropertyType::Create)
 
 Review comment:
   Can we implement and call \_\_REGISTER_OR_GET\_\_ here (which checks if it is part of map else calls \_\_REGISTER\_\_). This may be needed because it is possible that \_\_REGISTER\_\_ may be called twice on the same name leading to exception.

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