[RUNTIME][REFACTOR] Use object protocol to support runtime::Module

Previously runtime::Module was supported using shared_ptr.
This PR refactors the codebase to use the Object protocol.

It will open doors to allow easier interpolation between
Object containers and module in the future.

apps/android_deploy/app/src/main/jni/tvm_runtime.h

@@ -6,9 +6,9 @@
  * 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
@@ -18,7 +18,6 @@
  */
 
 /*!
- *  Copyright (c) 2018 by Contributors
  * \file tvm_runtime.h
  * \brief Pack all tvm runtime source files
  */
@@ -35,6 +34,7 @@
 #include "../src/runtime/file_util.cc"
 #include "../src/runtime/dso_module.cc"
 #include "../src/runtime/thread_pool.cc"
+#include "../src/runtime/object.cc"
 #include "../src/runtime/threading_backend.cc"
 #include "../src/runtime/ndarray.cc"
 

apps/android_rpc/app/src/main/jni/tvm_runtime.h

@@ -6,9 +6,9 @@
  * 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
@@ -55,6 +55,7 @@
 #include "../src/runtime/threading_backend.cc"
 #include "../src/runtime/graph/graph_runtime.cc"
 #include "../src/runtime/ndarray.cc"
+#include "../src/runtime/object.cc"
 
 #ifdef TVM_OPENCL_RUNTIME
 #include "../src/runtime/opencl/opencl_device_api.cc"

apps/bundle_deploy/runtime.cc

@@ -6,9 +6,9 @@
  * 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
@@ -32,5 +32,6 @@
 #include "../../src/runtime/threading_backend.cc"
 #include "../../src/runtime/thread_pool.cc"
 #include "../../src/runtime/ndarray.cc"
+#include "../../src/runtime/object.cc"
 #include "../../src/runtime/system_lib_module.cc"
 #include "../../src/runtime/graph/graph_runtime.cc"

apps/howto_deploy/tvm_runtime_pack.cc

@@ -47,6 +47,7 @@
 #include "../../src/runtime/threading_backend.cc"
 #include "../../src/runtime/thread_pool.cc"
 #include "../../src/runtime/ndarray.cc"
+#include "../../src/runtime/object.cc"
 
 // NOTE: all the files after this are optional modules
 // that you can include remove, depending on how much feature you use.

apps/ios_rpc/tvmrpc/TVMRuntime.mm

@@ -18,7 +18,6 @@
  */
 
 /*!
- *  Copyright (c) 2017 by Contributors
  * \file TVMRuntime.mm
  */
 #include "TVMRuntime.h"
@@ -35,6 +34,8 @@
 #include "../../../src/runtime/file_util.cc"
 #include "../../../src/runtime/dso_module.cc"
 #include "../../../src/runtime/ndarray.cc"
+#include "../../../src/runtime/object.cc"
+
 // RPC server
 #include "../../../src/runtime/rpc/rpc_session.cc"
 #include "../../../src/runtime/rpc/rpc_server_env.cc"

golang/src/tvm_runtime_pack.cc

@@ -18,7 +18,6 @@
  */
 
 /*!
- *  Copyright (c) 2018 by Contributors
  * \brief This is an all in one TVM runtime file.
  * \file tvm_runtime_pack.cc
  */
@@ -32,6 +31,7 @@
 #include "src/runtime/threading_backend.cc"
 #include "src/runtime/thread_pool.cc"
 #include "src/runtime/ndarray.cc"
+#include "src/runtime/object.cc"
 
 // NOTE: all the files after this are optional modules
 // that you can include remove, depending on how much feature you use.

include/tvm/runtime/module.h

@@ -27,28 +27,31 @@
 #define TVM_RUNTIME_MODULE_H_
 
 #include <dmlc/io.h>
+
+#include <tvm/runtime/c_runtime_api.h>
+#include <tvm/runtime/object.h>
+#include <tvm/runtime/memory.h>
+
 #include <memory>
 #include <vector>
 #include <string>
 #include <unordered_map>
-#include "c_runtime_api.h"
 
 namespace tvm {
 namespace runtime {
 
-// The internal container of module.
 class ModuleNode;
 class PackedFunc;
 
 /*!
  * \brief Module container of TVM.
  */
-class Module {
+class Module : public ObjectRef {
  public:
   Module() {}
   // constructor from container.
-  explicit Module(std::shared_ptr<ModuleNode> n)
-      : node_(n) {}
+  explicit Module(ObjectPtr<Object> n)
+      : ObjectRef(n) {}
   /*!
    * \brief Get packed function from current module by name.
    *
@@ -59,10 +62,6 @@ class Module {
    * \note Implemented in packed_func.cc
    */
   inline PackedFunc GetFunction(const std::string& name, bool query_imports = false);
-  /*! \return internal container */
-  inline ModuleNode* operator->();
-  /*! \return internal container */
-  inline const ModuleNode* operator->() const;
   // The following functions requires link with runtime.
   /*!
    * \brief Import another module into this module.
@@ -71,7 +70,11 @@ class Module {
    * \note Cyclic dependency is not allowed among modules,
    *  An error will be thrown when cyclic dependency is detected.
    */
-  TVM_DLL void Import(Module other);
+  inline void Import(Module other);
+  /*! \return internal container */
+  inline ModuleNode* operator->();
+  /*! \return internal container */
+  inline const ModuleNode* operator->() const;
   /*!
    * \brief Load a module from file.
    * \param file_name The name of the host function module.
@@ -81,20 +84,41 @@ class Module {
    */
   TVM_DLL static Module LoadFromFile(const std::string& file_name,
                                      const std::string& format = "");
-
- private:
-  std::shared_ptr<ModuleNode> node_;
+  // refer to the corresponding container.
+  using ContainerType = ModuleNode;
+  friend class ModuleNode;
 };
 
 /*!
- * \brief Base node container of module.
- *  Do not create this directly, instead use Module.
+ * \brief Base container of module.
+ *
+ * Please subclass ModuleNode to create a specific runtime module.
+ *
+ * \code
+ *
+ *  class MyModuleNode : public ModuleNode {
+ *   public:
+ *    // implement the interface
+ *  };
+ *
+ *  // use make_object to create a specific
+ *  // instace of MyModuleNode.
+ *  Module CreateMyModule() {
+ *    ObjectPtr<MyModuleNode> n =
+ *      tvm::runtime::make_object<MyModuleNode>();
+ *    return Module(n);
+ *  }
+ *
+ * \endcode
  */
-class ModuleNode {
+class ModuleNode : public Object {
  public:
   /*! \brief virtual destructor */
   virtual ~ModuleNode() {}
-  /*! \return The module type key */
+  /*!
+   * \return The per module type key.
+   * \note This key is used to for serializing custom modules.
+   */
   virtual const char* type_key() const = 0;
   /*!
    * \brief Get a PackedFunc from module.
@@ -105,7 +129,7 @@ class ModuleNode {
    *  For benchmarking, use prepare to eliminate
    *
    * \param name the name of the function.
-   * \param sptr_to_self The shared_ptr that points to this module node.
+   * \param sptr_to_self The ObjectPtr that points to this module node.
    *
    * \return PackedFunc(nullptr) when it is not available.
    *
@@ -115,7 +139,7 @@ class ModuleNode {
    */
   virtual PackedFunc GetFunction(
       const std::string& name,
-      const std::shared_ptr<ModuleNode>& sptr_to_self) = 0;
+      const ObjectPtr<Object>& sptr_to_self) = 0;
   /*!
    * \brief Save the module to file.
    * \param file_name The file to be saved to.
@@ -137,6 +161,24 @@ class ModuleNode {
    * \return Possible source code when available.
    */
   TVM_DLL virtual std::string GetSource(const std::string& format = "");
+  /*!
+   * \brief Get packed function from current module by name.
+   *
+   * \param name The name of the function.
+   * \param query_imports Whether also query dependency modules.
+   * \return The result function.
+   *  This function will return PackedFunc(nullptr) if function do not exist.
+   * \note Implemented in packed_func.cc
+   */
+  TVM_DLL PackedFunc GetFunction(const std::string& name, bool query_imports = false);
+  /*!
+   * \brief Import another module into this module.
+   * \param other The module to be imported.
+   *
+   * \note Cyclic dependency is not allowed among modules,
+   *  An error will be thrown when cyclic dependency is detected.
+   */
+  TVM_DLL void Import(Module other);
   /*!
    * \brief Get a function from current environment
    *  The environment includes all the imports as well as Global functions.
@@ -150,6 +192,13 @@ class ModuleNode {
     return imports_;
   }
 
+  // integration with the existing components.
+  static constexpr const uint32_t _type_index = TypeIndex::kRuntimeModule;
+  static constexpr const char* _type_key = "runtime.Module";
+  // NOTE: ModuleNode can still be sub-classed
+  //
+  TVM_DECLARE_FINAL_OBJECT_INFO(ModuleNode, Object);
+
  protected:
   friend class Module;
   /*! \brief The modules this module depend on */
@@ -180,16 +229,21 @@ constexpr const char* tvm_module_main = "__tvm_main__";
 }  // namespace symbol
 
 // implementations of inline functions.
+
+inline void Module::Import(Module other) {
+  return (*this)->Import(other);
+}
+
 inline ModuleNode* Module::operator->() {
-  return node_.get();
+  return static_cast<ModuleNode*>(get_mutable());
 }
 
 inline const ModuleNode* Module::operator->() const {
-  return node_.get();
+  return static_cast<const ModuleNode*>(get());
 }
 
 }  // namespace runtime
 }  // namespace tvm
 
-#include "packed_func.h"
+#include <tvm/runtime/packed_func.h>  // NOLINT(*)
 #endif  // TVM_RUNTIME_MODULE_H_

include/tvm/runtime/object.h

@@ -53,6 +53,7 @@ enum TypeIndex  {
   kVMTensor = 1,
   kVMClosure = 2,
   kVMADT = 3,
+  kRuntimeModule = 4,
   kStaticIndexEnd,
   /*! \brief Type index is allocated during runtime. */
   kDynamic = kStaticIndexEnd
@@ -302,19 +303,19 @@ class Object {
   template<typename>
   friend class ObjectPtr;
   friend class TVMRetValue;
-  friend class TVMObjectCAPI;
+  friend class FFIUtil;
 };
 
 /*!
  * \brief Get a reference type from a raw object ptr type
  *
  *  It is always important to get a reference type
  *  if we want to return a value as reference or keep
- *  the node alive beyond the scope of the function.
+ *  the object alive beyond the scope of the function.
  *
- * \param ptr The node pointer
+ * \param ptr The object pointer
  * \tparam RefType The reference type
- * \tparam ObjectType The node type
+ * \tparam ObjectType The object type
  * \return The corresponding RefType
  */
 template <typename RefType, typename ObjectType>
@@ -486,6 +487,8 @@ class ObjectPtr {
   friend class TVMArgValue;
   template <typename RefType, typename ObjType>
   friend RefType GetRef(const ObjType* ptr);
+  template <typename BaseType, typename ObjType>
+  friend ObjectPtr<BaseType> GetObjectPtr(ObjType* ptr);
 };
 
 /*! \brief Base class of all object reference */
@@ -513,7 +516,7 @@ class ObjectRef {
   }
   /*!
    * \brief Comparator
-   * \param other Another node ref.
+   * \param other Another object ref.
    * \return the compare result.
    */
   bool operator!=(const ObjectRef& other) const {
@@ -535,7 +538,7 @@ class ObjectRef {
   const Object* get() const {
     return data_.get();
   }
-  /*! \return the internal node pointer */
+  /*! \return the internal object pointer */
   const Object* operator->() const {
     return get();
   }
@@ -595,6 +598,16 @@ class ObjectRef {
   friend SubRef Downcast(BaseRef ref);
 };
 
+/*!
+ * \brief Get an object ptr type from a raw object ptr.
+ *
+ * \param ptr The object pointer
+ * \tparam BaseType The reference type
+ * \tparam ObjectType The object type
+ * \return The corresponding RefType
+ */
+template <typename BaseType, typename ObjectType>
+inline ObjectPtr<BaseType> GetObjectPtr(ObjectType* ptr);
 
 /*! \brief ObjectRef hash functor */
 struct ObjectHash {
@@ -781,6 +794,13 @@ inline RefType GetRef(const ObjType* ptr) {
   return RefType(ObjectPtr<Object>(const_cast<Object*>(static_cast<const Object*>(ptr))));
 }
 
+template <typename BaseType, typename ObjType>
+inline ObjectPtr<BaseType> GetObjectPtr(ObjType* ptr) {
+  static_assert(std::is_base_of<BaseType, ObjType>::value,
+                "Can only cast to the ref of same container type");
+  return ObjectPtr<BaseType>(static_cast<Object*>(ptr));
+}
+
 template <typename SubRef, typename BaseRef>
 inline SubRef Downcast(BaseRef ref) {
   CHECK(ref->template IsInstance<typename SubRef::ContainerType>())