Add Sync Machanism for Scope and VaraibleScope. Fix test_fetch_var (#37085)

paddle/fluid/framework/new_executor/new_executor_defs.h

@@ -474,13 +474,12 @@ struct VariableMetaInfo {
 // TODO(zhiqiu): Maybe we need to add rwlock for VariableScope?
 
 // NOTE(xiongkun03): Use scope as a member of VariableScope, we don't need
-// ScopeBase.
-//                   Scope manager the variables and VariableScope is just a
-//                   quick
-//                   access machanism.
-class VariableScope : public ScopeBase {
+// ScopeBase. Scope manager the variables and VariableScope is just a quick
+// access machanism. ScopeListener is the callback to sync changes in Original
+// Scope. We can make it a membership of VariableScope. Here we use inherent.
+class VariableScope : public ScopeBase, public ScopeListener {
  public:
-  VariableScope() {
+  VariableScope(Scope* outer_scope) {
     // for @EMPTY@ variable
     var_list_.push_back(nullptr);
     name2id_[kEmptyVarName] = 0;
@@ -488,9 +487,20 @@ class VariableScope : public ScopeBase {
     info.var_ref_count_ = 0;
     info.vardesc_ = nullptr;
     vec_meta_info_.push_back(info);
-    scope_ptr_.reset(new Scope());
+    outer_scope_ = outer_scope;
+
+    PADDLE_ENFORCE_NE(
+        outer_scope_, nullptr,
+        platform::errors::PreconditionNotMet(
+            "You have passed a nullptr to construct VariableScope."));
+    outer_scope->AddListener(this);
+  }
+
+  ~VariableScope() {
+    if (outer_scope_ != nullptr) outer_scope_->DelListener(this);
   }
-  const Scope* GetScope() const { return scope_ptr_.get(); }
+
+  const Scope* GetScope() const { return outer_scope_; }
 
   Variable* FindVar(const std::string& name) const {
     auto it = name2id_.find(name);
@@ -548,8 +558,9 @@ class VariableScope : public ScopeBase {
   size_t VarSize() const { return var_list_.size(); }
 
   void AddVar(const std::string& name, VarDesc* var_desc) {  // NOLINT
-    name2id_[name] = VarSize();
-    auto v = scope_ptr_->Var(name);
+    // AddVar -> Scope::Var -> onCreateVariable.
+    VLOG(4) << "Add variable: " << name << " through AddVar()";
+    auto v = outer_scope_->Var(name);
     if (nullptr == var_desc) {
       v->GetMutable<LoDTensor>();
     } else {
@@ -558,26 +569,13 @@ class VariableScope : public ScopeBase {
           var_desc
               ->GetType());  // Scope don't initialize variable recently created
     }
-    var_list_.push_back(v);
-
-    VariableMetaInfo info;
-    info.var_ref_count_ = 0;
-    info.vardesc_ = var_desc;
-    vec_meta_info_.push_back(info);
+    SetVarDesc(name, var_desc);
   }
 
   void AddVar(const std::string& name, Variable& var) {  // NOLINT
-    // must copy.
-    VLOG(4) << "Add variable: " << name << " through AddVar()";
-    auto v = scope_ptr_->Var(name);
-    *v = var;
-    name2id_[name] = VarSize();
-    var_list_.push_back(v);
-
-    VariableMetaInfo info;
-    info.var_ref_count_ = 0;
-    info.vardesc_ = nullptr;
-    vec_meta_info_.push_back(info);
+    // Though name existed in outer_scope_, we need
+    // add again to create name2id map.
+    outer_scope_->Var(name);
   }
 
   void SetVarDesc(const std::string& name, framework::VarDesc* var_desc) {
@@ -607,6 +605,32 @@ class VariableScope : public ScopeBase {
         platform::errors::NotFound("%s not in VariableScope.", name));
   }
 
+ public:  // callbacks from ScopeListener class
+  void onCreateVariable(const std::string& name) override {
+    auto v = outer_scope_->GetVar(name);  // must exsit in outer_scope_
+    if (!HasVar(name)) {                  // may exist in variable scope.
+      VLOG(4) << "Calling VariableScope::onCreateVariable with var_name: "
+              << name;
+      name2id_[name] = VarSize();
+      var_list_.push_back(v);
+
+      VariableMetaInfo info;
+      info.var_ref_count_ = 0;
+      info.vardesc_ = nullptr;  // set nullptr, then modifty it in AddVar()
+      vec_meta_info_.push_back(info);
+    }
+  }
+  void onDeleteVariable(const std::string& name) override {
+    if (HasVar(name)) {
+      VLOG(4) << "Calling VariableScope::onDeleteVariable with var_name: "
+              << name;
+    }
+  }
+  void onRenameVariable(const std::string& old_name,
+                        const std::string& new_name) override {}
+  void onCreateScope(Scope* Scope) override {}
+  void onDeleteScope(Scope* Scope) override {}
+  void onClear() override {}
   std::vector<VariableMetaInfo>& MutableVecMetaInfo() { return vec_meta_info_; }
 
   const std::vector<VariableMetaInfo>& VecMetaInfo() const {
@@ -617,7 +641,7 @@ class VariableScope : public ScopeBase {
   std::vector<Variable*> var_list_;
   std::map<std::string, int> name2id_;
   std::vector<VariableMetaInfo> vec_meta_info_;
-  std::unique_ptr<Scope> scope_ptr_;
+  Scope* outer_scope_ = nullptr;
 };
 
 class NextInstruction {

paddle/fluid/framework/new_executor/standalone_executor.cc

@@ -23,9 +23,9 @@ StandaloneExecutor::StandaloneExecutor(const platform::Place& place,
     : place_(place),
       startup_prog_(startup_prog),
       main_prog_(main_prog),
-      outer_scope_(scope) {
+      outer_scope_(scope),
+      global_scope_(scope) {
   paddle::framework::InitDevices();
-
   // init scope
   BuildVariableOuterScope(startup_prog, &global_scope_, scope);
 

paddle/fluid/framework/scope.cc

@@ -59,18 +59,35 @@ std::unique_ptr<Scope> Scope::NewTmpScope() const {
 }
 
 Variable* Scope::Var(const std::string& name) {
+  // NOTE(xiongkun03): add {} here to unlock. With {}, scope
+  // will do callback after unlock.
+  Variable* ret = nullptr;
+  {
     SCOPE_VARS_WRITER_LOCK
-  return VarInternal(name);
+    ret = VarInternal(name);
+  }
+  for (auto l : listeners_) {
+    l->onCreateVariable(name);
+  }
+  return ret;
 }
 
 Variable* Scope::Var(std::string* name) {
+  Variable* ret = nullptr;
+  std::string new_name;
+  {
     SCOPE_VARS_WRITER_LOCK
-  auto new_name = std::to_string(reinterpret_cast<uintptr_t>(this)) + "." +
+    new_name = std::to_string(reinterpret_cast<uintptr_t>(this)) + "." +
                std::to_string(vars_.size());
     if (name != nullptr) {
       *name = new_name;
     }
-  return VarInternal(new_name);
+    ret = VarInternal(new_name);
+  }
+  for (auto l : listeners_) {
+    l->onCreateVariable(new_name);
+  }
+  return ret;
 }
 
 Variable* Scope::FindVar(const std::string& name) const {
@@ -101,9 +118,14 @@ const Scope* Scope::FindScope(const std::string& name) const {
 }
 
 void Scope::DropKids() {
+  {
     SCOPE_KIDS_WRITER_LOCK
     for (Scope* s : kids_) delete s;
     kids_.clear();
+  }
+  for (auto l : listeners_) {
+    l->onClear();
+  }
 }
 
 bool Scope::HasKid(const Scope* scope) const {
@@ -125,6 +147,7 @@ std::vector<std::string> Scope::LocalVarNames() const {
 }
 
 void Scope::DeleteScope(Scope* scope) const {
+  {
     SCOPE_KIDS_WRITER_LOCK
     auto it = std::find(this->kids_.begin(), this->kids_.end(), scope);
     PADDLE_ENFORCE_NE(it, this->kids_.end(),
@@ -137,9 +160,14 @@ void Scope::DeleteScope(Scope* scope) const {
     } else {
       Async([scope] { delete scope; });
     }
+  }
+  for (auto l : listeners_) {
+    l->onDeleteScope(scope);
+  }
 }
 
 void Scope::EraseVars(const std::vector<std::string>& var_names) {
+  {
     std::set<std::string> var_set(var_names.begin(), var_names.end());
     SCOPE_VARS_WRITER_LOCK
     for (auto it = vars_.begin(); it != vars_.end();) {
@@ -149,18 +177,34 @@ void Scope::EraseVars(const std::vector<std::string>& var_names) {
         ++it;
       }
     }
+  }
+  for (auto l : listeners_) {
+    for (auto& var_name : var_names) {
+      l->onDeleteVariable(var_name);
+    }
+  }
 }
 
 void Scope::Rename(const std::string& origin_name,
                    const std::string& new_name) const {
+  {
     SCOPE_VARS_WRITER_LOCK
     RenameInternal(origin_name, new_name);
+  }
+  for (auto l : listeners_) {
+    l->onRenameVariable(origin_name, new_name);
+  }
 }
 
 std::string Scope::Rename(const std::string& origin_name) const {
-  SCOPE_VARS_WRITER_LOCK
   auto new_name = string::Sprintf("%p.%d", this, vars_.size());
+  {
+    SCOPE_VARS_WRITER_LOCK
     RenameInternal(origin_name, new_name);
+  }
+  for (auto l : listeners_) {
+    l->onRenameVariable(origin_name, new_name);
+  }
   return new_name;
 }
 
@@ -222,6 +266,17 @@ Variable* Scope::FindVarLocally(const std::string& name) const {
   return nullptr;
 }
 
+void Scope::AddListener(ScopeListener* listener) {
+  auto it = std::find(listeners_.begin(), listeners_.end(), listener);
+  if (it == listeners_.end()) {
+    listeners_.push_back(listener);
+  }
+}
+
+void Scope::DelListener(ScopeListener* listener) {
+  listeners_.remove(listener);
+}
+
 void Scope::EraseVarsExcept(const std::unordered_set<Variable*>& vars) {
   SCOPE_VARS_WRITER_LOCK
   for (auto iter = vars_.begin(); iter != vars_.end();) {

paddle/fluid/framework/scope.h

@@ -51,6 +51,22 @@ class ScopeBase {
 
 class Scope;
 
+class ScopeListener {
+  // NOTE(xiongkun03) Abstract Class, doesn't have any attributes.
+  // Used by VariableScope. If we modify the original scope, we
+  // need synchronize changes to VariableScope. So we add listerer
+  // in original Scope.
+ public:
+  virtual ~ScopeListener() {}
+  virtual void onCreateVariable(const std::string& name) {}
+  virtual void onDeleteVariable(const std::string& name) {}
+  virtual void onRenameVariable(const std::string& old_name,
+                                const std::string& new_name) {}
+  virtual void onCreateScope(Scope* Scope) {}
+  virtual void onDeleteScope(Scope* Scope) {}
+  virtual void onClear() {}
+};
+
 /**
  * @brief Scope that manage all variables.
  *
@@ -128,6 +144,10 @@ class Scope : public ScopeBase {
   // Rename variable to a new name and return the new name
   std::string Rename(const std::string& origin_name) const;
 
+  void AddListener(ScopeListener* listener);
+
+  void DelListener(ScopeListener* listener);
+
  protected:
   struct KeyHasher {
     std::size_t operator()(const std::string& key) const {
@@ -164,6 +184,7 @@ class Scope : public ScopeBase {
   // Scope in `kids_` are owned by this class.
   mutable std::list<Scope*> kids_;
   const Scope* parent_{nullptr};
+  std::list<ScopeListener*> listeners_;
 
   DISABLE_COPY_AND_ASSIGN(Scope);