From ef586c6fca20756d41962dac1bc0821e4431ad5f Mon Sep 17 00:00:00 2001
From: dzhwinter <dzhwinter@gmail.com>
Date: Tue, 24 Apr 2018 01:49:42 -0700
Subject: [PATCH 1/7] move from varhandle to variable header

---
 paddle/fluid/framework/CMakeLists.txt       |  2 +-
 paddle/fluid/framework/details/var_handle.h |  1 +
 paddle/fluid/framework/details/var_id.h     | 15 ++++++++
 paddle/fluid/framework/scope.cc             |  9 +++--
 paddle/fluid/framework/scope.h              | 20 +++++++---
 paddle/fluid/framework/type_defs.h          |  6 ++-
 paddle/fluid/framework/variable.h           | 41 +++++++++++++++++++++
 paddle/fluid/framework/variable_test.cc     | 19 +++++++++-
 paddle/fluid/platform/profiler.cc           |  9 +++++
 paddle/fluid/platform/profiler.h            |  2 +
 10 files changed, 111 insertions(+), 13 deletions(-)
 create mode 100644 paddle/fluid/framework/details/var_id.h

diff --git a/paddle/fluid/framework/CMakeLists.txt b/paddle/fluid/framework/CMakeLists.txt
index 340b891e41671d..bbcb1102ed0e2e 100644
--- a/paddle/fluid/framework/CMakeLists.txt
+++ b/paddle/fluid/framework/CMakeLists.txt
@@ -33,7 +33,7 @@ cc_test(variable_test SRCS variable_test.cc)
 cc_library(threadpool SRCS threadpool.cc DEPS enforce)
 cc_test(threadpool_test SRCS threadpool_test.cc DEPS threadpool)
 
-cc_library(scope SRCS scope.cc DEPS glog threadpool)
+cc_library(scope SRCS scope.cc DEPS glog threadpool profiler)
 cc_test(scope_test SRCS scope_test.cc DEPS scope)
 
 cc_library(data_device_transform SRCS data_device_transform.cc DEPS tensor)
diff --git a/paddle/fluid/framework/details/var_handle.h b/paddle/fluid/framework/details/var_handle.h
index 2b887c67e6fc6e..5feb3f15bc3858 100644
--- a/paddle/fluid/framework/details/var_handle.h
+++ b/paddle/fluid/framework/details/var_handle.h
@@ -68,6 +68,7 @@ struct DummyVarHandle : public VarHandleBase {
   std::string DebugString() const override;
 };
 
+
 }  // namespace details
 }  // namespace framework
 }  // namespace paddle
diff --git a/paddle/fluid/framework/details/var_id.h b/paddle/fluid/framework/details/var_id.h
new file mode 100644
index 00000000000000..d69ad91ebb460c
--- /dev/null
+++ b/paddle/fluid/framework/details/var_id.h
@@ -0,0 +1,15 @@
+#pragma once
+#include <string>
+
+namespace paddle {
+namespace framework {
+struct VarId {
+  explicit VarId(const std::string& name) : name(name), unique_id(-1) {}
+  VarId(const std::string& name, int id) : name(name), unique_id(id) {}
+  std::string name;
+  /*default -1 if uninitialized*/
+  int unique_id;
+};
+
+}  // namespace framework
+}  // namespace paddle
diff --git a/paddle/fluid/framework/scope.cc b/paddle/fluid/framework/scope.cc
index 194df3e4a8b507..5cd46846bee0df 100644
--- a/paddle/fluid/framework/scope.cc
+++ b/paddle/fluid/framework/scope.cc
@@ -18,6 +18,7 @@ limitations under the License. */
 #include <set>
 #include "glog/logging.h"
 #include "paddle/fluid/framework/threadpool.h"
+#include "paddle/fluid/platform/profiler.h"
 #include "paddle/fluid/string/printf.h"
 
 DEFINE_bool(benchmark, false,
@@ -43,7 +44,7 @@ Scope& Scope::NewScope() const {
   return *kids_.back();
 }
 
-Variable* Scope::Var(const std::string& name) {
+Variable* Scope::Var(const VarUUID& name) {
   auto* v = FindVarLocally(name);
   if (v != nullptr) return v;
   v = new Variable();
@@ -53,7 +54,7 @@ Variable* Scope::Var(const std::string& name) {
   return v;
 }
 
-Variable* Scope::Var(std::string* name) {
+Variable* Scope::Var(VarUUID* name) {
   auto var_name = string::Sprintf("%p.%d", this, vars_.size());
   if (name != nullptr) {
     *name = var_name;
@@ -61,7 +62,8 @@ Variable* Scope::Var(std::string* name) {
   return Var(var_name);
 }
 
-Variable* Scope::FindVar(const std::string& name) const {
+Variable* Scope::FindVar(const VarUUID& name) const {
+  platform::RecordEvent event("Scope");
   auto var = FindVarLocally(name);
   if (var != nullptr) {
     return var;
@@ -135,6 +137,7 @@ std::string Scope::Rename(const std::string& origin_name) const {
 }
 
 Variable* Scope::FindVarLocally(const std::string& name) const {
+  platform::RecordEvent event("Scope");
   auto it = vars_.find(name);
   if (it != vars_.end()) return it->second;
   return nullptr;
diff --git a/paddle/fluid/framework/scope.h b/paddle/fluid/framework/scope.h
index c8cb70549f1d13..f1bb0e5224af6a 100644
--- a/paddle/fluid/framework/scope.h
+++ b/paddle/fluid/framework/scope.h
@@ -47,16 +47,17 @@ class Scope {
   Scope& NewScope() const;
 
   /// Create a variable with given name if it doesn't exist.
-  Variable* Var(const std::string& name);
+  Variable* Var(const VarUUID& id);
 
   /// Create a variable with a scope-unique name.
-  Variable* Var(std::string* name = nullptr);
+  Variable* Var(VarUUID* id = nullptr);
 
-  void EraseVars(const std::vector<std::string>& var_names);
+  /// EraseVars in scope.
+  void EraseVars(const std::vector<VarUUID>& var_names);
 
   /// Find a variable in the scope or any of its ancestors.  Returns
   /// nullptr if cannot find.
-  Variable* FindVar(const std::string& name) const;
+  Variable* FindVar(const VarUUID& name) const;
 
   const Scope* parent() const { return parent_; }
 
@@ -78,13 +79,20 @@ class Scope {
   // Rename variable to a new name and return the new name
   std::string Rename(const std::string& origin_name) const;
 
-  Variable* FindVarLocally(const std::string& name) const;
+  Variable* FindVarLocally(const VarUUID& id) const;
 
  private:
   // Call Scope::NewScope for a sub-scope.
   explicit Scope(Scope const* parent) : parent_(parent) {}
 
-  mutable std::unordered_map<std::string, Variable*> vars_;
+  // mutable std::unordered_map<std::string, Variable*> vars_;
+  struct Hasher {
+    size_t operator() (const VarUUID& id) const {
+      return id.unique_id;
+    }
+  };
+  mutable std::unordered_map<VarUUID, Variable*, Hasher> vars_;
+
   mutable std::list<Scope*> kids_;
   Scope const* parent_{nullptr};
 
diff --git a/paddle/fluid/framework/type_defs.h b/paddle/fluid/framework/type_defs.h
index 4879209ece9fdf..b9e91736f8ce55 100644
--- a/paddle/fluid/framework/type_defs.h
+++ b/paddle/fluid/framework/type_defs.h
@@ -21,6 +21,7 @@ limitations under the License. */
 #include <unordered_set>
 #include <vector>
 #include "paddle/fluid/platform/variant.h"
+#include "paddle/fluid/framework/details/var_handle.h"
 
 namespace paddle {
 namespace framework {
@@ -29,7 +30,10 @@ class OpDesc;
 class InferShapeContext;
 class BlockDesc;
 
-using VariableNameMap = std::map<std::string, std::vector<std::string>>;
+using details::VarUUID;
+class VarUUID;
+// using VariableNameMap = std::map<std::string, std::vector<std::string>>;
+using VariableNameMap = std::map<std::string, std::vector<VarUUID>>;
 
 // The order should be as same as framework.proto
 using Attribute =
diff --git a/paddle/fluid/framework/variable.h b/paddle/fluid/framework/variable.h
index 87ddfe2ff9abfa..435ee417b317cf 100644
--- a/paddle/fluid/framework/variable.h
+++ b/paddle/fluid/framework/variable.h
@@ -16,12 +16,15 @@
 #include <memory>
 #include <typeindex>
 #include <typeinfo>
+#include <thread> // for call_once
+
 
 #include "paddle/fluid/platform/enforce.h"
 
 namespace paddle {
 namespace framework {
 
+
 class Variable {
  public:
   template <typename T>
@@ -91,5 +94,43 @@ class Variable {
   const std::string* name_;
 };
 
+/// variable unique_id generator, threadsafe singleton.
+class UUIDGenerator {
+public:
+  int operator()() {return engine();}
+  UUIDGenerator& Instance() {
+    std::call_once(once_flag, &UUIDGenerator::InitOnce);
+    return *g;
+  }
+private:
+  static void InitOnce() {g = new UUIDGenerator();}
+  UUIDGenerator() {
+    engine.seed(std::random_device()());
+  }
+  std::minstd_rand engine;
+  static UUIDGenerator *g;
+  static std::once_flag once_flag;
+};
+
+UUIDGenerator::UUIDGenerator* g = nullptr;
+std::once_flag UUIDGenerator::once_flag;
+
+// a runtime unique variable identity.
+struct VarUUID : public VarHandleBase {
+  explicit VarUUID(const std::string& name) : name(name), unique_id(-1) {}
+  VarUUID(const std::string& name, int id) : name(name), unique_id(id) {}
+  std::string DebugString() const override;
+  std::string name;
+  int unique_id; /*default -1 if uninitialized*/
+};
+
+inline std::ostream& operator<<(std::ostream& os, const VarUUID& var) {
+  os << var.name;
+  if (VLOG_IS_ON(5)) {
+    os << "[" << var.unique_id << "]";
+  }
+  return os;
+}
+
 }  // namespace framework
 }  // namespace paddle
diff --git a/paddle/fluid/framework/variable_test.cc b/paddle/fluid/framework/variable_test.cc
index c5c1d215f4a6af..ac1062e87a20bb 100644
--- a/paddle/fluid/framework/variable_test.cc
+++ b/paddle/fluid/framework/variable_test.cc
@@ -12,15 +12,17 @@
 // See the License for the specific language governing permissions and
 // limitations under the License.
 
+#include <vector>
 #include <memory>
 #include <string>
+#include <iostream>
 
 #include "gtest/gtest.h"
 #include "paddle/fluid/framework/variable.h"
 
-TEST(Variable, GetMutable) {
-  using paddle::framework::Variable;
+using paddle::framework::Variable;
 
+TEST(Variable, GetMutable) {
   struct Tensor {
     int content_;
   };
@@ -39,3 +41,16 @@ TEST(Variable, GetMutable) {
   const std::string& ss = v->Get<std::string>();
   EXPECT_EQ("hello", ss);
 }
+
+TEST(UUIDGenerator, Generate) {
+  constexpr int count = 10;
+  std::vector<int> ids;
+  UUIDGenerator gen = UUIDGenerator::Instance();
+  for (int i=0; i < count; ++i) {
+    ids.push_back(gen());
+  }
+  for(auto& id : ids) {
+    std::cout << id << " ";
+  }
+  std::cout << endl;
+}
diff --git a/paddle/fluid/platform/profiler.cc b/paddle/fluid/platform/profiler.cc
index 412cdda286c3a7..5878534c4d136e 100644
--- a/paddle/fluid/platform/profiler.cc
+++ b/paddle/fluid/platform/profiler.cc
@@ -176,6 +176,15 @@ RecordEvent::RecordEvent(const std::string& name, const DeviceContext* dev_ctx)
   SetCurAnnotation(name_);
 }
 
+RecordEvent::RecordEvent(const std::string& name) : start_ns_(PosixInNsec()) {
+  if (g_state == ProfilerState::kDisabled) return;
+  platform::CPUPlace place;
+  dev_ctx_ = DeviceContextPool::Instance().Get(place);
+  name_ = name;
+  PushEvent(name_, dev_ctx_);
+  SetCurAnnotation(name_);
+}
+
 RecordEvent::~RecordEvent() {
   if (g_state == ProfilerState::kDisabled) return;
   DeviceTracer* tracer = GetDeviceTracer();
diff --git a/paddle/fluid/platform/profiler.h b/paddle/fluid/platform/profiler.h
index b07427c8f6903e..37f80edc4631df 100644
--- a/paddle/fluid/platform/profiler.h
+++ b/paddle/fluid/platform/profiler.h
@@ -71,6 +71,8 @@ void PushEvent(const std::string& name, const DeviceContext* dev_ctx);
 void PopEvent(const std::string& name, const DeviceContext* dev_ctx);
 
 struct RecordEvent {
+  explicit RecordEvent(const std::string& name);
+
   RecordEvent(const std::string& name, const DeviceContext* dev_ctx);
 
   ~RecordEvent();

From 97b766c62135c4c6761519371990e16c5c84fc58 Mon Sep 17 00:00:00 2001
From: dzhwinter <dzhwinter@gmail.com>
Date: Tue, 24 Apr 2018 22:04:53 -0700
Subject: [PATCH 2/7] "add operator fix"

---
 .pre-commit-config.yaml                      |  8 ++---
 paddle/fluid/framework/details/var_handle.cc |  6 ++++
 paddle/fluid/framework/details/var_handle.h  | 29 ++++++++++++++++
 paddle/fluid/framework/operator.cc           | 16 ++++-----
 paddle/fluid/framework/operator.h            | 36 ++++++++++----------
 paddle/fluid/framework/scope.cc              | 26 +++++++-------
 paddle/fluid/framework/scope.h               |  7 +---
 paddle/fluid/framework/type_defs.h           |  2 --
 paddle/fluid/framework/variable.h            | 33 +++++-------------
 9 files changed, 89 insertions(+), 74 deletions(-)

diff --git a/.pre-commit-config.yaml b/.pre-commit-config.yaml
index 6140340890c0e5..9acb0515e868e7 100644
--- a/.pre-commit-config.yaml
+++ b/.pre-commit-config.yaml
@@ -1,16 +1,16 @@
 repos:
 -   repo: https://github.com/Lucas-C/pre-commit-hooks.git
-    sha: v1.0.1
+    rev: v1.1.5
     hooks:
     -   id: remove-crlf
         files: (?!.*third_party)^.*$ | (?!.*book)^.*$
 -   repo: https://github.com/PaddlePaddle/mirrors-yapf.git
-    sha: 0d79c0c469bab64f7229c9aca2b1186ef47f0e37
+    rev: v0.16.2
     hooks:
     -   id: yapf
         files: (.*\.(py|bzl)|BUILD|.*\.BUILD|WORKSPACE)$
 -   repo: https://github.com/pre-commit/pre-commit-hooks
-    sha: 5bf6c09bfa1297d3692cadd621ef95f1284e33c0
+    rev: v1.2.3
     hooks:
     -   id: check-added-large-files
     -   id: check-merge-conflict
@@ -35,7 +35,7 @@ repos:
         language: system
         files: \.(c|cc|cxx|cpp|cu|h|hpp|hxx)$
 -   repo: https://github.com/PaddlePaddle/pre-commit-golang
-    sha: 8337620115c25ff8333f1b1a493bd031049bd7c0
+    rev: v0.2
     hooks:
     -   id: go-fmt
         types:
diff --git a/paddle/fluid/framework/details/var_handle.cc b/paddle/fluid/framework/details/var_handle.cc
index 6f00abd9473a84..6e267cc4eb0d5f 100644
--- a/paddle/fluid/framework/details/var_handle.cc
+++ b/paddle/fluid/framework/details/var_handle.cc
@@ -13,6 +13,7 @@
 // limitations under the License.
 
 #include "paddle/fluid/framework/details/var_handle.h"
+#include "paddle/fluid/framework/variable.h"
 
 namespace paddle {
 namespace framework {
@@ -27,6 +28,11 @@ std::string VarHandle::DebugString() const {
 }
 
 std::string DummyVarHandle::DebugString() const { return "dummy"; }
+
+VarUUID::VarUUID(const std::strign& name) : name(name) {
+  unique_id = UUIDGenerator::Instance()(name);
+}
+
 }  // namespace details
 }  // namespace framework
 }  // namespace paddle
diff --git a/paddle/fluid/framework/details/var_handle.h b/paddle/fluid/framework/details/var_handle.h
index 5feb3f15bc3858..cedce45c834335 100644
--- a/paddle/fluid/framework/details/var_handle.h
+++ b/paddle/fluid/framework/details/var_handle.h
@@ -17,6 +17,7 @@
 #include <string>
 #include <unordered_set>
 #include <utility>
+#include <unordered_map>
 
 #include "paddle/fluid/platform/place.h"
 
@@ -68,6 +69,34 @@ struct DummyVarHandle : public VarHandleBase {
   std::string DebugString() const override;
 };
 
+// a runtime unique variable identity.
+struct VarUUID {
+  explicit VarUUID(const std::string& name);
+  VarUUID(const std::string& name, int id) : name(name), unique_id(id) {}
+  bool operator==(const VarUUID& rhs) const {
+    return unique_id == rhs.unique_id;
+  }
+  bool operator!=(const VarUUID& rhs) const {
+    return unique_id != rhs.unique_id;
+  }
+  std::string name;
+  int unique_id; /*default -1 if uninitialized*/
+};
+
+struct VarUUIDHash {
+  size_t operator() (const VarUUID& id) const {
+    return id.unique_id;
+  }
+};
+
+inline std::ostream& operator<<(std::ostream& os, const VarUUID& var) {
+  os << var.name;
+  if (VLOG_IS_ON(5)) {
+    os << "[" << var.unique_id << "]";
+  }
+  return os;
+}
+
 
 }  // namespace details
 }  // namespace framework
diff --git a/paddle/fluid/framework/operator.cc b/paddle/fluid/framework/operator.cc
index f97bd0827428fe..c513d72d0696b9 100644
--- a/paddle/fluid/framework/operator.cc
+++ b/paddle/fluid/framework/operator.cc
@@ -93,7 +93,7 @@ void OperatorBase::Run(const Scope& scope, const platform::Place& place) {
   RunImpl(scope, place);
 }
 
-std::string OperatorBase::Input(const std::string& name) const {
+VarUUID OperatorBase::Input(const std::string& name) const {
   auto& ins = Inputs(name);
   PADDLE_ENFORCE_LE(ins.size(), 1UL,
                     "Operator %s's input %s should contain only one variable.",
@@ -101,7 +101,7 @@ std::string OperatorBase::Input(const std::string& name) const {
   return ins.empty() ? kEmptyVarName : ins[0];
 }
 
-const std::vector<std::string>& OperatorBase::Inputs(
+const std::vector<VarUUID>& OperatorBase::Inputs(
     const std::string& name) const {
   auto it = inputs_.find(name);
   PADDLE_ENFORCE(it != inputs_.end(), "Operator %s does not have the input %s.",
@@ -109,7 +109,7 @@ const std::vector<std::string>& OperatorBase::Inputs(
   return it->second;
 }
 
-std::string OperatorBase::Output(const std::string& name) const {
+VarUUID OperatorBase::Output(const std::string& name) const {
   auto& outs = Outputs(name);
   PADDLE_ENFORCE_LE(outs.size(), 1UL,
                     "Operator %s's output %s should contain only one variable.",
@@ -117,7 +117,7 @@ std::string OperatorBase::Output(const std::string& name) const {
   return outs.empty() ? kEmptyVarName : outs[0];
 }
 
-const std::vector<std::string>& OperatorBase::Outputs(
+const std::vector<VarUUID>& OperatorBase::Outputs(
     const std::string& name) const {
   auto it = outputs_.find(name);
   PADDLE_ENFORCE(it != outputs_.end(),
@@ -191,8 +191,8 @@ OperatorBase::OperatorBase(const std::string& type,
   CheckAllInputOutputSet();
 }
 
-std::vector<std::string> OperatorBase::InputVars() const {
-  std::vector<std::string> ret_val;
+std::vector<VarUUID> OperatorBase::InputVars() const {
+  std::vector<VarUUID> ret_val;
   for (auto& o : inputs_) {
     ret_val.reserve(ret_val.size() + o.second.size());
     ret_val.insert(ret_val.end(), o.second.begin(), o.second.end());
@@ -200,8 +200,8 @@ std::vector<std::string> OperatorBase::InputVars() const {
   return ret_val;
 }
 
-std::vector<std::string> OperatorBase::OutputVars(bool has_intermediate) const {
-  std::vector<std::string> ret_val;
+std::vector<VarUUID> OperatorBase::OutputVars(bool has_intermediate) const {
+  std::vector<VarUUID> ret_val;
   if (has_intermediate) {
     // push all outputs into ret_val
     for (auto& o : outputs_) {
diff --git a/paddle/fluid/framework/operator.h b/paddle/fluid/framework/operator.h
index b7a7c69b4c8493..5d0f2d85e3ac0f 100644
--- a/paddle/fluid/framework/operator.h
+++ b/paddle/fluid/framework/operator.h
@@ -109,19 +109,19 @@ class OperatorBase {
   const VariableNameMap& Outputs() const { return outputs_; }
 
   //! Get a input with argument's name described in `op_proto`
-  std::string Input(const std::string& name) const;
+  VarUUID Input(const std::string& name) const;
   //! Get a input which has multiple variables.
-  const std::vector<std::string>& Inputs(const std::string& name) const;
+  const std::vector<VarUUID>& Inputs(const std::string& name) const;
 
-  std::vector<std::string> InputVars() const;
+  std::vector<VarUUID> InputVars() const;
 
   //! Get a output with argument's name described in `op_proto`
-  std::string Output(const std::string& name) const;
+  VarUUID Output(const std::string& name) const;
   //! Get an output which has multiple variables.
   //! TODO add a vector_view to prevent memory copy.
-  const std::vector<std::string>& Outputs(const std::string& name) const;
+  const std::vector<VarUUID>& Outputs(const std::string& name) const;
 
-  virtual std::vector<std::string> OutputVars(bool has_intermediate) const;
+  virtual std::vector<VarUUID> OutputVars(bool has_intermediate) const;
 
   const std::string& Type() const { return type_; }
   void SetType(const std::string& type) { type_ = type; }
@@ -207,12 +207,12 @@ class ExecutionContext {
 
   const Variable* InputVar(const std::string& name) const {
     auto ipt = op_.Input(name);
-    return ipt == kEmptyVarName ? nullptr : scope_.FindVar(ipt);
+    return ipt == VarUUID(kEmptyVarName) ? nullptr : scope_.FindVar(ipt);
   }
 
   Variable* OutputVar(const std::string& name) const {
     auto opt = op_.Output(name);
-    return opt == kEmptyVarName ? nullptr : scope_.FindVar(opt);
+    return opt == VarUUID(kEmptyVarName) ? nullptr : scope_.FindVar(opt);
   }
 
   const std::vector<const Variable*> MultiInputVar(
@@ -221,9 +221,9 @@ class ExecutionContext {
     std::vector<const Variable*> res;
     res.reserve(names.size());
     std::transform(names.begin(), names.end(), std::back_inserter(res),
-                   [this](const std::string& name) {
-                     return name == kEmptyVarName ? nullptr
-                                                  : scope_.FindVar(name);
+                   [this](const VarUUID& name) {
+                     return name == VarUUID(kEmptyVarName) ? nullptr
+                       : scope_.FindVar(name);
                    });
     return res;
   }
@@ -233,9 +233,9 @@ class ExecutionContext {
     std::vector<Variable*> res;
     res.reserve(names.size());
     std::transform(names.begin(), names.end(), std::back_inserter(res),
-                   [this](const std::string& name) {
-                     return name == kEmptyVarName ? nullptr
-                                                  : scope_.FindVar(name);
+                   [this](const VarUUID& name) {
+                     return name == VarUUID(kEmptyVarName) ? nullptr
+                       : scope_.FindVar(name);
                    });
     return res;
   }
@@ -258,7 +258,7 @@ class ExecutionContext {
     std::vector<const T*> res;
     res.reserve(names.size());
     std::transform(names.begin(), names.end(), std::back_inserter(res),
-                   [&](const std::string& sub_name) {
+                   [&](const VarUUID& sub_name) {
                      auto var = scope_.FindVar(sub_name);
                      return var == nullptr ? nullptr : &var->Get<T>();
                    });
@@ -271,7 +271,7 @@ class ExecutionContext {
     std::vector<T*> res;
     res.reserve(names.size());
     std::transform(names.begin(), names.end(), std::back_inserter(res),
-                   [&](const std::string& sub_name) {
+                   [&](const VarUUID& sub_name) {
                      auto var = scope_.FindVar(sub_name);
                      return var == nullptr ? nullptr : var->GetMutable<T>();
                    });
@@ -312,12 +312,12 @@ class ExecutionContext {
 #endif
 
   //! Get actual name vector for this input.
-  const std::vector<std::string>& Inputs(const std::string& name) const {
+  const std::vector<VarUUID>& Inputs(const std::string& name) const {
     return op_.Inputs(name);
   }
 
   //! Get actual name vector for this output.
-  const std::vector<std::string>& Outputs(const std::string& name) const {
+  const std::vector<VarUUID>& Outputs(const std::string& name) const {
     return op_.Outputs(name);
   }
 
diff --git a/paddle/fluid/framework/scope.cc b/paddle/fluid/framework/scope.cc
index 5cd46846bee0df..514aa0582ab61f 100644
--- a/paddle/fluid/framework/scope.cc
+++ b/paddle/fluid/framework/scope.cc
@@ -15,7 +15,7 @@ limitations under the License. */
 #include "paddle/fluid/framework/scope.h"
 
 #include <memory>  // for unique_ptr
-#include <set>
+#include <unordered_set>
 #include "glog/logging.h"
 #include "paddle/fluid/framework/threadpool.h"
 #include "paddle/fluid/platform/profiler.h"
@@ -48,18 +48,19 @@ Variable* Scope::Var(const VarUUID& name) {
   auto* v = FindVarLocally(name);
   if (v != nullptr) return v;
   v = new Variable();
-  vars_[name] = v;
+  vars_[VarUUID(name)] = v;
   VLOG(3) << "Create variable " << name;
-  v->name_ = &(vars_.find(name)->first);
+  v->name_ = &(vars_.find(name)->first.name);
   return v;
 }
 
 Variable* Scope::Var(VarUUID* name) {
   auto var_name = string::Sprintf("%p.%d", this, vars_.size());
+  VarUUID id(var_name);
   if (name != nullptr) {
-    *name = var_name;
+    *name = id;
   }
-  return Var(var_name);
+  return Var(id);
 }
 
 Variable* Scope::FindVar(const VarUUID& name) const {
@@ -88,7 +89,7 @@ std::vector<std::string> Scope::LocalVarNames() const {
   std::vector<std::string> known_vars;
   known_vars.reserve(this->vars_.size());
   for (auto& p : vars_) {
-    known_vars.emplace_back(p.first);
+    known_vars.emplace_back(p.first.name);
   }
   return known_vars;
 }
@@ -106,8 +107,8 @@ void Scope::DeleteScope(Scope* scope) {
   }
 }
 
-void Scope::EraseVars(const std::vector<std::string>& var_names) {
-  std::set<std::string> var_set(var_names.begin(), var_names.end());
+void Scope::EraseVars(const std::vector<VarUUID>& var_names) {
+  std::unordered_set<VarUUID, VarUUIDHash> var_set(var_names.begin(), var_names.end());
   for (auto it = vars_.begin(); it != vars_.end();) {
     if (var_set.find(it->first) != var_set.end()) {
       delete it->second;
@@ -120,13 +121,14 @@ void Scope::EraseVars(const std::vector<std::string>& var_names) {
 
 void Scope::Rename(const std::string& origin_name,
                    const std::string& new_name) const {
-  auto origin_it = vars_.find(origin_name);
+  auto origin_it = vars_.find(VarUUID(origin_name));
   PADDLE_ENFORCE(origin_it != vars_.end(),
                  "Cannot find original variable with name %s", origin_name);
-  auto new_it = vars_.find(new_name);
+  VarUUID new_var = VarUUID(new_name);
+  auto new_it = vars_.find(new_var);
   PADDLE_ENFORCE(new_it == vars_.end(),
                  "The variable with name %s is already in the scope", new_name);
-  vars_[new_name] = origin_it->second;
+  vars_[new_var] = origin_it->second;
   vars_.erase(origin_it);
 }
 
@@ -136,7 +138,7 @@ std::string Scope::Rename(const std::string& origin_name) const {
   return var_name;
 }
 
-Variable* Scope::FindVarLocally(const std::string& name) const {
+Variable* Scope::FindVarLocally(const VarUUID& name) const {
   platform::RecordEvent event("Scope");
   auto it = vars_.find(name);
   if (it != vars_.end()) return it->second;
diff --git a/paddle/fluid/framework/scope.h b/paddle/fluid/framework/scope.h
index f1bb0e5224af6a..81eead500c2dd6 100644
--- a/paddle/fluid/framework/scope.h
+++ b/paddle/fluid/framework/scope.h
@@ -86,12 +86,7 @@ class Scope {
   explicit Scope(Scope const* parent) : parent_(parent) {}
 
   // mutable std::unordered_map<std::string, Variable*> vars_;
-  struct Hasher {
-    size_t operator() (const VarUUID& id) const {
-      return id.unique_id;
-    }
-  };
-  mutable std::unordered_map<VarUUID, Variable*, Hasher> vars_;
+  mutable std::unordered_map<VarUUID, Variable*, VarUUIDHash> vars_;
 
   mutable std::list<Scope*> kids_;
   Scope const* parent_{nullptr};
diff --git a/paddle/fluid/framework/type_defs.h b/paddle/fluid/framework/type_defs.h
index b9e91736f8ce55..e0d85245cb17c5 100644
--- a/paddle/fluid/framework/type_defs.h
+++ b/paddle/fluid/framework/type_defs.h
@@ -31,8 +31,6 @@ class InferShapeContext;
 class BlockDesc;
 
 using details::VarUUID;
-class VarUUID;
-// using VariableNameMap = std::map<std::string, std::vector<std::string>>;
 using VariableNameMap = std::map<std::string, std::vector<VarUUID>>;
 
 // The order should be as same as framework.proto
diff --git a/paddle/fluid/framework/variable.h b/paddle/fluid/framework/variable.h
index 435ee417b317cf..8c64df9e55548b 100644
--- a/paddle/fluid/framework/variable.h
+++ b/paddle/fluid/framework/variable.h
@@ -18,8 +18,8 @@
 #include <typeinfo>
 #include <thread> // for call_once
 
-
 #include "paddle/fluid/platform/enforce.h"
+#include "paddle/fluid/framework/details/var_handle.h"
 
 namespace paddle {
 namespace framework {
@@ -94,43 +94,28 @@ class Variable {
   const std::string* name_;
 };
 
+using details::VarUUID;
+using details::VarUUIDHash;
 /// variable unique_id generator, threadsafe singleton.
 class UUIDGenerator {
 public:
-  int operator()() {return engine();}
+  int operator()(const std::string& name) {return hasher(name);}
   UUIDGenerator& Instance() {
     std::call_once(once_flag, &UUIDGenerator::InitOnce);
     return *g;
   }
 private:
   static void InitOnce() {g = new UUIDGenerator();}
-  UUIDGenerator() {
-    engine.seed(std::random_device()());
+  explicit UUIDGenerator() {
   }
-  std::minstd_rand engine;
-  static UUIDGenerator *g;
+  std::hash<std::string> hasher;
+  static UUIDGenerator* g;
   static std::once_flag once_flag;
+  DISABLE_COPY_AND_ASSIGN(UUIDGenerator);
 };
 
-UUIDGenerator::UUIDGenerator* g = nullptr;
+UUIDGenerator* UUIDGenerator::g = nullptr;
 std::once_flag UUIDGenerator::once_flag;
 
-// a runtime unique variable identity.
-struct VarUUID : public VarHandleBase {
-  explicit VarUUID(const std::string& name) : name(name), unique_id(-1) {}
-  VarUUID(const std::string& name, int id) : name(name), unique_id(id) {}
-  std::string DebugString() const override;
-  std::string name;
-  int unique_id; /*default -1 if uninitialized*/
-};
-
-inline std::ostream& operator<<(std::ostream& os, const VarUUID& var) {
-  os << var.name;
-  if (VLOG_IS_ON(5)) {
-    os << "[" << var.unique_id << "]";
-  }
-  return os;
-}
-
 }  // namespace framework
 }  // namespace paddle

From d387a2cf68aad40610f101ffff7473ffc3da8ded Mon Sep 17 00:00:00 2001
From: dzhwinter <dzhwinter@gmail.com>
Date: Tue, 24 Apr 2018 22:07:50 -0700
Subject: [PATCH 3/7] "update config"

---
 paddle/fluid/framework/details/var_handle.h |  7 ++-----
 paddle/fluid/framework/operator.h           | 10 ++++++----
 paddle/fluid/framework/scope.cc             |  3 ++-
 paddle/fluid/framework/type_defs.h          |  2 +-
 paddle/fluid/framework/variable.h           | 18 ++++++++----------
 5 files changed, 19 insertions(+), 21 deletions(-)

diff --git a/paddle/fluid/framework/details/var_handle.h b/paddle/fluid/framework/details/var_handle.h
index cedce45c834335..cef3621ff4629d 100644
--- a/paddle/fluid/framework/details/var_handle.h
+++ b/paddle/fluid/framework/details/var_handle.h
@@ -15,9 +15,9 @@
 #pragma once
 #include <sstream>
 #include <string>
+#include <unordered_map>
 #include <unordered_set>
 #include <utility>
-#include <unordered_map>
 
 #include "paddle/fluid/platform/place.h"
 
@@ -84,9 +84,7 @@ struct VarUUID {
 };
 
 struct VarUUIDHash {
-  size_t operator() (const VarUUID& id) const {
-    return id.unique_id;
-  }
+  size_t operator()(const VarUUID& id) const { return id.unique_id; }
 };
 
 inline std::ostream& operator<<(std::ostream& os, const VarUUID& var) {
@@ -97,7 +95,6 @@ inline std::ostream& operator<<(std::ostream& os, const VarUUID& var) {
   return os;
 }
 
-
 }  // namespace details
 }  // namespace framework
 }  // namespace paddle
diff --git a/paddle/fluid/framework/operator.h b/paddle/fluid/framework/operator.h
index 5d0f2d85e3ac0f..2d465fe549b408 100644
--- a/paddle/fluid/framework/operator.h
+++ b/paddle/fluid/framework/operator.h
@@ -222,8 +222,9 @@ class ExecutionContext {
     res.reserve(names.size());
     std::transform(names.begin(), names.end(), std::back_inserter(res),
                    [this](const VarUUID& name) {
-                     return name == VarUUID(kEmptyVarName) ? nullptr
-                       : scope_.FindVar(name);
+                     return name == VarUUID(kEmptyVarName)
+                                ? nullptr
+                                : scope_.FindVar(name);
                    });
     return res;
   }
@@ -234,8 +235,9 @@ class ExecutionContext {
     res.reserve(names.size());
     std::transform(names.begin(), names.end(), std::back_inserter(res),
                    [this](const VarUUID& name) {
-                     return name == VarUUID(kEmptyVarName) ? nullptr
-                       : scope_.FindVar(name);
+                     return name == VarUUID(kEmptyVarName)
+                                ? nullptr
+                                : scope_.FindVar(name);
                    });
     return res;
   }
diff --git a/paddle/fluid/framework/scope.cc b/paddle/fluid/framework/scope.cc
index 514aa0582ab61f..64a73b50ce0cbe 100644
--- a/paddle/fluid/framework/scope.cc
+++ b/paddle/fluid/framework/scope.cc
@@ -108,7 +108,8 @@ void Scope::DeleteScope(Scope* scope) {
 }
 
 void Scope::EraseVars(const std::vector<VarUUID>& var_names) {
-  std::unordered_set<VarUUID, VarUUIDHash> var_set(var_names.begin(), var_names.end());
+  std::unordered_set<VarUUID, VarUUIDHash> var_set(var_names.begin(),
+                                                   var_names.end());
   for (auto it = vars_.begin(); it != vars_.end();) {
     if (var_set.find(it->first) != var_set.end()) {
       delete it->second;
diff --git a/paddle/fluid/framework/type_defs.h b/paddle/fluid/framework/type_defs.h
index e0d85245cb17c5..40d18af1b4c51e 100644
--- a/paddle/fluid/framework/type_defs.h
+++ b/paddle/fluid/framework/type_defs.h
@@ -20,8 +20,8 @@ limitations under the License. */
 #include <unordered_map>
 #include <unordered_set>
 #include <vector>
-#include "paddle/fluid/platform/variant.h"
 #include "paddle/fluid/framework/details/var_handle.h"
+#include "paddle/fluid/platform/variant.h"
 
 namespace paddle {
 namespace framework {
diff --git a/paddle/fluid/framework/variable.h b/paddle/fluid/framework/variable.h
index 8c64df9e55548b..9db9e93c82dedb 100644
--- a/paddle/fluid/framework/variable.h
+++ b/paddle/fluid/framework/variable.h
@@ -14,17 +14,16 @@
 #pragma once
 
 #include <memory>
+#include <string>
 #include <typeindex>
 #include <typeinfo>
-#include <thread> // for call_once
 
-#include "paddle/fluid/platform/enforce.h"
 #include "paddle/fluid/framework/details/var_handle.h"
+#include "paddle/fluid/platform/enforce.h"
 
 namespace paddle {
 namespace framework {
 
-
 class Variable {
  public:
   template <typename T>
@@ -70,7 +69,7 @@ class Variable {
   // parameter of Variable.
   template <typename T>
   struct PlaceholderImpl : public Placeholder {
-    PlaceholderImpl(T* ptr) : ptr_(ptr), type_(typeid(T)) {}
+    explicit PlaceholderImpl(T* ptr) : ptr_(ptr), type_(typeid(T)) {}
 
     virtual const std::type_info& Type() const { return type_; }
     virtual void* Ptr() const { return static_cast<void*>(ptr_.get()); }
@@ -98,16 +97,15 @@ using details::VarUUID;
 using details::VarUUIDHash;
 /// variable unique_id generator, threadsafe singleton.
 class UUIDGenerator {
-public:
-  int operator()(const std::string& name) {return hasher(name);}
+ public:
+  int operator()(const std::string& name) { return hasher(name); }
   UUIDGenerator& Instance() {
     std::call_once(once_flag, &UUIDGenerator::InitOnce);
     return *g;
   }
-private:
-  static void InitOnce() {g = new UUIDGenerator();}
-  explicit UUIDGenerator() {
-  }
+
+ private:
+  static void InitOnce() { g = new UUIDGenerator(); }
   std::hash<std::string> hasher;
   static UUIDGenerator* g;
   static std::once_flag once_flag;

From f87fc04a0532d611b32cd4b6817088d60cdb29da Mon Sep 17 00:00:00 2001
From: dzhwinter <dzhwinter@gmail.com>
Date: Tue, 24 Apr 2018 23:47:44 -0700
Subject: [PATCH 4/7] 'add scope test'

---
 paddle/fluid/framework/details/var_handle.cc |  6 ++--
 paddle/fluid/framework/details/var_handle.h  | 29 +++++++++++++++++++-
 paddle/fluid/framework/operator.cc           | 19 +++++++------
 paddle/fluid/framework/scope_test.cc         | 26 +++++++++---------
 paddle/fluid/framework/variable.h            | 19 -------------
 paddle/fluid/pybind/pybind.cc                |  7 +++--
 6 files changed, 60 insertions(+), 46 deletions(-)

diff --git a/paddle/fluid/framework/details/var_handle.cc b/paddle/fluid/framework/details/var_handle.cc
index 6e267cc4eb0d5f..c2101c9794c6f1 100644
--- a/paddle/fluid/framework/details/var_handle.cc
+++ b/paddle/fluid/framework/details/var_handle.cc
@@ -29,9 +29,9 @@ std::string VarHandle::DebugString() const {
 
 std::string DummyVarHandle::DebugString() const { return "dummy"; }
 
-VarUUID::VarUUID(const std::strign& name) : name(name) {
-  unique_id = UUIDGenerator::Instance()(name);
-}
+// VarUUID::VarUUID(const std::strign& name) : name(name) {
+//   unique_id = UUIDGenerator::Instance()(name);
+// }
 
 }  // namespace details
 }  // namespace framework
diff --git a/paddle/fluid/framework/details/var_handle.h b/paddle/fluid/framework/details/var_handle.h
index cef3621ff4629d..82cc4a79a7b770 100644
--- a/paddle/fluid/framework/details/var_handle.h
+++ b/paddle/fluid/framework/details/var_handle.h
@@ -69,9 +69,35 @@ struct DummyVarHandle : public VarHandleBase {
   std::string DebugString() const override;
 };
 
+/// variable unique_id generator, threadsafe singleton.
+class UUIDGenerator {
+public:
+  int operator()(const std::string& name) { return hasher(name); }
+  int Hash(const std::string& name) { return hasher(name); }
+  static UUIDGenerator& Instance() {
+    std::call_once(once_flag, &UUIDGenerator::InitOnce);
+    return *g;
+  }
+
+private:
+  static void InitOnce() { g = new UUIDGenerator(); }
+  UUIDGenerator() {}
+  std::hash<std::string> hasher;
+  static UUIDGenerator* g;
+  static std::once_flag once_flag;
+  DISABLE_COPY_AND_ASSIGN(UUIDGenerator);
+};
+
+UUIDGenerator* UUIDGenerator::g = nullptr;
+std::once_flag UUIDGenerator::once_flag;
+
 // a runtime unique variable identity.
 struct VarUUID {
-  explicit VarUUID(const std::string& name);
+  explicit VarUUID(const std::string& name) : name(name) {
+    // UUIDGenerator& gen = UUIDGenerator::Instance();
+    // unique_id = gen(name);
+    unique_id = UUIDGenerator::Instance()(name);
+  }
   VarUUID(const std::string& name, int id) : name(name), unique_id(id) {}
   bool operator==(const VarUUID& rhs) const {
     return unique_id == rhs.unique_id;
@@ -95,6 +121,7 @@ inline std::ostream& operator<<(std::ostream& os, const VarUUID& var) {
   return os;
 }
 
+
 }  // namespace details
 }  // namespace framework
 }  // namespace paddle
diff --git a/paddle/fluid/framework/operator.cc b/paddle/fluid/framework/operator.cc
index c513d72d0696b9..e16437871ed911 100644
--- a/paddle/fluid/framework/operator.cc
+++ b/paddle/fluid/framework/operator.cc
@@ -14,6 +14,7 @@ limitations under the License. */
 #include <gflags/gflags.h>
 #include <glog/logging.h>
 
+#include <string>
 #include <algorithm>
 
 #include "paddle/fluid/framework/data_transform.h"
@@ -46,7 +47,7 @@ proto::VarType::Type GetDataTypeOfVar(const Variable* var) {
   }
 }
 
-static DDim GetDims(const Scope& scope, const std::string& name,
+static DDim GetDims(const Scope& scope, const VarUUID& name,
                     bool get_actual_dim = false) {
   Variable* var = scope.FindVar(name);
   if (var == nullptr) {
@@ -66,7 +67,7 @@ static DDim GetDims(const Scope& scope, const std::string& name,
   }
 }
 
-static LoD GetLoD(const Scope& scope, const std::string& name) {
+static LoD GetLoD(const Scope& scope, const VarUUID& name) {
   Variable* var = scope.FindVar(name);
   auto default_lod = LoD({{}});
 
@@ -98,7 +99,7 @@ VarUUID OperatorBase::Input(const std::string& name) const {
   PADDLE_ENFORCE_LE(ins.size(), 1UL,
                     "Operator %s's input %s should contain only one variable.",
                     type_, name);
-  return ins.empty() ? kEmptyVarName : ins[0];
+  return ins.empty() ? VarUUID(kEmptyVarName) : ins[0];
 }
 
 const std::vector<VarUUID>& OperatorBase::Inputs(
@@ -114,7 +115,7 @@ VarUUID OperatorBase::Output(const std::string& name) const {
   PADDLE_ENFORCE_LE(outs.size(), 1UL,
                     "Operator %s's output %s should contain only one variable.",
                     type_, name);
-  return outs.empty() ? kEmptyVarName : outs[0];
+  return outs.empty() ? VarUUID(kEmptyVarName) : outs[0];
 }
 
 const std::vector<VarUUID>& OperatorBase::Outputs(
@@ -244,11 +245,13 @@ void OperatorBase::CheckAllInputOutputSet() const {
 void OperatorBase::GenerateTemporaryNames() {
   static std::atomic<size_t> gUniqId(0UL);
   for (auto& output : outputs_) {
-    for (auto& output_name : output.second) {
-      if (output_name == kTempVarName) {
+    for (auto& output_id : output.second) {
+      if (output_id.name == kTempVarName) {
+        std::string output_name = "";
         output_name += type_;
         output_name += "@";
         output_name += std::to_string(gUniqId.fetch_add(1));
+        output_id = VarUUID(output_name);
       }
     }
   }
@@ -294,7 +297,7 @@ const std::vector<const Tensor*> ExecutionContext::MultiInput<Tensor>(
   std::vector<const Tensor*> res;
   res.reserve(names.size());
   std::transform(names.begin(), names.end(), std::back_inserter(res),
-                 [&](const std::string& sub_name) {
+                 [&](const VarUUID& sub_name) {
                    auto var = scope_.FindVar(sub_name);
                    return var == nullptr ? nullptr : GetTensorFromVar(var);
                  });
@@ -314,7 +317,7 @@ std::vector<Tensor*> ExecutionContext::MultiOutput<Tensor>(
   std::vector<Tensor*> res;
   res.reserve(names.size());
   std::transform(names.begin(), names.end(), std::back_inserter(res),
-                 [&](const std::string& sub_name) {
+                 [&](const VarUUID& sub_name) {
                    auto var = scope_.FindVar(sub_name);
                    return var == nullptr ? nullptr
                                          : GetMutableTensorFromVar(var);
diff --git a/paddle/fluid/framework/scope_test.cc b/paddle/fluid/framework/scope_test.cc
index ebf8178a8319cd..96d18cbd7d99a4 100644
--- a/paddle/fluid/framework/scope_test.cc
+++ b/paddle/fluid/framework/scope_test.cc
@@ -24,33 +24,33 @@ TEST(Scope, VarsShadowing) {
   Scope& ss1 = s.NewScope();
   Scope& ss2 = s.NewScope();
 
-  Variable* v0 = s.Var("a");
-  Variable* v1 = ss1.Var("a");
+  Variable* v0 = s.Var(VarUUID("a"));
+  Variable* v1 = ss1.Var(VarUUID("a"));
 
   EXPECT_NE(v0, v1);
 
-  EXPECT_EQ(v0, s.FindVar("a"));
-  EXPECT_EQ(v1, ss1.FindVar("a"));
-  EXPECT_EQ(v0, ss2.FindVar("a"));
+  EXPECT_EQ(v0, s.FindVar(VarUUID("a")));
+  EXPECT_EQ(v1, ss1.FindVar(VarUUID("a")));
+  EXPECT_EQ(v0, ss2.FindVar(VarUUID("a")));
 }
 
 TEST(Scope, FindVar) {
   Scope s;
   Scope& ss = s.NewScope();
 
-  EXPECT_EQ(nullptr, s.FindVar("a"));
-  EXPECT_EQ(nullptr, ss.FindVar("a"));
+  EXPECT_EQ(nullptr, s.FindVar(VarUUID("a")));
+  EXPECT_EQ(nullptr, ss.FindVar(VarUUID("a")));
 
-  ss.Var("a");
+  ss.Var(VarUUID("a"));
 
-  EXPECT_EQ(nullptr, s.FindVar("a"));
-  EXPECT_NE(nullptr, ss.FindVar("a"));
+  EXPECT_EQ(nullptr, s.FindVar(VarUUID("a")));
+  EXPECT_NE(nullptr, ss.FindVar(VarUUID("a")));
 }
 
 TEST(Scope, FindScope) {
   Scope s;
   Scope& ss = s.NewScope();
-  Variable* v = s.Var("a");
+  Variable* v = s.Var(VarUUID("a"));
 
   EXPECT_EQ(&s, s.FindScope(v));
   EXPECT_EQ(&s, ss.FindScope(v));
@@ -58,7 +58,7 @@ TEST(Scope, FindScope) {
 
 TEST(Scope, GetAllNames) {
   Scope s;
-  Variable* v = s.Var("a");
+  Variable* v = s.Var(VarUUID("a"));
   EXPECT_EQ(&s, s.FindScope(v));
 
   std::vector<std::string> ans = s.LocalVarNames();
@@ -67,5 +67,5 @@ TEST(Scope, GetAllNames) {
     str += var;
   }
 
-  EXPECT_STREQ("a", str.c_str());
+  EXPECT_STREQ(VarUUID("a"), str.c_str());
 }
diff --git a/paddle/fluid/framework/variable.h b/paddle/fluid/framework/variable.h
index 9db9e93c82dedb..e43bafbf27ef43 100644
--- a/paddle/fluid/framework/variable.h
+++ b/paddle/fluid/framework/variable.h
@@ -95,25 +95,6 @@ class Variable {
 
 using details::VarUUID;
 using details::VarUUIDHash;
-/// variable unique_id generator, threadsafe singleton.
-class UUIDGenerator {
- public:
-  int operator()(const std::string& name) { return hasher(name); }
-  UUIDGenerator& Instance() {
-    std::call_once(once_flag, &UUIDGenerator::InitOnce);
-    return *g;
-  }
-
- private:
-  static void InitOnce() { g = new UUIDGenerator(); }
-  std::hash<std::string> hasher;
-  static UUIDGenerator* g;
-  static std::once_flag once_flag;
-  DISABLE_COPY_AND_ASSIGN(UUIDGenerator);
-};
-
-UUIDGenerator* UUIDGenerator::g = nullptr;
-std::once_flag UUIDGenerator::once_flag;
 
 }  // namespace framework
 }  // namespace paddle
diff --git a/paddle/fluid/pybind/pybind.cc b/paddle/fluid/pybind/pybind.cc
index 64d92cac7eca10..5901b7a7281279 100644
--- a/paddle/fluid/pybind/pybind.cc
+++ b/paddle/fluid/pybind/pybind.cc
@@ -249,10 +249,13 @@ All parameter, weight, gradient are variables in Paddle.
   py::class_<Scope>(m, "Scope", "")
       .def("var",
            [](Scope &self, const std::string &name) -> Variable * {
-             return self.Var(name);
+             return self.Var(VarUUID(name));
            },
            py::return_value_policy::reference)
-      .def("find_var", &Scope::FindVar, py::return_value_policy::reference)
+    .def("find_var",[](const std::string& name) -> Variable* {
+        return self.FindVar(VarUUID(name));
+      }
+           , py::return_value_policy::reference)
       .def(py::init<>())
       .def("new_scope", [](Scope &self) -> Scope * { return &self.NewScope(); },
            py::return_value_policy::reference)

From a5b910025d563cb373244fe6ac8a86c874f3cb46 Mon Sep 17 00:00:00 2001
From: dzhwinter <dzhwinter@gmail.com>
Date: Wed, 25 Apr 2018 00:08:08 -0700
Subject: [PATCH 5/7] 'add testing'

---
 paddle/fluid/framework/operator.cc        |  8 ++++----
 paddle/fluid/framework/scope.cc           | 20 ++++++++++++++++++++
 paddle/fluid/framework/scope.h            |  4 ++++
 paddle/fluid/framework/shape_inference.h  |  4 ++--
 paddle/fluid/operators/prefetch_op.cc     |  4 ++--
 paddle/fluid/operators/send_barrier_op.cc |  4 ++--
 paddle/fluid/operators/while_op.cc        |  2 +-
 7 files changed, 35 insertions(+), 11 deletions(-)

diff --git a/paddle/fluid/framework/operator.cc b/paddle/fluid/framework/operator.cc
index e16437871ed911..6fe3367faae031 100644
--- a/paddle/fluid/framework/operator.cc
+++ b/paddle/fluid/framework/operator.cc
@@ -355,7 +355,7 @@ class RuntimeInferShapeContext : public InferShapeContext {
     PADDLE_ENFORCE_EQ(length, 1UL,
                       "Input %s should not have more than one inputs", name);
     auto ipt = ins[0];
-    auto* var = ipt == kEmptyVarName ? nullptr : scope_.FindVar(ipt);
+    auto* var = ipt == VarUUID(kEmptyVarName) ? nullptr : scope_.FindVar(ipt);
     return var != nullptr;
   }
 
@@ -368,7 +368,7 @@ class RuntimeInferShapeContext : public InferShapeContext {
     PADDLE_ENFORCE_EQ(length, 1UL,
                       "Output %s should not have more than one inputs", name);
     auto ipt = outs[0];
-    auto* var = ipt == kEmptyVarName ? nullptr : scope_.FindVar(ipt);
+    auto* var = ipt == VarUUID(kEmptyVarName) ? nullptr : scope_.FindVar(ipt);
     return var != nullptr;
   }
 
@@ -400,12 +400,12 @@ class RuntimeInferShapeContext : public InferShapeContext {
 
   AttrReader Attrs() const override { return AttrReader(op_.Attrs()); }
 
-  const std::vector<std::string>& Inputs(
+  const std::vector<VarUUID>& Inputs(
       const std::string& name) const override {
     return op_.Inputs(name);
   }
 
-  const std::vector<std::string>& Outputs(
+  const std::vector<VarUUID>& Outputs(
       const std::string& name) const override {
     return op_.Outputs(name);
   }
diff --git a/paddle/fluid/framework/scope.cc b/paddle/fluid/framework/scope.cc
index 64a73b50ce0cbe..4d78daadc16cb0 100644
--- a/paddle/fluid/framework/scope.cc
+++ b/paddle/fluid/framework/scope.cc
@@ -44,6 +44,10 @@ Scope& Scope::NewScope() const {
   return *kids_.back();
 }
 
+Variable* Scope::Var(const std::string& name) {
+  return Var(VarUUID(name));
+}
+
 Variable* Scope::Var(const VarUUID& name) {
   auto* v = FindVarLocally(name);
   if (v != nullptr) return v;
@@ -54,6 +58,14 @@ Variable* Scope::Var(const VarUUID& name) {
   return v;
 }
 
+Variable* Scope::Var(std::string* name) {
+  auto var_name = string::Sprintf("%p.%d", this, vars_.size());
+  if (name != nullptr) {
+    *name = var_name;
+  }
+  return Var(var_name);
+}
+
 Variable* Scope::Var(VarUUID* name) {
   auto var_name = string::Sprintf("%p.%d", this, vars_.size());
   VarUUID id(var_name);
@@ -63,6 +75,10 @@ Variable* Scope::Var(VarUUID* name) {
   return Var(id);
 }
 
+Variable* Scope::FindVar(const std::string& name) const {
+  return FindVar(VarUUID(name));
+}
+
 Variable* Scope::FindVar(const VarUUID& name) const {
   platform::RecordEvent event("Scope");
   auto var = FindVarLocally(name);
@@ -139,6 +155,10 @@ std::string Scope::Rename(const std::string& origin_name) const {
   return var_name;
 }
 
+Variable* Scope::FindVarLocally(const std::string& name) const {
+  return FindVarLocally(name);
+}
+
 Variable* Scope::FindVarLocally(const VarUUID& name) const {
   platform::RecordEvent event("Scope");
   auto it = vars_.find(name);
diff --git a/paddle/fluid/framework/scope.h b/paddle/fluid/framework/scope.h
index 81eead500c2dd6..58f8a81fbca2e4 100644
--- a/paddle/fluid/framework/scope.h
+++ b/paddle/fluid/framework/scope.h
@@ -48,9 +48,11 @@ class Scope {
 
   /// Create a variable with given name if it doesn't exist.
   Variable* Var(const VarUUID& id);
+  Variable* Var(const std::string& name);
 
   /// Create a variable with a scope-unique name.
   Variable* Var(VarUUID* id = nullptr);
+  Variable* Var(std::string* name = nullptr);
 
   /// EraseVars in scope.
   void EraseVars(const std::vector<VarUUID>& var_names);
@@ -58,6 +60,7 @@ class Scope {
   /// Find a variable in the scope or any of its ancestors.  Returns
   /// nullptr if cannot find.
   Variable* FindVar(const VarUUID& name) const;
+  Variable* FindVar(const std::string& name) const;
 
   const Scope* parent() const { return parent_; }
 
@@ -80,6 +83,7 @@ class Scope {
   std::string Rename(const std::string& origin_name) const;
 
   Variable* FindVarLocally(const VarUUID& id) const;
+  Variable* FindVarLocally(const std::string& name) const;
 
  private:
   // Call Scope::NewScope for a sub-scope.
diff --git a/paddle/fluid/framework/shape_inference.h b/paddle/fluid/framework/shape_inference.h
index bc02d700da5186..490937a19267f6 100644
--- a/paddle/fluid/framework/shape_inference.h
+++ b/paddle/fluid/framework/shape_inference.h
@@ -49,9 +49,9 @@ class InferShapeContext {
   void SetReaderDims(const std::string &name, const std::vector<DDim> &dims);
 
   virtual AttrReader Attrs() const = 0;
-  virtual const std::vector<std::string> &Inputs(
+  virtual const std::vector<VarUUID> &Inputs(
       const std::string &name) const = 0;
-  virtual const std::vector<std::string> &Outputs(
+  virtual const std::vector<VarUUID> &Outputs(
       const std::string &name) const = 0;
 
   virtual void ShareLoD(const std::string &in, const std::string &out,
diff --git a/paddle/fluid/operators/prefetch_op.cc b/paddle/fluid/operators/prefetch_op.cc
index f9ae01ab5d2972..79583ad86c0bab 100644
--- a/paddle/fluid/operators/prefetch_op.cc
+++ b/paddle/fluid/operators/prefetch_op.cc
@@ -42,10 +42,10 @@ class PrefetchOp : public framework::OperatorBase {
     auto& ctx = *pool.Get(place);
 
     auto client_var_name = Output("RPCClient");
-    PADDLE_ENFORCE_NOT_NULL(scope.FindVar(client_var_name),
+    PADDLE_ENFORCE_NOT_NULL(scope.FindVar(VarUUID(client_var_name)),
                             "Can not find variable '%s' in the scope.",
                             client_var_name);
-    auto* client_var = scope.FindVar(client_var_name);
+    auto* client_var = scope.FindVar(VarUUID(client_var_name));
     detail::RPCClient* rpc_client = client_var->GetMutable<detail::RPCClient>();
 
     for (size_t i = 0; i < ins.size(); i++) {
diff --git a/paddle/fluid/operators/send_barrier_op.cc b/paddle/fluid/operators/send_barrier_op.cc
index 12b844daaa3316..2664156a0d9f2f 100644
--- a/paddle/fluid/operators/send_barrier_op.cc
+++ b/paddle/fluid/operators/send_barrier_op.cc
@@ -38,10 +38,10 @@ class SendBarrierOp : public framework::OperatorBase {
     std::vector<std::string> eps = Attr<std::vector<std::string>>("endpoints");
 
     auto client_var_name = Output("RPCClient");
-    PADDLE_ENFORCE_NOT_NULL(scope.FindVar(client_var_name),
+    PADDLE_ENFORCE_NOT_NULL(scope.FindVar(VarUUID(client_var_name)),
                             "Can not find variable '%s' in the scope.",
                             client_var_name);
-    auto* client_var = scope.FindVar(client_var_name);
+    auto* client_var = scope.FindVar(VarUUID(client_var_name));
     detail::RPCClient* rpc_client = client_var->GetMutable<detail::RPCClient>();
 
     // need to wait before sending send_barrier message
diff --git a/paddle/fluid/operators/while_op.cc b/paddle/fluid/operators/while_op.cc
index 8b62b242cf8745..06be229fed9e07 100644
--- a/paddle/fluid/operators/while_op.cc
+++ b/paddle/fluid/operators/while_op.cc
@@ -131,7 +131,7 @@ class WhileGradOp : public framework::OperatorBase {
         VLOG(8) << "Linking outside " << outside_og_name << " --> inside "
                 << inside_og_name;
         auto &og_outside =
-            detail::Ref(scope.FindVar(outside_og_name),
+          detail::Ref(scope.FindVar(VarUUID(outside_og_name)),
                         "Cannot find Outside Gradient %s", outside_og_name);
         auto &og_inside =
             detail::Ref(cur_scope.Var(inside_og_name),

From 796633903c3c2f48b08a77258dd66b5198c07507 Mon Sep 17 00:00:00 2001
From: dzhwinter <dzhwinter@gmail.com>
Date: Wed, 25 Apr 2018 02:02:32 -0700
Subject: [PATCH 6/7] "re-commit"

---
 .pre-commit-config.yaml                 |  8 ++++++++
 paddle/fluid/framework/details/var_id.h | 15 ---------------
 2 files changed, 8 insertions(+), 15 deletions(-)
 delete mode 100644 paddle/fluid/framework/details/var_id.h

diff --git a/.pre-commit-config.yaml b/.pre-commit-config.yaml
index 2f55b26d5a0cc8..9acb0515e868e7 100644
--- a/.pre-commit-config.yaml
+++ b/.pre-commit-config.yaml
@@ -26,6 +26,14 @@ repos:
         entry: bash ./.clang_format.hook -i
         language: system
         files: \.(c|cc|cxx|cpp|cu|h|hpp|hxx|proto)$
+-   repo: local
+    hooks:
+    -   id: cpplint-cpp-source
+        name: cpplint
+        description: Check C++ code style using cpplint.py.
+        entry: bash ./tools/codestyle/cpplint_pre_commit.hook
+        language: system
+        files: \.(c|cc|cxx|cpp|cu|h|hpp|hxx)$
 -   repo: https://github.com/PaddlePaddle/pre-commit-golang
     rev: v0.2
     hooks:
diff --git a/paddle/fluid/framework/details/var_id.h b/paddle/fluid/framework/details/var_id.h
deleted file mode 100644
index d69ad91ebb460c..00000000000000
--- a/paddle/fluid/framework/details/var_id.h
+++ /dev/null
@@ -1,15 +0,0 @@
-#pragma once
-#include <string>
-
-namespace paddle {
-namespace framework {
-struct VarId {
-  explicit VarId(const std::string& name) : name(name), unique_id(-1) {}
-  VarId(const std::string& name, int id) : name(name), unique_id(id) {}
-  std::string name;
-  /*default -1 if uninitialized*/
-  int unique_id;
-};
-
-}  // namespace framework
-}  // namespace paddle

From 6c83e7d9e1985edb823896bfb959beb22dc3be63 Mon Sep 17 00:00:00 2001
From: dzhwinter <dzhwinter@gmail.com>
Date: Mon, 30 Apr 2018 06:45:54 -0700
Subject: [PATCH 7/7] "staged shape inference"

---
 paddle/fluid/framework/details/var_handle.h | 15 +++------------
 paddle/fluid/framework/shape_inference.cc   | 12 ++++++------
 paddle/fluid/framework/shape_inference.h    |  5 +++--
 3 files changed, 12 insertions(+), 20 deletions(-)

diff --git a/paddle/fluid/framework/details/var_handle.h b/paddle/fluid/framework/details/var_handle.h
index ade3e6b4823000..6d7f360f9127bc 100644
--- a/paddle/fluid/framework/details/var_handle.h
+++ b/paddle/fluid/framework/details/var_handle.h
@@ -77,30 +77,21 @@ struct DummyVarHandle : public VarHandleBase {
 /// variable unique_id generator, threadsafe singleton.
 class UUIDGenerator {
  public:
+  UUIDGenerator() {}
   int operator()(const std::string& name) { return hasher(name); }
-  int Hash(const std::string& name) { return hasher(name); }
   static UUIDGenerator& Instance() {
-    std::call_once(once_flag, &UUIDGenerator::InitOnce);
-    return *g;
+    static UUIDGenerator g;
+    return g;
   }
 
  private:
-  static void InitOnce() { g = new UUIDGenerator(); }
-  UUIDGenerator() {}
   std::hash<std::string> hasher;
-  static UUIDGenerator* g;
-  static std::once_flag once_flag;
   DISABLE_COPY_AND_ASSIGN(UUIDGenerator);
 };
 
-UUIDGenerator* UUIDGenerator::g = nullptr;
-std::once_flag UUIDGenerator::once_flag;
-
 // a runtime unique variable identity.
 struct VarUUID {
   explicit VarUUID(const std::string& name) : name(name) {
-    // UUIDGenerator& gen = UUIDGenerator::Instance();
-    // unique_id = gen(name);
     unique_id = UUIDGenerator::Instance()(name);
   }
   VarUUID(const std::string& name, int id) : name(name), unique_id(id) {}
diff --git a/paddle/fluid/framework/shape_inference.cc b/paddle/fluid/framework/shape_inference.cc
index ddff2c7c261746..0651d298034c74 100644
--- a/paddle/fluid/framework/shape_inference.cc
+++ b/paddle/fluid/framework/shape_inference.cc
@@ -23,7 +23,7 @@ namespace paddle {
 namespace framework {
 
 DDim InferShapeContext::GetInputDim(const std::string &name) const {
-  const std::vector<std::string> &arg_names = Inputs(name);
+  auto &arg_names = Inputs(name);
   PADDLE_ENFORCE_EQ(arg_names.size(), 1UL,
                     "Input(%s) should hold one element, but now it holds %d",
                     name, arg_names.size());
@@ -32,13 +32,13 @@ DDim InferShapeContext::GetInputDim(const std::string &name) const {
 
 std::vector<DDim> InferShapeContext::GetInputsDim(
     const std::string &name) const {
-  const std::vector<std::string> &arg_names = Inputs(name);
+  auto &arg_names = Inputs(name);
   return GetDims(arg_names);
 }
 
 std::vector<DDim> InferShapeContext::GetReaderDims(
     const std::string &name) const {
-  const std::vector<std::string> &arg_names = Inputs(name);
+  auto &arg_names = Inputs(name);
   PADDLE_ENFORCE_EQ(
       arg_names.size(), 1UL,
       "Reader input '%s' should hold one element, but now it holds %d", name,
@@ -68,7 +68,7 @@ void InferShapeContext::SetOutputsDim(const std::string &name,
 
 void InferShapeContext::SetReaderDims(const std::string &name,
                                       const std::vector<DDim> &dims) {
-  const std::vector<std::string> &arg_names = Outputs(name);
+  auto &arg_names = Outputs(name);
   PADDLE_ENFORCE_EQ(
       arg_names.size(), 1UL,
       "Reader output '%s' should hold one element, but now it holds %d", name,
@@ -78,7 +78,7 @@ void InferShapeContext::SetReaderDims(const std::string &name,
 
 std::vector<InferShapeVarPtr> InferShapeContext::GetInputVarPtrs(
     const std::string &name) {
-  const std::vector<std::string> arg_names = Inputs(name);
+  auto &arg_names = Inputs(name);
   std::vector<InferShapeVarPtr> res;
   res.reserve(arg_names.size());
   std::transform(
@@ -89,7 +89,7 @@ std::vector<InferShapeVarPtr> InferShapeContext::GetInputVarPtrs(
 
 std::vector<InferShapeVarPtr> InferShapeContext::GetOutputVarPtrs(
     const std::string &name) {
-  const std::vector<std::string> arg_names = Outputs(name);
+  auto &arg_names = Outputs(name);
   std::vector<InferShapeVarPtr> res;
   res.reserve(arg_names.size());
   std::transform(
diff --git a/paddle/fluid/framework/shape_inference.h b/paddle/fluid/framework/shape_inference.h
index b763f7bde7697f..46c8feec001584 100644
--- a/paddle/fluid/framework/shape_inference.h
+++ b/paddle/fluid/framework/shape_inference.h
@@ -51,8 +51,9 @@ class InferShapeContext {
   void SetReaderDims(const std::string &name, const std::vector<DDim> &dims);
 
   virtual AttrReader Attrs() const = 0;
-  virtual const std::vector<VarUUID> &Inputs(const std::string &name) const = 0;
-  virtual const std::vector<VarUUID> &Outputs(
+  virtual const std::vector<std::string> &Inputs(
+      const std::string &name) const = 0;
+  virtual const std::vector<std::string> &Outputs(
       const std::string &name) const = 0;
 
   virtual void ShareLoD(const std::string &in, const std::string &out,