[inspector] deduplicate stack frames

src/inspector/v8-stack-trace-impl.h

Index: src/inspector/v8-stack-trace-impl.h
diff --git a/src/inspector/v8-stack-trace-impl.h b/src/inspector/v8-stack-trace-impl.h
index 38722ea2f11324efa71b7bc6b9fe55a3239aced6..f6292f2e4ec4e13606a1d17dcdb773d9875b6b35 100644
--- a/src/inspector/v8-stack-trace-impl.h
+++ b/src/inspector/v8-stack-trace-impl.h
@@ -20,6 +20,28 @@ class AsyncStackTrace;
 class V8Debugger;
 class WasmTranslation;
 
+class StackFrame {
+ public:
+  explicit StackFrame(v8::Local<v8::StackFrame> frame);
+  ~StackFrame() = default;
+
+  void translate(WasmTranslation* wasmTranslation);
+
+  const String16& functionName() const;
+  const String16& scriptId() const;
+  const String16& sourceURL() const;
+  int lineNumber() const;    // 0-based.
+  int columnNumber() const;  // 0-based.
+  std::unique_ptr<protocol::Runtime::CallFrame> buildInspectorObject() const;
+
+ private:
+  String16 m_functionName;
+  String16 m_scriptId;
+  String16 m_sourceURL;
+  int m_lineNumber;    // 0-based.
+  int m_columnNumber;  // 0-based.
+};
+
 class V8StackTraceImpl : public V8StackTrace {
  public:
   static void setCaptureStackTraceForUncaughtExceptions(v8::Isolate*,
@@ -50,34 +72,13 @@ class V8StackTraceImpl : public V8StackTrace {
       const override;
   std::unique_ptr<StringBuffer> toString() const override;
 
-  class Frame {
-   public:
-    explicit Frame(v8::Local<v8::StackFrame> frame);
-    ~Frame() = default;
-
-    void translate(WasmTranslation* wasmTranslation);
-
-    const String16& functionName() const;
-    const String16& scriptId() const;
-    const String16& sourceURL() const;
-    int lineNumber() const;    // 0-based.
-    int columnNumber() const;  // 0-based.
-    std::unique_ptr<protocol::Runtime::CallFrame> buildInspectorObject() const;
-
-   private:
-    String16 m_functionName;
-    String16 m_scriptId;
-    String16 m_sourceURL;
-    int m_lineNumber;    // 0-based.
-    int m_columnNumber;  // 0-based.
-  };
-
  private:
-  V8StackTraceImpl(const std::vector<Frame> frames, int maxAsyncDepth,
+  V8StackTraceImpl(const std::vector<std::shared_ptr<StackFrame>>& frames,

[dgozman, 2017/04/19 20:29:04]

I remember that passing vector by value here and using std::move() on the call
sites prevents extra copy when the callsite doesn't store the frames later. I
think that would apply here nicely!

[kozy, 2017/04/20 00:06:49]

Done, but I think we should pass vector by reference and then move? otherwise I
think C++ will just create a copy on the call site.

+                   int maxAsyncDepth,
                    std::shared_ptr<AsyncStackTrace> asyncParent,
                    std::shared_ptr<AsyncStackTrace> asyncCreation);
 
-  std::vector<Frame> m_frames;
+  std::vector<std::shared_ptr<StackFrame>> m_frames;
   int m_maxAsyncDepth;
   std::weak_ptr<AsyncStackTrace> m_asyncParent;
   std::weak_ptr<AsyncStackTrace> m_asyncCreation;
@@ -102,14 +103,14 @@ class AsyncStackTrace {
 
  private:
   AsyncStackTrace(int contextGroupId, const String16& description,
-                  const std::vector<V8StackTraceImpl::Frame>& frames,
+                  const std::vector<std::shared_ptr<StackFrame>>& frames,

[dgozman, 2017/04/19 20:29:05]

ditto

[kozy, 2017/04/20 00:06:49]

Done.

                   std::shared_ptr<AsyncStackTrace> asyncParent,
                   std::shared_ptr<AsyncStackTrace> asyncCreation);
 
   int m_contextGroupId;
   String16 m_description;
 
-  std::vector<V8StackTraceImpl::Frame> m_frames;
+  std::vector<std::shared_ptr<StackFrame>> m_frames;
   std::weak_ptr<AsyncStackTrace> m_asyncParent;
   std::weak_ptr<AsyncStackTrace> m_asyncCreation;