[Tracing] V8 Tracing Controller - Add args and copy support

include/libplatform/v8-tracing.h

Index: include/libplatform/v8-tracing.h
diff --git a/include/libplatform/v8-tracing.h b/include/libplatform/v8-tracing.h
index dd0be2e6f153781d404e77292e78165c6299e003..f4543455711366d1f61b7442e24be9e5608cad11 100644
--- a/include/libplatform/v8-tracing.h
+++ b/include/libplatform/v8-tracing.h
@@ -13,9 +13,21 @@ namespace v8 {
 namespace platform {
 namespace tracing {
 
+const int kTraceMaxNumArgs = 2;
+
 class TraceObject {
  public:
+  union TraceValue {

[fmeawad, 2016/07/29 14:57:06]

We will need to add TracedValue later
See:
https://cs.chromium.org/chromium/src/cc/debug/traced_value.h?q=Traced&sq=pack...

So this name might be confusing, maybe ArgValue?

[rskang, 2016/07/29 19:48:13]

Done.

+    bool as_bool;
+    uint64_t as_uint;
+    int64_t as_int;
+    double as_double;
+    const void* as_pointer;
+    const char* as_string;
+  };
+
   TraceObject() {}
+  ~TraceObject();
   void Initialize(char phase, const uint8_t* category_enabled_flag,
                   const char* name, const char* scope, uint64_t id,
                   uint64_t bind_id, int num_args, const char** arg_names,
@@ -40,6 +52,9 @@ class TraceObject {
   const char* scope() const { return scope_; }
   uint64_t id() const { return id_; }
   uint64_t bind_id() const { return bind_id_; }

[fmeawad, 2016/07/29 14:57:06]

missing num_args getter?

[rskang, 2016/07/29 19:48:13]

Done.

+  TraceValue* arg_values() { return arg_values_; }

[fmeawad, 2016/07/29 14:57:06]

nit:
arg_names
arg_types
arg_values
To match the parameters order

[rskang, 2016/07/29 19:48:13]

Done.

+  const char** arg_names() { return arg_names_; }
+  uint8_t* arg_types() { return arg_types_; }
   unsigned int flags() const { return flags_; }
   int64_t ts() { return ts_; }
   int64_t tts() { return tts_; }
@@ -55,13 +70,15 @@ class TraceObject {
   const uint8_t* category_enabled_flag_;
   uint64_t id_;
   uint64_t bind_id_;
-  int num_args_;

[fmeawad, 2016/07/29 14:57:06]

I don't think you should remove num_args_, I think you should keep the value
passed in and/or clamp it as you did in the implementation. But leave the member
and add a getter.

[rskang, 2016/07/29 19:48:13]

Done.

+  TraceValue arg_values_[kTraceMaxNumArgs];
+  const char* arg_names_[kTraceMaxNumArgs];
+  uint8_t arg_types_[kTraceMaxNumArgs];
+  char* parameter_copy_storage_ = nullptr;
   unsigned int flags_;
   int64_t ts_;
   int64_t tts_;
   uint64_t duration_;
   uint64_t cpu_duration_;
-  // TODO(fmeawad): Add args support.
 
   // Disallow copy and assign
   TraceObject(const TraceObject&) = delete;