src: minor refactor of node_trace_events.cc

Avoid unnecessary copies/extra operations & align with our style guide, and add protection against throwing getters. PR-URL: #21867 Reviewed-By: James M Snell <[email protected]> Reviewed-By: Eugene Ostroukhov <[email protected]> Reviewed-By: Ali Ijaz Sheikh <[email protected]>

Author: addaleax

src/node_trace_events.cc

@@ -25,7 +25,7 @@ class NodeCategorySet : public BaseObject{
 staticvoidEnable(const FunctionCallbackInfo<Value>& args);
 staticvoidDisable(const FunctionCallbackInfo<Value>& args);
 
-const std::set<std::string>& GetCategories(){return categories_}
+const std::set<std::string>& GetCategories() const{return categories_}
 
 voidMemoryInfo(MemoryTracker* tracker) constoverride{
  tracker->TrackThis(this);
@@ -37,8 +37,8 @@ class NodeCategorySet : public BaseObject{
 private:
 NodeCategorySet(Environment* env,
  Local<Object> wrap,
- std::set<std::string> categories) :
-BaseObject(env, wrap), categories_(categories){
+ std::set<std::string>&& categories) :
+BaseObject(env, wrap), categories_(std::move(categories)){
 MakeWeak();
  }
 
@@ -52,12 +52,14 @@ void NodeCategorySet::New(const FunctionCallbackInfo<Value>& args){
 CHECK(args[0]->IsArray());
  Local<Array> cats = args[0].As<Array>();
 for (size_t n = 0; n < cats->Length(); n++){
- Local<Value> category = cats->Get(env->context(), n).ToLocalChecked();
+ Local<Value> category;
+if (!cats->Get(env->context(), n).ToLocal(&category)) return;
  Utf8Value val(env->isolate(), category);
+if (!*val) return;
  categories.emplace(*val);
  }
 CHECK_NOT_NULL(env->tracing_agent());
-newNodeCategorySet(env, args.This(), categories);
+newNodeCategorySet(env, args.This(), std::move(categories));
 }
 
 voidNodeCategorySet::Enable(const FunctionCallbackInfo<Value>& args){
@@ -91,13 +93,15 @@ void GetEnabledCategories(const FunctionCallbackInfo<Value>& args){
  args.GetReturnValue().Set(
 String::NewFromUtf8(env->isolate(),
  categories.c_str(),
- v8::NewStringType::kNormal).ToLocalChecked());
+ v8::NewStringType::kNormal,
+ categories.size()).ToLocalChecked());
  }
 }
 
 // The tracing APIs require category groups to be pointers to long-lived
 // strings. Those strings are stored here.
-static std::unordered_set<std::string> categoryGroups;
+static std::unordered_set<std::string> category_groups;
+static Mutex category_groups_mutex;
 
 // Gets a pointer to the category-enabled flags for a tracing category group,
 // if tracing is enabled for it.
@@ -107,14 +111,15 @@ static const uint8_t* GetCategoryGroupEnabled(const char* category_group){
 }
 
 staticconstchar* GetCategoryGroup(Environment* env,
-const Local<Value> categoryValue){
-CHECK(categoryValue->IsString());
+const Local<Value> category_value){
+CHECK(category_value->IsString());
 
- Utf8Value category(env->isolate(), categoryValue);
+ Utf8Value category(env->isolate(), category_value);
+ Mutex::ScopedLock lock(category_groups_mutex);
 // If the value already exists in the set, insertion.first will point
 // to the existing value. Thus, this will maintain a long lived pointer
 // to the category c-string.
-auto insertion = categoryGroups.insert(category.out());
+auto insertion = category_groups.insert(category.out());
 
 // The returned insertion is a pair whose first item is the object that was
 // inserted or that blocked the insertion and second item is a boolean
@@ -133,7 +138,7 @@ static void Emit(const FunctionCallbackInfo<Value>& args){
 // enabled.
 constchar* category_group = GetCategoryGroup(env, args[1]);
 constuint8_t* category_group_enabled =
-GetCategoryGroupEnabled(category_group);
+GetCategoryGroupEnabled(category_group);
 if (*category_group_enabled == 0) return;
 
 // get trace_event phase
@@ -142,8 +147,8 @@ static void Emit(const FunctionCallbackInfo<Value>& args){
 
 // get trace_event name
 CHECK(args[2]->IsString());
- Utf8Value nameValue(env->isolate(), args[2]);
-constchar* name = nameValue.out();
+ Utf8Value name_value(env->isolate(), args[2]);
+constchar* name = name_value.out();
 
 // get trace_event id
 int64_t id = 0;
@@ -212,7 +217,7 @@ static void CategoryGroupEnabled(const FunctionCallbackInfo<Value>& args){
 
 constchar* category_group = GetCategoryGroup(env, args[0]);
 constuint8_t* category_group_enabled =
-GetCategoryGroupEnabled(category_group);
+GetCategoryGroupEnabled(category_group);
  args.GetReturnValue().Set(*category_group_enabled > 0);
 }