Issue 3594 - remove circular references JsEngine-JsValue-JsEngine

src/JsValue.cpp

 /*
  * This file is part of Adblock Plus <https://adblockplus.org/>,
  * Copyright (C) 2006-2016 Eyeo GmbH
  *
  * Adblock Plus is free software: you can redistribute it and/or modify
  * it under the terms of the GNU General Public License version 3 as
  * published by the Free Software Foundation.
  *
  * Adblock Plus is distributed in the hope that it will be useful,
  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  * GNU General Public License for more details.
  *
  * You should have received a copy of the GNU General Public License
  * along with Adblock Plus.  If not, see <http://www.gnu.org/licenses/>.
  */
 
 #include <vector>
 #include <AdblockPlus.h>
 
 #include "JsContext.h"
 #include "JsError.h"
 #include "Utils.h"
 
 AdblockPlus::JsValue::JsValue(const std::weak_ptr<AdblockPlus::JsEngine>& jsEngine,
   v8::Handle<v8::Value> value)
-  : m_jsEngine(jsEngine)
-  , m_value(new v8::Persistent<v8::Value>(Utils::lockJsEngine(jsEngine)->GetIsolate(), value))
+  : jsEngine(jsEngine)
+  , value(new v8::Persistent<v8::Value>(Utils::lockJsEngine(jsEngine)->GetIsolate(), value))
 {
 }
 
 AdblockPlus::JsValue::JsValue(AdblockPlus::JsValue&& src)
-    : m_jsEngine(move(src.m_jsEngine)),
-      m_value(std::move(src.m_value))
+    : jsEngine(std::move(src.jsEngine)),
+      value(std::move(src.value))
 {
 }
 
 AdblockPlus::JsValue::~JsValue()
 {
   try
   {
-    JsContext context(m_jsEngine);
-    if (m_value)
+    JsContext context(jsEngine);

[sergei, 2016/12/01 22:24:37]

Although I have not seen a crash on practice there is still a race condition:
if there is already no JsEngine then v8::Persistent::Dispose still can be called
"simultaneously" from different threads. I will look into the code of a newer
version of v8 and check how it works.

+    if (value)
     {
-      m_value->Dispose();
-      m_value.reset();
+      value->Dispose();
+      value.reset();
     }
   }
   catch (const JsEngine::JsEngineNotAvailableException&)
   {
   }
 }
 
 bool AdblockPlus::JsValue::IsUndefined() const
 {
-  JsContext context(m_jsEngine);
-  return UnwrapValue(context.jsEngine())->IsUndefined();
+  JsContext context(jsEngine);
+  return UnwrapValue(context.GetJsEngine())->IsUndefined();
 }
 
 bool AdblockPlus::JsValue::IsNull() const
 {
-  JsContext context(m_jsEngine);
-  return UnwrapValue(context.jsEngine())->IsNull();
+  JsContext context(jsEngine);
+  return UnwrapValue(context.GetJsEngine())->IsNull();
 }
 
 bool AdblockPlus::JsValue::IsString() const
 {
-  JsContext context(m_jsEngine);
-  v8::Local<v8::Value> value = UnwrapValue(context.jsEngine());
+  JsContext context(jsEngine);
+  v8::Local<v8::Value> value = UnwrapValue(context.GetJsEngine());
   return value->IsString() || value->IsStringObject();
 }
 
 bool AdblockPlus::JsValue::IsNumber() const
 {
-  JsContext context(m_jsEngine);
-  v8::Local<v8::Value> value = UnwrapValue(context.jsEngine());
+  JsContext context(jsEngine);
+  v8::Local<v8::Value> value = UnwrapValue(context.GetJsEngine());
   return value->IsNumber() || value->IsNumberObject();
 }
 
 bool AdblockPlus::JsValue::IsBool() const
 {
-  JsContext context(m_jsEngine);
-  v8::Local<v8::Value> value = UnwrapValue(context.jsEngine());
+  JsContext context(jsEngine);
+  v8::Local<v8::Value> value = UnwrapValue(context.GetJsEngine());
   return value->IsBoolean() || value->IsBooleanObject();
 }
 
 bool AdblockPlus::JsValue::IsObject() const
 {
-  JsContext context(m_jsEngine);
-  return UnwrapValue(context.jsEngine())->IsObject();
+  JsContext context(jsEngine);
+  return UnwrapValue(context.GetJsEngine())->IsObject();
 }
 
 bool AdblockPlus::JsValue::IsArray() const
 {
-  JsContext context(m_jsEngine);
-  return UnwrapValue(context.jsEngine())->IsArray();
+  JsContext context(jsEngine);
+  return UnwrapValue(context.GetJsEngine())->IsArray();
 }
 
 bool AdblockPlus::JsValue::IsFunction() const
 {
-  JsContext context(m_jsEngine);
-  return UnwrapValue(context.jsEngine())->IsFunction();
+  JsContext context(jsEngine);
+  return UnwrapValue(context.GetJsEngine())->IsFunction();
 }
 
 std::string AdblockPlus::JsValue::AsString() const
 {
-  JsContext context(m_jsEngine);
-  return Utils::FromV8String(UnwrapValue(context.jsEngine()));
+  JsContext context(jsEngine);
+  return Utils::FromV8String(UnwrapValue(context.GetJsEngine()));
 }
 
 int64_t AdblockPlus::JsValue::AsInt() const
 {
-  JsContext context(m_jsEngine);
-  return UnwrapValue(context.jsEngine())->IntegerValue();
+  JsContext context(jsEngine);
+  return UnwrapValue(context.GetJsEngine())->IntegerValue();
 }
 
 bool AdblockPlus::JsValue::AsBool() const
 {
-  JsContext context(m_jsEngine);
-  return UnwrapValue(context.jsEngine())->BooleanValue();
+  JsContext context(jsEngine);
+  return UnwrapValue(context.GetJsEngine())->BooleanValue();
 }
 
 AdblockPlus::JsValueList AdblockPlus::JsValue::AsList() const
 {
-  JsContext context(m_jsEngine);
+  JsContext context(jsEngine);
   if (!IsArray())
     throw std::runtime_error("Cannot convert a non-array to list");
 
   JsValueList result;
-  v8::Local<v8::Array> array = v8::Local<v8::Array>::Cast(UnwrapValue(context.jsEngine()));
+  v8::Local<v8::Array> array = v8::Local<v8::Array>::Cast(UnwrapValue(context.GetJsEngine()));
   uint32_t length = array->Length();
   for (uint32_t i = 0; i < length; i++)
   {
     v8::Local<v8::Value> item = array->Get(i);
-    result.push_back(JsValuePtr(new JsValue(m_jsEngine, item)));
+    result.push_back(JsValuePtr(new JsValue(jsEngine, item)));
   }
   return result;
 }
 
 std::vector<std::string> AdblockPlus::JsValue::GetOwnPropertyNames() const
 {
-  JsContext context(m_jsEngine);
+  JsContext context(jsEngine);
   if (!IsObject())
     throw new std::runtime_error("Attempting to get propert list for a non-object");
 
-  v8::Local<v8::Object> object = v8::Local<v8::Object>::Cast(UnwrapValue(context.jsEngine()));
-  JsValueList properties = JsValuePtr(new JsValue(m_jsEngine, object->GetOwnPropertyNames()))->AsList();
+  v8::Local<v8::Object> object = v8::Local<v8::Object>::Cast(UnwrapValue(context.GetJsEngine()));
+  JsValueList properties = JsValuePtr(new JsValue(jsEngine, object->GetOwnPropertyNames()))->AsList();
   std::vector<std::string> result;
   for (JsValueList::iterator it = properties.begin(); it != properties.end(); ++it)
     result.push_back((*it)->AsString());
   return result;
 }
 
 
 AdblockPlus::JsValuePtr AdblockPlus::JsValue::GetProperty(const std::string& name) const
 {
-  JsContext context(m_jsEngine);
+  JsContext context(jsEngine);
   if (!IsObject())
     throw new std::runtime_error("Attempting to get property of a non-object");
 
-  v8::Local<v8::String> property = Utils::ToV8String(context.jsEngine().GetIsolate(), name);
-  v8::Local<v8::Object> obj = v8::Local<v8::Object>::Cast(UnwrapValue(context.jsEngine()));
-  return JsValuePtr(new JsValue(m_jsEngine, obj->Get(property)));
+  v8::Local<v8::String> property = Utils::ToV8String(context.GetJsEngine().GetIsolate(), name);
+  v8::Local<v8::Object> obj = v8::Local<v8::Object>::Cast(UnwrapValue(context.GetJsEngine()));
+  return JsValuePtr(new JsValue(jsEngine, obj->Get(property)));
 }
 
 void AdblockPlus::JsValue::SetProperty(const std::string& name, v8::Handle<v8::Value> val)
 {
-  JsContext context(m_jsEngine);
+  JsContext context(jsEngine);
   if (!IsObject())
     throw new std::runtime_error("Attempting to set property on a non-object");
 
-  v8::Local<v8::String> property = Utils::ToV8String(context.jsEngine().GetIsolate(), name);
-  v8::Local<v8::Object> obj = v8::Local<v8::Object>::Cast(UnwrapValue(context.jsEngine()));
+  v8::Local<v8::String> property = Utils::ToV8String(context.GetJsEngine().GetIsolate(), name);
+  v8::Local<v8::Object> obj = v8::Local<v8::Object>::Cast(UnwrapValue(context.GetJsEngine()));
   obj->Set(property, val);
 }
 
 v8::Local<v8::Value> AdblockPlus::JsValue::UnwrapValue(JsEngine& jsEngine) const
 {
-  return v8::Local<v8::Value>::New(jsEngine.GetIsolate(), *m_value);
+  return v8::Local<v8::Value>::New(jsEngine.GetIsolate(), *value);
 }
 
 void AdblockPlus::JsValue::SetProperty(const std::string& name, const std::string& val)
 {
-  JsContext context(m_jsEngine);
-  SetProperty(name, Utils::ToV8String(context.jsEngine().GetIsolate(), val));
+  JsContext context(jsEngine);
+  SetProperty(name, Utils::ToV8String(context.GetJsEngine().GetIsolate(), val));
 }
 
 void AdblockPlus::JsValue::SetProperty(const std::string& name, int64_t val)
 {
-  JsContext context(m_jsEngine);
-  SetProperty(name, v8::Number::New(context.jsEngine().GetIsolate(), val));
+  JsContext context(jsEngine);
+  SetProperty(name, v8::Number::New(context.GetJsEngine().GetIsolate(), val));
 }
 
 void AdblockPlus::JsValue::SetProperty(const std::string& name, const JsValuePtr& val)
 {
-  JsContext context(m_jsEngine);
-  SetProperty(name, val->UnwrapValue(context.jsEngine()));
+  JsContext context(jsEngine);
+  SetProperty(name, val->UnwrapValue(context.GetJsEngine()));
 }
 
 void AdblockPlus::JsValue::SetProperty(const std::string& name, bool val)
 {
-  JsContext context(m_jsEngine);
+  JsContext context(jsEngine);
   SetProperty(name, v8::Boolean::New(val));
 }
 
 std::string AdblockPlus::JsValue::GetClass() const
 {
-  JsContext context(m_jsEngine);
+  JsContext context(jsEngine);
   if (!IsObject())
     throw new std::runtime_error("Cannot get constructor of a non-object");
 
-  v8::Local<v8::Object> obj = v8::Local<v8::Object>::Cast(UnwrapValue(context.jsEngine()));
+  v8::Local<v8::Object> obj = v8::Local<v8::Object>::Cast(UnwrapValue(context.GetJsEngine()));
   return Utils::FromV8String(obj->GetConstructorName());
 }
 
 AdblockPlus::JsValuePtr AdblockPlus::JsValue::Call(const JsValueList& params, JsValuePtr thisPtr) const
 {
-  JsContext context(m_jsEngine);
+  JsContext context(jsEngine);
   if (!IsFunction())
     throw new std::runtime_error("Attempting to call a non-function");
 
   if (!thisPtr)
   {
     v8::Local<v8::Context> localContext = v8::Local<v8::Context>::New(
-      context.jsEngine().GetIsolate(), *context.jsEngine().context);
-    thisPtr = JsValuePtr(new JsValue(m_jsEngine, localContext->Global()));
+      context.GetJsEngine().GetIsolate(), *context.GetJsEngine().context);
+    thisPtr = JsValuePtr(new JsValue(jsEngine, localContext->Global()));
   }
   if (!thisPtr->IsObject())
     throw new std::runtime_error("`this` pointer has to be an object");
-  v8::Local<v8::Object> thisObj = v8::Local<v8::Object>::Cast(thisPtr->UnwrapValue(context.jsEngine()));
+  v8::Local<v8::Object> thisObj = v8::Local<v8::Object>::Cast(thisPtr->UnwrapValue(context.GetJsEngine()));
 
   std::vector<v8::Handle<v8::Value>> argv;
   for (JsValueList::const_iterator it = params.begin(); it != params.end(); ++it)
-    argv.push_back((*it)->UnwrapValue(context.jsEngine()));
+    argv.push_back((*it)->UnwrapValue(context.GetJsEngine()));
 
   const v8::TryCatch tryCatch;
-  v8::Local<v8::Function> func = v8::Local<v8::Function>::Cast(UnwrapValue(context.jsEngine()));
+  v8::Local<v8::Function> func = v8::Local<v8::Function>::Cast(UnwrapValue(context.GetJsEngine()));
   v8::Local<v8::Value> result = func->Call(thisObj, argv.size(),
       argv.size() ? &argv.front() : 0);
 
   if (tryCatch.HasCaught())
     throw JsError(tryCatch.Exception(), tryCatch.Message());
 
-  return JsValuePtr(new JsValue(m_jsEngine, result));
+  return JsValuePtr(new JsValue(jsEngine, result));
 }
 
 AdblockPlus::JsValuePtr AdblockPlus::JsValue::Call(const JsValue& arg) const
 {
-  JsContext context(m_jsEngine);
+  JsContext context(jsEngine);
   JsValueList params;
-  params.push_back(JsValuePtr(new JsValue(arg.m_jsEngine, arg.UnwrapValue(context.jsEngine()))));
+  params.push_back(JsValuePtr(new JsValue(arg.jsEngine, arg.UnwrapValue(context.GetJsEngine()))));
   return Call(params);
 }