Revert 186643 - Caused a 10% regression on SunSpider benchmark

chrome/renderer/extensions/module_system.cc

 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "chrome/renderer/extensions/module_system.h"
 
 #include "base/bind.h"
-#include "base/debug/alias.h"
 #include "base/stl_util.h"
-#include "base/string_util.h"
-#include "base/stringprintf.h"
-#include "chrome/common/extensions/extension_messages.h"
-#include "chrome/renderer/extensions/chrome_v8_context.h"
-#include "content/public/renderer/render_view.h"
 #include "third_party/WebKit/Source/WebKit/chromium/public/WebScopedMicrotaskSuppression.h"
 
 namespace {
 
 const char* kModuleSystem = "module_system";
 const char* kModuleName = "module_name";
 const char* kModuleField = "module_field";
 const char* kModulesField = "modules";
 
 } // namespace
 
 namespace extensions {
 
 ModuleSystem::ModuleSystem(v8::Handle<v8::Context> context,
                            SourceMap* source_map)
-    : ObjectBackedNativeHandler(context),
+    : NativeHandler(context->GetIsolate()),
+      context_(v8::Persistent<v8::Context>::New(context->GetIsolate(),
+                                                context)),
       source_map_(source_map),
       natives_enabled_(0) {
   RouteFunction("require",
       base::Bind(&ModuleSystem::RequireForJs, base::Unretained(this)));
   RouteFunction("requireNative",
-      base::Bind(&ModuleSystem::RequireNative, base::Unretained(this)));
+      base::Bind(&ModuleSystem::GetNative, base::Unretained(this)));
 
-  v8::Handle<v8::Object> global(context->Global());
+  v8::Handle<v8::Object> global(context_->Global());
   global->SetHiddenValue(v8::String::New(kModulesField), v8::Object::New());
   global->SetHiddenValue(v8::String::New(kModuleSystem),
                          v8::External::New(this));
 }
 
 ModuleSystem::~ModuleSystem() {
-  Invalidate();
-}
-
-void ModuleSystem::Invalidate() {
-  if (!is_valid())
-    return;
-  for (NativeHandlerMap::iterator it = native_handler_map_.begin();
-       it != native_handler_map_.end(); ++it) {
-    it->second->Invalidate();
-  }
-  ObjectBackedNativeHandler::Invalidate();
+  v8::HandleScope handle_scope;
+  // Deleting this value here prevents future lazy field accesses from
+  // referencing ModuleSystem after it has been freed.
+  context_->Global()->DeleteHiddenValue(v8::String::New(kModuleSystem));
+  context_.Dispose(context_->GetIsolate());
 }
 
 ModuleSystem::NativesEnabledScope::NativesEnabledScope(
     ModuleSystem* module_system)
     : module_system_(module_system) {
   module_system_->natives_enabled_++;
 }
 
 ModuleSystem::NativesEnabledScope::~NativesEnabledScope() {
   module_system_->natives_enabled_--;
   CHECK_GE(module_system_->natives_enabled_, 0);
 }
 
+// static
+bool ModuleSystem::IsPresentInCurrentContext() {
+  v8::Handle<v8::Object> global(v8::Context::GetCurrent()->Global());
+  if (global.IsEmpty())
+    return false;
+  v8::Handle<v8::Value> module_system =
+      global->GetHiddenValue(v8::String::New(kModuleSystem));
+  return !module_system.IsEmpty() && !module_system->IsUndefined();
+}
+
 void ModuleSystem::HandleException(const v8::TryCatch& try_catch) {
   DumpException(try_catch);
   if (exception_handler_.get())
     exception_handler_->HandleUncaughtException();
 }
 
 // static
-std::string ModuleSystem::CreateExceptionString(const v8::TryCatch& try_catch) {
+void ModuleSystem::DumpException(const v8::TryCatch& try_catch) {
+  v8::HandleScope handle_scope;
+
   v8::Handle<v8::Message> message(try_catch.Message());
   if (message.IsEmpty()) {
-    return "try_catch has no message";
+    LOG(ERROR) << "try_catch has no message";
+    return;
   }
 
   std::string resource_name = "<unknown resource>";
   if (!message->GetScriptResourceName().IsEmpty()) {
     resource_name =
         *v8::String::Utf8Value(message->GetScriptResourceName()->ToString());
   }
 
   std::string error_message = "<no error message>";
   if (!message->Get().IsEmpty())
     error_message = *v8::String::Utf8Value(message->Get());
 
-  return base::StringPrintf("%s:%d: %s",
-                            resource_name.c_str(),
-                            message->GetLineNumber(),
-                            error_message.c_str());
-}
-
-// static
-void ModuleSystem::DumpException(const v8::TryCatch& try_catch) {
-  v8::HandleScope handle_scope;
-
   std::string stack_trace = "<stack trace unavailable>";
   if (!try_catch.StackTrace().IsEmpty()) {
     v8::String::Utf8Value stack_value(try_catch.StackTrace());
     if (*stack_value)
       stack_trace.assign(*stack_value, stack_value.length());
     else
       stack_trace = "<could not convert stack trace to string>";
   }
 
-  LOG(ERROR) << CreateExceptionString(try_catch) << "{" << stack_trace << "}";
+  LOG(ERROR) << "[" << resource_name << "(" << message->GetLineNumber() << ")] "
+             << error_message
+             << "{" << stack_trace << "}";
 }
 
-v8::Handle<v8::Value> ModuleSystem::Require(const std::string& module_name) {
+void ModuleSystem::Require(const std::string& module_name) {
   v8::HandleScope handle_scope;
-  return handle_scope.Close(
-      RequireForJsInner(v8::String::New(module_name.c_str())));
+  RequireForJsInner(v8::String::New(module_name.c_str()));
 }
 
 v8::Handle<v8::Value> ModuleSystem::RequireForJs(const v8::Arguments& args) {
   v8::HandleScope handle_scope;
   v8::Handle<v8::String> module_name = args[0]->ToString();
   return handle_scope.Close(RequireForJsInner(module_name));
 }
 
 v8::Handle<v8::Value> ModuleSystem::RequireForJsInner(
     v8::Handle<v8::String> module_name) {
   v8::HandleScope handle_scope;
-  v8::Handle<v8::Object> global(v8_context()->Global());
+  v8::Handle<v8::Object> global(v8::Context::GetCurrent()->Global());
   v8::Handle<v8::Object> modules(v8::Handle<v8::Object>::Cast(
       global->GetHiddenValue(v8::String::New(kModulesField))));
   v8::Handle<v8::Value> exports(modules->Get(module_name));
   if (!exports->IsUndefined())
     return handle_scope.Close(exports);
 
   v8::Handle<v8::Value> source(GetSource(module_name));
   if (source->IsUndefined())
     return handle_scope.Close(v8::Undefined());
   v8::Handle<v8::String> wrapped_source(WrapSource(
@@ skipping 19 matching lines @@
     func->Call(global, 3, args);
     if (try_catch.HasCaught()) {
       HandleException(try_catch);
       return v8::Undefined();
     }
   }
   modules->Set(module_name, exports);
   return handle_scope.Close(exports);
 }
 
-v8::Local<v8::Value> ModuleSystem::CallModuleMethod(
-    const std::string& module_name,
-    const std::string& method_name) {
+void ModuleSystem::CallModuleMethod(const std::string& module_name,
+                                    const std::string& method_name) {
   std::vector<v8::Handle<v8::Value> > args;
-  return CallModuleMethod(module_name, method_name, &args);
+  CallModuleMethod(module_name, method_name, &args);
 }
 
 v8::Local<v8::Value> ModuleSystem::CallModuleMethod(
     const std::string& module_name,
     const std::string& method_name,
     std::vector<v8::Handle<v8::Value> >* args) {
   v8::HandleScope handle_scope;
   v8::Local<v8::Value> module =
       v8::Local<v8::Value>::New(
           RequireForJsInner(v8::String::New(module_name.c_str())));
   if (module.IsEmpty() || !module->IsObject())
     return v8::Local<v8::Value>();
   v8::Local<v8::Value> value =
       v8::Handle<v8::Object>::Cast(module)->Get(
           v8::String::New(method_name.c_str()));
   if (value.IsEmpty() || !value->IsFunction())
     return v8::Local<v8::Value>();
   v8::Handle<v8::Function> func =
       v8::Handle<v8::Function>::Cast(value);
-  v8::Handle<v8::Object> global(v8_context()->Global());
+  // TODO(jeremya/koz): refer to context_ here, not the current context.
+  v8::Handle<v8::Object> global(v8::Context::GetCurrent()->Global());
   v8::Local<v8::Value> result;
   {
     WebKit::WebScopedMicrotaskSuppression suppression;
     v8::TryCatch try_catch;
     try_catch.SetCaptureMessage(true);
     result = func->Call(global, args->size(), vector_as_array(args));
     if (try_catch.HasCaught())
       HandleException(try_catch);
   }
   return handle_scope.Close(result);
 }
 
-bool ModuleSystem::HasNativeHandler(const std::string& name) {
-  return native_handler_map_.find(name) != native_handler_map_.end();
-}
-
 void ModuleSystem::RegisterNativeHandler(const std::string& name,
     scoped_ptr<NativeHandler> native_handler) {
   native_handler_map_[name] =
       linked_ptr<NativeHandler>(native_handler.release());
 }
 
 void ModuleSystem::OverrideNativeHandler(const std::string& name) {
   overridden_native_handlers_.insert(name);
 }
 
 void ModuleSystem::RunString(const std::string& code, const std::string& name) {
   v8::HandleScope handle_scope;
   RunString(v8::String::New(code.c_str()), v8::String::New(name.c_str()));
 }
 
 // static
-v8::Handle<v8::Value> ModuleSystem::NativeLazyFieldGetter(
-    v8::Local<v8::String> property, const v8::AccessorInfo& info) {
-  return LazyFieldGetterInner(property,
-                              info,
-                              &ModuleSystem::RequireNativeFromString);
-}
-
-// static
 v8::Handle<v8::Value> ModuleSystem::LazyFieldGetter(
     v8::Local<v8::String> property, const v8::AccessorInfo& info) {
-  return LazyFieldGetterInner(property, info, &ModuleSystem::Require);
-}
-
-// static
-v8::Handle<v8::Value> ModuleSystem::LazyFieldGetterInner(
-    v8::Local<v8::String> property,
-    const v8::AccessorInfo& info,
-    RequireFunction require_function) {
   CHECK(!info.Data().IsEmpty());
   CHECK(info.Data()->IsObject());
   v8::HandleScope handle_scope;
   v8::Handle<v8::Object> parameters = v8::Handle<v8::Object>::Cast(info.Data());
-  // This context should be the same as v8_context_, but this method is static.
-  v8::Handle<v8::Context> context = parameters->CreationContext();
-  v8::Handle<v8::Object> global(context->Global());
+  v8::Handle<v8::Object> global(v8::Context::GetCurrent()->Global());
   v8::Handle<v8::Value> module_system_value =
       global->GetHiddenValue(v8::String::New(kModuleSystem));
   if (module_system_value.IsEmpty() || module_system_value->IsUndefined()) {
     // ModuleSystem has been deleted.
     return v8::Undefined();
   }
   ModuleSystem* module_system = static_cast<ModuleSystem*>(
       v8::Handle<v8::External>::Cast(module_system_value)->Value());
 
-  std::string name = *v8::String::AsciiValue(
-      parameters->Get(v8::String::New(kModuleName))->ToString());
-
-  // Switch to our v8 context because we need functions created while running
-  // the require()d module to belong to our context, not the current one.
-  v8::Context::Scope context_scope(context);
-  NativesEnabledScope natives_enabled_scope(module_system);
-
-  v8::TryCatch try_catch;
-  v8::Handle<v8::Object> module = v8::Handle<v8::Object>::Cast(
-      (module_system->*require_function)(name));
-  if (try_catch.HasCaught()) {
-    module_system->HandleException(try_catch);
-    return handle_scope.Close(v8::Handle<v8::Value>());
+  v8::Handle<v8::Object> module;
+  {
+    NativesEnabledScope scope(module_system);
+    module = v8::Handle<v8::Object>::Cast(module_system->RequireForJsInner(
+        parameters->Get(v8::String::New(kModuleName))->ToString()));
   }
-
   if (module.IsEmpty())
     return handle_scope.Close(v8::Handle<v8::Value>());
 
   v8::Handle<v8::String> field =
       parameters->Get(v8::String::New(kModuleField))->ToString();
 
-  // http://crbug.com/179741.
-  std::string field_name = *v8::String::AsciiValue(field);
-  char stack_debug[64];
-  base::debug::Alias(&stack_debug);
-  base::snprintf(stack_debug, arraysize(stack_debug),
-                 "%s.%s", name.c_str(), field_name.c_str());
-
-  v8::Local<v8::Value> new_field = module->Get(field);
-  v8::Handle<v8::Object> object = info.This();
-  // Delete the getter and set this field to |new_field| so the same object is
-  // returned every time a certain API is accessed.
-  // CHECK is for http://crbug.com/179741.
-  CHECK(!new_field.IsEmpty()) << "Empty require " << name << "." << field_name;
-  if (!new_field->IsUndefined()) {
-    object->Delete(property);
-    object->Set(property, new_field);
-  }
-  return handle_scope.Close(new_field);
+  return handle_scope.Close(module->Get(field));
 }
 
 void ModuleSystem::SetLazyField(v8::Handle<v8::Object> object,
                                 const std::string& field,
                                 const std::string& module_name,
                                 const std::string& module_field) {
-  SetLazyField(object, field, module_name, module_field,
-      &ModuleSystem::LazyFieldGetter);
-}
-
-void ModuleSystem::SetLazyField(v8::Handle<v8::Object> object,
-                                const std::string& field,
-                                const std::string& module_name,
-                                const std::string& module_field,
-                                v8::AccessorGetter getter) {
   v8::HandleScope handle_scope;
   v8::Handle<v8::Object> parameters = v8::Object::New();
   parameters->Set(v8::String::New(kModuleName),
                   v8::String::New(module_name.c_str()));
   parameters->Set(v8::String::New(kModuleField),
                   v8::String::New(module_field.c_str()));
+
   object->SetAccessor(v8::String::New(field.c_str()),
-                      getter,
+                      &ModuleSystem::LazyFieldGetter,
                       NULL,
                       parameters);
 }
 
-void ModuleSystem::SetNativeLazyField(v8::Handle<v8::Object> object,
-                                      const std::string& field,
-                                      const std::string& module_name,
-                                      const std::string& module_field) {
-  SetLazyField(object, field, module_name, module_field,
-      &ModuleSystem::NativeLazyFieldGetter);
-}
-
 v8::Handle<v8::Value> ModuleSystem::RunString(v8::Handle<v8::String> code,
                                               v8::Handle<v8::String> name) {
   v8::HandleScope handle_scope;
   WebKit::WebScopedMicrotaskSuppression suppression;
   v8::Handle<v8::Value> result;
   v8::TryCatch try_catch;
   try_catch.SetCaptureMessage(true);
   v8::Handle<v8::Script> script(v8::Script::New(code, name));
   if (try_catch.HasCaught()) {
     HandleException(try_catch);
     return handle_scope.Close(result);
   }
 
   result = script->Run();
   if (try_catch.HasCaught())
     HandleException(try_catch);
 
   return handle_scope.Close(result);
 }
 
 v8::Handle<v8::Value> ModuleSystem::GetSource(
     v8::Handle<v8::String> source_name) {
   v8::HandleScope handle_scope;
   std::string module_name = *v8::String::AsciiValue(source_name);
   if (!source_map_->Contains(module_name))
     return v8::Undefined();
   return handle_scope.Close(source_map_->GetSource(module_name));
 }
 
-v8::Handle<v8::Value> ModuleSystem::RequireNative(const v8::Arguments& args) {
+v8::Handle<v8::Value> ModuleSystem::GetNative(const v8::Arguments& args) {
   CHECK_EQ(1, args.Length());
-  std::string native_name = *v8::String::AsciiValue(args[0]->ToString());
-  return RequireNativeFromString(native_name);
-}
-
-v8::Handle<v8::Value> ModuleSystem::RequireNativeFromString(
-    const std::string& native_name) {
   if (natives_enabled_ == 0)
     return ThrowException("Natives disabled");
+  std::string native_name = *v8::String::AsciiValue(args[0]->ToString());
   if (overridden_native_handlers_.count(native_name) > 0u)
-    return RequireForJsInner(v8::String::New(native_name.c_str()));
+    return RequireForJs(args);
   NativeHandlerMap::iterator i = native_handler_map_.find(native_name);
   if (i == native_handler_map_.end())
     return v8::Undefined();
   return i->second->NewInstance();
 }
 
 v8::Handle<v8::String> ModuleSystem::WrapSource(v8::Handle<v8::String> source) {
   v8::HandleScope handle_scope;
   v8::Handle<v8::String> left = v8::String::New(
       "(function(require, requireNative, exports) {'use strict';");
   v8::Handle<v8::String> right = v8::String::New("\n})");
   return handle_scope.Close(
       v8::String::Concat(left, v8::String::Concat(source, right)));
 }
 
 v8::Handle<v8::Value> ModuleSystem::ThrowException(const std::string& message) {
   return v8::ThrowException(v8::String::New(message.c_str()));
 }
 
 }  // extensions