src: use ObjectTemplate for creating stream req objs

This allows V8 to avoid preparing a execution context for the constructor, to give a (kinda) small but noticeable perf gain. Benchmarks (only this commit): $ ./node benchmark/compare.js --new ./node --old ./node-master --filter net-c2s.js --set len=10 --set type=asc --runs 360 net | Rscript benchmark/compare.R [01:15:27|% 100| 1/1 files | 720/720 runs | 1/1 configs]: Done confidence improvement accuracy (*) (**) (***) net/net-c2s.js dur=5 type='asc' len=10 *** 0.69 % ±0.31% ±0.41% ±0.53% PR-URL: #18936 Reviewed-By: James M Snell <jasnell@gmail.com> Reviewed-By: Matteo Collina <matteo.collina@gmail.com>
nodejs · addaleax · Feb 24, 2018 · Feb 12, 2018 · Feb 22, 2018 · Mar 7, 2018
commit cf72772498b952b85f6fa88446ec72b7cfd2ab17
diff --git a/src/env.h b/src/env.h
@@ -329,7 +329,7 @@ struct PackageConfig {
   V(script_context_constructor_template, v8::FunctionTemplate)                \
   V(script_data_constructor_function, v8::Function)                           \
   V(secure_context_constructor_template, v8::FunctionTemplate)                \
-  V(shutdown_wrap_constructor_function, v8::Function)                         \
+  V(shutdown_wrap_template, v8::ObjectTemplate)                               \
   V(tcp_constructor_template, v8::FunctionTemplate)                           \
   V(tick_callback_function, v8::Function)                                     \
   V(timers_callback_function, v8::Function)                                   \
@@ -338,7 +338,7 @@ struct PackageConfig {
   V(udp_constructor_function, v8::Function)                                   \
   V(vm_parsing_context_symbol, v8::Symbol)                                    \
   V(url_constructor_function, v8::Function)                                   \
-  V(write_wrap_constructor_function, v8::Function)                            \
+  V(write_wrap_template, v8::ObjectTemplate)                                  \
   V(fs_use_promises_symbol, v8::Symbol)
 
 class Environment;

diff --git a/src/stream_base-inl.h b/src/stream_base-inl.h
@@ -164,8 +164,9 @@ inline int StreamBase::Shutdown(v8::Local<v8::Object> req_wrap_obj) {
 
   if (req_wrap_obj.IsEmpty()) {
     req_wrap_obj =
-        env->shutdown_wrap_constructor_function()
+        env->shutdown_wrap_template()
             ->NewInstance(env->context()).ToLocalChecked();
+    StreamReq::ResetObject(req_wrap_obj);
   }
 
   AsyncHooks::DefaultTriggerAsyncIdScope trigger_scope(GetAsyncWrap());
@@ -203,8 +204,9 @@ inline StreamWriteResult StreamBase::Write(
 
   if (req_wrap_obj.IsEmpty()) {
     req_wrap_obj =
-        env->write_wrap_constructor_function()
+        env->write_wrap_template()
             ->NewInstance(env->context()).ToLocalChecked();
+    StreamReq::ResetObject(req_wrap_obj);
   }
 
   AsyncHooks::DefaultTriggerAsyncIdScope trigger_scope(GetAsyncWrap());
@@ -427,6 +429,15 @@ inline void StreamReq::Done(int status, const char* error_str) {
   OnDone(status);
 }
 
+inline void StreamReq::ResetObject(v8::Local<v8::Object> obj) {
+#ifdef DEBUG
+  CHECK_GT(obj->InternalFieldCount(), StreamReq::kStreamReqField);
+#endif
+  ClearWrap(obj);
+  obj->SetAlignedPointerInInternalField(StreamReq::kStreamReqField, nullptr);
+}
+
+
 }  // namespace node
 
 #endif  // defined(NODE_WANT_INTERNALS) && NODE_WANT_INTERNALS

diff --git a/src/stream_base.h b/src/stream_base.h
@@ -46,6 +46,13 @@ class StreamReq {
 
   static StreamReq* FromObject(v8::Local<v8::Object> req_wrap_obj);
 
+  // Sets all internal fields of `req_wrap_obj` to `nullptr`.
+  // This is what the `WriteWrap` and `ShutdownWrap` JS constructors do,
+  // and what we use in C++ after creating these objects from their
+  // v8::ObjectTemplates, to avoid the overhead of calling the
+  // constructor explicitly.
+  static inline void ResetObject(v8::Local<v8::Object> req_wrap_obj);
+
  protected:
   virtual void OnDone(int status) = 0;
 

diff --git a/src/stream_wrap.cc b/src/stream_wrap.cc
@@ -60,9 +60,7 @@ void LibuvStreamWrap::Initialize(Local<Object> target,
   auto is_construct_call_callback =
       [](const FunctionCallbackInfo<Value>& args) {
     CHECK(args.IsConstructCall());
-    ClearWrap(args.This());
-    args.This()->SetAlignedPointerInInternalField(
-        StreamReq::kStreamReqField, nullptr);
+    StreamReq::ResetObject(args.This());
   };
   Local<FunctionTemplate> sw =
       FunctionTemplate::New(env->isolate(), is_construct_call_callback);
@@ -72,7 +70,7 @@ void LibuvStreamWrap::Initialize(Local<Object> target,
   sw->SetClassName(wrapString);
   AsyncWrap::AddWrapMethods(env, sw);
   target->Set(wrapString, sw->GetFunction());
-  env->set_shutdown_wrap_constructor_function(sw->GetFunction());
+  env->set_shutdown_wrap_template(sw->InstanceTemplate());
 
   Local<FunctionTemplate> ww =
       FunctionTemplate::New(env->isolate(), is_construct_call_callback);
@@ -82,7 +80,7 @@ void LibuvStreamWrap::Initialize(Local<Object> target,
   ww->SetClassName(writeWrapString);
   AsyncWrap::AddWrapMethods(env, ww);
   target->Set(writeWrapString, ww->GetFunction());
-  env->set_write_wrap_constructor_function(ww->GetFunction());
+  env->set_write_wrap_template(ww->InstanceTemplate());
 }