From 590001cc2a5c5a571c5064f9818ddb005b9608e1 Mon Sep 17 00:00:00 2001
From: Ben Noordhuis <info@bnoordhuis.nl>
Date: Wed, 25 Oct 2017 10:02:54 +0200
Subject: [PATCH] src: move handle properties to prototype
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Reduce the size of wrap objects by moving a couple of accessors from the
instance template to the prototype template.  They occupied one slot per
instance instead of one slot per class.

This commit fixes some instances of unwrapping twice since that code had
to be updated anyway to use `args.This()` instead of `args.Holder()`.

PR-URL: https://github.com/nodejs/node/pull/16482
Reviewed-By: Franziska Hinkelmann <franziska.hinkelmann@gmail.com>
Reviewed-By: Colin Ihrig <cjihrig@gmail.com>
Reviewed-By: Tobias Nießen <tniessen@tnie.de>
Reviewed-By: Anna Henningsen <anna@addaleax.net>
---
 src/stream_base-inl.h | 58 ++++++++++++++++++++-----------------------
 src/udp_wrap.cc       | 14 +++++------
 2 files changed, 34 insertions(+), 38 deletions(-)

diff --git a/src/stream_base-inl.h b/src/stream_base-inl.h
index 25293d2d06..562af2a533 100644
--- a/src/stream_base-inl.h
+++ b/src/stream_base-inl.h
@@ -33,26 +33,26 @@ void StreamBase::AddMethods(Environment* env,
 
   enum PropertyAttribute attributes =
       static_cast<PropertyAttribute>(v8::ReadOnly | v8::DontDelete);
-  t->InstanceTemplate()->SetAccessor(env->fd_string(),
-                                     GetFD<Base>,
-                                     nullptr,
-                                     env->as_external(),
-                                     v8::DEFAULT,
-                                     attributes);
-
-  t->InstanceTemplate()->SetAccessor(env->external_stream_string(),
-                                     GetExternal<Base>,
-                                     nullptr,
-                                     env->as_external(),
-                                     v8::DEFAULT,
-                                     attributes);
-
-  t->InstanceTemplate()->SetAccessor(env->bytes_read_string(),
-                                     GetBytesRead<Base>,
-                                     nullptr,
-                                     env->as_external(),
-                                     v8::DEFAULT,
-                                     attributes);
+  t->PrototypeTemplate()->SetAccessor(env->fd_string(),
+                                      GetFD<Base>,
+                                      nullptr,
+                                      env->as_external(),
+                                      v8::DEFAULT,
+                                      attributes);
+
+  t->PrototypeTemplate()->SetAccessor(env->external_stream_string(),
+                                      GetExternal<Base>,
+                                      nullptr,
+                                      env->as_external(),
+                                      v8::DEFAULT,
+                                      attributes);
+
+  t->PrototypeTemplate()->SetAccessor(env->bytes_read_string(),
+                                      GetBytesRead<Base>,
+                                      nullptr,
+                                      env->as_external(),
+                                      v8::DEFAULT,
+                                      attributes);
 
   env->SetProtoMethod(t, "readStart", JSMethod<Base, &StreamBase::ReadStart>);
   env->SetProtoMethod(t, "readStop", JSMethod<Base, &StreamBase::ReadStop>);
@@ -81,11 +81,10 @@ void StreamBase::AddMethods(Environment* env,
 template <class Base>
 void StreamBase::GetFD(Local<String> key,
                        const PropertyCallbackInfo<Value>& args) {
-  Base* handle = Unwrap<Base>(args.Holder());
-
   // Mimic implementation of StreamBase::GetFD() and UDPWrap::GetFD().
+  Base* handle;
   ASSIGN_OR_RETURN_UNWRAP(&handle,
-                          args.Holder(),
+                          args.This(),
                           args.GetReturnValue().Set(UV_EINVAL));
 
   StreamBase* wrap = static_cast<StreamBase*>(handle);
@@ -99,11 +98,10 @@ void StreamBase::GetFD(Local<String> key,
 template <class Base>
 void StreamBase::GetBytesRead(Local<String> key,
                               const PropertyCallbackInfo<Value>& args) {
-  Base* handle = Unwrap<Base>(args.Holder());
-
   // The handle instance hasn't been set. So no bytes could have been read.
+  Base* handle;
   ASSIGN_OR_RETURN_UNWRAP(&handle,
-                          args.Holder(),
+                          args.This(),
                           args.GetReturnValue().Set(0));
 
   StreamBase* wrap = static_cast<StreamBase*>(handle);
@@ -115,9 +113,8 @@ void StreamBase::GetBytesRead(Local<String> key,
 template <class Base>
 void StreamBase::GetExternal(Local<String> key,
                              const PropertyCallbackInfo<Value>& args) {
-  Base* handle = Unwrap<Base>(args.Holder());
-
-  ASSIGN_OR_RETURN_UNWRAP(&handle, args.Holder());
+  Base* handle;
+  ASSIGN_OR_RETURN_UNWRAP(&handle, args.This());
 
   StreamBase* wrap = static_cast<StreamBase*>(handle);
   Local<External> ext = External::New(args.GetIsolate(), wrap);
@@ -128,8 +125,7 @@ void StreamBase::GetExternal(Local<String> key,
 template <class Base,
           int (StreamBase::*Method)(const FunctionCallbackInfo<Value>& args)>
 void StreamBase::JSMethod(const FunctionCallbackInfo<Value>& args) {
-  Base* handle = Unwrap<Base>(args.Holder());
-
+  Base* handle;
   ASSIGN_OR_RETURN_UNWRAP(&handle, args.Holder());
 
   StreamBase* wrap = static_cast<StreamBase*>(handle);
diff --git a/src/udp_wrap.cc b/src/udp_wrap.cc
index d9dad98679..0461ef6a3b 100644
--- a/src/udp_wrap.cc
+++ b/src/udp_wrap.cc
@@ -113,12 +113,12 @@ void UDPWrap::Initialize(Local<Object> target,
 
   enum PropertyAttribute attributes =
       static_cast<PropertyAttribute>(v8::ReadOnly | v8::DontDelete);
-  t->InstanceTemplate()->SetAccessor(env->fd_string(),
-                                     UDPWrap::GetFD,
-                                     nullptr,
-                                     env->as_external(),
-                                     v8::DEFAULT,
-                                     attributes);
+  t->PrototypeTemplate()->SetAccessor(env->fd_string(),
+                                      UDPWrap::GetFD,
+                                      nullptr,
+                                      env->as_external(),
+                                      v8::DEFAULT,
+                                      attributes);
 
   env->SetProtoMethod(t, "bind", Bind);
   env->SetProtoMethod(t, "send", Send);
@@ -169,7 +169,7 @@ void UDPWrap::New(const FunctionCallbackInfo<Value>& args) {
 void UDPWrap::GetFD(Local<String>, const PropertyCallbackInfo<Value>& args) {
   int fd = UV_EBADF;
 #if !defined(_WIN32)
-  UDPWrap* wrap = Unwrap<UDPWrap>(args.Holder());
+  UDPWrap* wrap = Unwrap<UDPWrap>(args.This());
   if (wrap != nullptr)
     uv_fileno(reinterpret_cast<uv_handle_t*>(&wrap->handle_), &fd);
 #endif