From 7c69ca58e0e8424446a8236e4f67e7c9b66710db 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 8857843a3b421b..23a3f6e8cd7c1c 100644
--- a/src/stream_base-inl.h
+++ b/src/stream_base-inl.h
@@ -30,26 +30,26 @@ 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>);
@@ -78,11 +78,10 @@ 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);
@@ -96,11 +95,10 @@ 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);
@@ -112,9 +110,8 @@ 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);
@@ -125,8 +122,7 @@ 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 28970839afa0c3..7d2f8d7ebbbd5f 100644
--- a/src/udp_wrap.cc
+++ b/src/udp_wrap.cc
@@ -79,12 +79,12 @@ 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);
@@ -137,7 +137,7 @@ 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