handle_wrap: expose an `isRefed()` check to JS

This allows third-party tools to check whether or not a handle that
can be unreferenced is unreferenced at a particular time.
Notably, this should be helpful for inspection via AsyncWrap.

Also, this is useful even to node's internals, particularly timers.

Refs: https://github.com/nodejs/node/pull/5828
Refs: https://github.com/nodejs/node/pull/5827
PR-URL: https://github.com/nodejs/node/pull/5834
Reviewed-By: James M Snell <jasnell@gmail.com>
Reviewed-By: Colin Ihrig <cjihrig@gmail.com>
Reviewed-By: Trevor Norris <trev.norris@gmail.com>

9 files changed, 18 insertions, 0 deletions

diff --git a/src/handle_wrap.cc b/src/handle_wrap.cc
index 43c5490eefa..9af60d50258 100644
--- a/src/handle_wrap.cc
+++ b/src/handle_wrap.cc
@@ -9,6 +9,7 @@
 
 namespace node {
 
+using v8::Boolean;
 using v8::Context;
 using v8::FunctionCallbackInfo;
 using v8::HandleScope;
@@ -37,6 +38,15 @@ void HandleWrap::Unref(const FunctionCallbackInfo<Value>& args) {
 }
 
 
+void HandleWrap::IsRefed(const FunctionCallbackInfo<Value>& args) {
+  Environment* env = Environment::GetCurrent(args);
+  HandleWrap* wrap = Unwrap<HandleWrap>(args.Holder());
+
+  bool refed = IsAlive(wrap) && (wrap->flags_ & kUnref) == 0;
+  args.GetReturnValue().Set(refed);
+}
+
+
 void HandleWrap::Close(const FunctionCallbackInfo<Value>& args) {
   Environment* env = Environment::GetCurrent(args);
 
diff --git a/src/handle_wrap.h b/src/handle_wrap.h
index da712b33bef..cb3ba3f5d52 100644
--- a/src/handle_wrap.h
+++ b/src/handle_wrap.h
@@ -35,6 +35,7 @@ class HandleWrap : public AsyncWrap {
   static void Close(const v8::FunctionCallbackInfo<v8::Value>& args);
   static void Ref(const v8::FunctionCallbackInfo<v8::Value>& args);
   static void Unref(const v8::FunctionCallbackInfo<v8::Value>& args);
+  static void IsRefed(const v8::FunctionCallbackInfo<v8::Value>& args);
 
   static inline bool IsAlive(const HandleWrap* wrap) {
     return wrap != nullptr && wrap->GetHandle() != nullptr;
diff --git a/src/pipe_wrap.cc b/src/pipe_wrap.cc
index db2fd16715c..ec6ef32b08a 100644
--- a/src/pipe_wrap.cc
+++ b/src/pipe_wrap.cc
@@ -81,6 +81,7 @@ void PipeWrap::Initialize(Local<Object> target,
   env->SetProtoMethod(t, "close", HandleWrap::Close);
   env->SetProtoMethod(t, "unref", HandleWrap::Unref);
   env->SetProtoMethod(t, "ref", HandleWrap::Ref);
+  env->SetProtoMethod(t, "isRefed", HandleWrap::IsRefed);
 
   StreamWrap::AddMethods(env, t);
 
diff --git a/src/process_wrap.cc b/src/process_wrap.cc
index 7e9d2070bb9..dec93ddd0cd 100644
--- a/src/process_wrap.cc
+++ b/src/process_wrap.cc
@@ -40,6 +40,7 @@ class ProcessWrap : public HandleWrap {
 
     env->SetProtoMethod(constructor, "ref", HandleWrap::Ref);
     env->SetProtoMethod(constructor, "unref", HandleWrap::Unref);
+    env->SetProtoMethod(constructor, "isRefed", HandleWrap::IsRefed);
 
     target->Set(FIXED_ONE_BYTE_STRING(env->isolate(), "Process"),
                 constructor->GetFunction());
diff --git a/src/signal_wrap.cc b/src/signal_wrap.cc
index 5f6a6a52bcd..ca5201d81a4 100644
--- a/src/signal_wrap.cc
+++ b/src/signal_wrap.cc
@@ -32,6 +32,7 @@ class SignalWrap : public HandleWrap {
     env->SetProtoMethod(constructor, "close", HandleWrap::Close);
     env->SetProtoMethod(constructor, "ref", HandleWrap::Ref);
     env->SetProtoMethod(constructor, "unref", HandleWrap::Unref);
+    env->SetProtoMethod(constructor, "isRefed", HandleWrap::IsRefed);
     env->SetProtoMethod(constructor, "start", Start);
     env->SetProtoMethod(constructor, "stop", Stop);
 
diff --git a/src/tcp_wrap.cc b/src/tcp_wrap.cc
index 50fcb506aea..4bfe9dd0d83 100644
--- a/src/tcp_wrap.cc
+++ b/src/tcp_wrap.cc
@@ -88,6 +88,7 @@ void TCPWrap::Initialize(Local<Object> target,
 
   env->SetProtoMethod(t, "ref", HandleWrap::Ref);
   env->SetProtoMethod(t, "unref", HandleWrap::Unref);
+  env->SetProtoMethod(t, "isRefed", HandleWrap::IsRefed);
 
   StreamWrap::AddMethods(env, t, StreamBase::kFlagHasWritev);
 
diff --git a/src/timer_wrap.cc b/src/timer_wrap.cc
index 79fa86953d4..4a1cd3716a9 100644
--- a/src/timer_wrap.cc
+++ b/src/timer_wrap.cc
@@ -39,6 +39,7 @@ class TimerWrap : public HandleWrap {
     env->SetProtoMethod(constructor, "close", HandleWrap::Close);
     env->SetProtoMethod(constructor, "ref", HandleWrap::Ref);
     env->SetProtoMethod(constructor, "unref", HandleWrap::Unref);
+    env->SetProtoMethod(constructor, "isRefed", HandleWrap::IsRefed);
 
     env->SetProtoMethod(constructor, "start", Start);
     env->SetProtoMethod(constructor, "stop", Stop);
diff --git a/src/tty_wrap.cc b/src/tty_wrap.cc
index a78d2311456..567a504276a 100644
--- a/src/tty_wrap.cc
+++ b/src/tty_wrap.cc
@@ -37,6 +37,7 @@ void TTYWrap::Initialize(Local<Object> target,
 
   env->SetProtoMethod(t, "close", HandleWrap::Close);
   env->SetProtoMethod(t, "unref", HandleWrap::Unref);
+  env->SetProtoMethod(t, "isRefed", HandleWrap::IsRefed);
 
   StreamWrap::AddMethods(env, t, StreamBase::kFlagNoShutdown);
 
diff --git a/src/udp_wrap.cc b/src/udp_wrap.cc
index dc2804812fd..ac087f395ac 100644
--- a/src/udp_wrap.cc
+++ b/src/udp_wrap.cc
@@ -108,6 +108,7 @@ void UDPWrap::Initialize(Local<Object> target,
 
   env->SetProtoMethod(t, "ref", HandleWrap::Ref);
   env->SetProtoMethod(t, "unref", HandleWrap::Unref);
+  env->SetProtoMethod(t, "isRefed", HandleWrap::IsRefed);
 
   target->Set(FIXED_ONE_BYTE_STRING(env->isolate(), "UDP"), t->GetFunction());
   env->set_udp_constructor_function(t->GetFunction());