From 7e680807f861ba145dbc20ea3113a291df99cb81 Mon Sep 17 00:00:00 2001
From: Anna Henningsen <anna@addaleax.net>
Date: Tue, 21 Nov 2017 12:38:27 +0100
Subject: [PATCH] src: add optional keep-alive object to SetImmediate

Adds the possibility to keep a strong persistent reference to
a JS object while a `SetImmediate()` call is in effect.

Backport-PR-URL: https://github.com/nodejs/node/pull/18050
PR-URL: https://github.com/nodejs/node/pull/17183
Reviewed-By: James M Snell <jasnell@gmail.com>
Reviewed-By: Franziska Hinkelmann <franziska.hinkelmann@gmail.com>
Reviewed-By: Anatoli Papirovski <apapirovski@mac.com>
---
 src/env-inl.h | 11 +++++++++--
 src/env.cc    |  2 ++
 src/env.h     |  7 ++++++-
 3 files changed, 17 insertions(+), 3 deletions(-)

diff --git a/src/env-inl.h b/src/env-inl.h
index b627cc159eafd9..955cf2688f88fa 100644
--- a/src/env-inl.h
+++ b/src/env-inl.h
@@ -506,8 +506,15 @@ Environment::scheduled_immediate_count() {
   return scheduled_immediate_count_;
 }
 
-void Environment::SetImmediate(native_immediate_callback cb, void* data) {
-  native_immediate_callbacks_.push_back({ cb, data });
+void Environment::SetImmediate(native_immediate_callback cb,
+                               void* data,
+                               v8::Local<v8::Object> obj) {
+  native_immediate_callbacks_.push_back({
+    cb,
+    data,
+    std::unique_ptr<v8::Persistent<v8::Object>>(
+        obj.IsEmpty() ? nullptr : new v8::Persistent<v8::Object>(isolate_, obj))
+  });
   if (scheduled_immediate_count_[0] == 0)
     ActivateImmediateCheck();
   scheduled_immediate_count_[0] = scheduled_immediate_count_[0] + 1;
diff --git a/src/env.cc b/src/env.cc
index 8f8255819b4a28..64fc2dea04e8d1 100644
--- a/src/env.cc
+++ b/src/env.cc
@@ -276,6 +276,8 @@ void Environment::RunAndClearNativeImmediates() {
     native_immediate_callbacks_.swap(list);
     for (const auto& cb : list) {
       cb.cb_(this, cb.data_);
+      if (cb.keep_alive_)
+        cb.keep_alive_->Reset();
     }
 
 #ifdef DEBUG
diff --git a/src/env.h b/src/env.h
index 99491c5dbd11eb..9414e357162d93 100644
--- a/src/env.h
+++ b/src/env.h
@@ -661,7 +661,11 @@ class Environment {
   bool EmitNapiWarning();
 
   typedef void (*native_immediate_callback)(Environment* env, void* data);
-  inline void SetImmediate(native_immediate_callback cb, void* data);
+  // cb will be called as cb(env, data) on the next event loop iteration.
+  // obj will be kept alive between now and after the callback has run.
+  inline void SetImmediate(native_immediate_callback cb,
+                           void* data,
+                           v8::Local<v8::Object> obj = v8::Local<v8::Object>());
   // This needs to be available for the JS-land setImmediate().
   void ActivateImmediateCheck();
 
@@ -741,6 +745,7 @@ class Environment {
   struct NativeImmediateCallback {
     native_immediate_callback cb_;
     void* data_;
+    std::unique_ptr<v8::Persistent<v8::Object>> keep_alive_;
   };
   std::vector<NativeImmediateCallback> native_immediate_callbacks_;
   void RunAndClearNativeImmediates();