From b602835626dfc1532bf5c26b9d2c34054a2d8fac Mon Sep 17 00:00:00 2001
From: "Thiago Marcos P. Santos" <tmpsantos@gmail.com>
Date: Mon, 15 Jun 2015 01:55:20 +0300
Subject: [PATCH] Fix invalid NodeRequest reference

On the code path built with node v0.12.4, we are storing
an invalid reference to NodeRequest on the "pending" list. It will
crash when we need to access it like we do when canceling a request.

Ideally we should just have a "std::unordered_map<mbgl::Resource,
v8::UniquePersistent>" but that is not possible because the move
semantics are not fully implemented until V8 v4.3.22. It can be used
on a std::vector but not on a std::map.

See: https://code.google.com/p/v8/issues/detail?id=3669

The solution for keep using C++11 move semantics is to declare the
v8::CopyablePersistentTraits shenanigans and explicitly clear the
v8::Persistent (like we do already for node v0.10).

When Node gets V8 v4.3.22+ we can go back to v8::UniquePersistent
with a more clear implementation.
---
 src/node_file_source.cpp | 14 +++++---------
 src/node_file_source.hpp |  2 +-
 2 files changed, 6 insertions(+), 10 deletions(-)

diff --git a/src/node_file_source.cpp b/src/node_file_source.cpp
index 935bac427..3409f03af 100644
--- a/src/node_file_source.cpp
+++ b/src/node_file_source.cpp
@@ -121,12 +121,9 @@ void NodeFileSource::processAdd(const mbgl::Resource& resource) {
 
     auto handle = NanObjectWrapHandle(this);
     auto requestHandle = NanNew<v8::Object>(NodeRequest::Create(handle, resource));
-#if (NODE_MODULE_VERSION > NODE_0_10_MODULE_VERSION)
-    const v8::UniquePersistent<v8::Object> requestPersistent(v8::Isolate::GetCurrent(), requestHandle);
-#else
+
     v8::Persistent<v8::Object> requestPersistent;
     NanAssignPersistent(requestPersistent, requestHandle);
-#endif
     pending.emplace(resource, std::move(requestPersistent));
 
     v8::Local<v8::Value> argv[] = { requestHandle };
@@ -143,12 +140,9 @@ void NodeFileSource::processCancel(const mbgl::Resource& resource) {
     } else {
 #if (NODE_MODULE_VERSION > NODE_0_10_MODULE_VERSION)
         auto requestHandle = v8::Local<v8::Object>::New(v8::Isolate::GetCurrent(), it->second);
+        it->second.Reset();
 #else
         auto requestHandle = NanNew<v8::Object>(it->second);
-#endif
-
-        // Dispose and remove the persistent handle
-#if (NODE_MODULE_VERSION <= NODE_0_10_MODULE_VERSION)
         NanDisposePersistent(it->second);
 #endif
         pending.erase(it);
@@ -173,7 +167,9 @@ void NodeFileSource::notify(const mbgl::Resource& resource, const std::shared_pt
     // First, remove the request, since it might be destructed at any point now.
     auto it = pending.find(resource);
     if (it != pending.end()) {
-#if (NODE_MODULE_VERSION <= NODE_0_10_MODULE_VERSION)
+#if (NODE_MODULE_VERSION > NODE_0_10_MODULE_VERSION)
+        it->second.Reset();
+#else
         NanDisposePersistent(it->second);
 #endif
         pending.erase(it);
diff --git a/src/node_file_source.hpp b/src/node_file_source.hpp
index 5220cd235..06b1c3d32 100644
--- a/src/node_file_source.hpp
+++ b/src/node_file_source.hpp
@@ -49,7 +49,7 @@ private:
 
 private:
 #if (NODE_MODULE_VERSION > NODE_0_10_MODULE_VERSION)
-    std::unordered_map<mbgl::Resource, const v8::UniquePersistent<v8::Object> &, mbgl::Resource::Hash> pending;
+    std::unordered_map<mbgl::Resource, v8::Persistent<v8::Object, v8::CopyablePersistentTraits<v8::Object>>, mbgl::Resource::Hash> pending;
 #else
     std::unordered_map<mbgl::Resource, v8::Persistent<v8::Object>, mbgl::Resource::Hash> pending;
 #endif