[node] Need to have a singleton RunLoop instance

platform/node/src/node_file_source.cpp

@@ -1,5 +1,6 @@
 #include "node_file_source.hpp"
 #include "node_request.hpp"
+#include "node_mapbox_gl_native.hpp"
 
 namespace node_mbgl {
 
@@ -8,15 +9,8 @@ class NodeFileSourceRequest : public mbgl::FileRequest {
     std::unique_ptr<mbgl::WorkRequest> workRequest;
 };
 
-NodeFileSource::NodeFileSource(v8::Local<v8::Object> options_)
-    : nodeLoop(uv_default_loop()) {
+NodeFileSource::NodeFileSource(v8::Local<v8::Object> options_) {
     options.Reset(options_);
-
-    // This has the effect of unreffing an async handle, which otherwise would keep the
-    // default loop running. You would think we could do this in the destructor instead,
-    // but in fact the destructor might not get called if there's no GC pressure which
-    // would cause the NodeMap object which owns us to get destroyed.
-    nodeLoop.stop();
 }
 
 NodeFileSource::~NodeFileSource() {
@@ -28,7 +22,7 @@ std::unique_ptr<mbgl::FileRequest> NodeFileSource::request(const mbgl::Resource&
 
     // This function can be called from any thread. Make sure we're executing the
     // JS implementation in the node event loop.
-    req->workRequest = nodeLoop.invokeWithCallback([this] (mbgl::Resource res, Callback cb) {
+    req->workRequest = NodeRunLoop().invokeWithCallback([this] (mbgl::Resource res, Callback cb) {
         Nan::HandleScope scope;
 
         auto requestHandle = NodeRequest::Create(res, cb)->ToObject();

platform/node/src/node_file_source.hpp

@@ -1,7 +1,6 @@
 #pragma once
 
 #include <mbgl/storage/file_source.hpp>
-#include <mbgl/util/run_loop.hpp>
 
 #pragma GCC diagnostic push
 #pragma GCC diagnostic ignored "-Wunused-parameter"
@@ -21,7 +20,6 @@ class NodeFileSource : public mbgl::FileSource {
 
 private:
     Nan::Persistent<v8::Object> options;
-    mbgl::util::RunLoop nodeLoop;
 };
 
 }

platform/node/src/node_mapbox_gl_native.cpp

@@ -6,11 +6,26 @@
 #include <nan.h>
 #pragma GCC diagnostic pop
 
+#include "node_mapbox_gl_native.hpp"
 #include "node_map.hpp"
 #include "node_log.hpp"
 #include "node_request.hpp"
 
+namespace node_mbgl {
+
+mbgl::util::RunLoop& NodeRunLoop() {
+    static mbgl::util::RunLoop nodeRunLoop(uv_default_loop());
+    return nodeRunLoop;
+}
+
+}
+
 NAN_MODULE_INIT(RegisterModule) {
+    // This has the effect of:
+    //   a) Ensuring that the static local variable is initialized before any thread contention.
+    //   b) unreffing an async handle, which otherwise would keep the default loop running.
+    node_mbgl::NodeRunLoop().stop();
+
     node_mbgl::NodeMap::Init(target);
     node_mbgl::NodeRequest::Init(target);
 

platform/node/src/node_mapbox_gl_native.hpp

@@ -0,0 +1,9 @@
+#pragma once
+
+#include <mbgl/util/run_loop.hpp>
+
+namespace node_mbgl {
+
+mbgl::util::RunLoop& NodeRunLoop();
+
+}