src: add helper for addons to get the event loop

addaleax · addaleax · commit c0f3bc24de1c · 2017-11-21T08:33:19.000+01:00
Add a utility functions for addons to use when they need a reference to the current event loop. Currently, `uv_default_loop()` works if the embedder is the single-threaded default node executable, but even without the presence of e.g. workers that might not really an API guarantee for when Node is embedded. PR-URL: nodejs#17109 Reviewed-By: Ben Noordhuis <info@bnoordhuis.nl> Reviewed-By: Colin Ihrig <cjihrig@gmail.com>
diff --git a/src/node.cc b/src/node.cc
@@ -4332,6 +4332,15 @@ void RunAtExit(Environment* env) {
 }
 
 
+uv_loop_t* GetCurrentEventLoop(v8::Isolate* isolate) {
+  HandleScope handle_scope(isolate);
+  auto context = isolate->GetCurrentContext();
+  if (context.IsEmpty())
+    return nullptr;
+  return Environment::GetCurrent(context)->event_loop();
+}
+
+
 static uv_key_t thread_local_env;
 
 
diff --git a/src/node.h b/src/node.h
@@ -248,6 +248,10 @@ NODE_EXTERN void EmitBeforeExit(Environment* env);
 NODE_EXTERN int EmitExit(Environment* env);
 NODE_EXTERN void RunAtExit(Environment* env);
 
+// This may return nullptr if the current v8::Context is not associated
+// with a Node instance.
+NODE_EXTERN struct uv_loop_s* GetCurrentEventLoop(v8::Isolate* isolate);
+
 /* Converts a unixtime to V8 Date */
 #define NODE_UNIXTIME_V8(t) v8::Date::New(v8::Isolate::GetCurrent(),          \
     1000 * static_cast<double>(t))
diff --git a/test/addons/async-hello-world/binding.cc b/test/addons/async-hello-world/binding.cc
@@ -77,7 +77,7 @@ void Method(const v8::FunctionCallbackInfo<v8::Value>& args) {
   v8::Local<v8::Function> callback = v8::Local<v8::Function>::Cast(args[1]);
   req->callback.Reset(isolate, callback);
 
-  uv_queue_work(uv_default_loop(),
+  uv_queue_work(node::GetCurrentEventLoop(isolate),
                 &req->req,
                 DoAsync,
                 (uv_after_work_cb)AfterAsync<use_makecallback>);
diff --git a/test/addons/callback-scope/binding.cc b/test/addons/callback-scope/binding.cc
@@ -52,7 +52,10 @@ static void TestResolveAsync(const v8::FunctionCallbackInfo<v8::Value>& args) {
 
     uv_work_t* req = new uv_work_t;
 
-    uv_queue_work(uv_default_loop(), req, [](uv_work_t*) {}, Callback);
+    uv_queue_work(node::GetCurrentEventLoop(isolate),
+                  req,
+                  [](uv_work_t*) {},
+                  Callback);
   }
 
   v8::Local<v8::Promise::Resolver> local =

Original file line number	Diff line number	Diff line change
`@@ -52,7 +52,10 @@ static void TestResolveAsync(const v8::FunctionCallbackInfo<v8::Value>& args) {`
`52`	`52`
`53`	`53`	`uv_work_t* req = new uv_work_t;`
`54`	`54`
`55`		`- uv_queue_work(uv_default_loop(), req, [](uv_work_t*) {}, Callback);`
	`55`	`+ uv_queue_work(node::GetCurrentEventLoop(isolate),`
	`56`	`+ req,`
	`57`	`+ [](uv_work_t*) {},`
	`58`	`+ Callback);`
`56`	`59`	`}`
`57`	`60`
`58`	`61`	`v8::Local<v8::Promise::Resolver> local =`