src: refactor async callback handling

- Merge the two almost-but-not-quite identical `MakeCallback()`
  implementations
- Provide a public `CallbackScope` class for embedders in order
  to enable `MakeCallback()`-like behaviour without tying that
  to calling a JS function

PR-URL: https://github.com/nodejs/node/pull/14697
Reviewed-By: Tobias Nießen <tniessen@tnie.de>
Reviewed-By: Refael Ackermann <refack@gmail.com>
Reviewed-By: James M Snell <jasnell@gmail.com>

4 files changed, 87 insertions, 0 deletions

diff --git a/test/addons/callback-scope/binding.cc b/test/addons/callback-scope/binding.cc
new file mode 100644
index 0000000000..31317e5dae
--- /dev/null
+++ b/test/addons/callback-scope/binding.cc
@@ -0,0 +1,39 @@
+#include "node.h"
+#include "v8.h"
+
+#include <assert.h>
+#include <vector>
+
+namespace {
+
+void RunInCallbackScope(const v8::FunctionCallbackInfo<v8::Value>& args) {
+  v8::Isolate* isolate = args.GetIsolate();
+
+  assert(args.Length() == 4);
+  assert(args[0]->IsObject());
+  assert(args[1]->IsNumber());
+  assert(args[2]->IsNumber());
+  assert(args[3]->IsFunction());
+
+  node::async_context asyncContext = {
+    args[1].As<v8::Number>()->Value(),
+    args[2].As<v8::Number>()->Value()
+  };
+
+  node::CallbackScope scope(isolate, args[0].As<v8::Object>(), asyncContext);
+  v8::Local<v8::Function> fn = args[3].As<v8::Function>();
+
+  v8::MaybeLocal<v8::Value> ret =
+      fn->Call(isolate->GetCurrentContext(), args[0], 0, nullptr);
+
+  if (!ret.IsEmpty())
+    args.GetReturnValue().Set(ret.ToLocalChecked());
+}
+
+void Initialize(v8::Local<v8::Object> exports) {
+  NODE_SET_METHOD(exports, "runInCallbackScope", RunInCallbackScope);
+}
+
+}  // namespace
+
+NODE_MODULE(binding, Initialize)
diff --git a/test/addons/callback-scope/binding.gyp b/test/addons/callback-scope/binding.gyp
new file mode 100644
index 0000000000..7ede63d94a
--- /dev/null
+++ b/test/addons/callback-scope/binding.gyp
@@ -0,0 +1,9 @@
+{
+  'targets': [
+    {
+      'target_name': 'binding',
+      'defines': [ 'V8_DEPRECATION_WARNINGS=1' ],
+      'sources': [ 'binding.cc' ]
+    }
+  ]
+}
diff --git a/test/addons/callback-scope/test-async-hooks.js b/test/addons/callback-scope/test-async-hooks.js
new file mode 100644
index 0000000000..94b53efc53
--- /dev/null
+++ b/test/addons/callback-scope/test-async-hooks.js
@@ -0,0 +1,22 @@
+'use strict';
+
+const common = require('../../common');
+const assert = require('assert');
+const async_hooks = require('async_hooks');
+const { runInCallbackScope } = require(`./build/${common.buildType}/binding`);
+
+let insideHook = false;
+async_hooks.createHook({
+  before: common.mustCall((id) => {
+    assert.strictEqual(id, 1000);
+    insideHook = true;
+  }),
+  after: common.mustCall((id) => {
+    assert.strictEqual(id, 1000);
+    insideHook = false;
+  })
+}).enable();
+
+runInCallbackScope({}, 1000, 1000, () => {
+  assert(insideHook);
+});
diff --git a/test/addons/callback-scope/test.js b/test/addons/callback-scope/test.js
new file mode 100644
index 0000000000..2f2efe5f47
--- /dev/null
+++ b/test/addons/callback-scope/test.js
@@ -0,0 +1,17 @@
+'use strict';
+
+const common = require('../../common');
+const assert = require('assert');
+const { runInCallbackScope } = require(`./build/${common.buildType}/binding`);
+
+assert.strictEqual(runInCallbackScope({}, 0, 0, () => 42), 42);
+
+{
+  process.once('uncaughtException', common.mustCall((err) => {
+    assert.strictEqual(err.message, 'foo');
+  }));
+
+  runInCallbackScope({}, 0, 0, () => {
+    throw new Error('foo');
+  });
+}