src: split LoadEnvironment() at startExecution()

This makes it easier to cater to embedders which wish to skip
the `startExecution()` part.

PR-URL: #25320
Reviewed-By: Joyee Cheung <joyeec9h3@gmail.com>
Reviewed-By: Ben Noordhuis <info@bnoordhuis.nl>
Reviewed-By: Minwoo Jung <minwoo@nodesource.com>
Reviewed-By: Colin Ihrig <cjihrig@gmail.com>
Reviewed-By: James M Snell <jasnell@gmail.com>
Reviewed-By: Franziska Hinkelmann <franziska.hinkelmann@gmail.com>

Author: addaleax

lib/internal/bootstrap/node.js

@@ -319,7 +319,7 @@ function startup() {
   } = perf.constants;
   perf.markMilestone(NODE_PERFORMANCE_MILESTONE_BOOTSTRAP_COMPLETE);
 
-  startExecution();
+  return startExecution;
 }
 
 // There are various modes that Node can run in. The most common two
@@ -737,4 +737,4 @@ function checkScriptSyntax(source, filename) {
   new vm.Script(source, { displayErrors: true, filename });
 }
 
-startup();
+return startup();

src/env-inl.h

@@ -633,6 +633,14 @@ inline void Environment::set_can_call_into_js(bool can_call_into_js) {
   can_call_into_js_ = can_call_into_js;
 }
 
+inline bool Environment::has_run_bootstrapping_code() const {
+  return has_run_bootstrapping_code_;
+}
+
+inline void Environment::set_has_run_bootstrapping_code(bool value) {
+  has_run_bootstrapping_code_ = value;
+}
+
 inline bool Environment::is_main_thread() const {
   return thread_id_ == 0;
 }

src/env.h

@@ -369,6 +369,7 @@ constexpr size_t kFsStatsBufferLength = kFsStatsFieldsNumber * 2;
   V(script_data_constructor_function, v8::Function)                            \
   V(secure_context_constructor_template, v8::FunctionTemplate)                 \
   V(shutdown_wrap_template, v8::ObjectTemplate)                                \
+  V(start_execution_function, v8::Function)                                    \
   V(tcp_constructor_template, v8::FunctionTemplate)                            \
   V(tick_callback_function, v8::Function)                                      \
   V(timers_callback_function, v8::Function)                                    \
@@ -751,6 +752,9 @@ class Environment {
   inline bool can_call_into_js() const;
   inline void set_can_call_into_js(bool can_call_into_js);
 
+  inline bool has_run_bootstrapping_code() const;
+  inline void set_has_run_bootstrapping_code(bool has_run_bootstrapping_code);
+
   inline bool is_main_thread() const;
   inline uint64_t thread_id() const;
   inline void set_thread_id(uint64_t id);
@@ -976,6 +980,7 @@ class Environment {
   std::unique_ptr<performance::performance_state> performance_state_;
   std::unordered_map<std::string, uint64_t> performance_marks_;
 
+  bool has_run_bootstrapping_code_ = false;
   bool can_call_into_js_ = true;
   uint64_t thread_id_ = 0;
   std::unordered_set<worker::Worker*> sub_worker_contexts_;

src/node.cc

@@ -1079,6 +1079,14 @@ static MaybeLocal<Value> ExecuteBootstrapper(
 }
 
 void LoadEnvironment(Environment* env) {
+  RunBootstrapping(env);
+  StartExecution(env);
+}
+
+void RunBootstrapping(Environment* env) {
+  CHECK(!env->has_run_bootstrapping_code());
+  env->set_has_run_bootstrapping_code(true);
+
   HandleScope handle_scope(env->isolate());
   Isolate* isolate = env->isolate();
   Local<Context> context = env->context();
@@ -1140,11 +1148,29 @@ void LoadEnvironment(Environment* env) {
       loader_exports.ToLocalChecked(),
       Boolean::New(isolate, env->is_main_thread())};
 
-  if (ExecuteBootstrapper(
+  Local<Value> start_execution;
+  if (!ExecuteBootstrapper(
           env, "internal/bootstrap/node", &node_params, &node_args)
-          .IsEmpty()) {
+          .ToLocal(&start_execution)) {
     return;
   }
+
+  if (start_execution->IsFunction())
+    env->set_start_execution_function(start_execution.As<Function>());
+}
+
+void StartExecution(Environment* env) {
+  HandleScope handle_scope(env->isolate());
+  // We have to use Local<>::New because of the optimized way in which we access
+  // the object in the env->...() getters, which does not play well with
+  // resetting the handle while we're accessing the object through the Local<>.
+  Local<Function> start_execution =
+      Local<Function>::New(env->isolate(), env->start_execution_function());
+  env->set_start_execution_function(Local<Function>());
+
+  if (start_execution.IsEmpty()) return;
+  USE(start_execution->Call(
+      env->context(), Undefined(env->isolate()), 0, nullptr));
 }
 
 static void StartInspector(Environment* env, const char* path) {

src/node_internals.h

@@ -397,6 +397,9 @@ bool SafeGetenv(const char* key, std::string* text);
 
 void DefineZlibConstants(v8::Local<v8::Object> target);
 
+void RunBootstrapping(Environment* env);
+void StartExecution(Environment* env);
+
 }  // namespace node
 
 #endif  // defined(NODE_WANT_INTERNALS) && NODE_WANT_INTERNALS

test/message/assert_throws_stack.out

@@ -18,4 +18,3 @@ AssertionError [ERR_ASSERTION]: Expected values to be strictly deep-equal:
     at *
     at *
     at *
-    at *

test/message/error_exit.out

@@ -16,4 +16,3 @@ AssertionError [ERR_ASSERTION]: Expected values to be strictly equal:
     at Function.Module.runMain (internal/modules/cjs/loader.js:*:*)
     at executeUserCode (internal/bootstrap/node.js:*:*)
     at startExecution (internal/bootstrap/node.js:*:*)
-    at startup (internal/bootstrap/node.js:*:*)

test/message/eval_messages.out

@@ -11,8 +11,6 @@ SyntaxError: Strict mode code may not include a with statement
     at evalScript (internal/process/execution.js:*:*)
     at executeUserCode (internal/bootstrap/node.js:*:*)
     at startExecution (internal/bootstrap/node.js:*:*)
-    at startup (internal/bootstrap/node.js:*:*)
-    at internal/bootstrap/node.js:*:*
 42
 42
 [eval]:1
@@ -28,8 +26,6 @@ Error: hello
     at evalScript (internal/process/execution.js:*:*)
     at executeUserCode (internal/bootstrap/node.js:*:*)
     at startExecution (internal/bootstrap/node.js:*:*)
-    at startup (internal/bootstrap/node.js:*:*)
-    at internal/bootstrap/node.js:*:*
 
 [eval]:1
 throw new Error("hello")
@@ -44,8 +40,6 @@ Error: hello
     at evalScript (internal/process/execution.js:*:*)
     at executeUserCode (internal/bootstrap/node.js:*:*)
     at startExecution (internal/bootstrap/node.js:*:*)
-    at startup (internal/bootstrap/node.js:*:*)
-    at internal/bootstrap/node.js:*:*
 100
 [eval]:1
 var x = 100; y = x;
@@ -60,8 +54,6 @@ ReferenceError: y is not defined
     at evalScript (internal/process/execution.js:*:*)
     at executeUserCode (internal/bootstrap/node.js:*:*)
     at startExecution (internal/bootstrap/node.js:*:*)
-    at startup (internal/bootstrap/node.js:*:*)
-    at internal/bootstrap/node.js:*:*
 
 [eval]:1
 var ______________________________________________; throw 10

test/message/events_unhandled_error_nexttick.out

@@ -12,13 +12,10 @@ Error
     at Function.Module.runMain (internal/modules/cjs/loader.js:*:*)
     at executeUserCode (internal/bootstrap/node.js:*:*)
     at startExecution (internal/bootstrap/node.js:*:*)
-    at startup (internal/bootstrap/node.js:*:*)
 Emitted 'error' event at:
     at process.nextTick (*events_unhandled_error_nexttick.js:*:*)
     at processTicksAndRejections (internal/process/next_tick.js:*:*)
     at process.runNextTicks [as _tickCallback] (internal/process/next_tick.js:*:*)
     at Function.Module.runMain (internal/modules/cjs/loader.js:*:*)
     at executeUserCode (internal/bootstrap/node.js:*:*)
     at startExecution (internal/bootstrap/node.js:*:*)
-    at startup (internal/bootstrap/node.js:*:*)
-    at internal/bootstrap/node.js:*:*

test/message/events_unhandled_error_sameline.out

@@ -12,9 +12,8 @@ Error
     at Function.Module.runMain (internal/modules/cjs/loader.js:*:*)
     at executeUserCode (internal/bootstrap/node.js:*:*)
     at startExecution (internal/bootstrap/node.js:*:*)
-    at startup (internal/bootstrap/node.js:*:*)
 Emitted 'error' event at:
     at Object.<anonymous> (*events_unhandled_error_sameline.js:*:*)
     at Module._compile (internal/modules/cjs/loader.js:*:*)
     [... lines matching original stack trace ...]
-    at startup (internal/bootstrap/node.js:*:*)
+    at startExecution (internal/bootstrap/node.js:*:*)