src: yield empty maybes for failed AsyncWrap::MakeCallback calls

Use an empty `MaybeLocal<Value>` as the return value for
`AsyncWrap::MakeCallback()` if an exception occurred,
regardless of `MakeCallback` depth.

Unfortunately, the public API can not make this switch without
a breaking change (and possibly some kind of deprecation/renaming).

PR-URL: #22078
Backport-PR-URL: #22505
Reviewed-By: Michaël Zasso <targos@protonmail.com>

src/callback_scope.cc

@@ -59,7 +59,8 @@ InternalCallbackScope::InternalCallbackScope(Environment* env,
     AsyncWrap::EmitBefore(env, asyncContext.async_id);
   }
 
-  if (!IsInnerMakeCallback()) {
+  CHECK_GE(env->makecallback_depth(), 1);
+  if (env->makecallback_depth() == 1) {
     env->tick_info()->set_has_thrown(false);
   }
 
@@ -91,7 +92,7 @@ void InternalCallbackScope::Close() {
     AsyncWrap::EmitAfter(env_, async_context_.async_id);
   }
 
-  if (IsInnerMakeCallback()) {
+  if (env_->makecallback_depth() > 1) {
     return;
   }
 

src/env-inl.h

@@ -218,8 +218,8 @@ inline Environment::AsyncCallbackScope::~AsyncCallbackScope() {
   env_->makecallback_cntr_--;
 }
 
-inline bool Environment::AsyncCallbackScope::in_makecallback() const {
-  return env_->makecallback_cntr_ > 1;
+inline size_t Environment::makecallback_depth() const {
+  return makecallback_cntr_;
 }
 
 inline Environment::ImmediateInfo::ImmediateInfo(v8::Isolate* isolate)

src/env.h

@@ -503,14 +503,15 @@ class Environment {
     AsyncCallbackScope() = delete;
     explicit AsyncCallbackScope(Environment* env);
     ~AsyncCallbackScope();
-    inline bool in_makecallback() const;
 
    private:
     Environment* env_;
 
     DISALLOW_COPY_AND_ASSIGN(AsyncCallbackScope);
   };
 
+  inline size_t makecallback_depth() const;
+
   class ImmediateInfo {
    public:
     inline AliasedBuffer<uint32_t, v8::Uint32Array>& fields();

src/node.cc

@@ -758,7 +758,7 @@ MaybeLocal<Value> InternalMakeCallback(Environment* env,
   CHECK(!recv.IsEmpty());
   InternalCallbackScope scope(env, recv, asyncContext);
   if (scope.Failed()) {
-    return Undefined(env->isolate());
+    return MaybeLocal<Value>();
   }
 
   Local<Function> domain_cb = env->domain_callback();
@@ -773,15 +773,13 @@ MaybeLocal<Value> InternalMakeCallback(Environment* env,
   }
 
   if (ret.IsEmpty()) {
-    // NOTE: For backwards compatibility with public API we return Undefined()
-    // if the top level call threw.
     scope.MarkAsFailed();
-    return scope.IsInnerMakeCallback() ? ret : Undefined(env->isolate());
+    return MaybeLocal<Value>();
   }
 
   scope.Close();
   if (scope.Failed()) {
-    return Undefined(env->isolate());
+    return MaybeLocal<Value>();
   }
 
   return ret;
@@ -833,8 +831,14 @@ MaybeLocal<Value> MakeCallback(Isolate* isolate,
   // the two contexts need not be the same.
   Environment* env = Environment::GetCurrent(callback->CreationContext());
   Context::Scope context_scope(env->context());
-  return InternalMakeCallback(env, recv, callback,
-                              argc, argv, asyncContext);
+  MaybeLocal<Value> ret = InternalMakeCallback(env, recv, callback,
+                                               argc, argv, asyncContext);
+  if (ret.IsEmpty() && env->makecallback_depth() == 0) {
+    // This is only for legacy compatiblity and we may want to look into
+    // removing/adjusting it.
+    return Undefined(env->isolate());
+  }
+  return ret;
 }
 
 

src/node_internals.h

@@ -543,9 +543,6 @@ class InternalCallbackScope {
 
   inline bool Failed() const { return failed_; }
   inline void MarkAsFailed() { failed_ = true; }
-  inline bool IsInnerMakeCallback() const {
-    return callback_scope_.in_makecallback();
-  }
 
  private:
   Environment* env_;

src/timer_wrap.cc

@@ -37,6 +37,7 @@ using v8::FunctionTemplate;
 using v8::HandleScope;
 using v8::Integer;
 using v8::Local;
+using v8::MaybeLocal;
 using v8::Object;
 using v8::String;
 using v8::Value;
@@ -138,13 +139,12 @@ class TimerWrap : public HandleWrap {
     Environment* env = wrap->env();
     HandleScope handle_scope(env->isolate());
     Context::Scope context_scope(env->context());
-    Local<Value> ret;
+    MaybeLocal<Value> ret;
     Local<Value> args[1];
     do {
       args[0] = env->GetNow();
-      ret = wrap->MakeCallback(env->timers_callback_function(), 1, args)
-                .ToLocalChecked();
-    } while (ret->IsUndefined() &&
+      ret = wrap->MakeCallback(env->timers_callback_function(), 1, args);
+    } while ((ret.IsEmpty() || ret.ToLocalChecked()->IsUndefined()) &&
              !env->tick_info()->has_thrown() &&
              env->can_call_into_js() &&
              wrap->object()->Get(env->context(),