n-api: finalize during second-pass callback

Calling into the engine from a weak callback is unsafe, however, the engine offers a way to attach a second-pass weak callback which gets called when it is safe to call into JavaScript. This moves the point at which the N-API finalize callback gets called to this latter point. Fixes: #25927 PR-URL: #25992 Reviewed-By: Anna Henningsen <anna@addaleax.net> Reviewed-By: Colin Ihrig <cjihrig@gmail.com> Reviewed-By: Michael Dawson <michael_dawson@ca.ibm.com>

Author: Gabriel Schulhof

src/js_native_api_v8.cc

@@ -281,10 +281,25 @@ class Reference : private Finalizer {
  }
 
  private:
+ // The N-API finalizer callback may make calls into the engine. V8's heap is
+ // not in a consistent state during the weak callback, and therefore it does
+ // not support calls back into it. However, it provides a mechanism for adding
+ // a finalizer which may make calls back into the engine by allowing us to
+ // attach such a second-pass finalizer from the first pass finalizer. Thus,
+ // we do that here to ensure that the N-API finalizer callback is free to call
+ // into the engine.
  static void FinalizeCallback(const v8::WeakCallbackInfo<Reference>& data) {
  Reference* reference = data.GetParameter();
+
+ // The reference must be reset during the first pass.
  reference->_persistent.Reset();
 
+ data.SetSecondPassCallback(SecondPassCallback);
+ }
+
+ static void SecondPassCallback(const v8::WeakCallbackInfo<Reference>& data) {
+ Reference* reference = data.GetParameter();
+
  napi_env env = reference->_env;
 
  if (reference->_finalize_callback != nullptr) {