From 03ffcf76b7cdee745bb53d4b2144f037f0c3017a Mon Sep 17 00:00:00 2001 From: Gabriel Schulhof Date: Thu, 7 Feb 2019 12:11:01 -0800 Subject: [PATCH] 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: https://github.com/nodejs/node/issues/25927 PR-URL: https://github.com/nodejs/node/pull/25992 Reviewed-By: Anna Henningsen Reviewed-By: Colin Ihrig Reviewed-By: Michael Dawson --- src/js_native_api_v8.cc | 15 +++++++++++++++ 1 file changed, 15 insertions(+) diff --git a/src/js_native_api_v8.cc b/src/js_native_api_v8.cc index 9e67e2ca24b7c0..287142e2658907 100644 --- a/src/js_native_api_v8.cc +++ b/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& 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& data) { + Reference* reference = data.GetParameter(); + napi_env env = reference->_env; if (reference->_finalize_callback != nullptr) {