V8 snapshot with React Native not work as expected

[王梓童]

Hi, I am trying to use V8 snapshot to reduce my React-Native app's startup time. Unfortunately, when I create an Isolate and a context, then run a .js file, I just get the error "__fbBatchedBridgeConfig is not set, cannot invoke native modules". It seems the context needs some native modules. I wonder is it possible to use V8 snapshot on a React Native app? I would appreciate it for your reply.

Here is my code:

v8::StartupData CreateSnapshotDataBlob(const char* embedded_source) {
    // Create a new isolate and a new context from scratch, optionally run
    // a script to embed, and serialize to create a snapshot blob.
    v8::StartupData result = {nullptr, 0};
    {
        v8::Isolate* isolate = v8::Isolate::Allocate();
        v8::SnapshotCreator snapshot_creator(isolate);
        {
            v8::HandleScope scope(isolate);
            v8::Local<v8::Context> context = v8::Context::New(isolate);
           
            if (embedded_source != nullptr &&
                    !RunExtraCode(isolate, context, embedded_source, "<embedded>")) {
                return result;
            }
            snapshot_creator.SetDefaultContext(context);
        }
        result = snapshot_creator.CreateBlob(
                                             v8::SnapshotCreator::FunctionCodeHandling::kClear);
    }

    return result;
}

bool RunExtraCode(v8::Isolate* isolate, v8::Local<v8::Context> context, const char* utf8_source, const char* name) {
    v8::Context::Scope context_scope(context);
    v8::TryCatch try_catch(isolate);
    v8::Local<v8::String> source_string;
    if (!v8::String::NewFromUtf8(isolate, utf8_source, v8::NewStringType::kNormal).ToLocal(&source_string)) {
        return false;
    }
    v8::Local<v8::String> resource_name = v8::String::NewFromUtf8(isolate, name, v8::NewStringType::kNormal).ToLocalChecked();
    v8::ScriptOrigin origin(resource_name);
    v8::ScriptCompiler::Source source(source_string, origin);
    v8::Local<v8::Script> compileScript;
    if (!v8::ScriptCompiler::Compile(context, &source).ToLocal(&compileScript)) {
        return false;
    }
   
    if (compileScript->Run(context).IsEmpty()) {
        // this line will be executed, and the exception is "__fbBatchedBridgeConfig is not set, cannot invoke native modules". It seems the context need some native modules"
        std::string exception = *v8::String::Utf8Value(isolate, try_catch.Exception());
        return false;
    }
    std::cout << !try_catch.HasCaught() << std::endl;
    return true;
}

[Yang Guo]

V8 has the ability to serialize function bindings to native modules, e.g. described here. I'm not sure whether React Native uses it. Maybe +Jakob Gruber has some insights from past interaction?

Cheers,

Yang

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[Jakob Gruber]

On Wed, Jun 10, 2020 at 2:00 PM Yang Guo <yan...@chromium.org> wrote:

V8 has the ability to serialize function bindings to native modules, e.g. described here. I'm not sure whether React Native uses it. Maybe +Jakob Gruber has some insights from past interaction?

No sorry, no further insights.