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why V8 platform symbol not exported #34790
Description
Take https://github.com/nodejs/node-addon-examples/tree/master/1_hello_world/napi
patch hello.cc like this
#include <assert.h>
#include <node_api.h>
#include <v8.h>
#include <libplatform/libplatform.h>
napi_value Method(napi_env env, napi_callback_info info) {
napi_status status;
napi_value world;
status = napi_create_string_utf8(env, "world", 5, &world);
assert(status == napi_ok);
return world;
}
#define DECLARE_NAPI_METHOD(name, func) \
{ name, 0, func, 0, 0, 0, napi_default, 0 }
napi_value Init(napi_env env, napi_value exports) {
std::unique_ptr<v8::Platform> platform = v8::platform::NewDefaultPlatform();
v8::V8::InitializePlatform(platform.get());
v8::V8::Initialize();
napi_status status;
napi_property_descriptor desc = DECLARE_NAPI_METHOD("hello", Method);
status = napi_define_properties(env, exports, 1, &desc);
assert(status == napi_ok);
return exports;
}
NAPI_MODULE(NODE_GYP_MODULE_NAME, Init)Running it will result in
/usr/local/bin/node: symbol lookup error: /mnt/d/Developer/node-addon-examples/1_hello_world/napi/build/Release/hello.node: undefined symbol: _ZN2v88platform18NewDefaultPlatformEiNS0_15IdleTaskSupportENS0_21InProcessStackDumpingESt10unique_ptrINS_17TracingControllerESt14default_deleteIS4_EE
error Command failed with exit code 127.
info Visit https://yarnpkg.com/en/docs/cli/run for documentation about this command.As far as I understand, <libplatform/libplatform.h> is public V8 api, why related symbols not export.
Activity
bnoordhuis commentedon Aug 15, 2020
The
v8::Platforminstance is a singleton that's managed by the embedder. There's simply no reason why an add-on (which isn't an embedder) would ever need to create one.Your example add-on is not valid code. I mean, it compiles, but there's no way it'd work even if the symbols were exported.
gengjiawen commentedon Aug 16, 2020
I want to use v8 api without compiling the whole v8, that's why I choose add-on. Like showcase how to use v8 api to make a hello world.
Why is this ? Do you mean the code is not complete. I delibarately skip code call like
v8::Script::Compileto make it minimal.gengjiawen commentedon Aug 17, 2020
Looks like the symbol export controlled by macro
BUILDING_V8_PLATFORM_SHARED, I will give it a try on my local build Node.js.bnoordhuis commentedon Aug 17, 2020
To elaborate: there can be only a single
v8::Platforminstance and that singleton is owned and managed by Node.js. Add-ons can't create their own because they can't set up a completely separate instance of V8.Bad car analogy: a car has a single steering wheel and it's steered by the driver, not the passengers (heart attacks excepting!) Node is the driver, add-ons are the passengers.
targos commentedon Nov 20, 2021
@gengjiawen can we close this?