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node-api: allow napi_delete_reference in finalizers · nodejs/node@481770a · GitHub

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Commit 481770a

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legendecas
authored and
ruyadorno
committed
node-api: allow napi_delete_reference in finalizers
`napi_delete_reference` must be called immediately for a `napi_reference` returned from `napi_wrap` in the corresponding finalizer, in order to clean up the `napi_reference` timely. `napi_delete_reference` is safe to be invoked during GC. PR-URL: #55620 Reviewed-By: Gabriel Schulhof <gabrielschulhof@gmail.com> Reviewed-By: Michael Dawson <midawson@redhat.com> Reviewed-By: James M Snell <jasnell@gmail.com> Reviewed-By: Vladimir Morozov <vmorozov@microsoft.com>
1 parent 01eb308 commit 481770a

5 files changed

Lines changed: 71 additions & 5 deletions

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‎src/js_native_api_v8.cc‎

Lines changed: 3 additions & 1 deletion
Original file line numberDiff line numberDiff line change
@@ -2769,10 +2769,12 @@ napi_status NAPI_CDECL napi_create_reference(napi_env env,
27692769

27702770
// Deletes a reference. The referenced value is released, and may be GC'd unless
27712771
// there are other references to it.
2772+
// For a napi_reference returned from `napi_wrap`, this must be called in the
2773+
// finalizer.
27722774
napi_status NAPI_CDECL napi_delete_reference(napi_env env, napi_ref ref) {
27732775
// Omit NAPI_PREAMBLE and GET_RETURN_STATUS because V8 calls here cannot throw
27742776
// JS exceptions.
2775-
CHECK_ENV_NOT_IN_GC(env);
2777+
CHECK_ENV(env);
27762778
CHECK_ARG(env, ref);
27772779

27782780
delete reinterpret_cast<v8impl::Reference*>(ref);

‎test/js-native-api/6_object_wrap/6_object_wrap.cc‎

Lines changed: 34 additions & 3 deletions
Original file line numberDiff line numberDiff line change
@@ -3,17 +3,25 @@
33
#include "assert.h"
44
#include "myobject.h"
55

6+
typedef int32_t FinalizerData;
7+
68
napi_ref MyObject::constructor;
79

810
MyObject::MyObject(double value)
911
: value_(value), env_(nullptr), wrapper_(nullptr) {}
1012

1113
MyObject::~MyObject() { napi_delete_reference(env_, wrapper_); }
1214

13-
void MyObject::Destructor(
14-
napi_env env, void* nativeObject, void* /*finalize_hint*/) {
15+
void MyObject::Destructor(node_api_basic_env env,
16+
void* nativeObject,
17+
void* /*finalize_hint*/) {
1518
MyObject* obj = static_cast<MyObject*>(nativeObject);
1619
delete obj;
20+
21+
FinalizerData* data;
22+
NODE_API_BASIC_CALL_RETURN_VOID(
23+
env, napi_get_instance_data(env, reinterpret_cast<void**>(&data)));
24+
*data += 1;
1725
}
1826

1927
void MyObject::Init(napi_env env, napi_value exports) {
@@ -154,7 +162,7 @@ napi_value MyObject::Multiply(napi_env env, napi_callback_info info) {
154162
}
155163

156164
// This finalizer should never be invoked.
157-
void ObjectWrapDanglingReferenceFinalizer(napi_env env,
165+
void ObjectWrapDanglingReferenceFinalizer(node_api_basic_env env,
158166
void* finalize_data,
159167
void* finalize_hint) {
160168
assert(0 && "unreachable");
@@ -198,15 +206,38 @@ napi_value ObjectWrapDanglingReferenceTest(napi_env env,
198206
return ret;
199207
}
200208

209+
static napi_value GetFinalizerCallCount(napi_env env, napi_callback_info info) {
210+
size_t argc = 1;
211+
napi_value argv[1];
212+
FinalizerData* data;
213+
napi_value result;
214+
215+
NODE_API_CALL(env,
216+
napi_get_cb_info(env, info, &argc, argv, nullptr, nullptr));
217+
NODE_API_CALL(env,
218+
napi_get_instance_data(env, reinterpret_cast<void**>(&data)));
219+
NODE_API_CALL(env, napi_create_int32(env, *data, &result));
220+
return result;
221+
}
222+
223+
static void finalizeData(napi_env env, void* data, void* hint) {
224+
delete reinterpret_cast<FinalizerData*>(data);
225+
}
226+
201227
EXTERN_C_START
202228
napi_value Init(napi_env env, napi_value exports) {
229+
FinalizerData* data = new FinalizerData;
230+
*data = 0;
231+
NODE_API_CALL(env, napi_set_instance_data(env, data, finalizeData, nullptr));
232+
203233
MyObject::Init(env, exports);
204234

205235
napi_property_descriptor descriptors[] = {
206236
DECLARE_NODE_API_PROPERTY("objectWrapDanglingReference",
207237
ObjectWrapDanglingReference),
208238
DECLARE_NODE_API_PROPERTY("objectWrapDanglingReferenceTest",
209239
ObjectWrapDanglingReferenceTest),
240+
DECLARE_NODE_API_PROPERTY("getFinalizerCallCount", GetFinalizerCallCount),
210241
};
211242

212243
NODE_API_CALL(

‎test/js-native-api/6_object_wrap/binding.gyp‎

Lines changed: 7 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -5,6 +5,13 @@
55
"sources": [
66
"6_object_wrap.cc"
77
]
8+
},
9+
{
10+
"target_name": "6_object_wrap_basic_finalizer",
11+
"defines": [ "NAPI_EXPERIMENTAL" ],
12+
"sources": [
13+
"6_object_wrap.cc"
14+
]
815
}
916
]
1017
}

‎test/js-native-api/6_object_wrap/myobject.h‎

Lines changed: 3 additions & 1 deletion
Original file line numberDiff line numberDiff line change
@@ -6,7 +6,9 @@
66
class MyObject {
77
public:
88
static void Init(napi_env env, napi_value exports);
9-
static void Destructor(napi_env env, void* nativeObject, void* finalize_hint);
9+
static void Destructor(node_api_basic_env env,
10+
void* nativeObject,
11+
void* finalize_hint);
1012

1113
private:
1214
explicit MyObject(double value_ = 0);

‎test/js-native-api/6_object_wrap/test-basic-finalizer.js‎

Lines changed: 24 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -0,0 +1,24 @@
1+
// Flags: --expose-gc
2+
3+
'use strict';
4+
const common = require('../../common');
5+
const assert = require('assert');
6+
const addon = require(`./build/${common.buildType}/6_object_wrap_basic_finalizer`);
7+
8+
// This test verifies that ObjectWrap can be correctly finalized with a node_api_basic_finalizer
9+
// in the current JS loop tick
10+
(() => {
11+
let obj = new addon.MyObject(9);
12+
obj = null;
13+
// Silent eslint about unused variables.
14+
assert.strictEqual(obj, null);
15+
})();
16+
17+
for (let i = 0; i < 10; ++i) {
18+
global.gc();
19+
if (addon.getFinalizerCallCount() === 1) {
20+
break;
21+
}
22+
}
23+
24+
assert.strictEqual(addon.getFinalizerCallCount(), 1);

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