src: add support for addon instance data by gabrielschulhof · Pull Request #663 · nodejs/node-addon-api

gabrielschulhof · 2020-01-31T02:57:13Z

Support napi_get_instance_data() and napi_set_instance_data().
Fixes: #654

test/addon_data.cc

napi-inl.h

tniessen · 2020-02-03T16:48:03Z

Is the implicit initialization really helpful? I would imagine most use cases to be one of these:

For all calls into the module that require instance data, the module checks if instance data exists, and if it doesn't, it creates and initializes instance data. This PR takes away the ability to check if the instance data was newly created or if it previously existed.
One call into the module creates and initializes instance data, all other calls only retrieve it. In this case, if due to a bug the instance data is not initialized correctly, the consuming functions have no way to check that, and since this PR silently creates a new object in the background, it might not even crash immediately. With separate APIs to set and get instance data, the consuming functions could just do the equivalent of CHECK on the returned pointer to make sure it has been initialized correctly.

To work around these issues, most objects would probably have to have a member is_initialized or something similar, instead of just checking whether the instance data is NULL or not. In all cases, requiring T to be default constructible is restrictive.

gabrielschulhof · 2020-02-04T23:49:57Z

@tniessen @legendecas @addaleax I changed the interface to an accessor pair as @tniessen suggested.

Landing this requires nodejs/node#31638 otherwise it crashes 😕

Instance data associated with a `napi_env` is no longer stored on the env itself but is instead rendered as a reference. Since `v8impl::Reference` is tied to a JS object, this modification factors out the `v8impl::Reference` refcounting and the deletion process into a base class for `v8impl::Reference`, called `v8impl::RefBase`. The instance data is then stored as a `v8impl::RefBase`, along with other references, preventing a segfault that arises from the fact that, up until now, upon `napi_env` destruction, the instance data was freed after all references had already been forcefully freed. If the addon freed a reference during the `napi_set_instance_data` finalizer callback, such a reference had already been freed during environment teardown, causing a double free. Re: nodejs/node-addon-api#663

Instance data associated with a `napi_env` is no longer stored on the env itself but is instead rendered as a reference. Since `v8impl::Reference` is tied to a JS object, this modification factors out the `v8impl::Reference` refcounting and the deletion process into a base class for `v8impl::Reference`, called `v8impl::RefBase`. The instance data is then stored as a `v8impl::RefBase`, along with other references, preventing a segfault that arises from the fact that, up until now, upon `napi_env` destruction, the instance data was freed after all references had already been forcefully freed. If the addon freed a reference during the `napi_set_instance_data` finalizer callback, such a reference had already been freed during environment teardown, causing a double free. Re: nodejs/node-addon-api#663 PR-URL: #31638 Reviewed-By: Anna Henningsen <anna@addaleax.net> Reviewed-By: David Carlier <devnexen@gmail.com>

legendecas · 2020-03-25T11:07:14Z

napi-inl.h

  return Value(_env, result);
 }

+#ifdef NAPI_EXPERIMENTAL


I believe this guard can be replaced with NAPI_VERSION > 5?

mhdawson · 2020-03-30T13:57:05Z

napi.h

  ///
  /// In the V8 JavaScript engine, a N-API environment approximately corresponds to an Isolate.
  class Env {
+#ifdef NAPI_EXPERIMENTAL


Same comment as before here as well with respect to NAPI_VERSION > 5 and the next one as well.

mhdawson

LGTM once guards are updated.

Instance data associated with a `napi_env` is no longer stored on the env itself but is instead rendered as a reference. Since `v8impl::Reference` is tied to a JS object, this modification factors out the `v8impl::Reference` refcounting and the deletion process into a base class for `v8impl::Reference`, called `v8impl::RefBase`. The instance data is then stored as a `v8impl::RefBase`, along with other references, preventing a segfault that arises from the fact that, up until now, upon `napi_env` destruction, the instance data was freed after all references had already been forcefully freed. If the addon freed a reference during the `napi_set_instance_data` finalizer callback, such a reference had already been freed during environment teardown, causing a double free. Re: nodejs/node-addon-api#663 PR-URL: #31638 Reviewed-By: Anna Henningsen <anna@addaleax.net> Reviewed-By: David Carlier <devnexen@gmail.com>

gabrielschulhof · 2020-04-07T04:54:57Z

@mhdawson @legendecas I have updated the guards.

legendecas · 2020-04-12T11:51:55Z

napi-inl.h

+  napi_status status =
+      napi_set_instance_data(_env, data, [](napi_env, void* data, void*) {
+        fini(static_cast<T*>(data));
+      }, nullptr);


Just noted finalize hint has been hardcoded here. Is this intended?

gabrielschulhof · 2020-04-14T06:30:57Z

@legendecas I added an option that takes a hint.

gabrielschulhof · 2020-04-24T22:57:20Z

CI:

Version	Job	Status
v15.x	https://ci.nodejs.org/job/node-test-node-addon-api-new/2075/	✗
v14.x	https://ci.nodejs.org/job/node-test-node-addon-api-new/2076/	✗
v12.x	https://ci.nodejs.org/job/node-test-node-addon-api-new/2077/	✓
v10.x	https://ci.nodejs.org/job/node-test-node-addon-api-new/2078/	✗

gabrielschulhof · 2020-04-25T00:09:29Z

Investigating .o0o.o0o.

Support `napi_get_instance_data()` and `napi_set_instance_data()`. Fixes: nodejs#654

gabrielschulhof · 2020-04-25T01:57:33Z

The failure was caused by Windows' use of escape characters as path separators. The path to the addon was being passed through an unescape step.

gabrielschulhof · 2020-04-25T02:27:05Z

CI:

Version	Job	Status
v15.x	https://ci.nodejs.org/job/node-test-node-addon-api-new/2079/	✓
v14.x	https://ci.nodejs.org/job/node-test-node-addon-api-new/2080/	✓
v12.x	https://ci.nodejs.org/job/node-test-node-addon-api-new/2081/	✓
v10.x	https://ci.nodejs.org/job/node-test-node-addon-api-new/2082/	✓

Support `napi_get_instance_data()` and `napi_set_instance_data()`. Signed-off-by: Gabriel Schulhof <gabriel.schulhof@intel.com> Fixes: #654 PR-URL: #663 Reviewed-By: Chengzhong Wu <legendecas@gmail.com> Reviewed-By: Michael Dawson <michael_dawson@ca.ibm.com>

gabrielschulhof · 2020-04-25T05:32:24Z

Landed in 9c9accf.

Support `napi_get_instance_data()` and `napi_set_instance_data()`. Signed-off-by: Gabriel Schulhof <gabriel.schulhof@intel.com> Fixes: nodejs/node-addon-api#654 PR-URL: nodejs/node-addon-api#663 Reviewed-By: Chengzhong Wu <legendecas@gmail.com> Reviewed-By: Michael Dawson <michael_dawson@ca.ibm.com>

gabrielschulhof requested review from NickNaso, legendecas, mhdawson and tniessen January 31, 2020 02:57

legendecas reviewed Jan 31, 2020

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gabrielschulhof mentioned this pull request Jan 31, 2020

Best practice to store context-aware class constructor reference #654

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gabrielschulhof mentioned this pull request Feb 4, 2020

n-api: free instance data as reference nodejs/node#31638

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gabrielschulhof force-pushed the addon-class branch from 827b995 to 433a1a1 Compare February 4, 2020 23:47

mhdawson mentioned this pull request Mar 23, 2020

Next release of node-addon-api #689

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gabrielschulhof requested review from addaleax and legendecas March 23, 2020 16:33

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gabrielschulhof force-pushed the addon-class branch from 62cd556 to e0d376c Compare March 30, 2020 15:12

gabrielschulhof force-pushed the addon-class branch from e0d376c to 8174b51 Compare April 7, 2020 22:27

gabrielschulhof force-pushed the addon-class branch from 8174b51 to 7db12f7 Compare April 10, 2020 05:00

gabrielschulhof requested a review from legendecas April 11, 2020 15:29

legendecas approved these changes Apr 12, 2020

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gabrielschulhof force-pushed the addon-class branch from f8d6482 to ed7042c Compare April 14, 2020 06:31

gabrielschulhof force-pushed the addon-class branch from ed7042c to 2f6ac14 Compare April 24, 2020 22:54

src: add support for addon instance data

a8959b6

Support `napi_get_instance_data()` and `napi_set_instance_data()`. Fixes: nodejs#654

gabrielschulhof force-pushed the addon-class branch from 2f6ac14 to a8959b6 Compare April 25, 2020 01:42

gabrielschulhof closed this Apr 25, 2020

KevinEady mentioned this pull request Jun 22, 2020

ObjectWrap Factory? #744

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gabrielschulhof deleted the addon-class branch August 6, 2020 20:43

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