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node-api: run finalizers directly from GC
PR-URL: #42651 Reviewed-By: Gabriel Schulhof <[email protected]> Reviewed-By: Michael Dawson <[email protected]>
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doc/api/n-api.md

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@@ -5420,6 +5420,42 @@ invocation. If it is deleted before then, then the finalize callback may never
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be invoked. Therefore, when obtaining a reference a finalize callback is also
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required in order to enable correct disposal of the reference.
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#### `node_api_post_finalizer`
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<!-- YAML
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added: REPLACEME
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-->
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> Stability: 1 - Experimental
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```c
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napi_status node_api_post_finalizer(napi_env env,
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napi_finalize finalize_cb,
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void* finalize_data,
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void* finalize_hint);
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```
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* `[in] env`: The environment that the API is invoked under.
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* `[in] finalize_cb`: Native callback that will be used to free the
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native data when the JavaScript object has been garbage-collected.
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[`napi_finalize`][] provides more details.
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* `[in] finalize_data`: Optional data to be passed to `finalize_cb`.
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* `[in] finalize_hint`: Optional contextual hint that is passed to the
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finalize callback.
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Returns `napi_ok` if the API succeeded.
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Schedules a `napi_finalize` callback to be called asynchronously in the
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event loop.
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Normally, finalizers are called while the GC (garbage collector) collects
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objects. At that point calling any Node-API that may cause changes in the GC
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state will be disabled and will crash Node.js.
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`node_api_post_finalizer` helps to work around this limitation by allowing the
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add-on to defer calls to such Node-APIs to a point in time outside of the GC
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finalization.
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## Simple asynchronous operations
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Addon modules often need to leverage async helpers from libuv as part of their

src/js_native_api.h

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@@ -517,6 +517,16 @@ NAPI_EXTERN napi_status NAPI_CDECL napi_add_finalizer(napi_env env,
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#endif // NAPI_VERSION >= 5
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#ifdef NAPI_EXPERIMENTAL
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NAPI_EXTERN napi_status NAPI_CDECL
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node_api_post_finalizer(napi_env env,
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napi_finalize finalize_cb,
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void* finalize_data,
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void* finalize_hint);
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#endif // NAPI_EXPERIMENTAL
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#if NAPI_VERSION >= 6
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// BigInt

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