Struct nodex_api::context::NapiAsyncContext

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pub struct NapiAsyncContext { /* private fields */ }

Implementations

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pub fn new(env: NapiEnv, name: impl AsRef<str>) -> NapiResult<NapiAsyncContext>

The async_resource object needs to be kept alive until napi_async_destroy to keep async_hooks related API acts correctly. In order to retain ABI compatibility with previous versions, napi_async_contexts are not maintaining the strong reference to the async_resource objects to avoid introducing causing memory leaks. However, if the async_resource is garbage collected by JavaScript engine before the napi_async_context was destroyed by napi_async_destroy, calling napi_async_context related APIs like napi_open_callback_scope and napi_make_callback can cause problems like loss of async context when using the AsyncLocalStorage API. In order to retain ABI compatibility with previous versions, passing NULL for async_resource does not result in an error. However, this is not recommended as this will result poor results with async_hooks init hooks and async_hooks.executionAsyncResource() as the resource is now required by the underlying async_hooks implementation in order to provide the linkage between async callbacks.

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pub fn destroy(&mut self) -> NapiResult<()>

This API can be called even if there is a pending JavaScript exception.

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pub fn make_callback<R, T, const N: usize>(
 &self,
 this: JsObject,
 func: Function<R>,
 args: [T; N]
) -> NapiResult<R> where
 R: NapiValueT,
 T: NapiValueT + Clone,

This method allows a JavaScript function object to be called from a native add-on. This API is similar to napi_call_function. However, it is used to call from native code back into JavaScript after returning from an async operation (when there is no other script on the stack). It is a fairly simple wrapper around node::MakeCallback.

Note it is not necessary to use napi_make_callback from within a napi_async_complete_callback; in that situation the callback’s async context has already been set up, so a direct call to napi_call_function is sufficient and appropriate. Use of the napi_make_callback function may be required when implementing custom async behavior that does not use napi_create_async_work.

Any process.nextTicks or Promises scheduled on the microtask queue by JavaScript during he callback are ran before returning back to C/C++.