Struct nodex_api::context::NapiAsyncContext

pub struct NapiAsyncContext { /* private fields */ }

Implementations

impl NapiAsyncContext

pub fn env(&self) -> NapiEnv

pub fn raw(&self) -> napi_async_context

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.

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

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

pub fn make_callback<R, T>(
    &self,
    this: JsObject,
    func: Function<R>,
    args: T
) -> NapiResult<R> where
    R: NapiValueT,
    T: ToJsArgs, 

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++.

pub fn scope(&self) -> NapiResult<NapiCallbackScope>

There are cases (for example, resolving promises) where it is necessary to have the equivalent of the scope associated with a callback in place when making certain Node-API calls. If there is no other script on the stack the napi_open_callback_scope and napi_close_callback_scope functions can be used to open/close the required scope.

Trait Implementations

impl Clone for NapiAsyncContext

fn clone(&self) -> NapiAsyncContext

Returns a copy of the value.

fn clone_from(&mut self, source: &Self)

Performs copy-assignment from source.

impl Debug for NapiAsyncContext

fn fmt(&self, f: &mut Formatter<'_>) -> Result

Formats the value using the given formatter.

impl Drop for NapiAsyncContext

fn drop(&mut self)

Executes the destructor for this type.