napi-rs/napi/src/async_work.rs

122 lines
3.8 KiB
Rust

use std::mem;
use std::os::raw::{c_char, c_void};
use std::ptr;
use crate::{
check_status,
js_values::{NapiRaw, NapiValue},
sys, Env, JsError, JsObject, Result, Task,
};
struct AsyncWork<T: Task> {
inner_task: T,
deferred: sys::napi_deferred,
value: Result<mem::MaybeUninit<T::Output>>,
napi_async_work: sys::napi_async_work,
}
pub struct AsyncWorkPromise<'env> {
napi_async_work: sys::napi_async_work,
raw_promise: sys::napi_value,
env: &'env Env,
}
impl<'env> AsyncWorkPromise<'env> {
#[inline]
pub fn promise_object(&self) -> JsObject {
unsafe { JsObject::from_raw_unchecked(self.env.0, self.raw_promise) }
}
#[inline]
pub fn cancel(self) -> Result<()> {
check_status!(unsafe { sys::napi_cancel_async_work(self.env.0, self.napi_async_work) })
}
}
#[inline]
pub fn run<T: Task>(env: &Env, task: T) -> Result<AsyncWorkPromise<'_>> {
let mut raw_resource = ptr::null_mut();
check_status!(unsafe { sys::napi_create_object(env.0, &mut raw_resource) })?;
let mut raw_promise = ptr::null_mut();
let mut deferred = ptr::null_mut();
check_status!(unsafe { sys::napi_create_promise(env.0, &mut deferred, &mut raw_promise) })?;
let mut raw_name = ptr::null_mut();
let s = "napi_rs_async_work";
check_status!(unsafe {
sys::napi_create_string_utf8(env.0, s.as_ptr() as *const c_char, s.len(), &mut raw_name)
})?;
let result = Box::leak(Box::new(AsyncWork {
inner_task: task,
deferred,
value: Ok(mem::MaybeUninit::zeroed()),
napi_async_work: ptr::null_mut(),
}));
check_status!(unsafe {
sys::napi_create_async_work(
env.0,
raw_resource,
raw_name,
Some(execute::<T> as unsafe extern "C" fn(env: sys::napi_env, data: *mut c_void)),
Some(
complete::<T>
as unsafe extern "C" fn(env: sys::napi_env, status: sys::napi_status, data: *mut c_void),
),
result as *mut _ as *mut c_void,
&mut result.napi_async_work,
)
})?;
check_status!(unsafe { sys::napi_queue_async_work(env.0, result.napi_async_work) })?;
Ok(AsyncWorkPromise {
napi_async_work: result.napi_async_work,
raw_promise,
env,
})
}
unsafe impl<T: Task> Send for AsyncWork<T> {}
unsafe impl<T: Task> Sync for AsyncWork<T> {}
/// env here is the same with the one in `CallContext`.
/// So it actually could do nothing here, because `execute` function is called in the other thread mostly.
unsafe extern "C" fn execute<T: Task>(_env: sys::napi_env, data: *mut c_void) {
let mut work = Box::from_raw(data as *mut AsyncWork<T>);
let _ = mem::replace(
&mut work.value,
work.inner_task.compute().map(mem::MaybeUninit::new),
);
Box::leak(work);
}
unsafe extern "C" fn complete<T: Task>(
env: sys::napi_env,
status: sys::napi_status,
data: *mut c_void,
) {
let mut work = Box::from_raw(data as *mut AsyncWork<T>);
let value_ptr = mem::replace(&mut work.value, Ok(mem::MaybeUninit::zeroed()));
let deferred = mem::replace(&mut work.deferred, ptr::null_mut());
let napi_async_work = mem::replace(&mut work.napi_async_work, ptr::null_mut());
let value = match value_ptr {
Ok(v) => {
let output = v.assume_init();
work.inner_task.resolve(Env::from_raw(env), output)
}
Err(e) => work.inner_task.reject(Env::from_raw(env), e),
};
match check_status!(status).and_then(move |_| value) {
Ok(v) => {
let status = sys::napi_resolve_deferred(env, deferred, v.raw());
debug_assert!(status == sys::Status::napi_ok, "Reject promise failed");
}
Err(e) => {
let status = sys::napi_reject_deferred(env, deferred, JsError::from(e).into_value(env));
debug_assert!(status == sys::Status::napi_ok, "Reject promise failed");
}
};
let delete_status = sys::napi_delete_async_work(env, napi_async_work);
debug_assert!(
delete_status == sys::Status::napi_ok,
"Delete async work failed"
);
}