napi-rs/napi/src/promise.rs
2020-12-02 18:39:20 +08:00

122 lines
3.5 KiB
Rust

use futures::prelude::*;
use std::os::raw::{c_char, c_void};
use std::ptr;
use crate::{check_status, sys, Env, JsError, NapiValue, Result};
pub struct FuturePromise<T, V: NapiValue> {
deferred: sys::napi_deferred,
env: sys::napi_env,
tsfn: sys::napi_threadsafe_function,
async_resource_name: sys::napi_value,
resolver: Box<dyn FnOnce(&mut Env, T) -> Result<V>>,
}
unsafe impl<T, V: NapiValue> Send for FuturePromise<T, V> {}
impl<T, V: NapiValue> FuturePromise<T, V> {
#[inline]
pub fn create(
env: sys::napi_env,
raw_deferred: sys::napi_deferred,
resolver: Box<dyn FnOnce(&mut Env, T) -> Result<V>>,
) -> Result<Self> {
let mut async_resource_name = ptr::null_mut();
let s = "napi_resolve_promise_from_future";
check_status!(unsafe {
sys::napi_create_string_utf8(
env,
s.as_ptr() as *const c_char,
s.len(),
&mut async_resource_name,
)
})?;
Ok(FuturePromise {
deferred: raw_deferred,
resolver,
env,
tsfn: ptr::null_mut(),
async_resource_name,
})
}
#[inline]
pub(crate) fn start(self) -> Result<TSFNValue> {
let mut tsfn_value = ptr::null_mut();
let async_resource_name = self.async_resource_name;
let initial_thread_count = 1;
let env = self.env;
let self_ref = Box::leak(Box::from(self));
check_status!(unsafe {
sys::napi_create_threadsafe_function(
env,
ptr::null_mut(),
ptr::null_mut(),
async_resource_name,
0,
initial_thread_count,
ptr::null_mut(),
None,
self_ref as *mut _ as *mut c_void,
Some(call_js_cb::<T, V>),
&mut tsfn_value,
)
})?;
self_ref.tsfn = tsfn_value;
Ok(TSFNValue(tsfn_value))
}
}
pub(crate) struct TSFNValue(sys::napi_threadsafe_function);
unsafe impl Send for TSFNValue {}
#[inline]
pub(crate) async fn resolve_from_future<T: Send, F: Future<Output = Result<T>>>(
tsfn_value: TSFNValue,
fut: F,
) {
let val = fut.await;
check_status!(unsafe { sys::napi_acquire_threadsafe_function(tsfn_value.0) })
.expect("Failed to acquire thread safe function");
check_status!(unsafe {
sys::napi_call_threadsafe_function(
tsfn_value.0,
Box::into_raw(Box::from(val)) as *mut _ as *mut c_void,
sys::napi_threadsafe_function_call_mode::napi_tsfn_nonblocking,
)
})
.expect("Failed to call thread safe function");
}
unsafe extern "C" fn call_js_cb<T, V: NapiValue>(
raw_env: sys::napi_env,
_js_callback: sys::napi_value,
context: *mut c_void,
data: *mut c_void,
) {
let mut env = Env::from_raw(raw_env);
let future_promise = Box::from_raw(context as *mut FuturePromise<T, V>);
let value: Result<T> = ptr::read(data as *const _);
let resolver = future_promise.resolver;
let deferred = future_promise.deferred;
let tsfn = future_promise.tsfn;
let js_value_to_resolve = value.and_then(move |v| (resolver)(&mut env, v));
match js_value_to_resolve {
Ok(v) => {
let status = sys::napi_resolve_deferred(raw_env, deferred, v.raw());
debug_assert!(status == sys::Status::napi_ok, "Resolve promise failed");
}
Err(e) => {
let status =
sys::napi_reject_deferred(raw_env, deferred, JsError::from(e).into_value(raw_env));
debug_assert!(status == sys::Status::napi_ok, "Reject promise failed");
}
};
check_status!(sys::napi_release_threadsafe_function(
tsfn,
sys::napi_threadsafe_function_release_mode::napi_tsfn_release,
))
.expect("Release threadsafe function failed");
}