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use once_cell::sync::OnceCell;
use std::{
future::Future,
mem::ManuallyDrop,
panic,
pin::Pin,
sync::{Arc, Mutex},
task::{Context, Poll, Waker},
};
use super::*;
use crate::{test_util::TestError, Lift, RustBuffer, RustCallStatusCode};
// Sender/Receiver pair that we use for testing
struct Channel {
result: Option<Result<Result<String, TestError>, LiftArgsError>>,
waker: Option<Waker>,
}
struct Sender(Arc<Mutex<Channel>>);
impl Sender {
fn wake(&self) {
let inner = self.0.lock().unwrap();
if let Some(waker) = &inner.waker {
waker.wake_by_ref();
}
}
fn send(&self, value: Result<String, TestError>) {
let mut inner = self.0.lock().unwrap();
if inner.result.replace(Ok(value)).is_some() {
panic!("value already sent");
}
if let Some(waker) = &inner.waker {
waker.wake_by_ref();
}
}
fn send_lift_args_error(&self, arg_name: &'static str, error: anyhow::Error) {
let mut inner = self.0.lock().unwrap();
if inner
.result
.replace(Err(LiftArgsError { arg_name, error }))
.is_some()
{
panic!("value already sent");
}
if let Some(waker) = &inner.waker {
waker.wake_by_ref();
}
}
}
struct Receiver(Arc<Mutex<Channel>>);
impl Future for Receiver {
type Output = Result<Result<String, TestError>, LiftArgsError>;
fn poll(
self: Pin<&mut Self>,
context: &mut Context<'_>,
) -> Poll<Result<Result<String, TestError>, LiftArgsError>> {
let mut inner = self.0.lock().unwrap();
match inner.result.take() {
Some(v) => Poll::Ready(v),
None => {
inner.waker = Some(context.waker().clone());
Poll::Pending
}
}
}
}
// Create a sender and rust future that we can use for testing
fn channel() -> (Sender, Arc<dyn RustFutureFfi<RustBuffer>>) {
let channel = Arc::new(Mutex::new(Channel {
result: None,
waker: None,
}));
let rust_future = RustFuture::new(Receiver(channel.clone()), crate::UniFfiTag);
(Sender(channel), rust_future)
}
/// Poll a Rust future and get an OnceCell that's set when the continuation is called
fn poll(rust_future: &Arc<dyn RustFutureFfi<RustBuffer>>) -> Arc<OnceCell<RustFuturePoll>> {
let cell = Arc::new(OnceCell::new());
let handle = Arc::into_raw(cell.clone()) as u64;
rust_future.clone().ffi_poll(poll_continuation, handle);
cell
}
extern "C" fn poll_continuation(data: u64, code: RustFuturePoll) {
let cell = unsafe { Arc::from_raw(data as *const OnceCell<RustFuturePoll>) };
cell.set(code).expect("Error setting OnceCell");
}
fn complete(rust_future: Arc<dyn RustFutureFfi<RustBuffer>>) -> (RustBuffer, RustCallStatus) {
let mut out_status_code = RustCallStatus::default();
let return_value = rust_future.ffi_complete(&mut out_status_code);
(return_value, out_status_code)
}
#[test]
fn test_success() {
let (sender, rust_future) = channel();
// Test polling the rust future before it's ready
let continuation_result = poll(&rust_future);
assert_eq!(continuation_result.get(), None);
sender.wake();
assert_eq!(continuation_result.get(), Some(&RustFuturePoll::MaybeReady));
// Test polling the rust future when it's ready
let continuation_result = poll(&rust_future);
assert_eq!(continuation_result.get(), None);
sender.send(Ok("All done".into()));
assert_eq!(continuation_result.get(), Some(&RustFuturePoll::MaybeReady));
// Future polls should immediately return ready
let continuation_result = poll(&rust_future);
assert_eq!(continuation_result.get(), Some(&RustFuturePoll::Ready));
// Complete the future
let (return_buf, call_status) = complete(rust_future);
assert_eq!(call_status.code, RustCallStatusCode::Success);
assert_eq!(
<String as Lift<crate::UniFfiTag>>::try_lift(return_buf).unwrap(),
"All done"
);
}
#[test]
fn test_error() {
let (sender, rust_future) = channel();
let continuation_result = poll(&rust_future);
assert_eq!(continuation_result.get(), None);
sender.send(Err("Something went wrong".into()));
assert_eq!(continuation_result.get(), Some(&RustFuturePoll::MaybeReady));
let continuation_result = poll(&rust_future);
assert_eq!(continuation_result.get(), Some(&RustFuturePoll::Ready));
let (_, call_status) = complete(rust_future);
assert_eq!(call_status.code, RustCallStatusCode::Error);
assert_eq!(
<TestError as Lift<crate::UniFfiTag>>::try_lift_from_rust_buffer(ManuallyDrop::into_inner(
call_status.error_buf
))
.unwrap(),
TestError::from("Something went wrong"),
)
}
#[test]
fn test_lift_args_error() {
let (sender, rust_future) = channel();
let continuation_result = poll(&rust_future);
assert_eq!(continuation_result.get(), None);
sender.send_lift_args_error("arg0", anyhow::anyhow!("Invalid handle"));
assert_eq!(continuation_result.get(), Some(&RustFuturePoll::MaybeReady));
let continuation_result = poll(&rust_future);
assert_eq!(continuation_result.get(), Some(&RustFuturePoll::Ready));
let (_, call_status) = complete(rust_future);
assert_eq!(call_status.code, RustCallStatusCode::UnexpectedError);
assert_eq!(
<String as Lift<crate::UniFfiTag>>::try_lift(ManuallyDrop::into_inner(
call_status.error_buf
))
.unwrap(),
"Failed to convert arg 'arg0': Invalid handle",
)
}
// Once `complete` is called, the inner future should be released, even if wakers still hold a
// reference to the RustFuture
#[test]
fn test_cancel() {
let (_sender, rust_future) = channel();
let continuation_result = poll(&rust_future);
assert_eq!(continuation_result.get(), None);
rust_future.ffi_cancel();
// Cancellation should immediately invoke the callback with RustFuturePoll::Ready
assert_eq!(continuation_result.get(), Some(&RustFuturePoll::Ready));
// Future polls should immediately invoke the callback with RustFuturePoll::Ready
let continuation_result = poll(&rust_future);
assert_eq!(continuation_result.get(), Some(&RustFuturePoll::Ready));
let (_, call_status) = complete(rust_future);
assert_eq!(call_status.code, RustCallStatusCode::Cancelled);
}
// Once `free` is called, the inner future should be released, even if wakers still hold a
// reference to the RustFuture
#[test]
fn test_release_future() {
let (sender, rust_future) = channel();
// Create a weak reference to the channel to use to check if rust_future has dropped its
// future.
let channel_weak = Arc::downgrade(&sender.0);
drop(sender);
// Create an extra ref to rust_future, simulating a waker that still holds a reference to
// it
let rust_future2 = rust_future.clone();
// Complete the rust future
rust_future.ffi_free();
// Even though rust_future is still alive, the channel shouldn't be
assert!(Arc::strong_count(&rust_future2) > 0);
assert_eq!(channel_weak.strong_count(), 0);
assert!(channel_weak.upgrade().is_none());
}
// If `free` is called with a continuation still stored, we should call it them then.
//
// This shouldn't happen in practice, but it seems like good defensive programming
#[test]
fn test_complete_with_stored_continuation() {
let (_sender, rust_future) = channel();
let continuation_result = poll(&rust_future);
rust_future.ffi_free();
assert_eq!(continuation_result.get(), Some(&RustFuturePoll::Ready));
}
// Test what happens if we see a `wake()` call while we're polling the future. This can
// happen, for example, with futures that are handled by a tokio thread pool. We should
// schedule another poll of the future in this case.
#[test]
fn test_wake_during_poll() {
let mut first_time = true;
let future = std::future::poll_fn(move |ctx| {
if first_time {
first_time = false;
// Wake the future while we are in the middle of polling it
ctx.waker().wake_by_ref();
Poll::Pending
} else {
// The second time we're polled, we're ready
Poll::Ready(Ok("All done".to_owned()))
}
});
let rust_future: Arc<dyn RustFutureFfi<RustBuffer>> = RustFuture::new(future, crate::UniFfiTag);
let continuation_result = poll(&rust_future);
// The continuation function should called immediately
assert_eq!(continuation_result.get(), Some(&RustFuturePoll::MaybeReady));
// A second poll should finish the future
let continuation_result = poll(&rust_future);
assert_eq!(continuation_result.get(), Some(&RustFuturePoll::Ready));
let (return_buf, call_status) = complete(rust_future);
assert_eq!(call_status.code, RustCallStatusCode::Success);
assert_eq!(
<String as Lift<crate::UniFfiTag>>::try_lift(return_buf).unwrap(),
"All done"
);
}