Present Servo BGRA hardware surfaces

third_party/gpui/src/util.rs

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+use crate::{BackgroundExecutor, Task};
+use std::{
+    future::Future,
+    pin::Pin,
+    sync::atomic::{AtomicUsize, Ordering::SeqCst},
+    task,
+    time::Duration,
+};
+
+pub use util::*;
+
+/// A helper trait for building complex objects with imperative conditionals in a fluent style.
+pub trait FluentBuilder {
+    /// Imperatively modify self with the given closure.
+    fn map<U>(self, f: impl FnOnce(Self) -> U) -> U
+    where
+        Self: Sized,
+    {
+        f(self)
+    }
+
+    /// Conditionally modify self with the given closure.
+    fn when(self, condition: bool, then: impl FnOnce(Self) -> Self) -> Self
+    where
+        Self: Sized,
+    {
+        self.map(|this| if condition { then(this) } else { this })
+    }
+
+    /// Conditionally modify self with the given closure.
+    fn when_else(
+        self,
+        condition: bool,
+        then: impl FnOnce(Self) -> Self,
+        else_fn: impl FnOnce(Self) -> Self,
+    ) -> Self
+    where
+        Self: Sized,
+    {
+        self.map(|this| if condition { then(this) } else { else_fn(this) })
+    }
+
+    /// Conditionally unwrap and modify self with the given closure, if the given option is Some.
+    fn when_some<T>(self, option: Option<T>, then: impl FnOnce(Self, T) -> Self) -> Self
+    where
+        Self: Sized,
+    {
+        self.map(|this| {
+            if let Some(value) = option {
+                then(this, value)
+            } else {
+                this
+            }
+        })
+    }
+    /// Conditionally unwrap and modify self with the given closure, if the given option is None.
+    fn when_none<T>(self, option: &Option<T>, then: impl FnOnce(Self) -> Self) -> Self
+    where
+        Self: Sized,
+    {
+        self.map(|this| if option.is_some() { this } else { then(this) })
+    }
+}
+
+/// Extensions for Future types that provide additional combinators and utilities.
+pub trait FutureExt {
+    /// Requires a Future to complete before the specified duration has elapsed.
+    /// Similar to tokio::timeout.
+    fn with_timeout(self, timeout: Duration, executor: &BackgroundExecutor) -> WithTimeout<Self>
+    where
+        Self: Sized;
+}
+
+impl<T: Future> FutureExt for T {
+    fn with_timeout(self, timeout: Duration, executor: &BackgroundExecutor) -> WithTimeout<Self>
+    where
+        Self: Sized,
+    {
+        WithTimeout {
+            future: self,
+            timer: executor.timer(timeout),
+        }
+    }
+}
+
+#[pin_project::pin_project]
+pub struct WithTimeout<T> {
+    #[pin]
+    future: T,
+    #[pin]
+    timer: Task<()>,
+}
+
+#[derive(Debug, thiserror::Error)]
+#[error("Timed out before future resolved")]
+/// Error returned by with_timeout when the timeout duration elapsed before the future resolved
+pub struct Timeout;
+
+impl<T: Future> Future for WithTimeout<T> {
+    type Output = Result<T::Output, Timeout>;
+
+    fn poll(self: Pin<&mut Self>, cx: &mut task::Context) -> task::Poll<Self::Output> {
+        let this = self.project();
+
+        if let task::Poll::Ready(output) = this.future.poll(cx) {
+            task::Poll::Ready(Ok(output))
+        } else if this.timer.poll(cx).is_ready() {
+            task::Poll::Ready(Err(Timeout))
+        } else {
+            task::Poll::Pending
+        }
+    }
+}
+
+#[cfg(any(test, feature = "test-support"))]
+/// Uses smol executor to run a given future no longer than the timeout specified.
+/// Note that this won't "rewind" on `cx.executor().advance_clock` call, truly waiting for the timeout to elapse.
+pub async fn smol_timeout<F, T>(timeout: Duration, f: F) -> Result<T, ()>
+where
+    F: Future<Output = T>,
+{
+    let timer = async {
+        smol::Timer::after(timeout).await;
+        Err(())
+    };
+    let future = async move { Ok(f.await) };
+    smol::future::FutureExt::race(timer, future).await
+}
+
+/// Increment the given atomic counter if it is not zero.
+/// Return the new value of the counter.
+pub(crate) fn atomic_incr_if_not_zero(counter: &AtomicUsize) -> usize {
+    let mut loaded = counter.load(SeqCst);
+    loop {
+        if loaded == 0 {
+            return 0;
+        }
+        match counter.compare_exchange_weak(loaded, loaded + 1, SeqCst, SeqCst) {
+            Ok(x) => return x + 1,
+            Err(actual) => loaded = actual,
+        }
+    }
+}
+
+#[cfg(test)]
+mod tests {
+    use crate::TestAppContext;
+
+    use super::*;
+
+    #[gpui::test]
+    async fn test_with_timeout(cx: &mut TestAppContext) {
+        Task::ready(())
+            .with_timeout(Duration::from_secs(1), &cx.executor())
+            .await
+            .expect("Timeout should be noop");
+
+        let long_duration = Duration::from_secs(6000);
+        let short_duration = Duration::from_secs(1);
+        cx.executor()
+            .timer(long_duration)
+            .with_timeout(short_duration, &cx.executor())
+            .await
+            .expect_err("timeout should have triggered");
+
+        let fut = cx
+            .executor()
+            .timer(long_duration)
+            .with_timeout(short_duration, &cx.executor());
+        cx.executor().advance_clock(short_duration * 2);
+        futures::FutureExt::now_or_never(fut)
+            .unwrap_or_else(|| panic!("timeout should have triggered"))
+            .expect_err("timeout");
+    }
+}