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/* This Source Code Form is subject to the terms of the Mozilla Public
* License, v. 2.0. If a copy of the MPL was not distributed with this
//! This module contains code to handle foreign callbacks - C-ABI functions that are defined by a
//! foreign language, then registered with UniFFI. These callbacks are used to implement callback
//! interfaces, async scheduling etc. Foreign callbacks are registered at startup, when the foreign
//! code loads the exported library. For each callback type, we also define a "cell" type for
//! storing the callback.
use std::{
ptr::{null_mut, NonNull},
sync::atomic::{AtomicPtr, Ordering},
};
// Cell type that stores any NonNull<T>
#[doc(hidden)]
pub struct UniffiForeignPointerCell<T>(AtomicPtr<T>);
impl<T> UniffiForeignPointerCell<T> {
pub const fn new() -> Self {
Self(AtomicPtr::new(null_mut()))
}
pub fn set(&self, callback: NonNull<T>) {
self.0.store(callback.as_ptr(), Ordering::Relaxed);
}
pub fn get(&self) -> &T {
unsafe {
NonNull::new(self.0.load(Ordering::Relaxed))
.expect("Foreign pointer not set. This is likely a uniffi bug.")
.as_mut()
}
}
}
unsafe impl<T> Send for UniffiForeignPointerCell<T> {}
unsafe impl<T> Sync for UniffiForeignPointerCell<T> {}