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https://github.com/servo/servo
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00e07a6736
This is a prerequisite for using the new version of egui introduced in https://github.com/servo/servo/pull/42402. Testing: No new behaviour. Signed-off-by: Alice Boxhall <alice@igalia.com>
37 lines
1.4 KiB
Rust
37 lines
1.4 KiB
Rust
/* This Source Code Form is subject to the terms of the Mozilla Public
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* License, v. 2.0. If a copy of the MPL was not distributed with this
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* file, You can obtain one at https://mozilla.org/MPL/2.0/. */
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use std::sync::OnceLock;
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/// A OnceLock wrapping a type that is not considered threadsafe by the Rust compiler, but
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/// will be used in a threadsafe manner (it will not be mutated, after being initialized).
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///
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/// This is needed to allow using JS API types (which usually involve raw pointers) in static initializers,
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/// when Servo guarantees through the use of OnceLock that only one thread will ever initialize
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/// the value.
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pub struct ThreadUnsafeOnceLock<T>(OnceLock<T>);
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impl<T> ThreadUnsafeOnceLock<T> {
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pub const fn new() -> Self {
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Self(OnceLock::new())
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}
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/// Initialize the value inside this lock. Panics if the lock has been previously initialized.
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pub fn set(&self, val: T) {
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assert!(self.0.set(val).is_ok());
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}
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/// Get a reference to the value inside this lock. Panics if the lock has not been initialized.
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///
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/// # Safety
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/// The caller must ensure that it does not mutate value contained inside this lock
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/// (using interior mutability).
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pub unsafe fn get(&self) -> &T {
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self.0.get().unwrap()
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}
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}
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unsafe impl<T> Sync for ThreadUnsafeOnceLock<T> {}
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unsafe impl<T> Send for ThreadUnsafeOnceLock<T> {}
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