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https://github.com/neondatabase/neon.git
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a22be5af72
Migrates the remaining crates to edition 2024. We like to stay on the latest edition if possible. There is no functional changes, however some code changes had to be done to accommodate the edition's breaking changes. Like the previous migration PRs, this is comprised of three commits: * the first does the edition update and makes `cargo check`/`cargo clippy` pass. we had to update bindgen to make its output [satisfy the requirements of edition 2024](https://doc.rust-lang.org/edition-guide/rust-2024/unsafe-extern.html) * the second commit does a `cargo fmt` for the new style edition. * the third commit reorders imports as a one-off change. As before, it is entirely optional. Part of #10918
80 lines
2.0 KiB
Rust
80 lines
2.0 KiB
Rust
//! Try RCU extension lifted from <https://github.com/vorner/arc-swap/issues/94#issuecomment-1987154023>
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pub trait ArcSwapExt<T> {
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/// [`ArcSwap::rcu`](arc_swap::ArcSwap::rcu), but with Result that short-circuits on error.
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fn try_rcu<R, F, E>(&self, f: F) -> Result<T, E>
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where
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F: FnMut(&T) -> Result<R, E>,
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R: Into<T>;
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}
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impl<T, S> ArcSwapExt<T> for arc_swap::ArcSwapAny<T, S>
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where
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T: arc_swap::RefCnt,
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S: arc_swap::strategy::CaS<T>,
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{
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fn try_rcu<R, F, E>(&self, mut f: F) -> Result<T, E>
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where
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F: FnMut(&T) -> Result<R, E>,
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R: Into<T>,
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{
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fn ptr_eq<Base, A, B>(a: A, b: B) -> bool
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where
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A: arc_swap::AsRaw<Base>,
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B: arc_swap::AsRaw<Base>,
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{
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let a = a.as_raw();
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let b = b.as_raw();
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std::ptr::eq(a, b)
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}
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let mut cur = self.load();
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loop {
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let new = f(&cur)?.into();
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let prev = self.compare_and_swap(&*cur, new);
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let swapped = ptr_eq(&*cur, &*prev);
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if swapped {
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return Ok(arc_swap::Guard::into_inner(prev));
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} else {
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cur = prev;
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}
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}
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}
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}
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#[cfg(test)]
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mod tests {
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use std::sync::Arc;
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use arc_swap::ArcSwap;
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use super::*;
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#[test]
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fn test_try_rcu_success() {
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let swap = ArcSwap::from(Arc::new(42));
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let result = swap.try_rcu(|value| -> Result<_, String> { Ok(**value + 1) });
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assert!(result.is_ok());
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assert_eq!(**swap.load(), 43);
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}
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#[test]
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fn test_try_rcu_error() {
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let swap = ArcSwap::from(Arc::new(42));
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let result = swap.try_rcu(|value| -> Result<i32, _> {
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if **value == 42 {
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Err("err")
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} else {
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Ok(**value + 1)
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}
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});
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assert!(result.is_err());
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assert_eq!(result.unwrap_err(), "err");
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assert_eq!(**swap.load(), 42);
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}
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}
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