From 8dd16259287f58f9273002717ec4d27e97127719 Mon Sep 17 00:00:00 2001 From: Daniel Baumann Date: Wed, 12 Jun 2024 07:43:14 +0200 Subject: Merging upstream version 127.0. Signed-off-by: Daniel Baumann --- third_party/rust/getrandom/src/util.rs | 68 +--------------------------------- 1 file changed, 1 insertion(+), 67 deletions(-) (limited to 'third_party/rust/getrandom/src/util.rs') diff --git a/third_party/rust/getrandom/src/util.rs b/third_party/rust/getrandom/src/util.rs index 3162afad35..1c4e70ba4e 100644 --- a/third_party/rust/getrandom/src/util.rs +++ b/third_party/rust/getrandom/src/util.rs @@ -1,71 +1,5 @@ -// Copyright 2019 Developers of the Rand project. -// -// Licensed under the Apache License, Version 2.0 or the MIT license -// , at your -// option. This file may not be copied, modified, or distributed -// except according to those terms. #![allow(dead_code)] -use core::{ - mem::MaybeUninit, - ptr, - sync::atomic::{AtomicUsize, Ordering::Relaxed}, -}; - -// This structure represents a lazily initialized static usize value. Useful -// when it is preferable to just rerun initialization instead of locking. -// Both unsync_init and sync_init will invoke an init() function until it -// succeeds, then return the cached value for future calls. -// -// Both methods support init() "failing". If the init() method returns UNINIT, -// that value will be returned as normal, but will not be cached. -// -// Users should only depend on the _value_ returned by init() functions. -// Specifically, for the following init() function: -// fn init() -> usize { -// a(); -// let v = b(); -// c(); -// v -// } -// the effects of c() or writes to shared memory will not necessarily be -// observed and additional synchronization methods with be needed. -pub struct LazyUsize(AtomicUsize); - -impl LazyUsize { - pub const fn new() -> Self { - Self(AtomicUsize::new(Self::UNINIT)) - } - - // The initialization is not completed. - pub const UNINIT: usize = usize::max_value(); - - // Runs the init() function at least once, returning the value of some run - // of init(). Multiple callers can run their init() functions in parallel. - // init() should always return the same value, if it succeeds. - pub fn unsync_init(&self, init: impl FnOnce() -> usize) -> usize { - // Relaxed ordering is fine, as we only have a single atomic variable. - let mut val = self.0.load(Relaxed); - if val == Self::UNINIT { - val = init(); - self.0.store(val, Relaxed); - } - val - } -} - -// Identical to LazyUsize except with bool instead of usize. -pub struct LazyBool(LazyUsize); - -impl LazyBool { - pub const fn new() -> Self { - Self(LazyUsize::new()) - } - - pub fn unsync_init(&self, init: impl FnOnce() -> bool) -> bool { - self.0.unsync_init(|| init() as usize) != 0 - } -} +use core::{mem::MaybeUninit, ptr}; /// Polyfill for `maybe_uninit_slice` feature's /// `MaybeUninit::slice_assume_init_mut`. Every element of `slice` must have -- cgit v1.2.3