crossbeam_utils/
lib.rs

1//! Miscellaneous tools for concurrent programming.
2//!
3//! ## Atomics
4//!
5//! * [`AtomicCell`], a thread-safe mutable memory location.
6//! * [`AtomicConsume`], for reading from primitive atomic types with "consume" ordering.
7//!
8//! ## Thread synchronization
9//!
10//! * [`Parker`], a thread parking primitive.
11//! * [`ShardedLock`], a sharded reader-writer lock with fast concurrent reads.
12//! * [`WaitGroup`], for synchronizing the beginning or end of some computation.
13//!
14//! ## Utilities
15//!
16//! * [`Backoff`], for exponential backoff in spin loops.
17//! * [`CachePadded`], for padding and aligning a value to the length of a cache line.
18//! * [`scope`], for spawning threads that borrow local variables from the stack.
19//!
20//! [`AtomicCell`]: atomic::AtomicCell
21//! [`AtomicConsume`]: atomic::AtomicConsume
22//! [`Parker`]: sync::Parker
23//! [`ShardedLock`]: sync::ShardedLock
24//! [`WaitGroup`]: sync::WaitGroup
25//! [`scope`]: thread::scope
26
27#![doc(test(
28    no_crate_inject,
29    attr(
30        deny(warnings, rust_2018_idioms),
31        allow(dead_code, unused_assignments, unused_variables)
32    )
33))]
34#![warn(
35    missing_docs,
36    missing_debug_implementations,
37    rust_2018_idioms,
38    unreachable_pub
39)]
40#![cfg_attr(not(feature = "std"), no_std)]
41
42#[cfg(crossbeam_loom)]
43#[allow(unused_imports)]
44mod primitive {
45    pub(crate) mod hint {
46        pub(crate) use loom::hint::spin_loop;
47    }
48    pub(crate) mod sync {
49        pub(crate) mod atomic {
50            pub(crate) use loom::sync::atomic::{
51                AtomicBool, AtomicI16, AtomicI32, AtomicI64, AtomicI8, AtomicIsize, AtomicU16,
52                AtomicU32, AtomicU64, AtomicU8, AtomicUsize, Ordering,
53            };
54
55            // FIXME: loom does not support compiler_fence at the moment.
56            // https://github.com/tokio-rs/loom/issues/117
57            // we use fence as a stand-in for compiler_fence for the time being.
58            // this may miss some races since fence is stronger than compiler_fence,
59            // but it's the best we can do for the time being.
60            pub(crate) use loom::sync::atomic::fence as compiler_fence;
61        }
62        pub(crate) use loom::sync::{Arc, Condvar, Mutex};
63    }
64}
65#[cfg(not(crossbeam_loom))]
66#[allow(unused_imports)]
67mod primitive {
68    pub(crate) mod hint {
69        pub(crate) use core::hint::spin_loop;
70    }
71    pub(crate) mod sync {
72        pub(crate) mod atomic {
73            pub(crate) use core::sync::atomic::{compiler_fence, Ordering};
74            #[cfg(not(crossbeam_no_atomic))]
75            pub(crate) use core::sync::atomic::{
76                AtomicBool, AtomicI16, AtomicI8, AtomicIsize, AtomicU16, AtomicU8, AtomicUsize,
77            };
78            #[cfg(not(crossbeam_no_atomic))]
79            #[cfg(any(target_has_atomic = "32", not(target_pointer_width = "16")))]
80            pub(crate) use core::sync::atomic::{AtomicI32, AtomicU32};
81            #[cfg(not(crossbeam_no_atomic))]
82            #[cfg(any(
83                target_has_atomic = "64",
84                not(any(target_pointer_width = "16", target_pointer_width = "32")),
85            ))]
86            pub(crate) use core::sync::atomic::{AtomicI64, AtomicU64};
87        }
88
89        #[cfg(feature = "std")]
90        pub(crate) use std::sync::{Arc, Condvar, Mutex};
91    }
92}
93
94pub mod atomic;
95
96mod cache_padded;
97pub use crate::cache_padded::CachePadded;
98
99mod backoff;
100pub use crate::backoff::Backoff;
101
102use cfg_if::cfg_if;
103
104cfg_if! {
105    if #[cfg(feature = "std")] {
106        pub mod sync;
107
108        #[cfg(not(crossbeam_loom))]
109        pub mod thread;
110    }
111}
crossbeam_utils/lib.rs

crossbeam_utils/
lib.rs
