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#![no_std]
28#![doc(test(
29    no_crate_inject,
30    attr(
31        deny(warnings, rust_2018_idioms),
32        allow(dead_code, unused_assignments, unused_variables)
33    )
34))]
35#![warn(
36    missing_docs,
37    missing_debug_implementations,
38    rust_2018_idioms,
39    unreachable_pub
40)]
41
42#[cfg(feature = "std")]
43extern crate std;
44
45#[cfg(crossbeam_loom)]
46#[allow(unused_imports)]
47mod primitive {
48    pub(crate) mod hint {
49        pub(crate) use loom::hint::spin_loop;
50    }
51    pub(crate) mod sync {
52        pub(crate) mod atomic {
53            pub(crate) use loom::sync::atomic::{
54                AtomicBool, AtomicI16, AtomicI32, AtomicI64, AtomicI8, AtomicIsize, AtomicU16,
55                AtomicU32, AtomicU64, AtomicU8, AtomicUsize, Ordering,
56            };
57
58            // FIXME: loom does not support compiler_fence at the moment.
59            // https://github.com/tokio-rs/loom/issues/117
60            // we use fence as a stand-in for compiler_fence for the time being.
61            // this may miss some races since fence is stronger than compiler_fence,
62            // but it's the best we can do for the time being.
63            pub(crate) use loom::sync::atomic::fence as compiler_fence;
64        }
65        pub(crate) use loom::sync::{Arc, Condvar, Mutex};
66    }
67}
68#[cfg(not(crossbeam_loom))]
69#[allow(unused_imports)]
70mod primitive {
71    pub(crate) mod hint {
72        pub(crate) use core::hint::spin_loop;
73    }
74    pub(crate) mod sync {
75        pub(crate) mod atomic {
76            pub(crate) use core::sync::atomic::{compiler_fence, Ordering};
77            #[cfg(not(crossbeam_no_atomic))]
78            pub(crate) use core::sync::atomic::{
79                AtomicBool, AtomicI16, AtomicI8, AtomicIsize, AtomicU16, AtomicU8, AtomicUsize,
80            };
81            #[cfg(not(crossbeam_no_atomic))]
82            #[cfg(any(target_has_atomic = "32", not(target_pointer_width = "16")))]
83            pub(crate) use core::sync::atomic::{AtomicI32, AtomicU32};
84            #[cfg(not(crossbeam_no_atomic))]
85            #[cfg(any(
86                target_has_atomic = "64",
87                not(any(target_pointer_width = "16", target_pointer_width = "32")),
88            ))]
89            pub(crate) use core::sync::atomic::{AtomicI64, AtomicU64};
90        }
91
92        #[cfg(feature = "std")]
93        pub(crate) use std::sync::{Arc, Condvar, Mutex};
94    }
95}
96
97pub mod atomic;
98
99mod cache_padded;
100pub use crate::cache_padded::CachePadded;
101
102mod backoff;
103pub use crate::backoff::Backoff;
104
105#[cfg(feature = "std")]
106pub mod sync;
107
108#[cfg(feature = "std")]
109#[cfg(not(crossbeam_loom))]
110pub mod thread;
crossbeam_utils/lib.rs

crossbeam_utils/
lib.rs
