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//! Miscellaneous tools for concurrent programming.
//!
//! ## Atomics
//!
//! * [`AtomicCell`], a thread-safe mutable memory location.
//! * [`AtomicConsume`], for reading from primitive atomic types with "consume" ordering.
//!
//! ## Thread synchronization
//!
//! * [`Parker`], a thread parking primitive.
//! * [`ShardedLock`], a sharded reader-writer lock with fast concurrent reads.
//! * [`WaitGroup`], for synchronizing the beginning or end of some computation.
//!
//! ## Utilities
//!
//! * [`Backoff`], for exponential backoff in spin loops.
//! * [`CachePadded`], for padding and aligning a value to the length of a cache line.
//! * [`scope`], for spawning threads that borrow local variables from the stack.
//!
//! [`AtomicCell`]: atomic::AtomicCell
//! [`AtomicConsume`]: atomic::AtomicConsume
//! [`Parker`]: sync::Parker
//! [`ShardedLock`]: sync::ShardedLock
//! [`WaitGroup`]: sync::WaitGroup
//! [`scope`]: thread::scope
#![doc(test(
no_crate_inject,
attr(
deny(warnings, rust_2018_idioms),
allow(dead_code, unused_assignments, unused_variables)
)
))]
#![warn(
missing_docs,
missing_debug_implementations,
rust_2018_idioms,
unreachable_pub
)]
#![cfg_attr(not(feature = "std"), no_std)]
#[cfg(crossbeam_loom)]
#[allow(unused_imports)]
mod primitive {
pub(crate) mod sync {
pub(crate) mod atomic {
pub(crate) use loom::sync::atomic::spin_loop_hint;
pub(crate) use loom::sync::atomic::{
AtomicBool, AtomicI16, AtomicI32, AtomicI64, AtomicI8, AtomicIsize, AtomicU16,
AtomicU32, AtomicU64, AtomicU8, AtomicUsize,
};
// FIXME: loom does not support compiler_fence at the moment.
// we use fence as a stand-in for compiler_fence for the time being.
// this may miss some races since fence is stronger than compiler_fence,
// but it's the best we can do for the time being.
pub(crate) use loom::sync::atomic::fence as compiler_fence;
}
pub(crate) use loom::sync::{Arc, Condvar, Mutex};
}
}
#[cfg(not(crossbeam_loom))]
#[allow(unused_imports)]
mod primitive {
pub(crate) mod sync {
pub(crate) mod atomic {
pub(crate) use core::sync::atomic::compiler_fence;
// TODO(taiki-e): once we bump the minimum required Rust version to 1.49+,
// use [`core::hint::spin_loop`] instead.
#[allow(deprecated)]
pub(crate) use core::sync::atomic::spin_loop_hint;
#[cfg(not(crossbeam_no_atomic))]
pub(crate) use core::sync::atomic::{
AtomicBool, AtomicI16, AtomicI32, AtomicI8, AtomicIsize, AtomicU16, AtomicU32,
AtomicU8, AtomicUsize,
};
#[cfg(not(crossbeam_no_atomic_64))]
pub(crate) use core::sync::atomic::{AtomicI64, AtomicU64};
}
#[cfg(feature = "std")]
pub(crate) use std::sync::{Arc, Condvar, Mutex};
}
}
pub mod atomic;
mod cache_padded;
pub use crate::cache_padded::CachePadded;
mod backoff;
pub use crate::backoff::Backoff;
use cfg_if::cfg_if;
cfg_if! {
if #[cfg(feature = "std")] {
pub mod sync;
#[cfg(not(crossbeam_loom))]
pub mod thread;
}
}