blob: 21d993b6e305f383dad3e0265d56e5f572068329 [file] [log] [blame]
// Definition of global epoch state. The `get` function is the way to
// access this data externally (until const fn is stabilized...).
use std::sync::atomic::AtomicUsize;
use CachePadded;
use epoch::garbage;
use epoch::participants::Participants;
/// Global epoch state
#[derive(Debug)]
pub struct EpochState {
/// Current global epoch
pub epoch: CachePadded<AtomicUsize>,
// FIXME: move this into the `garbage` module, rationalize API
/// Global garbage bags
pub garbage: [CachePadded<garbage::ConcBag>; 3],
/// Participant list
pub participants: Participants,
}
unsafe impl Send for EpochState {}
unsafe impl Sync for EpochState {}
pub use self::imp::get;
#[cfg(not(feature = "nightly"))]
mod imp {
use std::mem;
use std::sync::atomic::{self, AtomicUsize};
use std::sync::atomic::Ordering::Relaxed;
use super::EpochState;
use CachePadded;
use epoch::participants::Participants;
impl EpochState {
fn new() -> EpochState {
EpochState {
epoch: CachePadded::zeroed(),
garbage: [CachePadded::zeroed(),
CachePadded::zeroed(),
CachePadded::zeroed()],
participants: Participants::new(),
}
}
}
static EPOCH: AtomicUsize = atomic::ATOMIC_USIZE_INIT;
pub fn get() -> &'static EpochState {
let mut addr = EPOCH.load(Relaxed);
if addr == 0 {
let boxed = Box::new(EpochState::new());
let raw = Box::into_raw(boxed);
addr = EPOCH.compare_and_swap(0, raw as usize, Relaxed);
if addr != 0 {
let boxed = unsafe { Box::from_raw(raw) };
mem::drop(boxed);
} else {
addr = raw as usize;
}
}
unsafe {
&*(addr as *mut EpochState)
}
}
}
#[cfg(feature = "nightly")]
mod imp {
use super::EpochState;
use CachePadded;
use epoch::participants::Participants;
impl EpochState {
const fn new() -> EpochState {
EpochState {
epoch: CachePadded::zeroed(),
garbage: [CachePadded::zeroed(),
CachePadded::zeroed(),
CachePadded::zeroed()],
participants: Participants::new(),
}
}
}
static EPOCH: EpochState = EpochState::new();
pub fn get() -> &'static EpochState { &EPOCH }
}