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epoch: Fix false sharing in Local struct #1026

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Sep 12, 2023
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epoch: Fix false sharing in Local struct #1026

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8 changes: 4 additions & 4 deletions crossbeam-epoch/src/internal.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -273,9 +273,6 @@ pub(crate) struct Local {
/// A node in the intrusive linked list of `Local`s.
entry: Entry,

/// The local epoch.
epoch: AtomicEpoch,

/// A reference to the global data.
///
/// When all guards and handles get dropped, this reference is destroyed.
Expand All @@ -294,6 +291,9 @@ pub(crate) struct Local {
///
/// This is just an auxiliary counter that sometimes kicks off collection.
pin_count: Cell<Wrapping<usize>>,

/// The local epoch.
epoch: CachePadded<AtomicEpoch>,
}

// Make sure `Local` is less than or equal to 2048 bytes.
Expand All @@ -320,12 +320,12 @@ impl Local {

let local = Owned::new(Local {
entry: Entry::default(),
epoch: AtomicEpoch::new(Epoch::starting()),
collector: UnsafeCell::new(ManuallyDrop::new(collector.clone())),
bag: UnsafeCell::new(Bag::new()),
guard_count: Cell::new(0),
handle_count: Cell::new(1),
pin_count: Cell::new(Wrapping(0)),
epoch: CachePadded::new(AtomicEpoch::new(Epoch::starting())),
})
.into_shared(unprotected());
collector.global.locals.insert(local, unprotected());
Expand Down