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Make Local less than 2048 bytes #552

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Sep 1, 2020
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Make Local less than 2048 bytes #552

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11 changes: 8 additions & 3 deletions crossbeam-epoch/src/internal.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -55,7 +55,7 @@ use crate::sync::queue::Queue;

/// Maximum number of objects a bag can contain.
#[cfg(not(feature = "sanitize"))]
const MAX_OBJECTS: usize = 64;
const MAX_OBJECTS: usize = 62;
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fwiw, if make Local to be less than or equal to 1024 bytes, MAX_OBJECTS needs to be 30 (1016 bytes)

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If I didn't misunderstand @stjepang's this comment, It seems fine with less than half of what it is now, so it may be okay with this.

#[cfg(feature = "sanitize")]
const MAX_OBJECTS: usize = 4;

Expand Down Expand Up @@ -174,8 +174,6 @@ impl Default for Bag {
Deferred::new(no_op_func),
Deferred::new(no_op_func),
Deferred::new(no_op_func),
Deferred::new(no_op_func),
Deferred::new(no_op_func),
],
};
#[cfg(feature = "sanitize")]
Expand Down Expand Up @@ -374,6 +372,13 @@ pub struct Local {
pin_count: Cell<Wrapping<usize>>,
}

// Make sure `Local` is less than or equal to 2048 bytes.
// https://github.com/crossbeam-rs/crossbeam/issues/551
#[test]
fn local_size() {
assert_eq!(2040, core::mem::size_of::<Local>());
}

impl Local {
/// Number of pinnings after which a participant will execute some deferred functions from the
/// global queue.
Expand Down