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channel: use AtomicUsize::get_mut in flavors::{array,list}::Channel::drop#811

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bors[bot] merged 3 commits intocrossbeam-rs:masterfrom
eb-64-64:mut_drop
Apr 11, 2022
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channel: use AtomicUsize::get_mut in flavors::{array,list}::Channel::drop#811
bors[bot] merged 3 commits intocrossbeam-rs:masterfrom
eb-64-64:mut_drop

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@eb-64-64 eb-64-64 commented Apr 6, 2022

As access to &mut self in Drop impls gives exclusive access, it's
unnecessary to atomically load self.head and self.tail there.

@eb-64-64
use get_mut in flavors::array::Channel::drop
97c7f2d 
As access to `&mut self` in `Drop` impls gives exclusive access, it's
unnecessary to atomically load `self.head` and `self.tail` there.
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eb-64-64 commented Apr 6, 2022

I stumbled across this as I was reading the code for educational purposes

@eb-64-64 eb-64-64 changed the title crossbeam-channel: use AtomicUsize::get_mut in flavors::array::Channel::drop channel: use AtomicUsize::get_mut in flavors::array::Channel::drop Apr 6, 2022
@eb-64-64 eb-64-64 changed the title channel: use AtomicUsize::get_mut in flavors::array::Channel::drop channel: use AtomicUsize::get_mut in flavors::{array,list}::Channel::drop Apr 7, 2022
@eb-64-64 eb-64-64 mentioned this pull request Apr 7, 2022
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taiki-e commented Apr 8, 2022

Thanks! I'll merge this once the upstream bugfix (rust-lang/rust#95621) which fixes the breakage on miri CI merged.

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RalfJung commented Apr 9, 2022

You could temporarily remove the -Zmiri-check-number-validity to work around the MPSC bug.
(Sorry for this, I didn't realize how widely used that flag is so I wasn't too worried when I noticed MPSC breaking with it.)

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taiki-e commented Apr 11, 2022

Thanks for the advice. This time I chose to wait for the patch to be merged since it had already been submitted that looked reasonable. It makes sense to temporarily remove the flag if the fix is going to take a long time.

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taiki-e commented Apr 11, 2022

bors r+

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bors Bot commented Apr 11, 2022

Build succeeded:

@bors bors Bot merged commit df9b0c9 into crossbeam-rs:master Apr 11, 2022
@eb-64-64 eb-64-64 deleted the mut_drop branch April 12, 2022 01:56
@taiki-e taiki-e mentioned this pull request Jul 21, 2022
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bors Bot added a commit that referenced this pull request Jul 21, 2022
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Merge #874
6baa072 
874: Use get_mut instead of atomic load in Drop impls r=taiki-e a=taiki-e

Similar to #811, but for deque and queue.

Co-authored-by: Taiki Endo <te316e89@gmail.com>
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@eb-64-64 @taiki-e @RalfJung