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Improve documentation for pg_atomic_unlocked_write_u32()

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After my recent commit 7902a47c20, Nathan noticed that
pg_atomic_unlocked_write_u64() was not accurately described by the comments
for the 32bit version. Turns out the 32bit version has suffered from
copy-and-paste-itis since its introduction. Fix.

Reported-by: Nathan Bossart <nathandbossart@gmail.com>
Reviewed-by: Tom Lane <tgl@sss.pgh.pa.us>
Reviewed-by: Nathan Bossart <nathandbossart@gmail.com>
Discussion: https://postgr.es/m/aTGt7q4Jvn97uGAx@nathan
This commit is contained in:
Andres Freund
2025-12-08 23:03:54 -05:00
parent 52382feb78
commit aa749bde32
1 changed files with 7 additions and 5 deletions
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12
src/include/port/atomics.h
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@@ -281,11 +281,13 @@ pg_atomic_write_u32(volatile pg_atomic_uint32 *ptr, uint32 val)
/*
* pg_atomic_unlocked_write_u32 - unlocked write to atomic variable.
*
* The write is guaranteed to succeed as a whole, i.e. it's not possible to
* observe a partial write for any reader. But note that writing this way is
* not guaranteed to correctly interact with read-modify-write operations like
* pg_atomic_compare_exchange_u32. This should only be used in cases where
* minor performance regressions due to atomics emulation are unacceptable.
* Write to an atomic variable, without atomicity guarantees. I.e. it is not
* guaranteed that a concurrent reader will not see a torn value, nor is this
* guaranteed to correctly interact with concurrent read-modify-write
* operations like pg_atomic_compare_exchange_u32. This should only be used
* in cases where minor performance regressions due to atomic operations are
* unacceptable and where exclusive access is guaranteed via some external
* means.
*
* No barrier semantics.
*/