diff options
Diffstat (limited to 'src/include/port/atomics.h')
| -rw-r--r-- | src/include/port/atomics.h | 25 |
1 files changed, 23 insertions, 2 deletions
diff --git a/src/include/port/atomics.h b/src/include/port/atomics.h index f7884d72c6..4e15ff8764 100644 --- a/src/include/port/atomics.h +++ b/src/include/port/atomics.h @@ -255,10 +255,12 @@ pg_atomic_read_u32(volatile pg_atomic_uint32 *ptr) } /* - * pg_atomic_write_u32 - unlocked write to atomic variable. + * pg_atomic_write_u32 - 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. + * observe a partial write for any reader. Note that this correctly interacts + * with pg_atomic_compare_exchange_u32, in contrast to + * pg_atomic_unlocked_write_u32(). * * No barrier semantics. */ @@ -271,6 +273,25 @@ 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. + * + * No barrier semantics. + */ +static inline void +pg_atomic_unlocked_write_u32(volatile pg_atomic_uint32 *ptr, uint32 val) +{ + AssertPointerAlignment(ptr, 4); + + pg_atomic_unlocked_write_u32_impl(ptr, val); +} + +/* * pg_atomic_exchange_u32 - exchange newval with current value * * Returns the old value of 'ptr' before the swap. |