diff options
| -rw-r--r-- | library/core/src/sync/atomic.rs | 18 |
1 files changed, 18 insertions, 0 deletions
diff --git a/library/core/src/sync/atomic.rs b/library/core/src/sync/atomic.rs index 0061e33f986..73180bde54a 100644 --- a/library/core/src/sync/atomic.rs +++ b/library/core/src/sync/atomic.rs @@ -716,6 +716,12 @@ impl AtomicBool { /// AcqRel | AcqRel | Acquire /// SeqCst | SeqCst | SeqCst /// + /// `compare_and_swap` and `compare_exchange` also differ in their return type. You can use + /// `compare_exchange(...).unwrap_or_else(|x| x)` to recover the behavior of `compare_and_swap`, + /// but in most cases it is more idiomatic to check whether the return value is `Ok` or `Err` + /// rather than to infer success vs failure based on the value that was read. + /// + /// During migration, consider whether it makes sense to use `compare_exchange_weak` instead. /// `compare_exchange_weak` is allowed to fail spuriously even when the comparison succeeds, /// which allows the compiler to generate better assembly code when the compare and swap /// is used in a loop. @@ -1651,6 +1657,12 @@ impl<T> AtomicPtr<T> { /// AcqRel | AcqRel | Acquire /// SeqCst | SeqCst | SeqCst /// + /// `compare_and_swap` and `compare_exchange` also differ in their return type. You can use + /// `compare_exchange(...).unwrap_or_else(|x| x)` to recover the behavior of `compare_and_swap`, + /// but in most cases it is more idiomatic to check whether the return value is `Ok` or `Err` + /// rather than to infer success vs failure based on the value that was read. + /// + /// During migration, consider whether it makes sense to use `compare_exchange_weak` instead. /// `compare_exchange_weak` is allowed to fail spuriously even when the comparison succeeds, /// which allows the compiler to generate better assembly code when the compare and swap /// is used in a loop. @@ -2771,6 +2783,12 @@ macro_rules! atomic_int { /// AcqRel | AcqRel | Acquire /// SeqCst | SeqCst | SeqCst /// + /// `compare_and_swap` and `compare_exchange` also differ in their return type. You can use + /// `compare_exchange(...).unwrap_or_else(|x| x)` to recover the behavior of `compare_and_swap`, + /// but in most cases it is more idiomatic to check whether the return value is `Ok` or `Err` + /// rather than to infer success vs failure based on the value that was read. + /// + /// During migration, consider whether it makes sense to use `compare_exchange_weak` instead. /// `compare_exchange_weak` is allowed to fail spuriously even when the comparison succeeds, /// which allows the compiler to generate better assembly code when the compare and swap /// is used in a loop. |