diff options
| -rw-r--r-- | library/core/src/sync/atomic.rs | 13 |
1 files changed, 9 insertions, 4 deletions
diff --git a/library/core/src/sync/atomic.rs b/library/core/src/sync/atomic.rs index 5f1f41e6865..ad8c70c6a3c 100644 --- a/library/core/src/sync/atomic.rs +++ b/library/core/src/sync/atomic.rs @@ -138,7 +138,7 @@ //! //! In general, *all* atomic accesses on read-only memory are Undefined Behavior. For instance, attempting //! to do a `compare_exchange` that will definitely fail (making it conceptually a read-only -//! operation) can still cause a page fault if the underlying memory page is mapped read-only. Since +//! operation) can still cause a segmentation fault if the underlying memory page is mapped read-only. Since //! atomic `load`s might be implemented using compare-exchange operations, even a `load` can fault //! on read-only memory. //! @@ -181,12 +181,13 @@ //! let spinlock = Arc::new(AtomicUsize::new(1)); //! //! let spinlock_clone = Arc::clone(&spinlock); +//! //! let thread = thread::spawn(move|| { -//! spinlock_clone.store(0, Ordering::SeqCst); +//! spinlock_clone.store(0, Ordering::Release); //! }); //! //! // Wait for the other thread to release the lock -//! while spinlock.load(Ordering::SeqCst) != 0 { +//! while spinlock.load(Ordering::Acquire) != 0 { //! hint::spin_loop(); //! } //! @@ -203,7 +204,11 @@ //! //! static GLOBAL_THREAD_COUNT: AtomicUsize = AtomicUsize::new(0); //! -//! let old_thread_count = GLOBAL_THREAD_COUNT.fetch_add(1, Ordering::SeqCst); +//! // Note that Relaxed ordering doesn't synchronize anything +//! // except the global thread counter itself. +//! let old_thread_count = GLOBAL_THREAD_COUNT.fetch_add(1, Ordering::Relaxed); +//! // Note that this number may not be true at the moment of printing +//! // because some other thread may have changed static value already. //! println!("live threads: {}", old_thread_count + 1); //! ``` |