Merge pull request #7 from taiki-e/compare_and_swap

Replace deprecated compare_and_swap with compare_exchange

Author: taiki-e

src/lib.rs

@@ -451,7 +451,7 @@ fn full_fence() {
         // a `SeqCst` fence.
         //
         // 1. `atomic::fence(SeqCst)`, which compiles into a `mfence` instruction.
-        // 2. `_.compare_and_swap(_, _, SeqCst)`, which compiles into a `lock cmpxchg` instruction.
+        // 2. `_.compare_exchange(_, _, SeqCst, SeqCst)`, which compiles into a `lock cmpxchg` instruction.
         //
         // Both instructions have the effect of a full barrier, but empirical benchmarks have shown
         // that the second one is sometimes a bit faster.
@@ -460,7 +460,7 @@ fn full_fence() {
         // temporary atomic variable and compare-and-exchanging its value. No sane compiler to
         // x86 platforms is going to optimize this away.
         let a = AtomicUsize::new(0);
-        a.compare_and_swap(0, 1, Ordering::SeqCst);
+        let _ = a.compare_exchange(0, 1, Ordering::SeqCst, Ordering::SeqCst);
     } else {
         atomic::fence(Ordering::SeqCst);
     }

src/single.rs

@@ -29,7 +29,8 @@ impl<T> Single<T> {
         // Lock and fill the slot.
         let state = self
             .state
-            .compare_and_swap(0, LOCKED | PUSHED, Ordering::SeqCst);
+            .compare_exchange(0, LOCKED | PUSHED, Ordering::SeqCst, Ordering::SeqCst)
+            .unwrap_or_else(|x| x);
 
         if state == 0 {
             // Write the value and unlock.
@@ -48,9 +49,15 @@ impl<T> Single<T> {
         let mut state = PUSHED;
         loop {
             // Lock and empty the slot.
-            let prev =
-                self.state
-                    .compare_and_swap(state, (state | LOCKED) & !PUSHED, Ordering::SeqCst);
+            let prev = self
+                .state
+                .compare_exchange(
+                    state,
+                    (state | LOCKED) & !PUSHED,
+                    Ordering::SeqCst,
+                    Ordering::SeqCst,
+                )
+                .unwrap_or_else(|x| x);
 
             if prev == state {
                 // Read the value and unlock.

src/unbounded.rs

@@ -172,8 +172,8 @@ impl<T> Unbounded<T> {
                 if self
                     .tail
                     .block
-                    .compare_and_swap(block, new, Ordering::Release)
-                    == block
+                    .compare_exchange(block, new, Ordering::Release, Ordering::Relaxed)
+                    .is_ok()
                 {
                     self.head.block.store(new, Ordering::Release);
                     block = new;