Merge pull request #4042 from dumarchie/cas

Make cas($target, &code) ~17% faster
rakudo · Nov 21, 2020 · 96ab6eb · 96ab6eb
2 parents 1cd8765 + 484f870
commit 96ab6eb
Showing 1 changed file with 9 additions and 6 deletions.
diff --git a/src/core.c/atomicops.pm6 b/src/core.c/atomicops.pm6
@@ -24,12 +24,15 @@ multi sub cas($target is rw, \expected, \value) {
 }
 multi sub cas($target is rw, &code) {
     my $current := nqp::atomicload($target);
-    loop {
-        my $updated := code($current);
-        my $seen := nqp::cas($target, $current, $updated);
-        return $updated if nqp::eqaddr($seen, $current);
-        $current := $seen;
-    }
+    nqp::until(
+      nqp::stmts(
+        (my $updated := code($current)),
+        (my $seen := nqp::cas($target, $current, $updated)),
+        nqp::eqaddr($seen, $current)
+      ),
+      $current := $seen
+    );
+    $updated
 }
 
 #== Native integer atomics only available on MoarVM ==============================