From 318da22448c73b51c681b94257b2eea99e989e1a Mon Sep 17 00:00:00 2001
From: Shivaram Lingamneni <slingamn@cs.stanford.edu>
Date: Mon, 2 Jul 2018 16:33:39 -0400
Subject: [PATCH] simplify CAS logic a bit

---
 irc/utils/bitset.go | 8 +++-----
 1 file changed, 3 insertions(+), 5 deletions(-)

diff --git a/irc/utils/bitset.go b/irc/utils/bitset.go
index 0dfe309a..e5358f68 100644
--- a/irc/utils/bitset.go
+++ b/irc/utils/bitset.go
@@ -37,17 +37,15 @@ func BitsetSet(set []uint64, position uint, on bool) (changed bool) {
 	mask = 1 << bit
 	for {
 		current := atomic.LoadUint64(addr)
-		previouslyOn := (current & mask) != 0
-		if on == previouslyOn {
-			return false
-		}
 		var desired uint64
 		if on {
 			desired = current | mask
 		} else {
 			desired = current & (^mask)
 		}
-		if atomic.CompareAndSwapUint64(addr, current, desired) {
+		if current == desired {
+			return false
+		} else if atomic.CompareAndSwapUint64(addr, current, desired) {
 			return true
 		}
 	}