Changeset 181461 in webkit

Timestamp:

Mar 12, 2015, 5:20:18 PM (11 years ago)

Author:

mark.lam@apple.com

Message:

Change WTF::ByteSpinLock to use std::atomic.
<​https://webkit.org/b/142644>

Reviewed by Filip Pizlo.

• wtf/ByteSpinLock.h:

(WTF::ByteSpinLock::ByteSpinLock):
(WTF::ByteSpinLock::lock):
(WTF::ByteSpinLock::unlock):
(WTF::ByteSpinLock::isHeld):

Location:

trunk/Source/WTF

Files:

• ChangeLog (modified) (1 diff)
• wtf/ByteSpinLock.h (modified) (3 diffs)

trunk/Source/WTF/ChangeLog

@@ +1 @@
+2015-03-12  Mark Lam  <mark.lam@apple.com>
+
+        Change WTF::ByteSpinLock to use std::atomic.
+        <https://webkit.org/b/142644>
+
+        Reviewed by Filip Pizlo.
+
+        * wtf/ByteSpinLock.h:
+        (WTF::ByteSpinLock::ByteSpinLock):
+        (WTF::ByteSpinLock::lock):
+        (WTF::ByteSpinLock::unlock):
+        (WTF::ByteSpinLock::isHeld):
+
 2015-03-12  Csaba Osztrogonác  <ossy@webkit.org>
 

trunk/Source/WTF/wtf/ByteSpinLock.h

@@ -27 +27 @@
 #define ByteSpinLock_h
 
+#include <atomic>
 #include <thread>
 #include <wtf/Assertions.h>
-#include <wtf/Atomics.h>
 #include <wtf/Locker.h>
 #include <wtf/Noncopyable.h>
@@ -39 +39 @@
 public:
     ByteSpinLock()
-        : m_lock(0)
+        : m_lock(false)
     {
     }
@@ -45 +45 @@
     void lock()
     {
-        while (!weakCompareAndSwap(&m_lock, 0, 1))
+        bool expected = false;
+        while (!m_lock.compare_exchange_weak(expected, true, std::memory_order_acquire)) {
             std::this_thread::yield();
-        memoryBarrierAfterLock();
+            expected = false;
+        }
     }
     
     void unlock()
     {
-        memoryBarrierBeforeUnlock();
-        m_lock = 0;
+        m_lock.store(false, std::memory_order_release);
     }
     
-    bool isHeld() const { return !!m_lock; }
+    bool isHeld() const { return m_lock.load(std::memory_order_acquire); }
     
 private:
-    uint8_t m_lock;
+    std::atomic<bool> m_lock;
 };