Spinlock: Removed superfluous load() in try_lock and cleaned up lock() loop

Reneg973 · Reneg973 · commit 2e82cf706094 · 2025-10-19T07:00:36.000Z
diff --git a/api/include/opentelemetry/common/spin_lock_mutex.h b/api/include/opentelemetry/common/spin_lock_mutex.h
@@ -82,8 +82,7 @@ class SpinLockMutex
    */
   bool try_lock() noexcept
   {
-    return !flag_.load(std::memory_order_relaxed) &&
-           !flag_.exchange(true, std::memory_order_acquire);
+    return !flag_.exchange(true, std::memory_order_acquire);
   }
 
   /**
@@ -95,13 +94,9 @@ class SpinLockMutex
    */
   void lock() noexcept
   {
-    for (;;)
+    // Try once
+    while (!try_lock())
     {
-      // Try once
-      if (!flag_.exchange(true, std::memory_order_acquire))
-      {
-        return;
-      }
       // Spin-Fast (goal ~10ns)
       for (std::size_t i = 0; i < SPINLOCK_FAST_ITERATIONS; ++i)
       {

Original file line number	Diff line number	Diff line change
`@@ -82,8 +82,7 @@ class SpinLockMutex`
`82`	`82`	`*/`
`83`	`83`	`bool try_lock() noexcept`
`84`	`84`	`{`
`85`		`- return !flag_.load(std::memory_order_relaxed) &&`
`86`		`- !flag_.exchange(true, std::memory_order_acquire);`
	`85`	`+ return !flag_.exchange(true, std::memory_order_acquire);`
`87`	`86`	`}`
`88`	`87`
`89`	`88`	`/**`
`@@ -95,13 +94,9 @@ class SpinLockMutex`
`95`	`94`	`*/`
`96`	`95`	`void lock() noexcept`
`97`	`96`	`{`
`98`		`- for (;;)`
	`97`	`+ // Try once`
	`98`	`+ while (!try_lock())`
`99`	`99`	`{`
`100`		`- // Try once`
`101`		`- if (!flag_.exchange(true, std::memory_order_acquire))`
`102`		`- {`
`103`		`- return;`
`104`		`- }`
`105`	`100`	`// Spin-Fast (goal ~10ns)`
`106`	`101`	`for (std::size_t i = 0; i < SPINLOCK_FAST_ITERATIONS; ++i)`
`107`	`102`	`{`