diff --git a/src/sync/once.go b/src/sync/once.go index b6399cfc3d100..3f58707e1cfc5 100644 --- a/src/sync/once.go +++ b/src/sync/once.go @@ -21,7 +21,7 @@ type Once struct { // The hot path is inlined at every call site. // Placing done first allows more compact instructions on some architectures (amd64/386), // and fewer instructions (to calculate offset) on other architectures. - done uint32 + done atomic.Uint32 m Mutex } @@ -48,7 +48,7 @@ type Once struct { func (o *Once) Do(f func()) { // Note: Here is an incorrect implementation of Do: // - // if atomic.CompareAndSwapUint32(&o.done, 0, 1) { + // if o.done.CompareAndSwap(0, 1) { // f() // } // @@ -58,9 +58,9 @@ func (o *Once) Do(f func()) { // call f, and the second would return immediately, without // waiting for the first's call to f to complete. // This is why the slow path falls back to a mutex, and why - // the atomic.StoreUint32 must be delayed until after f returns. + // the o.done.Store must be delayed until after f returns. - if atomic.LoadUint32(&o.done) == 0 { + if o.done.Load() == 0 { // Outlined slow-path to allow inlining of the fast-path. o.doSlow(f) } @@ -69,8 +69,8 @@ func (o *Once) Do(f func()) { func (o *Once) doSlow(f func()) { o.m.Lock() defer o.m.Unlock() - if o.done == 0 { - defer atomic.StoreUint32(&o.done, 1) + if o.done.Load() == 0 { + defer o.done.Store(1) f() } } diff --git a/test/inline_sync.go b/test/inline_sync.go index 69e2a0ead6eb9..eaa2176d5fdc3 100644 --- a/test/inline_sync.go +++ b/test/inline_sync.go @@ -37,7 +37,7 @@ var once *sync.Once func small7() { // ERROR "can inline small7" // the Do fast path should be inlined - once.Do(small5) // ERROR "inlining call to sync\.\(\*Once\)\.Do" + once.Do(small5) // ERROR "inlining call to sync\.\(\*Once\)\.Do" "inlining call to atomic\.\(\*Uint32\)\.Load" } var rwmutex *sync.RWMutex