diff options
Diffstat (limited to 'src')
| -rw-r--r-- | src/sync/once.go | 14 |
1 files changed, 7 insertions, 7 deletions
diff --git a/src/sync/once.go b/src/sync/once.go index 587eab0af9..b6399cfc3d 100644 --- a/src/sync/once.go +++ b/src/sync/once.go @@ -16,13 +16,13 @@ import ( // the return from f “synchronizes before” // the return from any call of once.Do(f). type Once struct { - m Mutex // done indicates whether the action has been performed. // It is first in the struct because it is used in the hot path. // 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 atomic.Bool + done uint32 + m Mutex } // Do calls the function f if and only if Do is being called for the @@ -48,7 +48,7 @@ type Once struct { func (o *Once) Do(f func()) { // Note: Here is an incorrect implementation of Do: // - // if o.done.CompareAndSwap(false, true) { + // if atomic.CompareAndSwapUint32(&o.done, 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 o.done.Store must be delayed until after f returns. + // the atomic.StoreUint32 must be delayed until after f returns. - if !o.done.Load() { + if atomic.LoadUint32(&o.done) == 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.Load() { - defer o.done.Store(true) + if o.done == 0 { + defer atomic.StoreUint32(&o.done, 1) f() } } |