同步/ mutex.go:
func (m *Mutex) Unlock() {
if race.Enabled {
_ = m.state
race.Release(unsafe.Pointer(m))
}
...
_ = m.state
的意思?我知道var _ interface = Object
意味着检查Object
是否实现了接口。
从提交日志中,原因是“_ = m.state”确保m不是nil。
commit 5bb3a66a973ea87494b9197091e8c1f122080627
Author: Rémy Oudompheng <[email protected]>
Date: Mon Apr 8 23:46:54 2013 +0200
sync, sync/atomic: do not corrupt race detector after a nil dereference.
The race detector uses a global lock to analyze atomic
operations. A panic in the middle of the code leaves the
lock acquired.
Similarly, the sync package may leave the race detectro
inconsistent when methods are called on nil pointers.
R=golang-dev, r, minux.ma, dvyukov, rsc, adg
CC=golang-dev
https://golang.org/cl/7981043
强制读取m.state并勾选竞赛检测器。