diff options
Diffstat (limited to 'src/sync')
| -rw-r--r-- | src/sync/rwmutex.go | 13 |
1 files changed, 13 insertions, 0 deletions
diff --git a/src/sync/rwmutex.go b/src/sync/rwmutex.go index ad52951311..1317624035 100644 --- a/src/sync/rwmutex.go +++ b/src/sync/rwmutex.go @@ -219,6 +219,19 @@ func (rw *RWMutex) Unlock() { } } +// syscall_hasWaitingReaders reports whether any goroutine is waiting +// to acquire a read lock on rw. This exists because syscall.ForkLock +// is an RWMutex, and we can't change that without breaking compatibility. +// We don't need or want RWMutex semantics for ForkLock, and we use +// this private API to avoid having to change the type of ForkLock. +// For more details see the syscall package. +// +//go:linkname syscall_hasWaitingReaders syscall.hasWaitingReaders +func syscall_hasWaitingReaders(rw *RWMutex) bool { + r := rw.readerCount.Load() + return r < 0 && r+rwmutexMaxReaders > 0 +} + // RLocker returns a Locker interface that implements // the Lock and Unlock methods by calling rw.RLock and rw.RUnlock. func (rw *RWMutex) RLocker() Locker { |