Method Lock

cmd/run/fd/fd.go:152–165

Lock waits until there is exactly one pending ref (the caller's). It panics if the *fd.FD isn't already in the closed state. In most situations, Lock should be called after the ClosingIncRef and before the close(2) syscall.

()

// if the *fd.FD isn't already in the closed state. In most situations, Lock
// should be called after the ClosingIncRef and before the close(2) syscall.
func (fd *FD) Lock() {
	refs := atomic.LoadUint32(&fd.refs)
	left := refs &^ uint32(flagClosed)
	if refs&flagClosed == 0 {
		panic("Lock called without marking file as closed")
	}
	if DEBUG {
		fmt.Printf("%p: %s: Lock: left=%d, closed=%v\n", fd, fd.String(), left, refs&flagClosed)
	}
	if left > 1 {
		// The last non-closing DecRef will do a semrelease.
		semacquire(&fd.sema)
	}
}

//go:linkname semacquire sync.runtime_Semacquire
func semacquire(addr *uint32)