pkg syscall (freebsd-386), const MSG_WAITALL = 64
pkg syscall (freebsd-386), const MS_ASYNC = 1
pkg syscall (freebsd-386), const MS_ASYNC ideal-int
pkg syscall (freebsd-386), const MS_INVALIDATE = 2
pkg syscall (freebsd-386), const MS_INVALIDATE ideal-int
pkg syscall (freebsd-386), const MS_SYNC = 0
pkg syscall (freebsd-386), const MS_SYNC ideal-int
pkg syscall (freebsd-386), const NET_RT_DUMP = 1

func TestScanRune(t *testing.T) {
	for n, test := range scanTests {
		buf := strings.NewReader(test)
		s := NewScanner(buf)
		s.Split(ScanRunes)
		var i, runeCount int
		var expect rune
		// Use a string range loop to validate the sequence of runes.
		for i, expect = range test {
			if !s.Scan() {
				break
			}
			runeCount++
			got, _ := utf8.DecodeRune(s.Bytes())
			if got != expect {

		key, value, residual, err := parsePAXRecord(sbuf)
		if err != nil {
			return nil, ErrHeader
		}
		sbuf = residual

		switch key {
		case paxGNUSparseOffset, paxGNUSparseNumBytes:
			// Validate sparse header order and value.
			if (len(sparseMap)%2 == 0 && key != paxGNUSparseOffset) ||
				(len(sparseMap)%2 == 1 && key != paxGNUSparseNumBytes) ||
				strings.Contains(value, ",") {
				return nil, ErrHeader

	print(b)
	print(a)
}

func main() {
	go f()
	g()
}
</pre>

<p>
it can happen that <code>g</code> prints <code>2</code> and then <code>0</code>.
</p>

<p>
This fact invalidates a few common idioms.
</p>

<p>
Double-checked locking is an attempt to avoid the overhead of synchronization.
For example, the <code>twoprint</code> program might be
incorrectly written as:
</p>

pkg syscall (freebsd-386-cgo), const MSG_TRUNC ideal-int
pkg syscall (freebsd-386-cgo), const MSG_WAITALL ideal-int
pkg syscall (freebsd-386-cgo), const MS_ASYNC ideal-int
pkg syscall (freebsd-386-cgo), const MS_INVALIDATE ideal-int
pkg syscall (freebsd-386-cgo), const MS_SYNC ideal-int
pkg syscall (freebsd-386-cgo), const NET_RT_DUMP ideal-int
pkg syscall (freebsd-386-cgo), const NET_RT_FLAGS ideal-int