// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package sync

// OnceFunc returns a function that invokes f only once. The returned function
// may be called concurrently.
//
// If f panics, the returned function will panic with the same value on every call.
func OnceFunc(f func()) func() {
	var (
		once  Once
		valid bool
		p     any
	)

			// never mutated and is a closure that could be inlined.
			// Too bad, because this is how OnceFunc will usually be used.
			onceFunc()
		}
	})
	b.Run("v=Local", func(b *testing.B) {
		b.ReportAllocs()
		// As of 3/2023, the compiler *does* recognize this local binding as an
		// inlinable closure. This is the best case for OnceFunc, but probably
		// not typical usage.

	return info.majorVersion, info.minorVersion, info.buildNumber
}

var (
	supportTCPKeepAliveIdle     bool
	supportTCPKeepAliveInterval bool
	supportTCPKeepAliveCount    bool
)

var initTCPKeepAlive = sync.OnceFunc(func() {
	s, err := WSASocket(syscall.AF_INET, syscall.SOCK_STREAM, syscall.IPPROTO_TCP, nil, 0, WSA_FLAG_NO_HANDLE_INHERIT)
	if err != nil {
		// Fallback to checking the Windows version.
		major, _, build := version()