// within 5 days of the previous reuse. See golang.org/issue/22990.
const (
	mtimeInterval = 1 * time.Hour
	trimInterval  = 24 * time.Hour
	trimLimit     = 5 * 24 * time.Hour
)

// used makes a best-effort attempt to update mtime on file,
// so that mtime reflects cache access time.
//
// Because the reflection only needs to be approximate,
// and to reduce the amount of disk activity caused by using

	}

	// check both fileInfo's have same number of versions, if not skip
	// the `other` entry.
	if len(eVers.versions) != len(oVers.versions) {
		eTime := eVers.latestModtime()
		oTime := oVers.latestModtime()
		if !eTime.Equal(oTime) {
			if eTime.After(oTime) {
				return e, false
			}
			return other, false
		}
		// Tiebreak on version count.
		if len(eVers.versions) > len(oVers.versions) {

	ESHUTDOWN       = syscall.Errno(0x6c)
	ESOCKTNOSUPPORT = syscall.Errno(0x5e)
	ESRMNT          = syscall.Errno(0x45)
	ESTALE          = syscall.Errno(0x74)
	ESTRPIPE        = syscall.Errno(0x56)
	ETIME           = syscall.Errno(0x3e)
	ETIMEDOUT       = syscall.Errno(0x6e)
	ETOOMANYREFS    = syscall.Errno(0x6d)
	EUCLEAN         = syscall.Errno(0x75)
	EUNATCH         = syscall.Errno(0x31)

	ESHUTDOWN       = syscall.Errno(0x6c)
	ESOCKTNOSUPPORT = syscall.Errno(0x5e)
	ESRMNT          = syscall.Errno(0x45)
	ESTALE          = syscall.Errno(0x74)
	ESTRPIPE        = syscall.Errno(0x56)
	ETIME           = syscall.Errno(0x3e)
	ETIMEDOUT       = syscall.Errno(0x6e)
	ETOOMANYREFS    = syscall.Errno(0x6d)
	EUCLEAN         = syscall.Errno(0x75)
	EUNATCH         = syscall.Errno(0x31)

	ESHUTDOWN       = syscall.Errno(0x6c)
	ESOCKTNOSUPPORT = syscall.Errno(0x5e)
	ESRMNT          = syscall.Errno(0x45)
	ESTALE          = syscall.Errno(0x74)
	ESTRPIPE        = syscall.Errno(0x56)
	ETIME           = syscall.Errno(0x3e)
	ETIMEDOUT       = syscall.Errno(0x6e)
	ETOOMANYREFS    = syscall.Errno(0x6d)
	EUCLEAN         = syscall.Errno(0x75)
	EUNATCH         = syscall.Errno(0x31)

	r := port_getn(portfd, &events[0], uint32(len(events)), &n, wait)
	e := errno()
	if r < 0 && e == _ETIME && n > 0 {
		// As per port_getn(3C), an ETIME failure does not preclude the
		// delivery of some number of events.  Treat a timeout failure
		// with delivered events as a success.
		r = 0
	}
	if r < 0 {
		if e != _EINTR && e != _ETIME {
			print("runtime: port_getn on fd ", portfd, " failed (errno=", e, ")\n")

	EPROCLIM           = Errno(1131)
	EUSERS             = Errno(1132)
	EDQUOT             = Errno(1133)
	ESTALE             = Errno(1134)
	EREMOTE            = Errno(1135)
	ENOSTR             = Errno(1136)
	ETIME              = Errno(1137)
	ENOSR              = Errno(1138)
	ENOMSG             = Errno(1139)
	EBADMSG            = Errno(1140)
	EIDRM              = Errno(1141)
	ENONET             = Errno(1142)

	Cgid uint32
	Mode uint32
	_    [0]uint8
	Seq  uint16
	_    uint16
	_    uint64
	_    uint64
}
type SysvShmDesc struct {
	Perm   SysvIpcPerm
	Segsz  uint64
	Atime  int64
	Dtime  int64
	Ctime  int64
	Cpid   int32
	Lpid   int32
	Nattch uint64
	_      uint64
	_      uint64

	Cgid uint32
	Mode uint32
	_    [0]uint8
	Seq  uint16
	_    uint16
	_    uint32
	_    uint32
}
type SysvShmDesc struct {
	Perm       SysvIpcPerm
	Segsz      uint32
	Atime      uint32
	Dtime      uint32
	Ctime      uint32
	Cpid       int32
	Lpid       int32
	Nattch     uint32
	Atime_high uint16
	Dtime_high uint16
	Ctime_high uint16
	_          uint16

	Uid  uint32
	Gid  uint32
	Cuid uint32
	Cgid uint32
	Mode uint32
	Seq  uint32
	_    uint32
	_    uint64
	_    uint64
}
type SysvShmDesc struct {
	Perm   SysvIpcPerm
	Atime  int64
	Dtime  int64
	Ctime  int64
	Segsz  uint64
	Cpid   int32
	Lpid   int32
	Nattch uint64
	_      uint64
	_      uint64