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|
package sys
import (
"math"
"syscall"
"time"
"unsafe"
)
const (
CLOCK_REALTIME = 0
TFD_CLOEXEC = 02000000
TFD_TIMER_ABSTIME = 1
TFD_TIMER_CANCEL_ON_SET = 2
)
type ITimerSpec struct {
Interval syscall.Timespec
Value syscall.Timespec
}
// System call wrapper for timerfd_create, generated with mksyscall.pl
func timerfdCreate(clockid int, flags int) (fd int, err error) {
r0, _, e1 := syscall.Syscall(syscall.SYS_TIMERFD_CREATE,
uintptr(clockid), uintptr(flags), 0)
fd = int(r0)
if e1 != 0 {
err = e1
}
return
}
// System call wrapper for timerfd_settime, generated with mksyscall.pl
func timerfdSettime(fd int, flags int, new_value *ITimerSpec,
old_value *ITimerSpec) (err error) {
_, _, e1 := syscall.Syscall6(syscall.SYS_TIMERFD_SETTIME, uintptr(fd),
uintptr(flags),
uintptr(unsafe.Pointer(new_value)),
uintptr(unsafe.Pointer(old_value)), 0, 0)
if e1 != 0 {
err = e1
}
return
}
/*
* Send a notification on @c when the system has just been resumed after
* sleep. This is implemented by watching for a change in real time compared
* with monotonic time. This may cause a spurious notification if the time
* is changed by a user or NTP jump.
*/
func NotifyResumed(c chan int) {
ts := ITimerSpec{Interval: syscall.Timespec{math.MaxInt32, 0},
Value: syscall.Timespec{0, 0}}
buf := make([]byte, 8)
for {
fd, err := timerfdCreate(CLOCK_REALTIME, TFD_CLOEXEC)
if err != nil {
return
}
err = timerfdSettime(fd, TFD_TIMER_ABSTIME|TFD_TIMER_CANCEL_ON_SET, &ts, nil)
if err != nil {
return
}
_, err = syscall.Read(fd, buf)
if err == syscall.ECANCELED {
// Wait a bit for the system to settle down after resuming
time.Sleep(time.Duration(1) * time.Second)
c <- 1
}
syscall.Close(fd)
}
}
|
