### Timer changes

Go 1.23 makes two significant changes to the implementation of
[time.Timer] and [time.Ticker].

<!-- go.dev/issue/61542 -->
First, `Timer`s and `Ticker`s that are no longer referred to by the program
become eligible for garbage collection immediately, even if their
`Stop` methods have not been called.
Earlier versions of Go did not collect unstopped `Timer`s until after
they had fired and never collected unstopped `Ticker`s.

	// bad when on update), or other timers will hang (if the timer in a
	// heap is in a bad state). There is no reliable way to test this, but
	// we wait on a short timer here as a smoke test (alternatively, timers
	// in later tests may hang).
	<-After(25 * Millisecond)
}

var (
	MinMonoTime = Time{wall: 1 << 63, ext: -1 << 63, loc: UTC}
	MaxMonoTime = Time{wall: 1 << 63, ext: 1<<63 - 1, loc: UTC}

//  limitations under the License.

package timer

import (
	"container/heap"
	"sync"
	"time"
)

type Queue struct {
	heap            timerHeap
	mutex           sync.Mutex
	stopCh          chan struct{}
	resetTimerCh    chan struct{}
	stopping        bool
	timer           *time.Timer
	currentDeadline time.Time
}

func NewQueue() *Queue {
	q := &Queue{

		// Interrupt I/O operation once timer has expired
		if mode == 'r' || mode == 'r'+'w' {
			var timer *time.Timer
			timer = time.AfterFunc(d, func() {
				fd.rmu.Lock()
				defer fd.rmu.Unlock()
				if fd.rtimer != timer {
					// deadline was changed
					return
				}
				fd.rtimedout = true
				if fd.raio != nil {
					fd.raio.Cancel()
				}
			})
			fd.rtimer = timer
		}

	// from the timer/ticker channel after Reset.
	// When using Go 1.23 sync timers/tickers, draining is never needed
	// (that's the whole point of the sync timer/ticker change).
	drain1 := func() {
		for range drainTries {
			select {
			case <-C:
				return
			default:
			}
			Sleep(sched)
		}
	}

	// drainAsync removes potential stale time values after Stop/Reset.

//
// Programs using times should typically store and pass them as values,
// not pointers. That is, time variables and struct fields should be of
// type [time.Time], not *time.Time.
//
// A Time value can be used by multiple goroutines simultaneously except
// that the methods [Time.GobDecode], [Time.UnmarshalBinary], [Time.UnmarshalJSON] and
// [Time.UnmarshalText] are not concurrency-safe.
//

import (
	"context"
	"sync"
	"time"

	"k8s.io/utils/clock"
)

// DelayFunc returns the next time interval to wait.
type DelayFunc func() time.Duration

// Timer takes an arbitrary delay function and returns a timer that can handle arbitrary interval changes.
// Use Backoff{...}.Timer() for simple delays and more efficient timers.
func (fn DelayFunc) Timer(c clock.Clock) Timer {
	return &variableTimer{fn: fn, new: c.NewTimer}

//go:build !windows

package runtime

// osRelaxMinNS is the number of nanoseconds of idleness to tolerate
// without performing an osRelax. Since osRelax may reduce the
// precision of timers, this should be enough larger than the relaxed
// timer precision to keep the timer error acceptable.
const osRelaxMinNS = 0

var haveHighResSleep = true

// osRelax is called by the scheduler when transitioning to and from
// all Ps being idle.

< allocmR,
  execR;
allocmR, execR, hchan < sched;
sched < allg, allp;

# Channels
NONE < notifyList;
hchan, notifyList < sudog;

hchan, pollDesc, wakeableSleep < timers;
timers, timerSend < timer < netpollInit;

# Semaphores
NONE < root;

# Itabs
NONE
< itab
< reflectOffs;

# User arena state
NONE < userArenaState;

# Tracing without a P uses a global trace buffer.

		{name: "no-op timer", backoff: Backoff{}, t: reflect.TypeOf(noopTimer{})},
	} {
		t.Run(test.name, func(t *testing.T) {
			var attempts int
			start := time.Now()
			timer := test.backoff.Timer()
			if test.t != reflect.ValueOf(timer).Type() {
				t.Fatalf("unexpected timer type %T: expected %v", timer, test.t)
			}