You are an expert in writing code in many different languages. Your goal is to perform code completion for the following code, keeping in mind the rest of the code and the file meta data.
    Metadata details:
    filename: clock_windows.go
    path of file: ./repos/juicefs/pkg/utils
    
    the code of the file until where you have to start completion: /*
 * JuiceFS, Copyright 2021 Juicedata, Inc.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package utils

import (
	"syscall"
	"time"
	"unsafe"
)

type clock struct {
	t    time.Time
	tick time.Duration
}

var last *clock

func Now() time.Time {
	c := last
	return c.t.Add(Clock() - c.tick)
}

// Clock returns the number of milliseconds that have elapsed
    
func init() {
	QPCTimer := func() func() time.Duration {
		lib, _ := syscall.LoadLibrary("kernel32.dll")
		qpc, _ := syscall.GetProcAddress(lib, "QueryPerformanceCounter")
		qpf, _ := syscall.GetProcAddress(lib, "QueryPerformanceFrequency")
		if qpc == 0 || qpf == 0 {
			return nil
		}

		var freq, start uint64
		syscall.Syscall(qpf, 1, uintptr(unsafe.Pointer(&freq)), 0, 0)
		syscall.Syscall(qpc, 1, uintptr(unsafe.Pointer(&start)), 0, 0)
		if freq <= 0 {
			return nil
		}

		freqns := float64(freq) / 1e9
		return func() time.Duration {
			var now uint64
			syscall.Syscall(qpc, 1, uintptr(unsafe.Pointer(&now)), 0, 0)
			return time.Duration(float64(now-start) / freqns)
		}
	}
	if Clock = QPCTimer(); Clock == nil {
		// Fallback implementation
		start := time.Now()
		Clock = func() time.Duration { return time.Since(start) }
	}
	last = &clock{time.Now(), Clock()}
	go func() {
		for {
			last = &clock{time.Now(), Clock()}
			time.Sleep(time.Hour)
		}
	}()
}