// Copyright 2018 The gVisor Authors.
//
// 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.

// +build go1.9
// +build !go1.16

// Check go:linkname function signatures when updating Go version.

package tcpip

import (
	"time"     // Used with go:linkname.
	_ "unsafe" // Required for go:linkname.
)

// StdClock implements Clock with the time package.
//
// +stateify savable
type StdClock struct{}

var _ Clock = (*StdClock)(nil)

//go:linkname now time.now
func now() (sec int64, nsec int32, mono int64)

// NowNanoseconds implements Clock.NowNanoseconds.
func (*StdClock) NowNanoseconds() int64 {
	sec, nsec, _ := now()
	return sec*1e9 + int64(nsec)
}

// NowMonotonic implements Clock.NowMonotonic.
func (*StdClock) NowMonotonic() int64 {
	_, _, mono := now()
	return mono
}

// AfterFunc implements Clock.AfterFunc.
func (*StdClock) AfterFunc(d time.Duration, f func()) Timer {
	return &stdTimer{
		t: time.AfterFunc(d, f),
	}
}

type stdTimer struct {
	t *time.Timer
}

var _ Timer = (*stdTimer)(nil)

// Stop implements Timer.Stop.
func (st *stdTimer) Stop() bool {
	return st.t.Stop()
}

// Reset implements Timer.Reset.
func (st *stdTimer) Reset(d time.Duration) {
	st.t.Reset(d)
}

// NewStdTimer returns a Timer implemented with the time package.
func NewStdTimer(t *time.Timer) Timer {
	return &stdTimer{t: t}
}