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time.go
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time.go
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package irtt
import (
"encoding/json"
"fmt"
"math"
"strings"
"time"
)
// InvalidDuration indicates a duration that is not valid.
const InvalidDuration = time.Duration(math.MaxInt64)
// Durations contains a slice of time.Duration.
type Durations []time.Duration
func (ds Durations) String() string {
dss := make([]string, len(ds))
for i, d := range ds {
dss[i] = d.String()
}
return strings.Join(dss, ",")
}
// ParseDurations returns a Durations value from a comma separated list of
// time.Duration string representations.
func ParseDurations(sdurs string) (durs Durations, err error) {
ss := strings.Split(sdurs, ",")
durs = make([]time.Duration, len(ss))
for i, s := range ss {
var err error
durs[i], err = time.ParseDuration(s)
if err != nil {
return nil, err
}
}
return durs, nil
}
// Time contains both wall clock (subject to system time adjustments) and
// monotonic clock (relative to a fixed start time, and not subject to system
// time adjustments) times in nanoseconds. The monotonic value should be used
// for calculating time differences, and the wall value must be used for
// comparing wall clock time. Comparisons between wall clock values are only as
// accurate as the synchronization between the clocks that produced the values.
type Time struct {
// Wall is the wall clock value as the number of nanoseconds elapsed since
// January 1, 1970 UTC.
Wall int64 `json:"wall,omitempty"`
// Monotonic is the monotonic clock value and may be relative to any start
// point in time.
Mono time.Duration `json:"monotonic,omitempty"`
}
// Sub returns the duration t-u. Monotonic times are used if both are non-zero.
func (t Time) Sub(u Time) time.Duration {
if t.Mono != 0 && u.Mono != 0 {
return t.Mono - u.Mono
} else if t.Wall != 0 && u.Wall != 0 {
return time.Duration(t.Wall - u.Wall)
}
panic("Time.Sub() clock mismatch")
}
// Add returns the time t+d.
func (t Time) Add(d time.Duration) Time {
ok := false
if t.Wall != 0 {
t.Wall += int64(d)
ok = true
}
if t.Mono != 0 {
t.Mono += d
ok = true
}
if !ok {
panic("Time.Add() for zero time")
}
return t
}
// After returns whether the time instant t is after u.
func (t Time) After(u Time) bool {
if t.Mono != 0 && u.Mono != 0 {
return t.Mono > u.Mono
} else if t.Wall != 0 && u.Wall != 0 {
return t.Wall > u.Wall
}
panic("Time.After() clock mismatch")
}
// Before returns whether the time instant t is before u.
func (t Time) Before(u Time) bool {
if t.Mono != 0 && u.Mono != 0 {
return t.Mono < u.Mono
} else if t.Wall != 0 && u.Wall != 0 {
return t.Wall < u.Wall
}
panic("Time.Before() clock mismatch")
}
// Midpoint returns the point in time halfway between t and u.
func (t Time) Midpoint(u Time) Time {
return t.Add(u.Sub(t) / 2)
}
// KeepClocks keeps only the specified clocks. Passing in Wall sets Mono to 0,
// Monotonic sets Wall to 0 and BothClocks does nothing.
func (t Time) KeepClocks(c Clock) Time {
switch c {
case Wall:
t.Mono = 0
case Monotonic:
t.Wall = 0
case BothClocks:
default:
panic(fmt.Sprintf("unknown clock %s", c))
}
return t
}
// IsWallZero returns true if Wall is zero.
func (t Time) IsWallZero() bool {
return t.Wall == 0
}
// IsMonoZero returns true if Mono is zero.
func (t Time) IsMonoZero() bool {
return t.Mono == 0
}
// IsZero returns true if both Wall and Mono are zero.
func (t Time) IsZero() bool {
return t.IsWallZero() && t.IsMonoZero()
}
// Timestamp stores receive and send times. If the Timestamp was set to the
// midpoint on the server, Receive and Send will be the same.
type Timestamp struct {
Receive Time `json:"receive"`
Send Time `json:"send"`
}
// IsBothMono returns true if there are both send and receive times from the
// monotonic clock.
func (t Timestamp) IsBothMono() bool {
return !t.Receive.IsMonoZero() && !t.Send.IsMonoZero()
}
// IsBothWall returns true if there are both send and receive times from the
// wall clock.
func (t Timestamp) IsBothWall() bool {
return !t.Receive.IsWallZero() && !t.Send.IsWallZero()
}
// BestSend returns the best send time. It prefers the actual send time, but
// returns the receive time if it's not available.
func (t Timestamp) BestSend() Time {
if t.Send.IsZero() {
return t.Receive
}
return t.Send
}
// BestReceive returns the best receive time. It prefers the actual receive
// time, but returns the receive time if it's not available.
func (t Timestamp) BestReceive() Time {
if t.Receive.IsZero() {
return t.Send
}
return t.Receive
}
// StampAt selects the time/s when timestamps are made on the server.
type StampAt int
// StampAt constants.
const (
AtNone StampAt = 0x00
AtSend StampAt = 0x01
AtReceive StampAt = 0x02
AtBoth StampAt = AtSend | AtReceive
AtMidpoint StampAt = 0x04
)
var sas = [...]string{"none", "send", "receive", "both", "midpoint"}
func (sa StampAt) String() string {
if int(sa) < 0 || int(sa) >= len(sas) {
return fmt.Sprintf("StampAt:%d", sa)
}
return sas[sa]
}
// StampAtFromInt returns a StampAt value from its int constant.
func StampAtFromInt(v int) (StampAt, error) {
if v < int(AtNone) || v > int(AtMidpoint) {
return AtNone, Errorf(InvalidStampAtInt, "invalid StampAt int: %d", v)
}
return StampAt(v), nil
}
// MarshalJSON implements the json.Marshaler interface.
func (sa StampAt) MarshalJSON() ([]byte, error) {
return json.Marshal(sa.String())
}
// ParseStampAt returns a StampAt value from its string.
func ParseStampAt(s string) (StampAt, error) {
for i, v := range sas {
if v == s {
return StampAt(i), nil
}
}
return AtNone, Errorf(InvalidStampAtString, "invalid StampAt string: %s", s)
}
// Clock selects the clock/s to use for timestamps.
type Clock int
// Clock constants.
const (
Wall Clock = 0x01
Monotonic Clock = 0x02
BothClocks Clock = Wall | Monotonic
)
var tcs = [...]string{"wall", "monotonic", "both"}
func (tc Clock) String() string {
if int(tc) < 1 || int(tc) > len(tcs) {
return fmt.Sprintf("Clock:%d", tc)
}
return tcs[tc-1]
}
// MarshalJSON implements the json.Marshaler interface.
func (tc Clock) MarshalJSON() ([]byte, error) {
return json.Marshal(tc.String())
}
// ClockFromInt returns a Clock value from its int constant.
func ClockFromInt(v int) (Clock, error) {
if v < int(Wall) || v > int(BothClocks) {
return Clock(0), Errorf(InvalidClockInt, "invalid Clock int: %d", v)
}
return Clock(v), nil
}
// ParseClock returns a Clock from a string.
func ParseClock(s string) (Clock, error) {
for i, v := range tcs {
if s == v {
return Clock(i + 1), nil
}
}
return Clock(0), Errorf(InvalidClockString, "invalid Clock string: %s", s)
}
// clockFromBools returns a Clock for wall and monotonic booleans. Either w or m
// must be true.
func clockFromBools(w bool, m bool) Clock {
if w {
if m {
return BothClocks
}
return Wall
}
if m {
return Monotonic
}
panic(fmt.Sprintf("invalid clock booleans %t, %t", w, m))
}
// AllowStamp selects the timestamps that are allowed by the server.
type AllowStamp int
// AllowStamp constants.
const (
NoStamp AllowStamp = iota
SingleStamp
DualStamps
)
var als = [...]string{"none", "single", "dual"}
// Restrict returns the StampAt allowed for a given StampAt requested.
func (a AllowStamp) Restrict(at StampAt) StampAt {
if at == AtNone {
return AtNone
}
switch a {
case NoStamp:
return AtNone
case SingleStamp:
switch at {
case AtBoth:
return AtMidpoint
default:
return at
}
case DualStamps:
return at
default:
panic(fmt.Sprintf("unknown AllowStamp %d", a))
}
}
func (a AllowStamp) String() string {
if int(a) < 0 || int(a) >= len(als) {
return fmt.Sprintf("AllowStamp:%d", a)
}
return als[a]
}
// ParseAllowStamp returns an AllowStamp from a string.
func ParseAllowStamp(s string) (AllowStamp, error) {
for i, v := range als {
if s == v {
return AllowStamp(i), nil
}
}
return NoStamp, Errorf(InvalidAllowStampString, "invalid AllowStamp string: %s", s)
}
// rdur rounds a Duration for improved readability.
func rdur(dur time.Duration) time.Duration {
d := dur
if d < 0 {
d = -d
}
if d < 1000 {
return dur
} else if d < 10000 {
return dur.Round(10 * time.Nanosecond)
} else if d < 100000 {
return dur.Round(100 * time.Nanosecond)
} else if d < 1000000 {
return dur.Round(1 * time.Microsecond)
} else if d < 100000000 {
return dur.Round(10 * time.Microsecond)
} else if d < 1000000000 {
return dur.Round(100 * time.Microsecond)
} else if d < 10000000000 {
return dur.Round(10 * time.Millisecond)
} else if d < 60000000000 {
return dur.Round(100 * time.Millisecond)
}
return dur.Round(time.Second)
}