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tstime: rely on stdlib parse functionality (#7482)

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The time.Parse function has been optimized to the point
where it is faster than our custom implementation.
See upstream changes in:

* https://go.dev/cl/429862
* https://go.dev/cl/425197
* https://go.dev/cl/425116

Performance:

	BenchmarkGoParse3339/Z     38.75 ns/op    0 B/op    0 allocs/op
	BenchmarkGoParse3339/TZ    54.02 ns/op    0 B/op    0 allocs/op
	BenchmarkParse3339/Z       40.17 ns/op    0 B/op    0 allocs/op
	BenchmarkParse3339/TZ      87.06 ns/op    0 B/op    0 allocs/op

We can see that the stdlib implementation is now faster.

Signed-off-by: Joe Tsai <joetsai@digital-static.net>
This commit is contained in:
Joe Tsai 2023-03-06 18:05:51 -08:00 committed by GitHub
parent 9112e78925
commit 7e6c5a2db4
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GPG Key ID: 4AEE18F83AFDEB23
2 changed files with 8 additions and 306 deletions
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135
tstime/tstime.go
View File

@ -6,145 +6,26 @@
import ( import (
"context" "context"
"errors"
"fmt"
"strconv" "strconv"
"strings" "strings"
"sync"
"time" "time"
"go4.org/mem"
) )
var memZ = mem.S("Z") // Parse3339 is a wrapper around time.Parse(time.RFC3339, s).
// zoneOf returns the RFC3339 zone suffix (either "Z" or like
// "+08:30"), or the empty string if it's invalid or not something we
// want to cache.
func zoneOf(s mem.RO) mem.RO {
if mem.HasSuffix(s, memZ) {
return memZ
}
if s.Len() < len("2020-04-05T15:56:00+08:00") {
// Too short, invalid? Let time.Parse fail on it.
return mem.S("")
}
zone := s.SliceFrom(s.Len() - len("+08:00"))
if c := zone.At(0); c == '+' || c == '-' {
min := zone.SliceFrom(len("+08:"))
if min.EqualString("00") || min.EqualString("15") || min.EqualString("30") {
return zone
}
}
return mem.S("")
}
// locCache maps from hash of zone offset suffix string ("+08:00") =>
// {zone string, *time.Location (from FixedLocation)}.
var locCache sync.Map
type locCacheEntry struct {
zone string
loc *time.Location
}
func getLocation(zone, timeValue mem.RO) (*time.Location, error) {
if zone.EqualString("Z") {
return time.UTC, nil
}
key := zone.MapHash()
if entry, ok := locCache.Load(key); ok {
// We're keying only on a hash; double-check zone to ensure no spurious collisions.
e := entry.(locCacheEntry)
if zone.EqualString(e.zone) {
return e.loc, nil
}
}
// TODO(bradfitz): just parse it and call time.FixedLocation.
// For now, just have time.Parse do it once:
t, err := time.Parse(time.RFC3339Nano, timeValue.StringCopy())
if err != nil {
return nil, err
}
loc := t.Location()
locCache.LoadOrStore(key, locCacheEntry{zone: zone.StringCopy(), loc: loc})
return loc, nil
}
func parse3339m(s mem.RO) (time.Time, error) {
zone := zoneOf(s)
if zone.Len() == 0 {
// Invalid or weird timezone offset. Use slow path,
// which'll probably return an error.
return time.Parse(time.RFC3339Nano, s.StringCopy())
}
loc, err := getLocation(zone, s)
if err != nil {
return time.Time{}, err
}
s = s.SliceTo(s.Len() - zone.Len()) // remove zone suffix
var year, mon, day, hr, min, sec, nsec int
const baseLen = len("2020-04-05T15:56:00")
if s.Len() < baseLen ||
!parseInt(s.SliceTo(4), &year) ||
s.At(4) != '-' ||
!parseInt(s.Slice(5, 7), &mon) ||
s.At(7) != '-' ||
!parseInt(s.Slice(8, 10), &day) ||
s.At(10) != 'T' ||
!parseInt(s.Slice(11, 13), &hr) ||
s.At(13) != ':' ||
!parseInt(s.Slice(14, 16), &min) ||
s.At(16) != ':' ||
!parseInt(s.Slice(17, 19), &sec) {
return time.Time{}, errors.New("invalid time")
}
nsStr := s.SliceFrom(baseLen)
if nsStr.Len() != 0 {
if nsStr.At(0) != '.' {
return time.Time{}, errors.New("invalid optional nanosecond prefix")
}
nsStr = nsStr.SliceFrom(1)
if !parseInt(nsStr, &nsec) {
return time.Time{}, fmt.Errorf("invalid optional nanosecond number %q", nsStr.StringCopy())
}
for i := 0; i < len("999999999")-nsStr.Len(); i++ {
nsec *= 10
}
}
return time.Date(year, time.Month(mon), day, hr, min, sec, nsec, loc), nil
}
func parseInt(s mem.RO, dst *int) bool {
if s.Len() == 0 || s.Len() > len("999999999") {
*dst = 0
return false
}
n := 0
for i := 0; i < s.Len(); i++ {
d := s.At(i) - '0'
if d > 9 {
*dst = 0
return false
}
n = n*10 + int(d)
}
*dst = n
return true
}
// Parse3339 is a wrapper around time.Parse(time.RFC3339Nano, s) that caches
// timezone Locations for future parses.
func Parse3339(s string) (time.Time, error) { func Parse3339(s string) (time.Time, error) {
return parse3339m(mem.S(s)) return time.Parse(time.RFC3339, s)
} }
// Parse3339B is Parse3339 but for byte slices. // Parse3339B is Parse3339 but for byte slices.
func Parse3339B(b []byte) (time.Time, error) { func Parse3339B(b []byte) (time.Time, error) {
return parse3339m(mem.B(b)) var t time.Time
if err := t.UnmarshalText(b); err != nil {
return Parse3339(string(b)) // reproduce same error message
}
return t, nil
} }
// ParseDuration is more expressive than time.ParseDuration, // ParseDuration is more expressive than [time.ParseDuration],
// also accepting 'd' (days) and 'w' (weeks) literals. // also accepting 'd' (days) and 'w' (weeks) literals.
func ParseDuration(s string) (time.Duration, error) { func ParseDuration(s string) (time.Duration, error) {
for { for {

179
tstime/tstime_test.go
View File

@ -6,101 +6,8 @@
import ( import (
"testing" "testing"
"time" "time"
"go4.org/mem"
) )
func TestParse3339(t *testing.T) {
tests := []string{
"2020-04-05T15:56:00Z",
"2020-04-05T15:56:00.1234Z",
"2020-04-05T15:56:00+08:00",
"2020-04-05T15:56:00.1+08:00",
"2020-04-05T15:56:00.12+08:00",
"2020-04-05T15:56:00.012+08:00",
"2020-04-05T15:56:00.0012+08:00",
"2020-04-05T15:56:00.148487491+08:00",
"2020x04-05T15:56:00.1234+08:00",
"2020-04x05T15:56:00.1234+08:00",
"2020-04-05x15:56:00.1234+08:00",
"2020-04-05T15x56:00.1234+08:00",
"2020-04-05T15:56x00.1234+08:00",
"2020-04-05T15:56:00x1234+08:00",
}
for _, s := range tests {
t.Run(s, func(t *testing.T) {
goTime, goErr := time.Parse(time.RFC3339Nano, s)
Parse3339(s) // prime the tz cache so next parse use fast path
got, err := Parse3339(s)
if (err == nil) != (goErr == nil) {
t.Fatalf("for %q, go err = %v; our err = %v", s, goErr, err)
}
if err != nil {
return
}
if !goTime.Equal(got) {
t.Errorf("for %q, times not Equal: we got %v, want go's %v", s, got, goTime)
}
if goStr, ourStr := goTime.Format(time.RFC3339Nano), got.Format(time.RFC3339Nano); goStr != ourStr {
t.Errorf("for %q, strings not equal: we got %q, want go's %q", s, ourStr, goStr)
}
})
}
}
func TestZoneOf(t *testing.T) {
tests := []struct {
in, want string
}{
{"2020-04-05T15:56:00+08:00", "+08:00"},
{"2020-04-05T15:56:00-08:00", "-08:00"},
{"2020-04-05T15:56:00.12345-08:00", "-08:00"},
{"2020-04-05T15:56:00.12345-08:00", "-08:00"},
{"2020-04-05T15:56:00.12345-08:30", "-08:30"},
{"2020-04-05T15:56:00.12345-08:15", "-08:15"},
{"2020-04-05T15:56:00.12345-08:17", ""}, // don't cache weird offsets
{"2020-04-05T15:56:00.12345Z", "Z"},
{"2020-04-05T15:56:00Z", "Z"},
{"123+08:00", ""}, // too short
{"+08:00", ""}, // too short
}
for _, tt := range tests {
if got := zoneOf(mem.S(tt.in)); !got.EqualString(tt.want) {
t.Errorf("zoneOf(%q) = %q; want %q", tt.in, got.StringCopy(), tt.want)
}
}
}
func TestParseInt(t *testing.T) {
tests := []struct {
in string
want int
ret bool
}{
{"", 0, false},
{"1", 1, true},
{"999999999", 999999999, true},
{"123456789", 123456789, true},
{"000000", 0, true},
{"bork", 0, false},
{"123bork", 0, false},
}
for _, tt := range tests {
var got int
gotRet := parseInt(mem.S(tt.in), &got)
if gotRet != tt.ret || got != tt.want {
t.Errorf("parseInt(%q) = %v, %d; want %v, %d", tt.in, gotRet, got, tt.ret, tt.want)
}
}
}
func TestParseDuration(t *testing.T) { func TestParseDuration(t *testing.T) {
tests := []struct { tests := []struct {
in string in string
@ -127,89 +34,3 @@ func TestParseDuration(t *testing.T) {
} }
} }
} }
func BenchmarkGoParse3339(b *testing.B) {
run := func(in string) func(*testing.B) {
return func(b *testing.B) {
b.ReportAllocs()
for i := 0; i < b.N; i++ {
_, err := time.Parse(time.RFC3339Nano, in)
if err != nil {
b.Fatal(err)
}
}
}
}
b.Run("Z", run("2020-04-05T15:56:00.148487491Z"))
b.Run("TZ", run("2020-04-05T15:56:00.148487491+08:00"))
}
func BenchmarkGoParse3339InLocation(b *testing.B) {
b.ReportAllocs()
const in = `2020-04-05T15:56:00.148487491+08:00`
t, err := time.Parse(time.RFC3339Nano, in)
if err != nil {
b.Fatal(err)
}
loc := t.Location()
t2, err := time.ParseInLocation(time.RFC3339Nano, in, loc)
if err != nil {
b.Fatal(err)
}
if !t.Equal(t2) {
b.Fatal("not equal")
}
if s1, s2 := t.Format(time.RFC3339Nano), t2.Format(time.RFC3339Nano); s1 != s2 {
b.Fatalf("times don't stringify the same: %q vs %q", s1, s2)
}
b.ResetTimer()
for i := 0; i < b.N; i++ {
_, err := time.ParseInLocation(time.RFC3339Nano, in, loc)
if err != nil {
b.Fatal(err)
}
}
}
func BenchmarkParse3339(b *testing.B) {
run := func(in string) func(*testing.B) {
return func(b *testing.B) {
b.ReportAllocs()
t, err := time.Parse(time.RFC3339Nano, in)
if err != nil {
b.Fatal(err)
}
t2, err := Parse3339(in)
if err != nil {
b.Fatal(err)
}
if !t.Equal(t2) {
b.Fatal("not equal")
}
if s1, s2 := t.Format(time.RFC3339Nano), t2.Format(time.RFC3339Nano); s1 != s2 {
b.Fatalf("times don't stringify the same: %q vs %q", s1, s2)
}
for i := 0; i < b.N; i++ {
_, err := Parse3339(in)
if err != nil {
b.Fatal(err)
}
}
}
}
b.Run("Z", run("2020-04-05T15:56:00.148487491Z"))
b.Run("TZ", run("2020-04-05T15:56:00.148487491+08:00"))
}
func BenchmarkParseInt(b *testing.B) {
b.ReportAllocs()
var out int
for i := 0; i < b.N; i++ {
parseInt(mem.S("148487491"), &out)
}
}