mirror of
https://github.com/tailscale/tailscale.git
synced 2024-12-01 22:15:51 +00:00
b925e18f70
Makes parsing 4.6x faster. name old time/op new time/op delta ParseInt-12 32.1ns ± 1% 6.9ns ± 2% -78.55% (p=0.000 n=10+9) Signed-off-by: David Anderson <danderson@tailscale.com>
123 lines
2.9 KiB
Go
123 lines
2.9 KiB
Go
// Copyright (c) 2020 Tailscale Inc & AUTHORS All rights reserved.
|
|
// Use of this source code is governed by a BSD-style
|
|
// license that can be found in the LICENSE file.
|
|
|
|
// Package tstime defines Tailscale-specific time utilities.
|
|
package tstime
|
|
|
|
import (
|
|
"errors"
|
|
"fmt"
|
|
"strings"
|
|
"sync"
|
|
"time"
|
|
)
|
|
|
|
// 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 string) string {
|
|
if strings.HasSuffix(s, "Z") {
|
|
return "Z"
|
|
}
|
|
if len(s) < len("2020-04-05T15:56:00+08:00") {
|
|
// Too short, invalid? Let time.Parse fail on it.
|
|
return ""
|
|
}
|
|
zone := s[len(s)-len("+08:00"):]
|
|
if c := zone[0]; c == '+' || c == '-' {
|
|
min := zone[len("+08:"):]
|
|
switch min {
|
|
case "00", "15", "30":
|
|
return zone
|
|
}
|
|
}
|
|
return ""
|
|
}
|
|
|
|
// locCache maps from zone offset suffix string ("+08:00") =>
|
|
// *time.Location (from FixedLocation).
|
|
var locCache sync.Map
|
|
|
|
func getLocation(zone, timeValue string) (*time.Location, error) {
|
|
if zone == "Z" {
|
|
return time.UTC, nil
|
|
}
|
|
if loci, ok := locCache.Load(zone); ok {
|
|
return loci.(*time.Location), 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)
|
|
if err != nil {
|
|
return nil, err
|
|
}
|
|
loc := t.Location()
|
|
locCache.LoadOrStore(zone, loc)
|
|
return loc, nil
|
|
|
|
}
|
|
|
|
// Parse3339 is a wrapper around time.Parse(time.RFC3339Nano, s) that caches
|
|
// timezone Locations for future parses.
|
|
func Parse3339(s string) (time.Time, error) {
|
|
zone := zoneOf(s)
|
|
if zone == "" {
|
|
// Invalid or weird timezone offset. Use slow path,
|
|
// which'll probably return an error.
|
|
return time.Parse(time.RFC3339Nano, s)
|
|
}
|
|
loc, err := getLocation(zone, s)
|
|
if err != nil {
|
|
return time.Time{}, err
|
|
}
|
|
s = s[:len(s)-len(zone)] // remove zone suffix
|
|
var year, mon, day, hr, min, sec, nsec int
|
|
const baseLen = len("2020-04-05T15:56:00")
|
|
if len(s) < baseLen ||
|
|
!parseInt(s[:4], &year) ||
|
|
s[4] != '-' ||
|
|
!parseInt(s[5:7], &mon) ||
|
|
s[7] != '-' ||
|
|
!parseInt(s[8:10], &day) ||
|
|
s[10] != 'T' ||
|
|
!parseInt(s[11:13], &hr) ||
|
|
s[13] != ':' ||
|
|
!parseInt(s[14:16], &min) ||
|
|
s[16] != ':' ||
|
|
!parseInt(s[17:19], &sec) {
|
|
return time.Time{}, errors.New("invalid time")
|
|
}
|
|
nsStr := s[baseLen:]
|
|
if nsStr != "" {
|
|
if nsStr[0] != '.' {
|
|
return time.Time{}, errors.New("invalid optional nanosecond prefix")
|
|
}
|
|
if !parseInt(nsStr[1:], &nsec) {
|
|
return time.Time{}, fmt.Errorf("invalid optional nanosecond number %q", nsStr[1:])
|
|
}
|
|
for i := 0; i < len("999999999")-(len(nsStr)-1); i++ {
|
|
nsec *= 10
|
|
}
|
|
}
|
|
return time.Date(year, time.Month(mon), day, hr, min, sec, nsec, loc), nil
|
|
}
|
|
|
|
func parseInt(s string, dst *int) bool {
|
|
if len(s) == 0 || len(s) > len("999999999") {
|
|
*dst = 0
|
|
return false
|
|
}
|
|
n := 0
|
|
for i := 0; i < len(s); i++ {
|
|
d := s[i] - '0'
|
|
if d > 9 {
|
|
*dst = 0
|
|
return false
|
|
}
|
|
n = n*10 + int(d)
|
|
}
|
|
*dst = n
|
|
return true
|
|
}
|