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objectid.go
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objectid.go
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// Package objectid package implements MongoDB's ObjectID type.
package objectid
import (
"encoding/base64"
"errors"
"fmt"
"math/rand"
"os"
"strconv"
"sync/atomic"
"time"
)
// ErrInvalidHex is returned when an invalid hex string is provided.
var ErrInvalidHex = errors.New("invalid hex")
// ErrInvalidBase64 is returned when an invalid base64 string is provided.
var ErrInvalidBase64 = errors.New("invalid base64")
// ErrInvalidTimeFormat is returned when an invalid time format is provided.
var ErrInvalidTimeFormat = errors.New("invalid time format")
// ObjectID is a 12-byte unique identifier for a MongoDB document.
type ObjectID [12]byte
// String returns the hex encoding of the ObjectID as a string.
func (id ObjectID) String() string {
return id.Hex()
}
// Hex returns the hex encoding of the ObjectID as a string.
func (id ObjectID) Hex() string {
return fmt.Sprintf("%x", []byte(id[:]))
}
// Base64 returns the hex encoding of the ObjectID as a string.
func (id ObjectID) Base64() string {
return base64.StdEncoding.EncodeToString(id[:])
}
// Time returns the timestamp part of the ObjectID.
func (id ObjectID) Time() time.Time {
t := (uint(id[0]) << 24) | (uint(id[1]) << 16) | (uint(id[2]) << 8) | uint(id[3])
return time.Unix(int64(t), 0)
}
var objectRand [5]byte
var counter atomic.Uint32
var now = time.Now
func init() {
r := rand.New(rand.NewSource(now().UnixNano()))
machineID := r.Intn(0xffffff)
pid := os.Getpid()
objectRand = [5]byte{
byte(machineID >> 16),
byte(machineID >> 8),
byte(machineID),
byte(pid >> 8),
byte(pid),
}
counter.Store(uint32(r.Intn(0xffffff)))
}
// New generates a new ObjectID.
func New() ObjectID {
var oid ObjectID
GenerateTo(&oid)
return oid
}
// GenerateTo generates a new ObjectID and writes it to the provided ObjectID
// pointer.
func GenerateTo(objectID *ObjectID) {
c := counter.Add(1)
generateTo(objectID, now(), c, objectRand)
}
func generateTo(objectID *ObjectID, t time.Time, c uint32, r [5]byte) {
timestamp := t.Unix()
objectID[0] = byte(timestamp >> 24)
objectID[1] = byte(timestamp >> 16)
objectID[2] = byte(timestamp >> 8)
objectID[3] = byte(timestamp)
objectID[4] = r[0]
objectID[5] = r[1]
objectID[6] = r[2]
objectID[7] = r[3]
objectID[8] = r[4]
objectID[9] = byte(c >> 16)
objectID[10] = byte(c >> 8)
objectID[11] = byte(c)
}
// FromHex creates a new ObjectID from a hex string.
func FromHex(str string) (ObjectID, error) {
var oid ObjectID
if len(str) != 24 {
return oid, fmt.Errorf("invalid objectid length: %d, %w", len(str), ErrInvalidHex)
}
for i := 0; i < 12; i++ {
b, err := strconv.ParseUint(str[i*2:i*2+2], 16, 8)
if err != nil {
return oid, errors.Join(err, ErrInvalidHex)
}
oid[i] = byte(b)
}
return oid, nil
}
// FromBase64 decodes a base64 string into an ObjectID.
func FromBase64(str string) (ObjectID, error) {
var oid ObjectID
if len(str) != 16 {
return oid, fmt.Errorf("invalid objectid length: %d, %w", len(str), ErrInvalidBase64)
}
base64Bytes, err := base64.StdEncoding.DecodeString(str)
if err != nil {
return oid, errors.Join(err, ErrInvalidBase64)
}
return ObjectID(base64Bytes), err
}
func parseTime(str string) (time.Time, error) {
formats := []string{
time.RFC3339,
"2006-01-02T15:04-07:00",
"2006-01-02T15:04",
"2006-01-02T15-07:00",
"2006-01-02",
}
for _, format := range formats {
t, err := time.Parse(format, str)
if err == nil {
return t, nil
}
}
return time.Time{}, fmt.Errorf("%w: %s", ErrInvalidTimeFormat, str)
}
// FromTime creates a new ObjectID from a time string.
// The time string must be in one of the formats:
// RFC3339,
// "2006-01-02T15:04-07:00",
// "2006-01-02T15:04",
// "2006-01-02T15-07:00",
// "2006-01-02",
func FromTime(str string) (ObjectID, error) {
t, err := parseTime(str)
if err != nil {
return ObjectID{}, err
}
var oid ObjectID
generateTo(&oid, t, 0, [5]byte{0, 0, 0, 0, 0})
return oid, nil
}