下表是生成uuid 库的比较，可以根据实际需求选择相应的库
| package | id | format |
|---|---|---|
| github.com/segmentio/ksuid | 0pPKHjWprnVxGH7dEsAoXX2YQvU |
4 bytes of time (seconds) + 16 random bytes |
| github.com/rs/xid | b50vl5e54p1000fo3gh0 |
4 bytes of time (seconds) + 3 byte machine id + 2 byte process id + 3 bytes random |
| github.com/kjk/betterguid | -Kmdih_fs4ZZccpx2Hl1 |
8 bytes of time (milliseconds) + 9 random bytes |
| github.com/sony/sonyflake | 20f8707d6000108 |
~6 bytes of time (10 ms) + 1 byte sequence + 2 bytes machine id |
| github.com/oklog/ulid | 01BJMVNPBBZC3E36FJTGVF0C4S |
6 bytes of time (milliseconds) + 8 bytes random |
| github.com/chilts/sid | 1JADkqpWxPx-4qaWY47~FqI |
8 bytes of time (ns) + 8 random bytes |
| github.com/satori/go.uuid | 5b52d72c-82b3-4f8e-beb5-437a974842c |
UUIDv4 from RFC 4112 for comparison |
另外一些库
- nu7hatch/gouuid - This package provides immutable UUID structs and the functions NewV3, NewV4, NewV5 and Parse() for generating versions 3, 4 and 5 UUIDs as specified in RFC 4122.
- pborman/uuid - The uuid package generates and inspects UUIDs based on RFC 4122 and DCE 1.1: Authentication and Security Services.
- goid - Generate and Parse RFC4122 compliant V4 UUIDs.
- uuid - Generate, encode, and decode UUIDs v1 with fast or cryptographic-quality random node identifier.
基于时间的 uuid 例子
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package main
import (
"crypto/rand"
"fmt"
"time"
)
func main() {
// generate 32 bits timestamp
unix32bits := uint32(time.Now().UTC().Unix())
buff := make([]byte, 12)
numRead, err := rand.Read(buff)
if numRead != len(buff) || err != nil {
panic(err)
}
fmt.Printf("%x-%x-%x-%x-%x-%x\n", unix32bits, buff[0:2], buff[2:4], buff[4:6], buff[6:8], buff[8:])
}
输出：
159658c4d-5b7e-bd35-b887-c6f4-41bcc1be
利用linux 系统命令生成 /usr/bin/uuidgen，但这种方式比较慢， 可用 nu7hatch/gouuid 或 satori/go.uuid
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package main
import (
"fmt"
"log"
"os/exec"
)
func main() {
out, err := exec.Command("uuidgen").Output()
if err != nil {
log.Fatal(err)
}
fmt.Printf("%s", out)
}
输出：
1FEDDB383-F25D-4F08-A40C-FF7D587417C3
一般场景推荐使用 https://github.com/rs/xid，其性能好、字符串较短，特性如下：
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Size: 12 bytes (96 bits), smaller than UUID, larger than snowflake
Base32 hex encoded by default (20 chars when transported as printable string, still sortable)
Non configured, you don't need set a unique machine and/or data center id
K-ordered
Embedded time with 1 second precision
Unicity guaranteed for 16,777,216 (24 bits) unique ids per second and per host/process
Lock-free (i.e.: unlike UUIDv1 and v2)
但 Xid 取决于系统时间，是个递增的计数器，因此不具有加密安全性。 如果你的应用里 ID 的不可预测性很重要，则不应使用 Xid 。 值得注意的是，大多数其他类似 UUID 的实现也不具有加密安全性。 如果你想要一个真正的随机 ID 生成器，你应该使用依赖于加密安全源的库（如 unix 上的 /dev/urandom，golang中的 crypto/rand ）。
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