Overview

• WUID is a globally unique number generator, while it is NOT a UUID implementation.
• WUID is 10-135 times faster than UUID and 4600 times faster than generating unique numbers with Redis.
• Each WUID instance generates unique 64-bit integers in sequence. The high 28 bits are loaded from a data store. By now, Redis, MySQL, MongoDB and Callback are supported.

Benchmarks

BenchmarkWUID       187500764            6.38 ns/op        0 B/op          0 allocs/op
BenchmarkRand       97180698            12.2 ns/op         0 B/op          0 allocs/op
BenchmarkTimestamp  17126514            67.8 ns/op         0 B/op          0 allocs/op
BenchmarkUUID_V1    11986558            99.6 ns/op         0 B/op          0 allocs/op
BenchmarkUUID_V2    12017754           101 ns/op           0 B/op          0 allocs/op
BenchmarkUUID_V3     4925020           242 ns/op         144 B/op          4 allocs/op
BenchmarkUUID_V4    14184271            84.1 ns/op        16 B/op          1 allocs/op
BenchmarkUUID_V5     4277338           274 ns/op         176 B/op          4 allocs/op
BenchmarkRedis         35462         35646 ns/op         176 B/op          5 allocs/op
BenchmarkSnowflake   4931476           244 ns/op           0 B/op          0 allocs/op
BenchmarkULID        8410358           141 ns/op          16 B/op          1 allocs/op
BenchmarkXID        15000969            79.2 ns/op         0 B/op          0 allocs/op
BenchmarkShortID     1738039           698.9 ns/op       311 B/op         11 allocs/op

Features

• Extremely fast
• Thread-safe
• Being unique across time
• Being unique within a data center
• Being unique globally if all data centers share a same data store, or they use different section IDs
• Being capable of generating 100M unique numbers in a single second with each WUID instance
• Auto-renew when the low 36 bits are about to run out

Install

go get -u github.com/edwingeng/wuid

Usage examples

Redis

import "github.com/edwingeng/wuid/redis/wuid"

newClient := func() (redis.Cmdable, bool, error) {
    var client redis.Cmdable
    // ...
    return client, true, nil
}

// Setup
g := NewWUID("default", nil)
_ = g.LoadH28FromRedis(newClient, "wuid")

// Generate
for i := 0; i < 10; i++ {
    fmt.Printf("%#016x\n", g.Next())
}

MySQL

import "github.com/edwingeng/wuid/mysql/wuid"

newDB := func() (*sql.DB, bool, error) {
    var db *sql.DB
    // ...
    return db, true, nil
}

// Setup
g := NewWUID("default", nil)
_ = g.LoadH28FromMysql(newDB, "wuid")

// Generate
for i := 0; i < 10; i++ {
    fmt.Printf("%#016x\n", g.Next())
}

MongoDB

import "github.com/edwingeng/wuid/mongo/wuid"

newClient := func() (*mongo.Client, bool, error) {
    var client *mongo.Client
    // ...
    return client, true, nil
}

// Setup
g := NewWUID("default", nil)
_ = g.LoadH28FromMongo(newClient, "test", "wuid", "default")

// Generate
for i := 0; i < 10; i++ {
    fmt.Printf("%#016x\n", g.Next())
}

Callback

import "github.com/edwingeng/wuid/callback/wuid"

// Setup
g := NewWUID("default", nil)
_ = g.LoadH28WithCallback(func() (int64, func(), error) {
    resp, err := http.Get("https://stackoverflow.com/")
    if resp != nil {
        defer func() {
            _ = resp.Body.Close()
        }()
    }
    if err != nil {
        return 0, nil, err
    }

    bytes, err := ioutil.ReadAll(resp.Body)
    if err != nil {
        return 0, nil, err
    }

    fmt.Printf("Page size: %d (%#06x)\n\n", len(bytes), len(bytes))
    return int64(len(bytes)), nil, nil
})

// Generate
for i := 0; i < 10; i++ {
    fmt.Printf("%#016x\n", g.Next())
}

Mysql table creation

CREATE TABLE IF NOT EXISTS `wuid` (
    `h` int(10) NOT NULL AUTO_INCREMENT,
    `x` tinyint(4) NOT NULL DEFAULT '0',
    PRIMARY KEY (`x`),
    UNIQUE KEY `h` (`h`)
) ENGINE=InnoDB DEFAULT CHARSET=latin1;

Section ID

You can specify a custom section ID for the generated numbers with wuid.WithSection when you call wuid.NewWUID. The section ID must be in between [0, 7].

Step

You can customize the step value of Next() with wuid.WithStep.

Best practices

• Pass a logger to wuid.NewWUID and keep an eye on the warnings that include "renew failed", which means that the low 36 bits are about to run out in hours to hundreds of hours, and WUID fails to get a new number from your data store.

Special thanks

• dustinfog