Overview

• WUID is a 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.
• WUID generates unique 64-bit integers in sequence. The high 28 bits are loaded from a data store. By now, Redis, MySQL, PostgreSQL, and MongoDB are supported.

Benchmarks

BenchmarkWUID       100000000           10.3 ns/op         0 B/op          0 allocs/op
BenchmarkRand        50000000           24.6 ns/op         0 B/op          0 allocs/op
BenchmarkTimestamp  100000000           12.3 ns/op         0 B/op          0 allocs/op
BenchmarkUUID_V1     20000000          107 ns/op           0 B/op          0 allocs/op
BenchmarkUUID_V2     20000000          106 ns/op           0 B/op          0 allocs/op
BenchmarkUUID_V3      5000000          359 ns/op         144 B/op          4 allocs/op
BenchmarkUUID_V4      1000000         1376 ns/op          16 B/op          1 allocs/op
BenchmarkUUID_V5      3000000          424 ns/op         176 B/op          4 allocs/op
BenchmarkRedis          30000        46501 ns/op         176 B/op          5 allocs/op
BenchmarkSnowflake    5000000          244 ns/op           0 B/op          0 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 the same data store, or they use different section IDs
• Being capable of generating 100M unique numbers in a single second
• 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() (uint64, 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 uint64(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 [1, 15]. It occupies the highest 4 bits of the generated numbers.

Best practices

• Use different keys/tables/docs for different purposes.
• 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 or hundreds of hours, and WUID fails to get a new number from your data store.
• Give a reasonalbe bound to the high 28 bits with wuid.WithH28Verifier.

Special thanks

• dustinfog