github.com/influx6/npkg@v0.8.8/nxid/README.md (about) 1 # Globally Unique ID Generator 2 3 [](https://godoc.org/github.com/rs/xid) [](https://raw.githubusercontent.com/rs/xid/master/LICENSE) [](https://travis-ci.org/rs/xid) [](http://gocover.io/github.com/rs/xid) 4 5 Package xid is a globally unique id generator library, ready to be used safely directly in your server code. 6 7 Xid is using Mongo Object ID algorithm to generate globally unique ids with a different serialization (base64) to make it shorter when transported as a string: 8 https://docs.mongodb.org/manual/reference/object-id/ 9 10 - 4-byte value representing the seconds since the Unix epoch, 11 - 3-byte machine identifier, 12 - 2-byte process id, and 13 - 3-byte counter, starting with a random value. 14 15 The binary representation of the id is compatible with Mongo 12 bytes Object IDs. 16 The string representation is using base32 hex (w/o padding) for better space efficiency 17 when stored in that form (20 bytes). The hex variant of base32 is used to retain the 18 sortable property of the id. 19 20 Xid doesn't use base64 because case sensitivity and the 2 non alphanum chars may be an 21 issue when transported as a string between various systems. Base36 wasn't retained either 22 because 1/ it's not standard 2/ the resulting size is not predictable (not bit aligned) 23 and 3/ it would not remain sortable. To validate a base32 `xid`, expect a 20 chars long, 24 all lowercase sequence of `a` to `v` letters and `0` to `9` numbers (`[0-9a-v]{20}`). 25 26 UUIDs are 16 bytes (128 bits) and 36 chars as string representation. Twitter Snowflake 27 ids are 8 bytes (64 bits) but require machine/data-center configuration and/or central 28 generator servers. xid stands in between with 12 bytes (96 bits) and a more compact 29 URL-safe string representation (20 chars). No configuration or central generator server 30 is required so it can be used directly in server's code. 31 32 | Name | Binary Size | String Size | Features 33 |-------------|-------------|----------------|---------------- 34 | [UUID] | 16 bytes | 36 chars | configuration free, not sortable 35 | [shortuuid] | 16 bytes | 22 chars | configuration free, not sortable 36 | [Snowflake] | 8 bytes | up to 20 chars | needs machin/DC configuration, needs central server, sortable 37 | [MongoID] | 12 bytes | 24 chars | configuration free, sortable 38 | xid | 12 bytes | 20 chars | configuration free, sortable 39 40 [UUID]: https://en.wikipedia.org/wiki/Universally_unique_identifier 41 [shortuuid]: https://github.com/stochastic-technologies/shortuuid 42 [Snowflake]: https://blog.twitter.com/2010/announcing-snowflake 43 [MongoID]: https://docs.mongodb.org/manual/reference/object-id/ 44 45 Features: 46 47 - Size: 12 bytes (96 bits), smaller than UUID, larger than snowflake 48 - Base32 hex encoded by default (20 chars when transported as printable string, still sortable) 49 - Non configured, you don't need set a unique machine and/or data center id 50 - K-ordered 51 - Embedded time with 1 second precision 52 - Unicity guaranteed for 16,777,216 (24 bits) unique ids per second and per host/process 53 - Lock-free (i.e.: unlike UUIDv1 and v2) 54 55 Best used with [zerolog](https://github.com/rs/zerolog)'s 56 [RequestIDHandler](https://godoc.org/github.com/rs/zerolog/hlog#RequestIDHandler). 57 58 Notes: 59 60 - Xid is dependent on the system time, a monotonic counter and so is not cryptographically secure. If unpredictability of IDs is important, you should not use Xids. It is worth noting that most of the other UUID like implementations are also not cryptographically secure. You shoud use libraries that rely on cryptographically secure sources (like /dev/urandom on unix, crypto/rand in golang), if you want a truly random ID generator. 61 62 References: 63 64 - http://www.slideshare.net/davegardnerisme/unique-id-generation-in-distributed-systems 65 - https://en.wikipedia.org/wiki/Universally_unique_identifier 66 - https://blog.twitter.com/2010/announcing-snowflake 67 - Python port by [Graham Abbott](https://github.com/graham): https://github.com/graham/python_xid 68 - Scala port by [Egor Kolotaev](https://github.com/kolotaev): https://github.com/kolotaev/ride 69 70 ## Install 71 72 go get github.com/influx6/npkg/nxid 73 74 ## Usage 75 76 ```go 77 guid := xid.New() 78 79 println(guid.String()) 80 // Output: 9m4e2mr0ui3e8a215n4g 81 ``` 82 83 Get `xid` embedded info: 84 85 ```go 86 guid.Machine() 87 guid.Pid() 88 guid.Time() 89 guid.Counter() 90 ``` 91 92 ## Benchmark 93 94 Benchmark against Go [Maxim Bublis](https://github.com/satori)'s [UUID](https://github.com/satori/go.uuid). 95 96 ``` 97 BenchmarkXID 20000000 91.1 ns/op 32 B/op 1 allocs/op 98 BenchmarkXID-2 20000000 55.9 ns/op 32 B/op 1 allocs/op 99 BenchmarkXID-4 50000000 32.3 ns/op 32 B/op 1 allocs/op 100 BenchmarkUUIDv1 10000000 204 ns/op 48 B/op 1 allocs/op 101 BenchmarkUUIDv1-2 10000000 160 ns/op 48 B/op 1 allocs/op 102 BenchmarkUUIDv1-4 10000000 195 ns/op 48 B/op 1 allocs/op 103 BenchmarkUUIDv4 1000000 1503 ns/op 64 B/op 2 allocs/op 104 BenchmarkUUIDv4-2 1000000 1427 ns/op 64 B/op 2 allocs/op 105 BenchmarkUUIDv4-4 1000000 1452 ns/op 64 B/op 2 allocs/op 106 ``` 107 108 Note: UUIDv1 requires a global lock, hence the performence degrading as we add more CPUs. 109 110 ## Licenses 111 112 All source code is licensed under the [MIT License](https://raw.github.com/rs/xid/master/LICENSE).