mirror of
https://github.com/cwinfo/matterbridge.git
synced 2024-11-10 14:30:26 +00:00
116 lines
5.8 KiB
Markdown
116 lines
5.8 KiB
Markdown
# Globally Unique ID Generator
|
|
|
|
[](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)
|
|
|
|
Package xid is a globally unique id generator library, ready to safely be used directly in your server code.
|
|
|
|
Xid uses the Mongo Object ID algorithm to generate globally unique ids with a different serialization (base64) to make it shorter when transported as a string:
|
|
https://docs.mongodb.org/manual/reference/object-id/
|
|
|
|
- 4-byte value representing the seconds since the Unix epoch,
|
|
- 3-byte machine identifier,
|
|
- 2-byte process id, and
|
|
- 3-byte counter, starting with a random value.
|
|
|
|
The binary representation of the id is compatible with Mongo 12 bytes Object IDs.
|
|
The string representation is using base32 hex (w/o padding) for better space efficiency
|
|
when stored in that form (20 bytes). The hex variant of base32 is used to retain the
|
|
sortable property of the id.
|
|
|
|
Xid doesn't use base64 because case sensitivity and the 2 non alphanum chars may be an
|
|
issue when transported as a string between various systems. Base36 wasn't retained either
|
|
because 1/ it's not standard 2/ the resulting size is not predictable (not bit aligned)
|
|
and 3/ it would not remain sortable. To validate a base32 `xid`, expect a 20 chars long,
|
|
all lowercase sequence of `a` to `v` letters and `0` to `9` numbers (`[0-9a-v]{20}`).
|
|
|
|
UUIDs are 16 bytes (128 bits) and 36 chars as string representation. Twitter Snowflake
|
|
ids are 8 bytes (64 bits) but require machine/data-center configuration and/or central
|
|
generator servers. xid stands in between with 12 bytes (96 bits) and a more compact
|
|
URL-safe string representation (20 chars). No configuration or central generator server
|
|
is required so it can be used directly in server's code.
|
|
|
|
| Name | Binary Size | String Size | Features
|
|
|-------------|-------------|----------------|----------------
|
|
| [UUID] | 16 bytes | 36 chars | configuration free, not sortable
|
|
| [shortuuid] | 16 bytes | 22 chars | configuration free, not sortable
|
|
| [Snowflake] | 8 bytes | up to 20 chars | needs machine/DC configuration, needs central server, sortable
|
|
| [MongoID] | 12 bytes | 24 chars | configuration free, sortable
|
|
| xid | 12 bytes | 20 chars | configuration free, sortable
|
|
|
|
[UUID]: https://en.wikipedia.org/wiki/Universally_unique_identifier
|
|
[shortuuid]: https://github.com/stochastic-technologies/shortuuid
|
|
[Snowflake]: https://blog.twitter.com/2010/announcing-snowflake
|
|
[MongoID]: https://docs.mongodb.org/manual/reference/object-id/
|
|
|
|
Features:
|
|
|
|
- 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)
|
|
|
|
Best used with [zerolog](https://github.com/rs/zerolog)'s
|
|
[RequestIDHandler](https://godoc.org/github.com/rs/zerolog/hlog#RequestIDHandler).
|
|
|
|
Notes:
|
|
|
|
- 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 other UUID-like implementations are also not cryptographically secure. You should 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.
|
|
|
|
References:
|
|
|
|
- http://www.slideshare.net/davegardnerisme/unique-id-generation-in-distributed-systems
|
|
- https://en.wikipedia.org/wiki/Universally_unique_identifier
|
|
- https://blog.twitter.com/2010/announcing-snowflake
|
|
- Python port by [Graham Abbott](https://github.com/graham): https://github.com/graham/python_xid
|
|
- Scala port by [Egor Kolotaev](https://github.com/kolotaev): https://github.com/kolotaev/ride
|
|
- Rust port by [Jérôme Renard](https://github.com/jeromer/): https://github.com/jeromer/libxid
|
|
- Ruby port by [Valar](https://github.com/valarpirai/): https://github.com/valarpirai/ruby_xid
|
|
- Java port by [0xShamil](https://github.com/0xShamil/): https://github.com/0xShamil/java-xid
|
|
|
|
## Install
|
|
|
|
go get github.com/rs/xid
|
|
|
|
## Usage
|
|
|
|
```go
|
|
guid := xid.New()
|
|
|
|
println(guid.String())
|
|
// Output: 9m4e2mr0ui3e8a215n4g
|
|
```
|
|
|
|
Get `xid` embedded info:
|
|
|
|
```go
|
|
guid.Machine()
|
|
guid.Pid()
|
|
guid.Time()
|
|
guid.Counter()
|
|
```
|
|
|
|
## Benchmark
|
|
|
|
Benchmark against Go [Maxim Bublis](https://github.com/satori)'s [UUID](https://github.com/satori/go.uuid).
|
|
|
|
```
|
|
BenchmarkXID 20000000 91.1 ns/op 32 B/op 1 allocs/op
|
|
BenchmarkXID-2 20000000 55.9 ns/op 32 B/op 1 allocs/op
|
|
BenchmarkXID-4 50000000 32.3 ns/op 32 B/op 1 allocs/op
|
|
BenchmarkUUIDv1 10000000 204 ns/op 48 B/op 1 allocs/op
|
|
BenchmarkUUIDv1-2 10000000 160 ns/op 48 B/op 1 allocs/op
|
|
BenchmarkUUIDv1-4 10000000 195 ns/op 48 B/op 1 allocs/op
|
|
BenchmarkUUIDv4 1000000 1503 ns/op 64 B/op 2 allocs/op
|
|
BenchmarkUUIDv4-2 1000000 1427 ns/op 64 B/op 2 allocs/op
|
|
BenchmarkUUIDv4-4 1000000 1452 ns/op 64 B/op 2 allocs/op
|
|
```
|
|
|
|
Note: UUIDv1 requires a global lock, hence the performance degradation as we add more CPUs.
|
|
|
|
## Licenses
|
|
|
|
All source code is licensed under the [MIT License](https://raw.github.com/rs/xid/master/LICENSE).
|