README
¶
fastuuid
-- import "github.com/rogpeppe/fastuuid"
Package fastuuid provides fast UUID generation of 192 bit universally unique identifiers.
It also provides simple support for 128-bit RFC-4122 V4 UUID strings.
Note that the generated UUIDs are not unguessable - each UUID generated from a Generator is adjacent to the previously generated UUID.
By way of comparison with two other popular UUID-generation packages, github.com/satori/go.uuid and github.com/google/uuid, here are some benchmarks:
BenchmarkNext-4 128272185 9.20 ns/op
BenchmarkHex128-4 14323180 76.4 ns/op
BenchmarkContended-4 45741997 26.4 ns/op
BenchmarkSatoriNext-4 1231281 967 ns/op
BenchmarkSatoriHex128-4 1000000 1041 ns/op
BenchmarkSatoriContended-4 1765520 666 ns/op
BenchmarkGoogleNext-4 1256250 958 ns/op
BenchmarkGoogleHex128-4 1000000 1044 ns/op
BenchmarkGoogleContended-4 1746570 690 ns/op
Usage
func Hex128
func Hex128(uuid [24]byte) string
Hex128 returns an RFC4122 V4 representation of the first 128 bits of the given UUID. For example:
f81d4fae-7dec-41d0-8765-00a0c91e6bf6.
Note: before encoding, it swaps bytes 6 and 9 so that all the varying bits of the UUID as returned from Generator.Next are reflected in the Hex128 representation.
If you want unpredictable UUIDs, you might want to consider hashing the uuid (using SHA256, for example) before passing it to Hex128.
func ValidHex128
func ValidHex128(id string) bool
ValidHex128 reports whether id is a valid UUID as returned by Hex128 and various other UUID packages, such as github.com/satori/go.uuid's NewV4 function.
Note that it does not allow upper case hex.
type Generator
type Generator struct {
}
Generator represents a UUID generator that generates UUIDs in sequence from a random starting point.
func MustNewGenerator
func MustNewGenerator() *Generator
MustNewGenerator is like NewGenerator but panics on failure.
func NewGenerator
func NewGenerator() (*Generator, error)
NewGenerator returns a new Generator. It can fail if the crypto/rand read fails.
func (*Generator) Hex128
func (g *Generator) Hex128() string
Hex128 is a convenience method that returns Hex128(g.Next()).
func (*Generator) Next
func (g *Generator) Next() [24]byte
Next returns the next UUID from the generator. Only the first 8 bytes can differ from the previous UUID, so taking a slice of the first 16 bytes is sufficient to provide a somewhat less secure 128 bit UUID.
It is OK to call this method concurrently.
Documentation
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Overview ¶
Package fastuuid provides fast UUID generation of 192 bit universally unique identifiers.
It also provides simple support for 128-bit RFC-4122 V4 UUID strings.
Note that the generated UUIDs are not unguessable - each UUID generated from a Generator is adjacent to the previously generated UUID.
By way of comparison with two other popular UUID-generation packages, github.com/satori/go.uuid and github.com/google/uuid, here are some benchmarks:
BenchmarkNext-4 128272185 9.20 ns/op BenchmarkHex128-4 14323180 76.4 ns/op BenchmarkContended-4 45741997 26.4 ns/op BenchmarkSatoriNext-4 1231281 967 ns/op BenchmarkSatoriHex128-4 1000000 1041 ns/op BenchmarkSatoriContended-4 1765520 666 ns/op BenchmarkGoogleNext-4 1256250 958 ns/op BenchmarkGoogleHex128-4 1000000 1044 ns/op BenchmarkGoogleContended-4 1746570 690 ns/op
Index ¶
Constants ¶
This section is empty.
Variables ¶
This section is empty.
Functions ¶
func Hex128 ¶ added in v1.1.0
Hex128 returns an RFC4122 V4 representation of the first 128 bits of the given UUID. For example:
f81d4fae-7dec-41d0-8765-00a0c91e6bf6.
Note: before encoding, it swaps bytes 6 and 9 so that all the varying bits of the UUID as returned from Generator.Next are reflected in the Hex128 representation.
If you want unpredictable UUIDs, you might want to consider hashing the uuid (using SHA256, for example) before passing it to Hex128.
func ValidHex128 ¶ added in v1.1.0
ValidHex128 reports whether id is a valid UUID as returned by Hex128 and various other UUID packages, such as github.com/satori/go.uuid's NewV4 function.
Note that it does not allow upper case hex.
Types ¶
type Generator ¶
type Generator struct {
// contains filtered or unexported fields
}
Generator represents a UUID generator that generates UUIDs in sequence from a random starting point.
func MustNewGenerator ¶
func MustNewGenerator() *Generator
MustNewGenerator is like NewGenerator but panics on failure.
func NewGenerator ¶
NewGenerator returns a new Generator. It can fail if the crypto/rand read fails.
func (*Generator) Hex128 ¶ added in v1.1.0
Hex128 is a convenience method that returns Hex128(g.Next()).
Source Files