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diff --git a/vendor/github.com/oklog/ulid/README.md b/vendor/github.com/oklog/ulid/README.md new file mode 100644 index 0000000..0a3d2f8 --- /dev/null +++ b/vendor/github.com/oklog/ulid/README.md @@ -0,0 +1,150 @@ +# Universally Unique Lexicographically Sortable Identifier + + +[](http://travis-ci.org/oklog/ulid) +[](https://goreportcard.com/report/oklog/ulid) +[](https://coveralls.io/github/oklog/ulid?branch=master) +[](https://godoc.org/github.com/oklog/ulid) +[](https://raw.githubusercontent.com/oklog/ulid/master/LICENSE) + +A Go port of [alizain/ulid](https://github.com/alizain/ulid) with binary format implemented. + +## Background + +A GUID/UUID can be suboptimal for many use-cases because: + +- It isn't the most character efficient way of encoding 128 bits +- UUID v1/v2 is impractical in many environments, as it requires access to a unique, stable MAC address +- UUID v3/v5 requires a unique seed and produces randomly distributed IDs, which can cause fragmentation in many data structures +- UUID v4 provides no other information than randomness which can cause fragmentation in many data structures + +A ULID however: + +- Is compatible with UUID/GUID's +- 1.21e+24 unique ULIDs per millisecond (1,208,925,819,614,629,174,706,176 to be exact) +- Lexicographically sortable +- Canonically encoded as a 26 character string, as opposed to the 36 character UUID +- Uses Crockford's base32 for better efficiency and readability (5 bits per character) +- Case insensitive +- No special characters (URL safe) +- Monotonic sort order (correctly detects and handles the same millisecond) + +## Install + +```shell +go get github.com/oklog/ulid +``` + +## Usage + +An ULID is constructed with a `time.Time` and an `io.Reader` entropy source. +This design allows for greater flexibility in choosing your trade-offs. + +Please note that `rand.Rand` from the `math` package is *not* safe for concurrent use. +Instantiate one per long living go-routine or use a `sync.Pool` if you want to avoid the potential contention of a locked `rand.Source` as its been frequently observed in the package level functions. + + +```go +func ExampleULID() { + t := time.Unix(1000000, 0) + entropy := ulid.Monotonic(rand.New(rand.NewSource(t.UnixNano())), 0) + fmt.Println(ulid.MustNew(ulid.Timestamp(t), entropy)) + // Output: 0000XSNJG0MQJHBF4QX1EFD6Y3 +} + +``` + +## Specification + +Below is the current specification of ULID as implemented in this repository. + +### Components + +**Timestamp** +- 48 bits +- UNIX-time in milliseconds +- Won't run out of space till the year 10895 AD + +**Entropy** +- 80 bits +- User defined entropy source. +- Monotonicity within the same millisecond with [`ulid.Monotonic`](https://godoc.org/github.com/oklog/ulid#Monotonic) + +### Encoding + +[Crockford's Base32](http://www.crockford.com/wrmg/base32.html) is used as shown. +This alphabet excludes the letters I, L, O, and U to avoid confusion and abuse. + +``` +0123456789ABCDEFGHJKMNPQRSTVWXYZ +``` + +### Binary Layout and Byte Order + +The components are encoded as 16 octets. Each component is encoded with the Most Significant Byte first (network byte order). + +``` +0 1 2 3 + 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 ++-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +| 32_bit_uint_time_high | ++-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +| 16_bit_uint_time_low | 16_bit_uint_random | ++-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +| 32_bit_uint_random | ++-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +| 32_bit_uint_random | ++-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +``` + +### String Representation + +``` + 01AN4Z07BY 79KA1307SR9X4MV3 +|----------| |----------------| + Timestamp Entropy + 10 chars 16 chars + 48bits 80bits + base32 base32 +``` + +## Test + +```shell +go test ./... +``` + +## Benchmarks + +On a Intel Core i7 Ivy Bridge 2.7 GHz, MacOS 10.12.1 and Go 1.8.0beta1 + +``` +BenchmarkNew/WithCryptoEntropy-8 2000000 771 ns/op 20.73 MB/s 16 B/op 1 allocs/op +BenchmarkNew/WithEntropy-8 20000000 65.8 ns/op 243.01 MB/s 16 B/op 1 allocs/op +BenchmarkNew/WithoutEntropy-8 50000000 30.0 ns/op 534.06 MB/s 16 B/op 1 allocs/op +BenchmarkMustNew/WithCryptoEntropy-8 2000000 781 ns/op 20.48 MB/s 16 B/op 1 allocs/op +BenchmarkMustNew/WithEntropy-8 20000000 70.0 ns/op 228.51 MB/s 16 B/op 1 allocs/op +BenchmarkMustNew/WithoutEntropy-8 50000000 34.6 ns/op 462.98 MB/s 16 B/op 1 allocs/op +BenchmarkParse-8 50000000 30.0 ns/op 866.16 MB/s 0 B/op 0 allocs/op +BenchmarkMustParse-8 50000000 35.2 ns/op 738.94 MB/s 0 B/op 0 allocs/op +BenchmarkString-8 20000000 64.9 ns/op 246.40 MB/s 32 B/op 1 allocs/op +BenchmarkMarshal/Text-8 20000000 55.8 ns/op 286.84 MB/s 32 B/op 1 allocs/op +BenchmarkMarshal/TextTo-8 100000000 22.4 ns/op 714.91 MB/s 0 B/op 0 allocs/op +BenchmarkMarshal/Binary-8 300000000 4.02 ns/op 3981.77 MB/s 0 B/op 0 allocs/op +BenchmarkMarshal/BinaryTo-8 2000000000 1.18 ns/op 13551.75 MB/s 0 B/op 0 allocs/op +BenchmarkUnmarshal/Text-8 100000000 20.5 ns/op 1265.27 MB/s 0 B/op 0 allocs/op +BenchmarkUnmarshal/Binary-8 300000000 4.94 ns/op 3240.01 MB/s 0 B/op 0 allocs/op +BenchmarkNow-8 100000000 15.1 ns/op 528.09 MB/s 0 B/op 0 allocs/op +BenchmarkTimestamp-8 2000000000 0.29 ns/op 27271.59 MB/s 0 B/op 0 allocs/op +BenchmarkTime-8 2000000000 0.58 ns/op 13717.80 MB/s 0 B/op 0 allocs/op +BenchmarkSetTime-8 2000000000 0.89 ns/op 9023.95 MB/s 0 B/op 0 allocs/op +BenchmarkEntropy-8 200000000 7.62 ns/op 1311.66 MB/s 0 B/op 0 allocs/op +BenchmarkSetEntropy-8 2000000000 0.88 ns/op 11376.54 MB/s 0 B/op 0 allocs/op +BenchmarkCompare-8 200000000 7.34 ns/op 4359.23 MB/s 0 B/op 0 allocs/op +``` + +## Prior Art + +- [alizain/ulid](https://github.com/alizain/ulid) +- [RobThree/NUlid](https://github.com/RobThree/NUlid) +- [imdario/go-ulid](https://github.com/imdario/go-ulid) |