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2021-04-15 11:04:49 +08:00
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5
.gitignore vendored Normal file
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.code
.git
.idea
*.DS_Store
/vendor

31
atomic_resolver.go Normal file
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package snowflake
import "sync/atomic"
var lastTime int64
var lastSeq uint32
// AtomicResolver define as atomic sequence resolver, base on standard sync/atomic.
func AtomicResolver(ms int64) (uint16, error) {
var last int64
var seq, localSeq uint32
for {
last = atomic.LoadInt64(&lastTime)
localSeq = atomic.LoadUint32(&lastSeq)
if last > ms {
return MaxSequence, nil
}
if last == ms {
seq = MaxSequence & (localSeq + 1)
if seq == 0 {
return MaxSequence, nil
}
}
if atomic.CompareAndSwapInt64(&lastTime, last, ms) && atomic.CompareAndSwapUint32(&lastSeq, localSeq, seq) {
return uint16(seq), nil
}
}
}

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atomic_resolver_test.go Normal file
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package snowflake_test
import (
"testing"
"github.com/godruoyi/go-snowflake"
)
func TestAtomicResolver(t *testing.T) {
id, _ := snowflake.AtomicResolver(1)
if id != 0 {
t.Error("Sequence should be equal 0")
}
}
func BenchmarkCombinationParallel(b *testing.B) {
b.RunParallel(func(pb *testing.PB) {
for pb.Next() {
snowflake.AtomicResolver(1)
}
})
}
func BenchmarkAtomicResolver(b *testing.B) {
for i := 0; i < b.N; i++ {
snowflake.AtomicResolver(1)
}
}

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example/example.go Normal file
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package main
import (
"fmt"
"github.com/godruoyi/go-snowflake"
)
func main() {
id := snowflake.ID()
fmt.Println(id)
sid := snowflake.ParseID(id)
// SID {
// Sequence: 0
// MachineID: 0
// Timestamp: x
// ID: x
// }
fmt.Println(sid)
}

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go.mod Normal file
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module github.com/godruoyi/go-snowflake
go 1.15

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package.go Normal file
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// Package snowflake is a network service for generating unique ID numbers at high scale with some simple guarantees.
// The first bit is unused sign bit.
// The second part consists of a 41-bit timestamp (milliseconds) whose value is the offset of the current time relative to a certain time.
// The 5 bits of the third and fourth parts represent data center and worker, and max value is 2^5 -1 = 31.
// The last part consists of 12 bits, its means the length of the serial number generated per millisecond per working node, a maximum of 2^12 -1 = 4095 IDs can be generated in the same millisecond.
// In a distributed environment, five-bit datacenter and worker mean that can deploy 31 datacenters, and each datacenter can deploy up to 31 nodes.
// The binary length of 41 bits is at most 2^41 -1 millisecond = 69 years. So the snowflake algorithm can be used for up to 69 years, In order to maximize the use of the algorithm, you should specify a start time for it.
package snowflake

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privateip.go Normal file
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package snowflake
import (
"errors"
"net"
)
// PrivateIPToMachineID convert private ip to machine id.
// From https://github.com/sony/sonyflake/blob/master/sonyflake.go
func PrivateIPToMachineID() uint16 {
ip, err := lower16BitPrivateIP()
if err != nil {
return 0
}
return ip
}
//--------------------------------------------------------------------
// private function defined.
//--------------------------------------------------------------------
func privateIPv4() (net.IP, error) {
as, err := net.InterfaceAddrs()
if err != nil {
return nil, err
}
for _, a := range as {
ipnet, ok := a.(*net.IPNet)
if !ok || ipnet.IP.IsLoopback() {
continue
}
ip := ipnet.IP.To4()
if isPrivateIPv4(ip) {
return ip, nil
}
}
return nil, errors.New("no private ip address")
}
func isPrivateIPv4(ip net.IP) bool {
return ip != nil &&
(ip[0] == 10 || ip[0] == 172 && (ip[1] >= 16 && ip[1] < 32) || ip[0] == 192 && ip[1] == 168)
}
func lower16BitPrivateIP() (uint16, error) {
ip, err := privateIPv4()
if err != nil {
return 0, err
}
// Snowflake macnineID max length is 10, max value is 1023
// If ip[2] > 3, return ip[2] + ip[3], but:
// 10.21.5.211 => return 5 + 211 = 216
// 10.21.4.212 => return 4 + 212 = 216
// need help if you can do this.
if ip[2] > 3 {
return uint16(ip[2] + ip[3]), nil
}
return uint16(ip[2])<<8 + uint16(ip[3]), nil
}

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privateip_test.go Normal file
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package snowflake_test
import (
"testing"
"github.com/godruoyi/go-snowflake"
)
func TestPrivateIPToMachineID(t *testing.T) {
mid := snowflake.PrivateIPToMachineID()
if mid <= 0 {
t.Error("MachineID should be > 0")
}
}

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readme.md Normal file
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<div>
<p align="center">
<image src="https://www.pngkey.com/png/full/105-1052235_snowflake-png-transparent-background-snowflake-with-clear-background.png" width="250" height="250">
</p>
<p align="center">An Lock Free ID Generator for Golang based on Snowflake Algorithm (Twitter announced).</p>
<!-- <p align="center">
<a href="https://scrutinizer-ci.com/g/godruoyi/go-snowflake/">
<image src="https://scrutinizer-ci.com/g/godruoyi/go-snowflake/badges/quality-score.png?b=master" alt="quality score">
</a>
<a href="https://github.com/godruoyi/go-snowflake">
<image src="https://github.styleci.io/repos/201936013/shield?branch=master" alt="godruoyi go-snowflake">
</a>
<a href="https://github.com/godruoyi/go-snowflake">
<image src="https://poser.pugx.org/godruoyi/go-snowflake/license" alt="License">
</a>
<a href="https://packagist.org/packages/godruoyi/go-snowflake">
<image src="https://poser.pugx.org/godruoyi/go-snowflake/v/stable" alt="Packagist Version">
</a>
<a href="https://scrutinizer-ci.com/g/godruoyi/go-snowflake/">
<image src="https://scrutinizer-ci.com/g/godruoyi/go-snowflake/badges/build.png?b=master" alt="build passed">
</a>
<a href="https://github.com/godruoyi/go-snowflake">
<image src="https://poser.pugx.org/godruoyi/go-snowflake/downloads" alt="Total Downloads">
</a>
</p> -->
</div>
## Description
An Lock Free ID Generator for Golang implementation.
![file](https://images.godruoyi.com/logos/201908/13/_1565672621_LPW65Pi8cG.png)
Snowflake is a network service for generating unique ID numbers at high scale with some simple guarantees.
* The first bit is unused sign bit.
* The second part consists of a 41-bit timestamp (milliseconds) whose value is the offset of the current time relative to a certain time.
* The 10 bits machineID, and max value is 2^10 -1 = 1023.
* The last part consists of 12 bits, its means the length of the serial number generated per millisecond per working node, a maximum of 2^12 -1 = 4095 IDs can be generated in the same millisecond.
* The binary length of 41 bits is at most 2^41 -1 millisecond = 69 years. So the snowflake algorithm can be used for up to 69 years, In order to maximize the use of the algorithm, you should specify a start time for it.
> You must know, The ID generated by the snowflake algorithm is not guaranteed to be unique.
> For example, when two different requests enter the same machine at the same time, and the sequence generated by the node is the same, the generated ID will be duplicated.
So if you want use the snowflake algorithm to generate unique ID, You must ensure: The sequence-number generated in the same millisecond of the same node is unique.
Based on this, we created this package and integrated multiple sequence-number providers into it.
* AtomicResolver (base sync/atmoic)
* Custom (you can custom)
> Each provider only needs to ensure that the serial number generated in the same millisecond is different. You can get a unique ID.
## Installation
```shell
$ go get github.com/godruoyi/go-snowflake
```
## Useage
1. simple to use.
```go
import (
"fmt"
"github.com/godruoyi/go-snowflake"
)
func main() {
id := snowflake.ID()
fmt.Println(id)
// 1537200202186752
}
```
2. Specify the MachineID.
```go
import (
"fmt"
"github.com/godruoyi/go-snowflake"
)
func main() {
snowflake.SetMachineID(1)
id := snowflake.ID()
fmt.Println(id)
}
```
3. Specify start time.
```go
import (
"fmt"
"time"
"github.com/godruoyi/go-snowflake"
)
func main() {
snowflake.SetStartTime(time.Date(2014, 9, 1, 0, 0, 0, 0, time.UTC))
id := snowflake.ID()
fmt.Println(id)
}
```
4. Parse ID.
```go
import (
"fmt"
"time"
"github.com/godruoyi/go-snowflake"
)
func main() {
id := snowflake.ID()
sid := snowflake.ParseID(id)
fmt.Println(sid.ID) //
fmt.Println(sid.MachineID) //
fmt.Println(sid.Sequence) //
fmt.Println(sid.Timestamp) //
fmt.Println(sid.GenerateTime()) //
}
```
## Best practices
> ⚠️⚠️ All SetXXX method is thread-unsafe, recommended you call him in the main function.
```go
import (
"fmt"
"time"
"net/http"
"github.com/godruoyi/go-snowflake"
)
func main() {
snowflake.SetMachineID(1) // change to your machineID
snowflake.SetStartTime(time.Date(2014, 9, 1, 0, 0, 0, 0, time.UTC))
http.HandleFunc("/order", submitOrder)
http.ListenAndServe(":8090", nil)
}
func submitOrder(w http.ResponseWriter, req *http.Request) {
orderId := snowflake.ID()
// save order
}
```
## Advanced
1. Custom sequence resolver.
You can customize the sequence-number resolver by following way:
```go
import (
"fmt"
"time"
"github.com/godruoyi/go-snowflake"
)
func yourSequenceNumber(ms int64) (uint16, error) {
}
// usage
snowflake.SetSequenceResolver(yourSequenceNumber)
snowflake.ID()
```
And you can use closure:
## License
MIT

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snowflake.go Normal file
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package snowflake
import (
"errors"
"time"
)
// These constants are the bit lengths of snowflake ID parts.
const (
TimestampLength = 41
MachineIDLength = 10
SequenceLength = 12
MaxSequence = 1<<SequenceLength - 1
MaxTimestamp = 1<<TimestampLength - 1
MaxMachineID = 1<<MachineIDLength - 1
machineIDMoveLength = SequenceLength
timestampMoveLength = MachineIDLength + SequenceLength
)
// SequenceResolver the snowflake sequence resolver.
//
// When you want use the snowflake algorithm to generate unique ID, You must ensure: The sequence-number generated in the same millisecond of the same node is unique.
// Based on this, we create this interface provide following reslover:
// AtomicResolver : base sync/atomic (by default).
type SequenceResolver func(ms int64) (uint16, error)
// default start time is 2014-09-01 00:00:00UTC
// default machineID is 0
// default resolver is AtomicResolver
var (
resolver SequenceResolver
machineID = 0
startTime = time.Date(2014, 9, 1, 0, 0, 0, 0, time.UTC)
)
// ID use ID to generate snowflake id and it will ignore error. if you want error info, you need use NextID method.
// This function is thread safe.
func ID() uint64 {
id, _ := NextID()
return id
}
// NextID use NextID to generate snowflake id and return an error.
// This function is thread safe.
func NextID() (uint64, error) {
c := currentMillis()
seqResolver := callSequenceResolver()
seq, err := seqResolver(c)
if err != nil {
return 0, err
}
for seq >= MaxSequence {
c = waitForNextMillis(c)
seq, err = seqResolver(c)
if err != nil {
return 0, err
}
}
df := int(elapsedTime(startTime))
if df < 0 || df > MaxTimestamp {
return 0, errors.New("The maximum life cycle of the snowflake algorithm is 2^41-1(millis), please check starttime")
}
id := uint64(df<<timestampMoveLength | machineID<<machineIDMoveLength | int(seq))
return id, nil
}
// SetStartTime set the start time for snowflake algorithm.
//
// It will panic when:
// s IsZero
// s > current millisecond
// current millisecond - s > 2^41(69 years).
// This function is thread-unsafe, recommended you call him in the main function.
func SetStartTime(s time.Time) {
s = s.UTC()
if s.IsZero() {
panic("The start time cannot be a zero value")
}
if s.After(time.Now()) {
panic("The s cannot be greater than the current millisecond")
}
// Because s must after now, so the `df` not < 0.
df := elapsedTime(s)
if df > MaxTimestamp {
panic("The maximum life cycle of the snowflake algorithm is 69 years")
}
startTime = s
}
// SetMachineID specify the machine ID. It will panic when machineid > max limit for 2^10-1.
// This function is thread-unsafe, recommended you call him in the main function.
func SetMachineID(m uint16) {
if m > MaxMachineID {
panic("The machineid cannot be greater than 1023")
}
machineID = int(m)
}
// SetSequenceResolver set an custom sequence resolver.
// This function is thread-unsafe, recommended you call him in the main function.
func SetSequenceResolver(seq SequenceResolver) {
if seq != nil {
resolver = seq
}
}
// SID snowflake id
type SID struct {
Sequence uint64
MachineID uint64
Timestamp uint64
ID uint64
}
// GenerateTime snowflake generate at, return a UTC time.
func (id *SID) GenerateTime() time.Time {
ms := startTime.UTC().UnixNano()/1e6 + int64(id.Timestamp)
return time.Unix(0, (ms * int64(time.Millisecond))).UTC()
}
// ParseID parse snowflake it to SID struct.
func ParseID(id uint64) SID {
time := id >> (SequenceLength + MachineIDLength)
sequence := id & MaxSequence
machineID := (id & (MaxMachineID << SequenceLength)) >> SequenceLength
return SID{
ID: id,
Sequence: sequence,
MachineID: machineID,
Timestamp: time,
}
}
//--------------------------------------------------------------------
// private function defined.
//--------------------------------------------------------------------
func waitForNextMillis(last int64) int64 {
now := currentMillis()
for now == last {
now = currentMillis()
}
return now
}
func callSequenceResolver() SequenceResolver {
if resolver == nil {
return AtomicResolver
}
return resolver
}
func elapsedTime(s time.Time) int64 {
return currentMillis() - s.UTC().UnixNano()/1e6
}
// currentMillis get current millisecond.
func currentMillis() int64 {
return time.Now().UTC().UnixNano() / 1e6
}

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package snowflake_test
import (
"errors"
"testing"
"time"
"github.com/godruoyi/go-snowflake"
)
func TestID(t *testing.T) {
id := snowflake.ID()
if id <= 0 {
t.Error("The snowflake should't < 0.")
}
}
func TestSetStartTime(t *testing.T) {
t.Run("A nil time", func(tt *testing.T) {
defer func() {
if e := recover(); e == nil {
tt.Error("Should throw a error when start time is zero")
} else if e.(string) != "The start time cannot be a zero value" {
tt.Error("The error message should equal [The start time cannot be a zero value]")
}
}()
var time time.Time
snowflake.SetStartTime(time)
})
t.Run("Start time too big", func(tt *testing.T) {
defer func() {
if e := recover(); e == nil {
tt.Error("Should throw a error when start time is too big")
} else if e.(string) != "The s cannot be greater than the current millisecond" {
tt.Error("The error message should equal [The s cannot be greater than the current millisecond]")
}
}()
time := time.Date(2035, 1, 1, 1, 0, 0, 0, time.UTC)
snowflake.SetStartTime(time)
})
t.Run("Start time too small", func(tt *testing.T) {
defer func() {
if e := recover(); e == nil {
tt.Error("Should throw a error when starttime is too small")
} else if e.(string) != "The maximum life cycle of the snowflake algorithm is 69 years" {
tt.Error("The error message should equal [The maximum life cycle of the snowflake algorithm is 69 years]")
}
}()
// because 2021-69 = 1952, set df time > 69 years to test.
time := time.Date(1951, 1, 1, 1, 0, 0, 0, time.UTC)
snowflake.SetStartTime(time)
})
t.Run("Default start time", func(tt *testing.T) {
defaultTime := time.Date(2014, 9, 1, 0, 0, 0, 0, time.UTC)
defaultNano := defaultTime.UTC().UnixNano() / 1e6
sid := snowflake.ParseID(snowflake.ID())
currentTime := sid.Timestamp + uint64(defaultNano)
nowNano := time.Now().UTC().UnixNano() / 1e6
// approximate equality, Assuming that the program is completed in one second.
if currentTime/1000 != uint64(nowNano)/1000 {
t.Error("The timestamp should be equal")
}
})
t.Run("Basic", func(tt *testing.T) {
date := time.Date(2002, 1, 1, 1, 0, 0, 0, time.UTC)
snowflake.SetStartTime(date)
nowNano := time.Now().UTC().UnixNano() / 1e6
startNano := date.UTC().UnixNano() / 1e6
df := nowNano - startNano
sid := snowflake.ParseID(snowflake.ID())
// approximate equality, Assuming that the program is completed in one second.
if sid.Timestamp/1000 != uint64(df)/1000 {
t.Error("The timestamp should be equal")
}
})
}
func TestSetMachineID(t *testing.T) {
// first test,
sid := snowflake.ParseID(snowflake.ID())
if sid.MachineID != 0 {
t.Error("MachineID should be equal 0")
}
t.Run("No Panic", func(tt *testing.T) {
defer func() {
if err := recover(); err != nil {
t.Error("An error should not be returned")
}
}()
snowflake.SetMachineID(1)
id := snowflake.ID()
sid := snowflake.ParseID(id)
if sid.MachineID != 1 {
tt.Error("The machineID should be equal 1")
}
})
t.Run("Panic", func(tt *testing.T) {
defer func() {
if err := recover(); err == nil {
tt.Error("Should throw a error")
} else if err.(string) != "The machineid cannot be greater than 1023" {
tt.Error("The error message should be eq 「The machineid cannot be greater than 1023」")
}
}()
snowflake.SetMachineID(1024)
})
snowflake.SetMachineID(100)
sid = snowflake.ParseID(snowflake.ID())
if sid.MachineID != 100 {
t.Error("MachineID should be equal 100")
}
}
func TestSetSequenceResolver(t *testing.T) {
snowflake.SetSequenceResolver(func(c int64) (uint16, error) {
return 100, nil
})
id := snowflake.ID()
sid := snowflake.ParseID(id)
if sid.Sequence != 100 {
t.Error("The snowflake number part of sequence should be equal 100")
}
time.Sleep(time.Millisecond)
id = snowflake.ID()
sid2 := snowflake.ParseID(id)
if sid2.Sequence != 100 {
t.Error("The snowflake number part of sequence should be equal 100")
}
if sid2.Timestamp <= sid.Timestamp {
t.Error("It should be bigger than the previous time")
}
}
func TestNextID(t *testing.T) {
_, err := snowflake.NextID()
if err != nil {
t.Error(err)
return
}
snowflake.SetSequenceResolver(func(ms int64) (uint16, error) {
return 0, errors.New("test error")
})
_, e := snowflake.NextID()
if e == nil {
t.Error("Should be throw error")
} else if e.Error() != "test error" {
t.Error("NextID error message should be equal [test error]")
}
}
func TestParseID(t *testing.T) {
time := 101 << (snowflake.MachineIDLength + snowflake.SequenceLength)
machineid := 1023 << snowflake.SequenceLength
seq := 999
id := uint64(time | machineid | seq)
d := snowflake.ParseID(id)
if d.Sequence != 999 {
t.Error("Sequence should be equal 999")
}
if d.MachineID != 1023 {
t.Error("MachineID should be equal 1023")
}
if d.Timestamp != 101 {
t.Error("Timestamp should be equal 101")
}
}
func TestSID_GenerateTime(t *testing.T) {
sid := snowflake.ParseID(snowflake.ID())
if sid.GenerateTime().UTC().Second() != time.Now().UTC().Second() {
t.Error("The id generate time should be equal")
}
}