This is a fork of snowflake by bwmarrin, with additional features to generate a block of IDs.

• A very simple Twitter snowflake generator.
• Methods to parse existing snowflake IDs.
• Methods to convert a snowflake ID into several other data types and back.
• JSON Marshal/Unmarshal functions to easily use snowflake IDs within a JSON API.
• Monotonic Clock calculations protect from clock drift.
• Advanced use-case to generate a block of IDs.

By default, the ID format follows the original Twitter snowflake format.

• The ID is a 63 bit integer stored in an int64
• 41 bits are used to store a millisecond timestamp, using a custom epoch.
• 10 bits are used to store a node id, range from 0 through 1023.
• 12 bits are used to store a sequence number, range from 0 through 4095.

You can alter the number of bits used for the node id and step number (sequence) by specifying Config.NodeBits and Config.StepBits when initialising node using NewNodeWithConfig(). Remember that there is a maximum of 22 bits available that can be shared between the two. You do not have to use all 22 bits.

By default the Twitter Epoch of 1288834974657 or Nov 04 2010 01:42:54 is used. You can specify your own epoch value in milliseconds in Config.Epoch when initialising node using NewNodeWithConfig().

Each time you generate an ID, it works, like this.

• A timestamp with millisecond precision is stored using 41 bits of the ID.
• Then the NodeID is added in subsequent bits.
• Then the Sequence Number is added, starting at 0 and incrementing for each ID generated in the same millisecond. If you generate enough IDs in the same millisecond, so that the sequence would roll over or overfill, then the generate function will pause until the next millisecond.

The default Twitter format shown below.

 -------------------------------------------------------------------------- 
| 1 Bit Unused | 41 Bit Timestamp |  10 Bit NodeID  |   12 Bit Sequence ID |
 -------------------------------------------------------------------------- 

Using the default settings, this allows for 4096 unique IDs to be generated every millisecond, per Node ID.

go get github.com/redmatter/snowflake

package main

import (
	"fmt"

	"github.com/redmatter/snowflake"
)

func main() {

	// Create a new Node with a Node number of 1
	node, err := snowflake.NewNode(1)
	if err != nil {
		fmt.Println(err)
		return
	}

	// Generate a snowflake ID.
	id := node.Generate()

	// Print out the ID in a few different ways.
	fmt.Printf("Int64  ID: %d\n", id)
	fmt.Printf("String ID: %s\n", id)
	fmt.Printf("Base2  ID: %s\n", id.Base2())
	fmt.Printf("Base64 ID: %s\n", id.Base64())

	// Generate and print, all in one.
	fmt.Printf("ID       : %d\n", node.Generate().Int64())
}

With default settings, this snowflake generator should be sufficiently fast enough on most systems to generate 4096 unique ID's per millisecond. This is the maximum that the snowflake ID format supports. That is, around 243-244 nanoseconds per operation.

Since the snowflake generator is single threaded the primary limitation will be the maximum speed of a single processor on your system.

To benchmark the generator on your system run the following command inside the snowflake package directory.

go test -run=^$ -bench=.

If your curious, check out this commit that shows benchmarks that compare a few different ways of implementing a snowflake generator in Go.

• https://github.com/redmatter/snowflake/tree/9befef8908df13f4102ed21f42b083dd862b5036