3n0ugh / snowflake

Unique id generator based on Twitter Snowflake

snowflake

Here is the twitter blog about snowflake.

• The first bit is an unused assigned 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 the data center and worker node, and the max value is
  2^5-1 = 31.
• The last part consists of 8 bits, which means the length of the serial number generated per millisecond per working node, a maximum of 2^8-1 = 4095 IDs can be generated in the same millisecond.
• In a distributed environment, a five-bit data center and worker mean that can deploy 31 data centers. Each data center 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.

Usage

• Check the example program.

   // Create a node
   n, err := snowflake.NewNode(30, 3)
   if err != nil {
      fmt.Println(err)
   }
    
   // Then, generate a id
   id, err := n.Generate()
   if err != nil {
      fmt.Println(err)
   }

   fmt.Printf("ID: %d\n", id)
   fmt.Printf("String: %s\n", id.String())
   fmt.Printf("Uint64: %d\n", id.UInt64())
   
   fmt.Printf("DecomposeID: %v\n", snowflake.DecomposeID(id))

Test and Benchmarking

• Test:

  go test -v . 

• Benchmark:

  go test -bench=. -count=10 -benchtime=2s . 

Attention

• If you need to handle IDs in Javascript, use a string instead of uint64. Because Javascript's maximum integer value you can safely store 53 bits.