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Allow custom NodeBits and StepBits to be set.

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You can now set the snowflake.NodeBits or snowflake.StepBits to
custom values.  Please keep in mind you have a total of 22 bits
available to use between these two values.  Setting these to
inappropriate values may break things.  So take care to understand
what you're doing here.

This is not the best way of doing this but it does not break
API compatibility with existing users of this package. I will
release a version 2 of this package which will implement this
feature better.
This commit is contained in:
Bruce Marriner 2018-03-19 21:07:06 +00:00
parent 07b209d699
commit a685984f2e
1 changed files with 26 additions and 14 deletions
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40
snowflake.go
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@ -11,15 +11,24 @@ import (
"time"
)
const (
spareBits = 22
nodeBits = 10
stepBits = spareBits - nodeBits
nodeMax = -1 ^ (-1 << nodeBits)
nodeMask = nodeMax << stepBits
stepMask int64 = -1 ^ (-1 << stepBits)
timeShift uint8 = nodeBits + stepBits
nodeShift uint8 = stepBits
var (
// Epoch is set to the twitter snowflake epoch of Nov 04 2010 01:42:54 UTC
// You may customize this to set a different epoch for your application.
Epoch int64 = 1288834974657
// Number of bits to use for Node
// Remember, you have a total 22 bits to share between Node/Step
NodeBits uint8 = 10
// Number of bits to use for Step
// Remember, you have a total 22 bits to share between Node/Step
StepBits uint8 = 12
nodeMax int64 = -1 ^ (-1 << NodeBits)
nodeMask int64 = nodeMax << StepBits
stepMask int64 = -1 ^ (-1 << StepBits)
timeShift uint8 = NodeBits + StepBits
nodeShift uint8 = StepBits
)
const encodeBase32Map = "ybndrfg8ejkmcpqxot1uwisza345h769"
@ -63,10 +72,6 @@ var ErrInvalidBase58 = errors.New("invalid base58")
// ErrInvalidBase32 is returned by ParseBase32 when given an invalid []byte
var ErrInvalidBase32 = errors.New("invalid base32")
// Epoch is set to the twitter snowflake epoch of 2006-03-21:20:50:14 GMT
// You may customize this to set a different epoch for your application.
var Epoch int64 = 1288834974657
// A Node struct holds the basic information needed for a snowflake generator
// node
type Node struct {
@ -88,6 +93,13 @@ func NewNode(node int64) (*Node, error) {
return nil, errors.New("Node number must be between 0 and 1023")
}
// re-calc in case custom NodeBits or StepBits were set
nodeMax = -1 ^ (-1 << NodeBits)
nodeMask = nodeMax << StepBits
stepMask = -1 ^ (-1 << StepBits)
timeShift = NodeBits + StepBits
nodeShift = StepBits
return &Node{
time: 0,
node: node,
@ -242,7 +254,7 @@ func (f ID) IntBytes() [8]byte {
// Time returns an int64 unix timestamp of the snowflake ID time
func (f ID) Time() int64 {
return (int64(f) >> 22) + Epoch
return (int64(f) >> timeShift) + Epoch
}
// Node returns an int64 of the snowflake ID node number