Rename to snowflake

snowflake.go

@@ -0,0 +1,150 @@
+// Package snowflake provides a very simple Twitter snowflake generator and parser.
+package snowflake
+
+import (
+	"encoding/base64"
+	"fmt"
+	"strconv"
+	"strings"
+	"sync"
+	"time"
+)
+
+const (
+	timeBits = 41
+	nodeBits = 10
+	stepBits = 12
+
+	timeMask int64 = -1 ^ (-1 << timeBits)
+	nodeMask int64 = -1 ^ (-1 << nodeBits)
+	stepMask int64 = -1 ^ (-1 << stepBits)
+
+	nodeMax = -1 ^ (-1 << nodeBits)
+
+	timeShift uint8 = nodeBits + stepBits
+	nodeShift uint8 = stepBits
+)
+
+// 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 {
+	sync.Mutex
+	time int64
+	node int64
+	step int64
+}
+
+// An ID is a custom type used for a snowflake ID.  This is used so we can
+// attach methods onto the ID.
+type ID int64
+
+// NewNode returns a new snowflake node that can be used to generate snowflake
+// IDs
+func NewNode(node int64) (*Node, error) {
+
+	if node < 0 || node > nodeMax {
+		return nil, fmt.Errorf("Node number must be between 0 and 1023")
+	}
+
+	return &Node{
+		time: 0,
+		node: node,
+		step: 0,
+	}, nil
+}
+
+// Generate creates and returns a unique snowflake ID
+func (n *Node) Generate() (ID, error) {
+
+	n.Lock()
+	defer n.Unlock()
+
+	now := time.Now().UnixNano() / 1000000
+
+	if n.time == now {
+		n.step = (n.step + 1) & stepMask
+
+		if n.step == 0 {
+			for now <= n.time {
+				now = time.Now().UnixNano() / 1000000
+			}
+		}
+	} else {
+		n.step = 0
+	}
+
+	n.time = now
+
+	return ID((now-Epoch)<<timeShift |
+		(n.node << nodeShift) |
+		(n.step),
+	), nil
+}
+
+// Int64 returns an int64 of the snowflake ID
+func (f ID) Int64() int64 {
+	return int64(f)
+}
+
+// String returns a string of the snowflake ID
+func (f ID) String() string {
+	return fmt.Sprintf("%d", f)
+}
+
+// Base2 returns a string base2 of the snowflake ID
+func (f ID) Base2() string {
+	return strconv.FormatInt(int64(f), 2)
+}
+
+// Base36 returns a base36 string of the snowflake ID
+func (f ID) Base36() string {
+	return strconv.FormatInt(int64(f), 36)
+}
+
+// Base64 returns a base64 string of the snowflake ID
+func (f ID) Base64() string {
+	return base64.StdEncoding.EncodeToString(f.Bytes())
+}
+
+// Bytes returns a byte array of the snowflake ID
+func (f ID) Bytes() []byte {
+	return []byte(f.String())
+}
+
+// Time returns an int64 unix timestamp of the snowflake ID time
+func (f ID) Time() int64 {
+	return (int64(f) >> 22) + Epoch
+}
+
+// Node returns an int64 of the snowflake ID node number
+func (f ID) Node() int64 {
+	return int64(f) & 0x00000000003FF000 >> 12
+}
+
+// Step returns an int64 of the snowflake step (or sequence) number
+func (f ID) Step() int64 {
+	return int64(f) & 0x0000000000000FFF
+}
+
+// MarshalJSON returns a json byte array string of the snowflake ID.
+func (f ID) MarshalJSON() ([]byte, error) {
+	return []byte(`"` + f.String() + `"`), nil
+}
+
+// UnmarshalJSON converts a json byte array of a snowflake ID into an ID type.
+func (f *ID) UnmarshalJSON(b []byte) error {
+
+	s := strings.Replace(string(b), `"`, ``, 2)
+	i, err := strconv.ParseInt(s, 10, 64)
+	if err != nil {
+		return err
+	}
+
+	*f = ID(i)
+
+	return nil
+}