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uidgen.go
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uidgen.go
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package uidgen
import (
"database/sql/driver"
"fmt"
"io"
"math/rand"
"sync"
"time"
"github.com/oklog/ulid"
)
// ValueType ...
type ValueType uint8
// ValueType constants ...
const (
BINARY16 ValueType = iota
VARCHAR26
)
// UID ...
type UID struct {
id ulid.ULID
bin bool
}
// Bytes ...
func (u UID) Bytes() []byte {
return u.id[:]
}
func (u UID) String() string {
return u.id.String()
}
// Scan ...
func (u *UID) Scan(src interface{}) error {
return u.id.Scan(src)
}
// Value ...
func (u *UID) Value() (driver.Value, error) {
if u.bin {
return u.id.Value()
}
return u.id.String(), nil
}
// UIDGen ...
type UIDGen struct {
ofs uint64
erp *entropyReaderPool
vt ValueType
}
//func (id stringValuer) Value() (driver.Value, error) {
// return ULID(id).String(), nil
// }
// New ...
func New(offset uint64, vt ValueType) *UIDGen {
g := UIDGen{
ofs: offset,
erp: newEntropyReaderPool(),
vt: vt,
}
return &g
}
// UID ...
func (g *UIDGen) UID() UID {
ms := ulid.Timestamp(time.Now()) - g.ofs
r := g.erp.get()
lid, err := ulid.New(ms, r)
g.erp.put(r)
if err != nil {
panic(fmt.Sprintf("uidgen: %s", err))
}
return UID{id: lid, bin: g.vt == BINARY16}
}
// Parse ...
func (g *UIDGen) Parse(s string) (UID, bool) {
lid, err := ulid.Parse(s)
if err != nil {
return UID{}, false
}
return UID{id: lid, bin: g.vt == BINARY16}, true
}
type entropyReaderPool struct {
p sync.Pool
}
func newEntropyReaderPool() *entropyReaderPool {
return &entropyReaderPool{
p: sync.Pool{
New: func() interface{} {
t := time.Now()
rnr := rand.New(rand.NewSource(t.UnixNano()))
return ulid.Monotonic(rnr, 0)
},
},
}
}
func (p *entropyReaderPool) get() io.Reader {
return p.p.Get().(io.Reader)
}
func (p *entropyReaderPool) put(r io.Reader) {
p.p.Put(r)
}