Add ulid package

ulid/ulid.go

@@ -0,0 +1,51 @@
+package ulid
+
+import (
+	cryptorand "crypto/rand"
+	"encoding/binary"
+	"io"
+	mathrand "math/rand"
+	"os"
+	"sync"
+	"time"
+
+	oklid "github.com/oklog/ulid/v2"
+	"go.ntppool.org/common/logger"
+)
+
+var monotonicPool = sync.Pool{
+	New: func() interface{} {
+
+		log := logger.Setup()
+
+		var seed int64
+		err := binary.Read(cryptorand.Reader, binary.BigEndian, &seed)
+		if err != nil {
+			log.Error("crypto/rand error", "err", err)
+			os.Exit(10)
+		}
+
+		rand := mathrand.New(mathrand.NewSource(seed))
+
+		inc := uint64(mathrand.Int63())
+
+		// log.Printf("seed: %d", seed)
+		// log.Printf("inc:  %d", inc)
+
+		// inc = inc & ^uint64(1<<63) // only want 63 bits
+		mono := oklid.Monotonic(rand, inc)
+		return mono
+	},
+}
+
+func MakeULID(t time.Time) (*oklid.ULID, error) {
+
+	mono := monotonicPool.Get().(io.Reader)
+
+	id, err := oklid.New(oklid.Timestamp(t), mono)
+	if err != nil {
+		return nil, err
+	}
+
+	return &id, nil
+}