adding id generator

Author: kcajmagic

device/device.go

@@ -4,7 +4,7 @@ import (
 	"bytes"
 	"encoding/json"
 	"fmt"
-	"github.com/segmentio/ksuid"
+	"github.com/xmidt-org/webpa-common/device/sessionid"
 	"sync/atomic"
 	"time"
 
@@ -185,7 +185,7 @@ func newDevice(o deviceOptions) *device {
 		transactions: NewTransactions(),
 		partnerIDs:   partnerIDs,
 		satClientID:  o.SatClientID,
-		sessionID:    ksuid.New().String(),
+		sessionID:    sessionid.GenerateID(),
 		trust:        o.Trust,
 	}
 }

device/device_test.go

@@ -120,3 +120,4 @@ func TestDeviceSessionID(t *testing.T) {
 	assert.Equal(sessionOne.ID(), sessionTwo.ID())
 	assert.NotEqual(sessionOne.SessionID(), sessionTwo.SessionID())
 }
+

device/sessionid/id.go

@@ -0,0 +1,33 @@
+package sessionid
+
+import (
+	"encoding/base64"
+	"encoding/binary"
+	"errors"
+	"math/rand"
+	"time"
+)
+
+func GenerateID() string {
+	return GenerateIDWithTime(time.Now())
+}
+
+func GenerateIDWithTime(t time.Time) string {
+	var buffer [16]byte
+	rand.Read(buffer[:])
+	ts := uint32(t.Unix())
+	binary.BigEndian.PutUint32(buffer[:4], ts)
+	return base64.RawURLEncoding.EncodeToString(buffer[:])
+}
+
+func ParseID(id string) (time.Time, error) {
+	buffer, err := base64.RawURLEncoding.DecodeString(id)
+	if err != nil {
+		return time.Time{}, err
+	}
+	if len(buffer) != 16 {
+		return time.Time{}, errors.New("byte array is wrong length")
+	}
+	ts := binary.BigEndian.Uint32(buffer[:4])
+	return time.Unix(int64(ts), 0), nil
+}

device/sessionid/id_test.go

@@ -0,0 +1,24 @@
+package sessionid
+
+import (
+	"github.com/stretchr/testify/assert"
+	"testing"
+	"time"
+)
+
+func TestGenerateID(t *testing.T) {
+	assert := assert.New(t)
+	now := time.Now()
+	id := GenerateIDWithTime(now)
+	assert.NotEmpty(id)
+
+	ts, err := ParseID(id)
+	assert.NoError(err)
+	assert.Equal(ts.Unix(), now.Unix())
+
+	_, err = ParseID("")
+	assert.Error(err)
+
+	_, err = ParseID("XjS1ECGCZU8WP18PmmIdc")
+	assert.Error(err)
+}

go.mod

@@ -39,7 +39,6 @@ require (
 	github.com/prometheus/client_golang v0.9.2
 	github.com/rubyist/circuitbreaker v2.2.0+incompatible
 	github.com/samuel/go-zookeeper v0.0.0-20180130194729-c4fab1ac1bec
-	github.com/segmentio/ksuid v1.0.2
 	github.com/smartystreets/goconvey v0.0.0-20190731233626-505e41936337 // indirect
 	github.com/spaolacci/murmur3 v0.0.0-20150829172844-0d12bf811670 // indirect
 	github.com/spf13/pflag v1.0.3

go.sum

@@ -153,8 +153,6 @@ github.com/samuel/go-zookeeper v0.0.0-20180130194729-c4fab1ac1bec h1:6ncX5ko6B9L
 github.com/samuel/go-zookeeper v0.0.0-20180130194729-c4fab1ac1bec/go.mod h1:gi+0XIa01GRL2eRQVjQkKGqKF3SF9vZR/HnPullcV2E=
 github.com/sean-/seed v0.0.0-20170313163322-e2103e2c3529 h1:nn5Wsu0esKSJiIVhscUtVbo7ada43DJhG55ua/hjS5I=
 github.com/sean-/seed v0.0.0-20170313163322-e2103e2c3529/go.mod h1:DxrIzT+xaE7yg65j358z/aeFdxmN0P9QXhEzd20vsDc=
-github.com/segmentio/ksuid v1.0.2 h1:9yBfKyw4ECGTdALaF09Snw3sLJmYIX6AbPJrAy6MrDc=
-github.com/segmentio/ksuid v1.0.2/go.mod h1:BXuJDr2byAiHuQaQtSKoXh1J0YmUDurywOXgB2w+OSU=
 github.com/sirupsen/logrus v1.2.0/go.mod h1:LxeOpSwHxABJmUn/MG1IvRgCAasNZTLOkJPxbbu5VWo=
 github.com/smartystreets/assertions v0.0.0-20180927180507-b2de0cb4f26d h1:zE9ykElWQ6/NYmHa3jpm/yHnI4xSofP+UP6SpjHcSeM=
 github.com/smartystreets/assertions v0.0.0-20180927180507-b2de0cb4f26d/go.mod h1:OnSkiWE9lh6wB0YB77sQom3nweQdgAjqCqsofrRNTgc=