Add functions to get ID elements (#35)

* Refactoring

* Add functions to get ID elements

sonyflake.go

@@ -117,8 +117,8 @@ func currentElapsedTime(startTime int64) int64 {
 }
 
 func sleepTime(overtime int64) time.Duration {
-	return time.Duration(overtime)*10*time.Millisecond -
-		time.Duration(time.Now().UTC().UnixNano()%sonyflakeTimeUnit)*time.Nanosecond
+	return time.Duration(overtime*sonyflakeTimeUnit) -
+		time.Duration(time.Now().UTC().UnixNano()%sonyflakeTimeUnit)
 }
 
 func (sf *Sonyflake) toID() (uint64, error) {
@@ -165,15 +165,33 @@ func lower16BitPrivateIP() (uint16, error) {
 	return uint16(ip[2])<<8 + uint16(ip[3]), nil
 }
 
+// ElapsedTime returns the elapsed time when the given Sonyflake ID was generated.
+func ElapsedTime(id uint64) time.Duration {
+	return time.Duration(elapsedTime(id) * sonyflakeTimeUnit)
+}
+
+func elapsedTime(id uint64) uint64 {
+	return id >> (BitLenSequence + BitLenMachineID)
+}
+
+// SequenceNumber returns the sequence number of a Sonyflake ID.
+func SequenceNumber(id uint64) uint64 {
+	const maskSequence = uint64((1<<BitLenSequence - 1) << BitLenMachineID)
+	return id & maskSequence >> BitLenMachineID
+}
+
+// MachineID returns the machine ID of a Sonyflake ID.
+func MachineID(id uint64) uint64 {
+	const maskMachineID = uint64(1<<BitLenMachineID - 1)
+	return id & maskMachineID
+}
+
 // Decompose returns a set of Sonyflake ID parts.
 func Decompose(id uint64) map[string]uint64 {
-	const maskSequence = uint64((1<<BitLenSequence - 1) << BitLenMachineID)
-	const maskMachineID = uint64(1<<BitLenMachineID - 1)
-
 	msb := id >> 63
-	time := id >> (BitLenSequence + BitLenMachineID)
-	sequence := id & maskSequence >> BitLenMachineID
-	machineID := id & maskMachineID
+	time := elapsedTime(id)
+	sequence := SequenceNumber(id)
+	machineID := MachineID(id)
 	return map[string]uint64{
 		"id":         id,
 		"msb":        msb,

sonyflake_test.go

@@ -36,34 +36,28 @@ func nextID(t *testing.T) uint64 {
 }
 
 func TestSonyflakeOnce(t *testing.T) {
-	sleepTime := uint64(50)
-	time.Sleep(time.Duration(sleepTime) * 10 * time.Millisecond)
+	sleepTime := time.Duration(50 * sonyflakeTimeUnit)
+	time.Sleep(sleepTime)
 
 	id := nextID(t)
-	parts := Decompose(id)
 
-	actualMSB := parts["msb"]
-	if actualMSB != 0 {
-		t.Errorf("unexpected msb: %d", actualMSB)
-	}
-
-	actualTime := parts["time"]
-	if actualTime < sleepTime || actualTime > sleepTime+1 {
+	actualTime := ElapsedTime(id)
+	if actualTime < sleepTime || actualTime > sleepTime+sonyflakeTimeUnit {
 		t.Errorf("unexpected time: %d", actualTime)
 	}
 
-	actualSequence := parts["sequence"]
+	actualSequence := SequenceNumber(id)
 	if actualSequence != 0 {
 		t.Errorf("unexpected sequence: %d", actualSequence)
 	}
 
-	actualMachineID := parts["machine-id"]
+	actualMachineID := MachineID(id)
 	if actualMachineID != machineID {
 		t.Errorf("unexpected machine id: %d", actualMachineID)
 	}
 
 	fmt.Println("sonyflake id:", id)
-	fmt.Println("decompose:", parts)
+	fmt.Println("decompose:", Decompose(id))
 }
 
 func currentTime() int64 {
@@ -187,3 +181,9 @@ func TestNextIDError(t *testing.T) {
 		t.Errorf("time is not over")
 	}
 }
+
+func TestSonyflakeTimeUnit(t *testing.T) {
+	if time.Duration(sonyflakeTimeUnit) != 10*time.Millisecond {
+		t.Errorf("unexpected time unit")
+	}
+}