Use 48 bits of timestamp

hlc.go

@@ -18,28 +18,28 @@ type timestamp uint64
 // hybridLogicalClock is a hybrid logical clock implementation for rosmar that produces timestamps that will always be increasing regardless of clock changes.
 type hybridLogicalClock struct {
 	clock       clock
-	counter     timestamp
-	highestTime timestamp
+	counter     uint16
+	highestTime uint64
 	mutex       sync.Mutex
 }
 
 // clock interface is used to abstract the system clock for testing purposes.
 type clock interface {
 	// getTime returns the current time in nanoseconds.
-	getTime() timestamp
+	getTime() uint64
 }
 
 type systemClock struct{}
 
 // getTime returns the current time in nanoseconds.
-func (c *systemClock) getTime() timestamp {
-	return timestamp(time.Now().UnixNano())
+func (c *systemClock) getTime() uint64 {
+	return uint64(time.Now().UnixNano())
 }
 
 // NewHybridLogicalClock returns a new HLC from a previously initialized time.
 func NewHybridLogicalClock(lastTime timestamp) *hybridLogicalClock {
 	return &hybridLogicalClock{
-		highestTime: lastTime,
+		highestTime: uint64(lastTime),
 		clock:       &systemClock{},
 	}
 }
@@ -55,5 +55,5 @@ func (c *hybridLogicalClock) Now() timestamp {
 		c.counter = 0
 		c.highestTime = physicalTime
 	}
-	return c.highestTime + c.counter
+	return timestamp((c.highestTime << 16) | uint64(c.counter))
 }

hlc_test.go

@@ -68,10 +68,10 @@ loop:
 }
 
 type fakeClock struct {
-	time timestamp
+	time uint64
 }
 
-func (c *fakeClock) getTime() timestamp {
+func (c *fakeClock) getTime() uint64 {
 	return c.time
 }
 
@@ -82,19 +82,24 @@ func TestHLCReverseTime(t *testing.T) {
 	require.Equal(t, timestamp(2), hlc.Now())
 
 	// reverse time no counter
-	clock.time = timestamp(0)
+	clock.time = 0
 	require.Equal(t, timestamp(3), hlc.Now())
 
 	// reset time to normal
-	clock.time = timestamp(6)
-	require.Equal(t, timestamp(6), hlc.Now())
+	clock.time = 6
+	require.Equal(t, timestamp(0x60000), hlc.Now())
 
 	// reverse time again
-	clock.time = timestamp(1)
-	require.Equal(t, timestamp(7), hlc.Now())
+	clock.time = 1
+	require.Equal(t, timestamp(0x60001), hlc.Now())
 
 	// jump to a value we had previously
-	clock.time = timestamp(6)
-	require.Equal(t, int(timestamp(8)), int(hlc.Now()))
-	require.Equal(t, int(timestamp(9)), int(hlc.Now()))
+	clock.time = 6
+	require.Equal(t, timestamp(0x60002), hlc.Now())
+	require.Equal(t, timestamp(0x60003), hlc.Now())
+
+	// continue forward
+	clock.time = 7
+	require.Equal(t, timestamp(0x70000), hlc.Now())
+
 }