Generics for clocks

clock/clock.go

@@ -2,9 +2,18 @@ package clock
 
 import (
 	"errors"
+	"fmt"
 )
 
-func max(x, y uint) uint {
+type Uint interface {
+	uint32 | uint64
+}
+
+type VectorClock[T Uint] struct {
+	clock []T
+}
+
+func max[T Uint](x, y T) T {
 	if x >= y {
 		return x
 	} else {
@@ -12,11 +21,6 @@ func max(x, y uint) uint {
 	}
 }
 
-// VectorClock type is used for determining the partial ordering of events in a distributed system.
-type VectorClock struct {
-	clock []uint
-}
-
 // GetClock returns a copy of the internal vector clock.
 //
 // This method provides a snapshot of the current state of the vector clock
@@ -26,15 +30,36 @@ type VectorClock struct {
 //
 // Returns:
 //
-//	[]int: A copy of the internal vector clock slice, where each element
-//	represents the logical time for a corresponding process.
-func (vc *VectorClock) GetClock() []uint {
-	clock := make([]uint, len(vc.clock))
+//	[]T: A copy of the internal vector clock slice, where each element
+//	represents the logical time for a corresponding process. The type T
+//	is constrained by the Uint interface and can be either uint32 or uint64.
+func (vc *VectorClock[T]) GetClock() []T {
+	clock := make([]T, len(vc.clock))
 	copy(clock, vc.clock)
 	return clock
 }
 
-func (vc *VectorClock) Sync(v VectorClock) ([]uint, error) {
+// Sync synchronizes the current VectorClock with another VectorClock of the same type.
+//
+// This method takes another VectorClock instance, compares the logical times for each
+// process, and updates the current VectorClock to hold the maximum logical time for
+// each process. The synchronization ensures that the resulting vector clock reflects
+// the latest logical times for both clocks.
+//
+// If the lengths of the two VectorClocks differ, an error is returned.
+//
+// Parameters:
+//
+//	v VectorClock[T]: The other VectorClock instance to synchronize with. It must be
+//	of the same type T (either uint32 or uint64), as constrained by the Uint interface.
+//
+// Returns:
+//
+//	[]T: A copy of the synchronized vector clock, where each element represents the
+//	updated logical time for the corresponding process.
+//
+//	error: An error is returned if the two VectorClocks have different lengths.
+func (vc *VectorClock[T]) Sync(v VectorClock[T]) ([]T, error) {
 	compClock := v.GetClock()
 
 	if len(vc.clock) != len(compClock) {
@@ -48,24 +73,39 @@ func (vc *VectorClock) Sync(v VectorClock) ([]uint, error) {
 	return vc.GetClock(), nil
 }
 
-// NewVectorClock creates a new VectorClock initialized to zero.
+func (vc *VectorClock[T]) Increment(index int) ([]T, error) {
+	if index > len(vc.clock) || vc.clock == nil {
+		return nil, errors.New(fmt.Sprintf("Cannot access index: %d, clock is of length %d", index, len(vc.clock)))
+	}
+
+	// TODO handle Uint overflow?
+	vc.clock[index] = vc.clock[index] + 1
+	return vc.GetClock(), nil
+
+}
+
+// NewVectorClock creates a new generic VectorClock initialized to zero.
+//
+// This function creates a new instance of VectorClock for the specified type T,
+// which can be either uint32 or uint64, depending on the needs of the application.
 //
 // Parameters:
 //
-//	size (int): The number of entries in the vector clock, typically
-//	corresponding to the number of processes or nodes.
+//	size (T): The number of entries in the vector clock, typically corresponding
+//	to the number of processes or nodes. The size is of type T, which can be uint32
+//	or uint64, as defined by the Uint constraint.
 //
 // Returns:
 //
-//	*VectorClock: A pointer to the newly created VectorClock instance, with all
-//	elements of the clock initialized to zero.
-func NewVectorClock(size uint) *VectorClock {
-	return &VectorClock{
-		clock: make([]uint, size),
+//	*VectorClock[T]: A pointer to the newly created VectorClock instance, where all
+//	elements of the clock are initialized to zero.
+func NewVectorClock[T Uint](size int) *VectorClock[T] {
+	return &VectorClock[T]{
+		clock: make([]T, size),
 	}
 }
 
-// ArrayToVectorClock converts an integer array into a VectorClock instance.
+// ArrayToVectorClock converts an array of type T into a VectorClock instance.
 //
 // This function creates a new VectorClock where the internal clock is initialized
 // by copying the values from the provided array. The input array's values are
@@ -73,15 +113,17 @@ func NewVectorClock(size uint) *VectorClock {
 //
 // Parameters:
 //
-//	a []uint: An array of integers representing logical times for each process.
+//	a []T: An array of type T (either uint32 or uint64) representing logical
+//	times for each process. The type T is constrained by the Uint interface, which
+//	ensures it is either uint32 or uint64.
 //
 // Returns:
 //
-//	*VectorClock: A pointer to a newly created VectorClock instance where the
+//	*VectorClock[T]: A pointer to a newly created VectorClock instance where the
 //	internal clock is a copy of the provided array.
-func ArrayToVectorClock(a []uint) *VectorClock {
-	vc := &VectorClock{
-		clock: make([]uint, len(a)),
+func ArrayToVectorClock[T Uint](a []T) *VectorClock[T] {
+	vc := &VectorClock[T]{
+		clock: make([]T, len(a)),
 	}
 	copy(vc.clock, a)
 	return vc

clock/clock_test.go

@@ -1,11 +1,12 @@
 package clock
 
 import (
+	"math"
 	"reflect"
 	"testing"
 )
 
-func assertClocksEqual(t testing.TB, got, want []uint) {
+func assertClocksEqual[T Uint](t testing.TB, got, want []T) {
 	t.Helper()
 
 	if !reflect.DeepEqual(got, want) {
@@ -16,24 +17,51 @@ func assertClocksEqual(t testing.TB, got, want []uint) {
 
 func TestVectorClock(t *testing.T) {
 
-	t.Run("start value sync", func(t *testing.T) {
+	t.Run("test cases for uint32 type", func(t *testing.T) {
 		testCases := []struct {
-			a        []uint
-			b        []uint
-			expected []uint
+			a        []uint32
+			b        []uint32
+			expected []uint32
 		}{
-			{[]uint{0, 0}, []uint{0, 0}, []uint{0, 0}},
-			{[]uint{2, 0}, []uint{0, 2}, []uint{2, 2}},
-			{[]uint{4, 11}, []uint{3, 10}, []uint{4, 11}},
-			{[]uint{5, 9}, []uint{8, 12}, []uint{8, 12}},
-			{[]uint{1, 1}, []uint{1, 1}, []uint{1, 1}},
-			// {[]uint{math.MaxUint32, 1}, []uint{(math.MaxUint32 + 1), 1}, []uint{1, 1}},
+			{[]uint32{0, 0}, []uint32{0, 0}, []uint32{0, 0}},
+			{[]uint32{2, 0}, []uint32{0, 2}, []uint32{2, 2}},
+			{[]uint32{4, 11}, []uint32{3, 10}, []uint32{4, 11}},
+			{[]uint32{5, 9}, []uint32{8, 12}, []uint32{8, 12}},
+			{[]uint32{1, 1}, []uint32{1, 1}, []uint32{1, 1}},
+			{[]uint32{math.MaxUint32, 1}, []uint32{2, 1}, []uint32{4294967295, 1}},
 		}
 
 		for _, tc := range testCases {
-			vc := VectorClock{clock: tc.a}
+			vc := VectorClock[uint32]{clock: tc.a}
 
-			clock, err := vc.Sync(VectorClock{clock: tc.b})
+			clock, err := vc.Sync(VectorClock[uint32]{clock: tc.b})
+
+			if err != nil {
+				t.Errorf("Sync should not have errored")
+			}
+
+			assertClocksEqual(t, clock, tc.expected)
+		}
+	})
+
+	t.Run("test cases for uint64 type", func(t *testing.T) {
+		testCases := []struct {
+			a        []uint64
+			b        []uint64
+			expected []uint64
+		}{
+			{[]uint64{0, 0}, []uint64{0, 0}, []uint64{0, 0}},
+			{[]uint64{2, 0}, []uint64{0, 2}, []uint64{2, 2}},
+			{[]uint64{4, 11}, []uint64{3, 10}, []uint64{4, 11}},
+			{[]uint64{5, 9}, []uint64{8, 12}, []uint64{8, 12}},
+			{[]uint64{1, 1}, []uint64{1, 1}, []uint64{1, 1}},
+			{[]uint64{math.MaxUint64, 1}, []uint64{2, 1}, []uint64{18446744073709551615, 1}},
+		}
+
+		for _, tc := range testCases {
+			vc := VectorClock[uint64]{clock: tc.a}
+
+			clock, err := vc.Sync(VectorClock[uint64]{clock: tc.b})
 
 			if err != nil {
 				t.Errorf("Sync should not have errored")
@@ -44,51 +72,89 @@ func TestVectorClock(t *testing.T) {
 
 	})
 
-	t.Run("basic sync 2", func(t *testing.T) {
-		vc := VectorClock{clock: []uint{4, 11}}
+	t.Run("test empty new", func(t *testing.T) {
 
-		clock, err := vc.Sync(VectorClock{clock: []uint{4, 10}})
+		got := NewVectorClock[uint32](2)
+		want := VectorClock[uint32]{clock: []uint32{0, 0}}
+
+		assertClocksEqual(t, got.GetClock(), want.GetClock())
+	})
+
+	t.Run("test new vc for uint32", func(t *testing.T) {
+		vc := VectorClock[uint32]{clock: []uint32{4, 11}}
+
+		clock, err := vc.Increment(0)
 
 		if err != nil {
-			t.Errorf("Sync should not have errored")
+			t.Errorf("Increment should not have errored")
 		}
 
-		assertClocksEqual(t, clock, []uint{4, 11})
+		assertClocksEqual(t, clock, []uint32{5, 11})
 
-	})
+		clock, err = vc.Increment(1)
 
-	t.Run("basic sync", func(t *testing.T) {
+		if err != nil {
+			t.Errorf("Increment should not have errored")
+		}
+
+		assertClocksEqual(t, clock, []uint32{5, 12})
 
 	})
-	t.Run("basic sync", func(t *testing.T) {
+
+	t.Run("test overflow condition", func(t *testing.T) {
+		vc := VectorClock[uint32]{clock: []uint32{math.MaxUint32, 11}}
+
+		clock, err := vc.Increment(0)
+
+		if err != nil {
+			t.Errorf("Increment should not have errored")
+		}
+
+		assertClocksEqual(t, clock, []uint32{0, 11})
 
 	})
-	vc := VectorClock{clock: []uint{2, 0}}
 
-	clock, err := vc.Sync(VectorClock{clock: []uint{0, 2}})
+	t.Run("test index cannot be incremented", func(t *testing.T) {
+		vc := VectorClock[uint64]{}
 
-	if err != nil {
-		t.Errorf("Sync should not have errored")
-	}
+		clock, err := vc.Increment(0)
 
-	assertClocksEqual(t, clock, []uint{2, 2})
+		if clock != nil {
+			t.Errorf("Clock should be nil")
+		}
 
+		if err == nil {
+			t.Errorf("There should have been an error")
+		}
+
+	})
 }
 
 func TestNewVectorClock(t *testing.T) {
-	got := NewVectorClock(2)
-	want := VectorClock{clock: []uint{0, 0}}
+	t.Run("test new vc for uint32", func(t *testing.T) {
+
+		got := NewVectorClock[uint32](2)
+		want := VectorClock[uint32]{clock: []uint32{0, 0}}
+
+		assertClocksEqual(t, got.GetClock(), want.GetClock())
+	})
+
+	t.Run("test new vc for uint64", func(t *testing.T) {
+
+		got := NewVectorClock[uint64](2)
+		want := VectorClock[uint64]{clock: []uint64{0, 0}}
 
-	assertClocksEqual(t, got.GetClock(), want.GetClock())
+		assertClocksEqual(t, got.GetClock(), want.GetClock())
+	})
 
 }
 
 func TestArrayToVectorClock(t *testing.T) {
 
 	t.Run("from empty slice", func(t *testing.T) {
-		got := ArrayToVectorClock([]uint{})
-		want := VectorClock{
-			clock: []uint{},
+		got := ArrayToVectorClock([]uint32{})
+		want := VectorClock[uint32]{
+			clock: []uint32{},
 		}
 
 		if len(got.GetClock()) != 0 {
@@ -101,34 +167,34 @@ func TestArrayToVectorClock(t *testing.T) {
 	})
 
 	t.Run("from zero slice", func(t *testing.T) {
-		got := ArrayToVectorClock(make([]uint, 6))
-		want := VectorClock{
-			clock: []uint{0, 0, 0, 0, 0, 0},
+		got := ArrayToVectorClock(make([]uint64, 6))
+		want := VectorClock[uint64]{
+			clock: []uint64{0, 0, 0, 0, 0, 0},
 		}
 
 		assertClocksEqual(t, got.GetClock(), want.GetClock())
 	})
 
 	t.Run("from start clock", func(t *testing.T) {
-		want := NewVectorClock(3)
+		want := NewVectorClock[uint64](3)
 		got := ArrayToVectorClock(want.GetClock())
 
 		assertClocksEqual(t, got.GetClock(), want.GetClock())
 	})
 
 	t.Run("from a populated clock", func(t *testing.T) {
-		want := VectorClock{
-			clock: []uint{2, 3},
+		want := VectorClock[uint32]{
+			clock: []uint32{2, 3},
 		}
 		got := ArrayToVectorClock(want.GetClock())
 		assertClocksEqual(t, got.GetClock(), want.GetClock())
 	})
 
 	t.Run("from a slice that is then modified", func(t *testing.T) {
-		initial_a := []uint{1, 2, 3, 4}
+		initial_a := []uint64{1, 2, 3, 4}
 		got := ArrayToVectorClock(initial_a)
 
-		want := make([]uint, len(initial_a))
+		want := make([]uint64, len(initial_a))
 		copy(want, initial_a)
 
 		initial_a[0] = 12