Merge pull request #14318 from hashicorp/cleanup-create-pointer-compare

cleanup: create pointer.Compare helper function

helper/funcs.go

@@ -74,14 +74,6 @@ func HashUUID(input string) (output string, hashed bool) {
 	return output, true
 }
 
-// CompareTimePtrs return true if a is the same as b.
-func CompareTimePtrs(a, b *time.Duration) bool {
-	if a == nil || b == nil {
-		return a == b
-	}
-	return *a == *b
-}
-
 // Min returns the minimum of a and b.
 func Min[T constraints.Ordered](a, b T) T {
 	if a < b {

helper/funcs_test.go

@@ -6,9 +6,7 @@ import (
 	"reflect"
 	"sort"
 	"testing"
-	"time"
 
-	"github.com/hashicorp/nomad/helper/pointer"
 	"github.com/shoenig/test/must"
 	"github.com/stretchr/testify/require"
 )
@@ -132,25 +130,6 @@ func TestStringHasPrefixInSlice(t *testing.T) {
 
 }
 
-func TestCompareTimePtrs(t *testing.T) {
-	t.Run("nil", func(t *testing.T) {
-		a := (*time.Duration)(nil)
-		b := (*time.Duration)(nil)
-		require.True(t, CompareTimePtrs(a, b))
-		c := pointer.Of(3 * time.Second)
-		require.False(t, CompareTimePtrs(a, c))
-		require.False(t, CompareTimePtrs(c, a))
-	})
-
-	t.Run("not nil", func(t *testing.T) {
-		a := pointer.Of(1 * time.Second)
-		b := pointer.Of(1 * time.Second)
-		c := pointer.Of(2 * time.Second)
-		require.True(t, CompareTimePtrs(a, b))
-		require.False(t, CompareTimePtrs(a, c))
-	})
-}
-
 func TestCompareSliceSetString(t *testing.T) {
 	cases := []struct {
 		A      []string

helper/pointer/pointer.go

@@ -1,6 +1,10 @@
 // Package pointer provides helper functions related to Go pointers.
 package pointer
 
+import (
+	"golang.org/x/exp/constraints"
+)
+
 // Of returns a pointer to a.
 func Of[A any](a A) *A {
 	return &a
@@ -14,3 +18,21 @@ func Copy[A any](a *A) *A {
 	na := *a
 	return &na
 }
+
+// Primitive represents basic types that are safe to do basic comparisons by
+// pointer dereference (checking nullity first).
+type Primitive interface {
+	constraints.Ordered // just so happens to be the types we want
+}
+
+// Eq returns whether a and b are equal in underlying value.
+//
+// May only be used on pointers to primitive types, where the comparison is
+// guaranteed to be sensible. For complex types (i.e. structs) consider implementing
+// an Equals method.
+func Eq[P Primitive](a, b *P) bool {
+	if a == nil || b == nil {
+		return a == b
+	}
+	return *a == *b
+}

helper/pointer/pointer_test.go

@@ -2,6 +2,7 @@ package pointer
 
 import (
 	"testing"
+	"time"
 
 	"github.com/shoenig/test/must"
 )
@@ -16,3 +17,51 @@ func Test_Of(t *testing.T) {
 	sPtr = &b
 	must.NotEq(t, s, *sPtr)
 }
+
+func Test_Copy(t *testing.T) {
+	orig := Of(1)
+	dup := Copy(orig)
+	orig = Of(7)
+	must.EqOp(t, 7, *orig)
+	must.EqOp(t, 1, *dup)
+}
+
+func Test_Compare(t *testing.T) {
+	t.Run("int", func(t *testing.T) {
+		a := 1
+		b := 2
+		c := 1
+		var n *int // nil
+		must.False(t, Eq(&a, &b))
+		must.True(t, Eq(&a, &c))
+		must.False(t, Eq(nil, &a))
+		must.False(t, Eq(n, &a))
+		must.True(t, Eq(n, nil))
+	})
+
+	t.Run("string", func(t *testing.T) {
+		a := "cat"
+		b := "dog"
+		c := "cat"
+		var n *string
+
+		must.False(t, Eq(&a, &b))
+		must.True(t, Eq(&a, &c))
+		must.False(t, Eq(nil, &a))
+		must.False(t, Eq(n, &a))
+		must.True(t, Eq(n, nil))
+	})
+
+	t.Run("duration", func(t *testing.T) {
+		a := time.Duration(1)
+		b := time.Duration(2)
+		c := time.Duration(1)
+		var n *time.Duration
+
+		must.False(t, Eq(&a, &b))
+		must.True(t, Eq(&a, &c))
+		must.False(t, Eq(nil, &a))
+		must.False(t, Eq(n, &a))
+		must.True(t, Eq(n, nil))
+	})
+}

nomad/structs/services.go

@@ -1210,7 +1210,7 @@ func (t *SidecarTask) Equals(o *SidecarTask) bool {
 		return false
 	}
 
-	if !helper.CompareTimePtrs(t.KillTimeout, o.KillTimeout) {
+	if !pointer.Eq(t.KillTimeout, o.KillTimeout) {
 		return false
 	}
 
@@ -1218,7 +1218,7 @@ func (t *SidecarTask) Equals(o *SidecarTask) bool {
 		return false
 	}
 
-	if !helper.CompareTimePtrs(t.ShutdownDelay, o.ShutdownDelay) {
+	if !pointer.Eq(t.ShutdownDelay, o.ShutdownDelay) {
 		return false
 	}
 
@@ -1811,7 +1811,7 @@ func (p *ConsulGatewayProxy) Equals(o *ConsulGatewayProxy) bool {
 		return p == o
 	}
 
-	if !helper.CompareTimePtrs(p.ConnectTimeout, o.ConnectTimeout) {
+	if !pointer.Eq(p.ConnectTimeout, o.ConnectTimeout) {
 		return false
 	}